TY - JOUR A1 - Maennig, Wolfgang-Werner T1 - Gegenwärtiger Stand und künftige Ziele der Betriebsfestigkeitsforschung - Kolloquium des Laboratoriums für Betriebsfestigkeit, gemeinnütziges Forschungsinstitut der Fraunhofer-Gesellschaft N2 - In diesem Jahr feierte das Laboratorium für Betriebsfestigkeit das 30jährige Bestehen, sein Leiter, Prof. Dr.-Ing. Ernst Gassner den 60. Geburtstag. Aus diesem Anlaß fand in Darmstadt am 27.5.1968 eine international besuchte, gut organisierte Veranstaltung statt, bei der Behörden, Institutionen und zahlreiche Fachkollegen ihre Glückwünsche überbrachten und außerdem mehrere Vorträge gehalten wurden. PY - 1968 SN - 0025-5300 VL - 10 IS - 8 SP - 285 EP - 287 PB - Carl Hanser Verlag CY - München AN - OPUS4-10695 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Klaffke, Dieter A1 - Maennig, Wolfgang-Werner T1 - Dynamische Untersuchung von Dauerschwingproben im Rasterelektronenmikroskop (Kurzfassung) N2 - Wechselbiege-Beanspruchungen werden unter dem Rasterelektronenmikroskop betrachtet. Der Einfluß der Kristallitorientierung wird erfaßt; Oberflächendeformationen, Rißbildung und Rißwachstum werden so untersucht. Der Vortrag ist Bestandteil der vorgesehenen Promotion des ersten Verfassers; deshalb bleibt eine ausführlichere Veröffentlichung einem späteren Zeitpunkt vorbehalten. PY - 1975 SN - 0025-5300 VL - 17 IS - 6 SP - 180 PB - Carl Hanser Verlag CY - München AN - OPUS4-8301 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Klaffke, Dieter A1 - Maennig, Wolfgang-Werner A1 - Westphal, K. T1 - Wechselbiegeapparatur für die in situ-Untersuchung von Zerrüttungsvorgängen im Rasterelektronenmikroskop T1 - Specimen support for the in situ observation of bending fatigue N2 - Es wird eine Belastungsapparatur vorgestellt, mit der die Entwicklung der Verformungstopographie kontinuierlich während eines Zerrüttungs-Versuches im Objektraum des SEM verfolgt werden kann. Die dadurch möglich werdenden Lastphasen-Bilder gestatten abgesicherte Aussagen über die Rißverteilung an Probenoberflächen sowie qualitative Aussagen über Rißwachstumsvorgänge. PY - 1979 SN - 0161-0457 SN - 1932-8745 VL - 2 IS - 3 SP - 129 EP - 134 PB - Wiley CY - Hoboken, NJ AN - OPUS4-9146 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kannengießer, Thomas A1 - Böllinghaus, Thomas A1 - Zimmer, Peter T1 - Investigations of cold cracking by the CTS-Test at various cooling conditions N2 - Numerous national and international activities of regulation and standardization of cold cracking tests are currently being undertaken. Most of these test procedures operate as crack-no-crack tests and are focussed on the determination of technological parameters, as for instance the welding conditions and the heat input as well as pre- and postheating temperature and times. Such parameters predominantly influence the cooling conditions of the weld, which significantly affect the three well known local parameters on hydrogen cracking microstructure, hydrogen concentration and mechanical load. As one of the test procedures, the CTS-Test is currently standardized in the draft standard prEN ISO17642 which has been prepared on the European level by CEN/TC 121/WG 13 (destructive tests on welds). As compared to other cold cracking tests, quite extensive specimen cooling procedures are prescribed for the CTS-Test. As a contribution to the ongoing discussion the present document highlights the effect of different cooling procedures after welding propagated for the modified CTS-Test. The major part of the work includes a comparison of experimentally determined cooling curves at specific weld locations with respective thermal finite element analyses. As a result, it turned out that the prescribed water cooling after welding does not alter the microstructure relevant cooling time Δt(8/5) and the cold cracking relevant cooling time Δt(3/1) as compared to simple air cooling. With increasing preheating temperature the effect of water cooling becomes more pronounced on the cooling time Δt(3/1), but still does not affect the cooling time Δt(8/5). The effects of rapid cooling of the CTS specimens after welding have thus to be reconsidered, in particular, with respect to its transferability to component welds and to additional non-realistic quenching effects. T2 - 56th IIW Annual Assembly - International Conference on Welded Construction for Urban Infrastructure CY - Bucharest, Romania DA - 10.07.2003 KW - Kaltrisstests KW - Schweißsicherheit PY - 2003 SP - 1 EP - 12 PB - International Institute of Welding CY - Roissy AN - OPUS4-2630 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schulz, Eckhard A1 - Schulte, K. T1 - Fachausschuss "Gefüge und Eigenschaften von Polymerwerkstoffen" N2 - Die in zunehmenden Maße Mitte der 80er Jahre einsetzende Substitution von metallischen Materialien z. B. durch hochleistungsfähige polymere Werkstoffe und Verbundwerkstoffe wurde u. a. von der DGM zum Anlass genommen, ihre zukünftigen Aufgaben neu zu definieren und gleichzeitig mit der Gründung des Fachausschusses "Gefüge und Eigenschaften von Polymerwerkstoffen" dieser neuen Entwicklung in der Materialkunde auf dem Gebiet der Kunststoffe und ihrer Anwendungen Rechnung zu tragen. KW - Aufgaben KW - Ziele PY - 2004 DO - https://doi.org/10.1515/ijmr-2004-0141 SN - 0044-3093 VL - 95 IS - 9 (85 Jahre DGM) SP - 742 EP - 743 PB - Hanser CY - München AN - OPUS4-5988 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nolze, Gert T1 - Characterization of the fcc/bcc orientation relationship by EBSD using pole figures and variants N2 - The orientation relationship (OR) between fcc and bcc lattices are described by crystallographic fundamentals using the example of Kurdjumov-Sachs (K-S) and Nishiyama-Wassermann (N-W). Complete pole figures containing all variants will be used to distinguish even between slightly different ORs. EBSD on iron meteorites and duplex steel has been used to analyse a large number of crystal orientations with regard to a high statistical significance and a high probability to capture all variants in a single measurement. It is shown that the use of fixed OR models like K-S, N-W, Bain, Pitsch, or Greninger-Troiano does not satisfacturally reflect the observed experimental pole distributions. It is not convenient to use high-indexed lattice planes and directions to describe the small deviations from the given models. The Euler subspace representation offers a readily comprehensible tool to get an idea about the characteristic of the experimentally detected OR. KW - EBSD KW - Duplex steel KW - Iron meteorite KW - Pole figure KW - Orientation relationship PY - 2004 DO - https://doi.org/10.1515/ijmr-2004-0142 SN - 0044-3093 VL - 95 IS - 9 (85 Jahre DGM) SP - 744 EP - 755 PB - Hanser CY - München AN - OPUS4-13972 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Munz, Martin A1 - Sturm, Heinz T1 - Structure formation on the surface of indium phosphide irradiated by femtosecond laser pulses N2 - Laser-induced periodic surface structures (LIPSS; ripples) with different spatial characteristics have been observed after irradiation of single-crystalline indium phosphide (c-InP) with multiple linearly polarized femtosecond pulses (130 fs, 800 nm) in air. With an increasing number of pulses per spot, N, up to 100, a characteristic evolution of two different types of ripples has been observed, i.e., (i) the growth of a grating perpendicular to the polarization vector consisting of nearly wavelength-sized periodic lines and (ii), in a specific pulse number regime (N = 5-30), the additional formation of equally oriented ripples with a spatial period close to half of the laser wavelength. For pulse numbers higher than 50, the formation of micrometer-spaced grooves has been found, which are oriented perpendicular to the ripples. These topographical surface alterations are discussed in the frame of existing LIPSS theories. KW - Femtosecond laser irradiation KW - Indium phosphide KW - Microstructure KW - Laser induced periodic surface structures KW - LIPSS KW - SEM PY - 2005 DO - https://doi.org/10.1063/1.1827919 SN - 0021-8979 SN - 1089-7550 VL - 97 SP - 1 EP - 9 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-5992 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Beckmann, Jörg A1 - Redmer, Birgit A1 - Finn, Monika A1 - Glaubitz, Steffen T1 - Bestimmung der elastischen Eigenschaften von Festkörpern - Teil 1 N2 - ür die Berücksichtigung mechanischer Belastungen unterhalb der Streckgrenze ist im Rahmen einer zuverlässigen Bauteilauslegung die Kenntnis der elastischen Konstanten von besonderer Bedeutung. Für die experimentelle Bestimmung des Elastizitätsmoduls wurde eine Vielzahl von Verfahren entwickelt, die zum Teil werkstoffspezifisch Eingang in die Normung gefunden haben. Prinzipiell können diese Verfahren in zwei Gruppen unterteilt werden: die statischen und die dynamischen Prüfverfahren. Die statischen Verfahren beruhen auf der direkten Messung des Spannungs-Dehnungs-Zusammenhangs während einer mechanischen Belastung im elastischen Verformungsbereich (Zug, Biegung, Druck). Die dynamischen Verfahren basieren auf der Schwingungsanregung eines Prüfkörpers und der Analyse der resultierenden Schwingungen (Resonanzmethode oder Impulsanregungsmethode) oder auf der Messung der Ultraschallausbreitungsgeschwindigkeit. Stellvertretend für die dynamischen Verfahren wird im ersten Teil dieses Beitrages die Resonanzmethode vorgestellt. Der zweite Teil dieses Beitrages fasst die werkstoffabhängigen Ergebnisse der E-Modulbestimmung mit statischen Verfahren im Zug- und Biegeversuch zusammen. KW - Modul KW - Resonanzmessung PY - 2006 DO - https://doi.org/10.1515/mt-2006-0003 SN - 0025-5300 VL - 48 IS - 6 SP - 274 EP - 281 PB - De Gruyter CY - Berlin AN - OPUS4-54602 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kromm, Arne A1 - Kannengießer, Thomas T1 - In-situ-phase analysis using synchrotron radiation of low transformation temperature (LTT) welding material N2 - Cold cracking resistance is a relevant evaluation criterion for welded joints and affected by residual stresses which result from the welding procedure. Compressive residual stresses can thereby have a positive influence on preventing cracking. A unique possibility of generating compressive residual stresses already during the welding procedure is offered by the so-called Low Transformation Temperature (LTT) filler wires. Compared to conventional wires, these materials show decreased phase transformation temperatures which can work against the cooling-specific contraction. In consequence, distinct compressive residual stresses can be observed within the weld and adjacent areas. The strength of these fillers makes them potentially applicable to high-strength steel welding. Investigations were carried out to determine the phase transformation behaviour of different LTT-filler materials. Transformation temperatures were identified using Single Sensor Differential Thermal Analysis (SS-DTA). Additionally Synchrotron radiation was used to measure the transformation kinetics of all involved crystalline phases during heating and cooling of a simulated weld thermal cycle. KW - In-situ phase analysis KW - Energy dispersive diffraction KW - Phase transformation KW - Low Transformation Temperature filler wire PY - 2009 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-205922 DO - https://doi.org/10.1590/S0104-92242009000100010 SN - 0104-9224 SN - 1980-6973 VL - 14 IS - 1 SP - 82 EP - 88 PB - Associação Brasileira de Soldagem, ABS CY - Rio de Janeiro AN - OPUS4-20592 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kannengießer, Thomas A1 - Kromm, Arne T1 - Formation of welding residual stresses in low transformation temperature (LTT) materials N2 - For the safety and cost efficiency of welded high-strength steel structures, precise knowledge of the level and distribution of welding- and cooling-specific stresses and residual stresses is essential, since they exert a decisive influence on strength, crack resistance, and finally on the bearable service load. This paper presents innovative filler materials, of which the phase transformation temperature was deliberately adjusted via the chemical composition. The transformation behaviour of these martensitic Low Transformation Temperature (LTT-) filler materials shows direct effects on the local residual stresses in the weld and the HAZ. These effects can purposefully be exploited to counteract the thermally induced shrinkage of the material and to produce significant compressive residual stresses in the weld. Comparative welding experiments were carried out on 690 MPa high-strength base materials using various LTT-filler materials. High energy synchrotron radiation was used for residual stress measurement. Particularly the use of high energy synchrotron radiation makes it possible to detect the residual stress condition fast without destruction of material. Thereby, residual stress depth gradients can be determined simultaneously without removing material. In steel, gradients of up to 150 µm can be resolved in such a way. Furthermore, the application of high energy radiation permits determination of residual stresses of any available residual austenite contents. Results show significant dependence of transformation temperatures on the resulting residual stress level and distribution. KW - Phase specific residual stresses KW - Phase transformation KW - Low transformation temperature filler wire KW - Energy dispersive diffraction KW - High strength steel PY - 2009 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-205909 DO - https://doi.org/10.1590/S0104-92242009000100009 SN - 0104-9224 SN - 1980-6973 VL - 14 IS - 1 SP - 74 EP - 81 PB - Associação Brasileira de Soldagem, ABS CY - Rio de Janeiro AN - OPUS4-20590 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Karrasch, Andrea A1 - Wawrzyn, Eliza A1 - Schartel, Bernhard A1 - Jäger, Christian T1 - Solid-state NMR on thermal and fire residues of bisphenol A polycarbonate/silicone acrylate rubber/bisphenol A bis(diphenyl-phosphate)/(PC(SiR/BDP) and PC/SiR/BDP/zinc borate (PC/SiR/BDP/ZnB) - Part 1: PC charring and the impact of BDP and ZnB N2 - Structural changes in the condensed phase of bisphenol A polycarbonate (containing 0.45 wt% poly (tetrafluoroethylene))/silicone acrylate rubber/bisphenol A bis(diphenyl-phosphate) (PC/SiR/BDP) and PC/SiR/BDP/zinc borate (PC/SiR/BDP/ZnB) during thermal treatment in nitrogen atmosphere and in fire residues were investigated by solid-state NMR. H-1, B-11, C-13 and P-31 NMR experiments using direct excitation with a single pulse and H-1-P-31 cross-polarization (CP) were carried out including 31P(1 H) and C-13{P-31}double-resonance techniques (REDOR: Rotational Echo Double Resonance) on a series of heat-treated samples (580 K-850 K). Because many amorphous phases occur in the solid residues, and solid-state NMR spectroscopy addresses the most important sites carbon, phosphorus and boron, this paper is the key analytical approach for understanding the pyrolysis and flame retarding phenomenon in the condensed phase of PC/SiR/BDP and PC/SiR/BDP/ZnB. For the system PC/SiR/BDP it is shown that (i) at temperatures around 750-770 K (main decomposition step) carbonaceous charring of PC occurs and arylphosphate structures are still present, reacted in part with the decomposing PC; (ii) for higher temperatures from 770 K the phosphorus remaining in the solid phase increasingly converts to amorphous phosphonates and inorganic orthophosphates with a minor amount of crystalline orthophosphates; and (iii) H-1-P-31{H-1} CP REDOR and H-1-C-13{P-31} CP REDOR NMR experiments suggest that the phosphates and phosphonates are bound via oxygen to aromatic carbons, indicating the interaction with the carbonaceous char. When ZnB is added to the system PC/SiR/BDP, (i) ZnB leads to a slightly enhanced PC decomposition for temperatures below 750 K; (ii) alpha-Zn-3(PO4)(2) and borophosphate (BPO4) are formed in small amounts at high temperatures suggesting a reaction between BDP and ZnB during thermal decomposition; and (iii) most of the borate remains in the solid residues, forming an amorphous pure borate network, with the BO3/BO4 ratio increasing with higher temperatures. The NMR data of thermal and fire residues are highly correlated, underlining the importance of this work for understanding the pyrolysis and flame retardancy mechanisms in the condensed phase during the burning of the PC/SiR blends. (C) 2010 Elsevier Ltd. All rights reserved. KW - Flame retardance KW - NMR KW - Polycarbonate (PC) blends KW - Bisphenol-A bis(diphenyl)phosphate (BDP) KW - Zinc borate PY - 2010 DO - https://doi.org/10.1016/j.polymdegradstab.2010.07.034 SN - 0141-3910 SN - 1873-2321 VL - 95 IS - 12 SP - 2525 EP - 2533 PB - Applied Science Publ. CY - London AN - OPUS4-22647 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pawlowski, Kristin A1 - Schartel, Bernhard A1 - Fichera, Mario Augusto A1 - Jäger, Christian T1 - Flame retardancy mechanisms of bisphenol A bis(diphenyl phosphate) in combination with zinc borate in bisphenol A polycarbonate/Acrylonitrile-butadiene-styrene blends N2 - Bisphenol A polycarbonate/acrylonitrile–butadiene–styrene (PC/ABS) with and without bisphenol A bis(diphenyl phosphate) (BDP) and 5 wt.% zinc borate (Znb) were investigated. The pyrolysis was studied by thermogravimetry (TG), TG-FTIR and NMR, the fire behaviour with a cone calorimeter applying different heat fluxes, LOI and UL 94. Fire residues were examined with NMR. BDP affects the decomposition of PC/ABS and acts as a flame retardant in the gas and condensed phases. The addition of Znb results in an additional hydrolysis of PC. The fire behaviour is similar to PC/ABS, aside from a slightly increased LOI and a reduced peak heat release rate, both caused by borates improving the barrier properties of the char. In PC/ABS + BDP + Znb, the addition of Znb yields a borate network and amorphous phosphates. Znb also reacts with BDP to form alpha-zinc phosphate and borophosphates that suppress the original flame retardancy mechanisms of BDP. The inorganic–organic residue formed provides more effective flame retardancy, in particular at low irradiation in the cone calorimeter, and a clear synergy in LOI, whereas for more developed fires BDP + Znb become less effective than BDP in PC/ABS with respect to the total heat evolved. KW - Flame retardancy KW - PC/ABS KW - Aryl phosphate KW - Zinc borate KW - Flammability PY - 2010 DO - https://doi.org/10.1016/j.tca.2009.10.007 SN - 0040-6031 SN - 1872-762X VL - 498 IS - 1-2 SP - 92 EP - 99 PB - Elsevier CY - Amsterdam AN - OPUS4-20746 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mull, Birte A1 - Horn, Wolfgang A1 - Jann, Oliver T1 - Methode zur Bestimmung von flüchtigen Estern der Phthalsäure im Innenraum und in Emissionsmesskammern N2 - Die Analytik von Phthalaten (DMP bis DEHP) in der Luft ist mit thermischer Desorption unter Verwendung von Quarzwolle als Adsorbens erfolgreich realisierbar. Dies wurde durch eine Methodenvalidierung bestätigt. Es wurden sowohl Messungen im Innenraum als auch in Emissionskammern vorgenommen. In den Emissionskammermessungen wurden mögliche Senkeneffekte der Kammeroberfläche (Glas) untersucht. Unter Zuhilfenahme der idealen Abklingkurve wird bestätigt, dass diese Oberfläche eine Senke darstellt. PY - 2010 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-209870 UR - http://www.gefahrstoffe.de SN - 0949-8036 SN - 1436-4891 VL - 70 IS - 3 SP - 93 EP - 97 PB - VDI Fachmedien CY - Düsseldorf AN - OPUS4-20987 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schartel, Bernhard T1 - Phosphorus-based flame retardancy mechanisms - Old hat or a starting point for future development? N2 - Different kinds of additive and reactive flame retardants containing phosphorus are increasingly successful as halogen-free alternatives for various polymeric materials and applications. Phosphorus can act in the condensed phase by enhancing charring, yielding intumescence, or through inorganic glass formation; and in the gas phase through flame inhibition. Occurrence and efficiency depend, not only on the flame retardant itself, but also on its interaction with pyrolysing polymeric material and additives. Flame retardancy is sensitive to modification of the flame retardant, the use of synergists/adjuvants, and changes to the polymeric material. A detailed understanding facilitates the launch of tailored and targeted development. KW - Fire retardancy KW - Red phosphorus KW - Phosphate KW - Phosphonate KW - Phosphinate KW - Phosphine oxide KW - Flame inhibition KW - Charring KW - Intumescence PY - 2010 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-220368 DO - https://doi.org/10.3390/ma3104710 SN - 1996-1944 VL - 3 IS - 10 SP - 4710 EP - 4745 PB - MDPI CY - Basel AN - OPUS4-22036 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Perret, Birgit A1 - Schartel, Bernhard A1 - Stöß, K. A1 - Ciesielski, M. A1 - Diederichs, J. A1 - Döring, M. A1 - Krämer, J. A1 - Altstädt, V. T1 - A new halogen-free flame retardant based on 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide for epoxy resins and their carbon fiber composites for the automotive and aviation industries N2 - The pyrolysis and fire behavior of halogen-free flame-retarded DGEBA/DMC, RTM6 and their corresponding 60 vol.-% carbon fibers (CF) composites were investigated. A novel phosphorous compound (DOPI) was used. Its action is dependent on the epoxy matrix. DGEBA/DMC and DOPI decompose independently of each other. Only flame inhibition occurs in the gas phase. RTM6 shows flame inhibition and a condensed phase interaction increasing charring. Both mechanisms decrease with increasing irradiance, whereas in RTM6-CF charring is suppressed at low ones. RTM6+DOPI shows a higher LOI (34.2%) than DGEBA/DMC+DOPI and a V-0 classification in UL 94. Adding CF only enhances the LOI, DOPI+CF leads to a superposition in LOI for DGEBA/DMC-CF+DOPI (31.8%, V-0) and a synergism for RTM6-CF+DOPI (47.7%, V-0). KW - Composites KW - Flame retardancy KW - Glass transition KW - Pyrolysis KW - Thermosets PY - 2011 DO - https://doi.org/10.1002/mame.201000242 SN - 1438-7492 SN - 1439-2054 VL - 296 IS - 1 SP - 14 EP - 30 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-22957 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Woydt, Mathias A1 - Scholz, C. A1 - Burbank, J. A1 - Spaltmann, Dirk T1 - Slip-rolling resistant steel alloys up to P0max of 3,920 MPa N2 - Downsizing (power-to-weight ratio) and higher speeds lead to a rise in Hertzian contact pressures in combination with an increase in surface or oil temperatures. Under such conditions, commonly used bearing steels, such as 100Cr6, reach their limits, creating a demand for alternative slip-rolling resistant steel alloys. The present work therefore compares the slip-rolling performance of various steel types with Maraging- and PM-type steel alloys such as e.g. CSS-42L™, ASP2012, BIMAX42+, in the Hertzian contact pressure range up to P0max of 4 GPa. Through-hardened 100Cr6H (AISI 52100), case-hardened 20MnCr5 (AISI 5120H) and nitrogen alloyed Croni-dur30 (AMS 5898) still compete in terms of slip-rolling and wear resistance and load carrying capacity, whereas Maraging- and PM-type steel alloys offer superior strength and toughness properties. KW - Steel KW - Alloy KW - Slip-rolling KW - Friction KW - Wear rate KW - Contact pressure KW - 100Cr6 KW - BIMAX42 KW - CSS-42L KW - ASP20212 PY - 2012 DO - https://doi.org/10.1016/j.wear.2021.203707 VL - 474-475 SP - 203707 PB - Elsevier B.V. AN - OPUS4-52549 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wallstabe, Ronald T1 - Laser-assisted surface modification of alumina and its tribological behavior N2 - High performance friction systems, e.g., dry clutches and brakes, require a good wear resistance and a friction coefficient that is nearly independent from sliding velocity and environmental conditions. Organic-based friction materials have reached their limitations regarding higher power densities. Engineering ceramics such as alumina (Al2O3) or silicon carbide (SiC) offer a great potential since remarkably higher thermal and mechanical loading is possible. However, the tribological performance of these monolithic ceramics is still insufficient. The aim of the present study was to assess the potential of a laser-assisted surface modification process in order to improve the tribological performance with regard to the application in dry friction systems. Therefore, commercially available alumina was modified using a newly developed laser-assisted preheating process and subsequent melting of the ceramic’s surface using a CO2-laser and modification by additives such as TiC, TiN, B4C, WC, ZrB2, Cr, Ni, Cu, and Ti. A systematic variation of additives and process parameters led to different multiphase microstructures. Subsequently, these were characterized using scanning electron microscopy and surface analysis methods (wavelength dispersive X-ray spectroscopy, energy dispersive X-ray spectroscopy). Finally, the tribological properties were investigated using a laboratory tribometer. The surface-modified ceramics were tested in unidirectional sliding motion against steel disks. The tribological results of the surface-modified ceramics were compared to those of monolithic Al2O3 and SiC ceramics and showed a reduced dependence of friction coefficient on sliding velocity. Moreover, the multi-phase ceramics possessed a higher wear resistance than the monolithic ones. KW - Alumina KW - Ceramics KW - Ceramic matrix composites KW - Dry sliding KW - Laser-assisted surface modification KW - Steel KW - Tribology KW - Wear resistance PY - 2012 DO - https://doi.org/10.1007/s11665-012-0215-2 SN - 1059-9495 SN - 1544-1024 SP - 1 EP - 13(?) PB - ASM international CY - Materials Park, Ohio AN - OPUS4-25842 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wallstabe, Ronald A1 - Klinger, Christian T1 - Cause of an implant fracture: material- or fabrication failure? N2 - Intramedullary hip screws (IMHSs) are implanted for the fixture of pertrochanteric femoral fractures (thigh bone). The present work investigates the failure of an IMHS implant after the rehabilitation period which required a revision surgery where the upper femur had to be replaced by a hip endoprosthesis. Due to litigation the corresponding failure analysis was conducted at BAM Federal Institute for Materials Research and Testing and is the subject of this article. By order of the customer failure causes due to material and fabrication failures should be particularly investigated. Therefore, thorough fractographic, chemical as well as metallographic investigations were carried out. In order to assess possible fabrication failures selected dimensions of the components were compared with the technical drawings and the surface topography was analysed. The investigation revealed several causes for the fracture of the lag screw which is the implant component intended to fix the position of the femoral head. These are in descending order of relevance: (1) the screw was placed incorrectly and therefore had a smaller bending stiffness, (2) the femoral fracture zone was not stable, i.e., the lag screw 'moved out' of its proper position and (3) the laser marking on the lag screw was relatively large and led to a metallurgical notch at the now, because of the above mentioned points, severely stressed region. A material- or fabrication failure was not the root cause for the fracture of the lag screw. It was mainly due to its incorrect placement during surgery and the instability of the bone fracture. Furthermore, the implant geometry with 130° was not well-suited for the patient's anatomy. A 135°-IMHS might have been biomechanically preferable. Based on the determined failure causes and influences a relative lifetime estimation led to about 10% of the lifetime of a correctly placed 135°-IMHS assuming a sufficiently stable bone fracture zone. KW - Implant fracture KW - Intramedullary hip screw (IMHS) KW - Austenitic steel KW - Laser-marking KW - Implant placement PY - 2012 DO - https://doi.org/10.1016/j.engfailanal.2012.05.010 SN - 1350-6307 SN - 1873-1961 VL - 25 SP - 261 EP - 270 PB - Elsevier Science Publ. CY - Oxford AN - OPUS4-26238 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weber, Gert A1 - Brauser, Stephan A1 - Gaul, Holger A1 - Rethmeier, Michael T1 - Study of fatigue behavior for spot welded tensile shear specimens of advanced high strength steels N2 - For automotive body-in-white applications the influence of manufacture-related gaps between the steel sheets and also of manufacture-related surface cracks on the fatigue behavior of tensile shear specimens for spot welded TRIP steel was analyzed. It was shown that gaps between the steel sheets reduce the fatigue strength, whereas the fatigue behavior is neither influenced by cracks in the electrode indentation area nor in the heat effected zone. KW - Automotive manufacteuring KW - Fatigue behavior KW - TRIP Steel HCT690T PY - 2012 DO - https://doi.org/10.1002/srin.201100286 SN - 1611-3683 SN - 0177-4832 VL - 83 IS - 10 SP - 988 EP - 994 PB - Verl. Stahleisen CY - Düsseldorf AN - OPUS4-27632 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thiermann, Raphael A1 - Mueller, W. A1 - Montesinos-Castellanos, A. A1 - Metzke, D. A1 - Löb, P. A1 - Hessel, V. A1 - Maskos, Michael T1 - Size controlled polymersomes by continous self-assembly in micromixers N2 - The formation of vesicles based on the self-assembly of amphiphilic poly(butadiene)-b-poly(ethylene oxide) (PB130-b-PEO66) block copolymer in water has been studied using THF as co-solvent. To obtain a highly controlled mixing process for the polymer/THF- and the water-phase, we employed micro mixers with different mixing geometries. The high impact of this preparation method on the self-assembling process was verified by TEM and DLS characterization of the obtained structures. Spherical micelles, vesicles and worm-like micelles were found depending on the parameters of mixing. By additional parameter adjustment in the vesicle regime, the size of the assembled vesicles was controlled between 45 and 100 nm. This demonstrates the continuous preparation of narrowly distributed vesicle structures with controlled sizes. KW - Vesicles KW - Polymersomes KW - Micromixers PY - 2012 DO - https://doi.org/10.1016/j.polymer.2012.03.058 SN - 0032-3861 SN - 1873-2291 VL - 53 IS - 11 SP - 2205 EP - 2210 PB - Springer CY - Berlin AN - OPUS4-25884 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kricheldorf, H.R. A1 - Weidner, Steffen A1 - Scheliga, F. T1 - Poly(Epsilon-caprolactone) by combined ring-opening polymerization and azeotropic polycondensation - the role of cyclization and equilibration N2 - Using three different catalysts, water-initiated polymerizations of ε-caprolactone were conducted in bulk with variation of the monomer/water ratio. The resulting CH2OH and CO2H- terminated polylactones were subjected in situ to azeotropic polycondensations. With Bi-triflate and temperatures, the polycondensations were not much successful and involved side reactions. With ZnCl2, and especially SnCl2, considerably higher molar masses were achieved. The substitution of toluene for chlorobenzene for refluxing gave better results. The polycondensations broadened the molar mass distribution of the ROP-based prepolymers, and polydispersities between 1.4–1.8 were obtained. The MALDI–TOF mass spectra revealed that the polycondensations significantly enhanced the fraction of rings due to efficient 'end-biting' reactions. By comparison with copolymerization experiments and Sn methoxide-initiated polymerizations, it was demonstrated that equilibration reactions, such as the formation of rings by 'back-biting,' did not occur. KW - Ring-opening polymerization KW - Epsilon-caprolactone (e-CL) KW - Cyclization KW - MALDI-TOF mass spectrometry KW - Polycondensation KW - Polyesters PY - 2012 DO - https://doi.org/10.1002/pola.26222 SN - 0360-6376 SN - 0887-624X VL - 50 IS - 20 SP - 4206 EP - 4214 PB - Wiley CY - Hoboken, NJ AN - OPUS4-26500 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Symietz, Christian A1 - Lehmann, Erhard A1 - Gildenhaar, Renate A1 - Hackbarth, Andreas A1 - Berger, Georg A1 - Krüger, Jörg T1 - Mechanical stability of Ti6Al4V implant material after femtosecond laser irradiation N2 - The surface of a titanium alloy (Ti6Al4V) implant material was covered with a bioactive calcium alkali phosphate ceramic with the aim to accelerate the healing and to form a stronger bond to living bone tissue. To fix the ceramic powder we used a femtosecond laser, which causes a thin surface melting of the metal. It is a requirement to prove that the laser irradiation would not reduce the lifetime of implants. Here we present the results of mechanical stability tests, determined by the rotating bending fatigue strength of sample rods. After describing the sample surfaces and their modifications caused by the laser treatment we give evidence for an unchanged mechanical stability. This applies not only to the ceramic fixation but also to a comparatively strong laser ablation. KW - Aluminium alloys KW - Bending strength KW - Bioceramics KW - Bone KW - Calcium compounds KW - Fatigue KW - Fatigue testing KW - High-speed optical techniques KW - Laser ablation KW - Melting KW - Orthopaedics KW - Prosthetics KW - Rods (structures) KW - Surface treatment KW - Titanium alloys KW - Vanadium alloys PY - 2012 DO - https://doi.org/10.1063/1.4737576 SN - 0021-8979 SN - 1089-7550 VL - 112 IS - 2 SP - 1 EP - 5 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-26200 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vöse, Markus A1 - Fedelich, Bernard A1 - Owen, J. T1 - A simplified model for creep induced grain boundary cavitation validated by multiple cavity growth simulations N2 - Simulations of cavitation processes on a grain boundary under creep conditions have been carried out, taking into account nucleation, growth, coalescence and sintering of multiple cavities. Cavity growth rates have been calculated through a resolution procedure based on the use of holomorphic complex functions. Three dimensionless parameters have been identified that are responsible for the cavitation development. Parameter studies have been carried out in order to characterise the mechanisms that are responsible for the cavitation development. These studies have been used to develop a physically motivated, simplified model in order to describe the cavitation development of the simulations in terms of global state variables. The simplified model is able to reproduce the cavitation development for all considered combinations of the dimensionless parameters and allows the description of the thickening behaviour of a cavitating grain boundary. KW - Creep damage KW - Grain boundary diffusion KW - Cavitation KW - Simulation PY - 2012 DO - https://doi.org/10.1016/j.commatsci.2012.01.033 SN - 0927-0256 VL - 58 SP - 201 EP - 213 PB - Elsevier CY - Amsterdam AN - OPUS4-25630 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hussung, D. R. A1 - Kurz, J. H. A1 - Stoppel, Markus T1 - Automatisierte, zerstörungsfreie Prüftechnik für großflächige Stahlbetontragwerke - Ein Anwendungsbeispiel T1 - Automated non-destructive inspection techniques for large reinforced concrete constructions - An example of use N2 - Eine Vielzahl zerstörungsfreier Prüfverfahren hat in den letzten Jahren Einzug in die Bauwerksuntersuchung gehalten. Um die Aussagekraft der Einzelverfahren zu erhöhen und den wirtschaftlichen Einsatz weiter voranzubringen, lag es nahe, die Verfahren kombiniert auf einer automatisierten Plattform zu montieren. Zu diesem Zweck wurde das BetoScan-System entwickelt. Um weitere Erfahrungen mit dem BetoScan-System zu erhalten, wurde ein langjährig genutztes Parkhaus aus Stahlbeton mit Gussasphaltfahrbahn als Untersuchungsobjekt ausgewählt. Bei der experimentellen Bauwerksuntersuchung wurden die Verfahren Wirbelstrom, Radar, Ultraschall und Mikrowelle zum Einsatz gebracht. Von der Anwendung des Systems und der Auswertung der Ergebnisse wird in diesem Beitrag berichtet. N2 - In recent years a variety of non-destructive evaluation methods are more and more used for the inspection of constructions. Increasing the information value of inspections and the economic aspects of applications leads to a combination of methods on an automated system. Therefore, the BetoScan robot was developed. Gaining more experience in applications was realized with the inspection of a car park which was unused for several years. The building was made of reinforced concrete with melted asphalt as floor coating. Within the frame of the inspections eddy current, radar, ultrasound and microwaves were used. The application of the BetoScan system and the results are presented in this article. KW - Automatisierte zerstörungsfreie Prüfung KW - Bauwesen KW - Kombination KW - Verfahren KW - Bauwerksüberwachung KW - BetoScan-System KW - Dauerhaftigkeit KW - Gussasphalt KW - Instandsetzung KW - Lebensdauer KW - Mikrowelle KW - Nachhaltigkeit KW - Qualitätssicherung KW - Radar KW - Ultraschall-Prüfung KW - ZfP-Verfahren KW - Bauwerkserhaltung/Sanierung KW - Allgemeines PY - 2012 DO - https://doi.org/10.1002/best.201200048 SN - 0005-9900 SN - 1437-1006 VL - 107 IS - 12 SP - 794 EP - 804 PB - Ernst CY - Berlin AN - OPUS4-27588 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stoppel, Markus A1 - Taffe, Alexander A1 - Wiggenhauser, Herbert A1 - Kurz, J. H. A1 - Boller, C. ED - Grantham, M. ED - Mechtcherine, V. ED - Schneck, U. T1 - Automated multi-sensor systems in civil engineering for condition assessment of concrete structures N2 - Infrastructure is subject to continuous ageing. This has given life cycle management of infrastructure an important role. Therefore an increasing demand for reliable inspection and monitoring tools is noticeable. A combination of different non-destructive test methods is often necessary to receive reliable results for material characterization, flaw detection and the determination of component specific geometry Parameters. Regarding concrete structures thickness measurements are combined with flaw detection and additional Information about reinforcement and tendon ducts is required. Therefore, a multi-sensor measurement approach is necessary with a high degree of automation. Otherwise a time consuming succession of manual measurements has to be performed which would prevent practical applications. A modular control and data acquisition approach is described and the application of two different automated measurement devices is shown. The BetoScan System consists of a self-navigating mobile robot. The System is especially designed for the Investigation of reinforced concrete floors exposed to de-icing salts. The data acquisition of the OSSCAR System, a multi-sensor Scanner, is similar to the robot approach. These different applications are based on a similar kernel allowing the modular use of different contact and non-contact sensors. The described general concept of multi-sensor data acquisition and data analysis presented here is not limited to the field of civil engineering applications. T2 - Concrete Solutions 2011 - 4th International Conference on Concrete Repair CY - Dresden, Germany DA - 26.09.2011 KW - Multi sensor KW - Data aquisition KW - Assessment of concrete structures KW - Scanner KW - NDT PY - 2012 SN - 978-0-415-61-622-5 SP - 397 EP - 403 PB - Taylor & Francis CY - London AN - OPUS4-24659 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Andrade, M. A. B. A1 - Stindt, Arne A1 - Panne, Ulrich A1 - Riedel, Jens A1 - Adamowski, J. C. T1 - Numerical and experimental determination of the sound pressure distribution in single-axis acoustic levitators N2 - This paper presents a numerical and an experimental procedure to obtain the pressure field in single-axis acoustic levitators. Numerically, the pressure field is determined by a matrix method based on the Rayleigh integral that take into account the multiple wave reflections that occur between the transducer and the reflector. The numerical pressure field is compared with the acoustic pressure measured by an earplug microphone, that is connected to a hollow needle. The tip of the needle is moved by a µm translation stage through the field and the signal is recorded using a lock-in amplifier locked to the levitator frequency. The pressure field obtained numerically show good agreement with that obtained experimentally. T2 - 2012 IEEE International Ultrasonics Symposium (IUS) CY - Dresden, Germany DA - 07.10.2012 KW - Acoustic levitation KW - Matrix method KW - Pressure field PY - 2012 SN - 978-1-4673-4562-0 DO - https://doi.org/10.1109/ULTSYM.2012.0690 SP - 2754 EP - 2757 PB - Institute of Electrical and Electronics Engineers (IEEE) CY - Piscataway, NJ AN - OPUS4-32587 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Waegner, M. A1 - Schröder, M. A1 - Suchaneck, G. A1 - Sturm, Heinz A1 - Weimann, Christiane A1 - Eng, L. M. A1 - Gerlach, G. T1 - Enhanced piezoelectric response in nano-patterned lead zirconate titanate thin films N2 - In this work, Pb(Zr,Ti)O3 thin films were used to fabricate well-ordered nanodot arrays by means of nanosphere lithography. This technique is based on a two-step etch process that enables excellent control of the fabrication of ordered nanodisc arrays of defined height, diameter, and pitch. Piezoresponse force microscopy was used to investigate both non-patterned and patterned films. The topography and both the out-of-plane and the in-plane polarization were deduced in this mode. Grains of nanodots with a low aspect ratio form domain structures comparable to domains in non-patterned two-dimensional films. In contrast, nanodots with a higher aspect ratio form particular structures like bi-sectioned domain assemblies, c-shaped domains or multi-domains surrounding a center domain. The patterning of the ferroelectric material was shown to affect the formation of ferroelectric domains. The initial polycrystalline films with random polarization orientation re-orient upon patterning and then show domain structures dependent on the nanodisc diameter and aspect ratio. KW - Nanostructures KW - Ferroelectric KW - Nanodots PY - 2012 DO - https://doi.org/10.1143/JJAP.51.11PG04 SN - 0021-4922 VL - 51 SP - 1 EP - 5 PB - IOP Publ. CY - Bristol AN - OPUS4-27697 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sturm, Heinz A1 - Schröter, Maria-Astrid A1 - Weimann, Christiane T1 - Imaging method for vibrating scanning force microscopy cantilevers for the analysis of mode shapes and nonlinear harmonic motion N2 - A specially designed scanning force microscope (SFM, atomic force microscope – AFM) was incorporated into the chamber of a commercial scanning electron microscope (SEM) to investigate vibrating SFM cantilevers at their resonance. Inherently, the spatial resolution of electron microscopy is higher than that of optical methods. In this paper we present vibration modes (eigenmodes) of two different SFM cantilevers. Their nonlinear behavior is also explored in order to depict their 2nd harmonics (twice the fundamental frequency). Imaging of the local vibration is performed by measuring the frequency- and phase-selective responses of the SE signal at different X and Y positions of the scanned electron beam. KW - Electron microscopy KW - Scanning force microscopy KW - Motion detection KW - Cantilever KW - Eigenmode KW - Harmonic KW - Nonlinearity KW - Harmonix cantilever PY - 2012 DO - https://doi.org/10.1016/j.mee.2012.07.088 SN - 0167-9317 SN - 1873-5568 VL - 98 SP - 492 EP - 496 PB - Elsevier Science CY - Amsterdam, Netherlands AN - OPUS4-26431 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wachtendorf, Volker A1 - Schulz, Ulrich A1 - Geburtig, Anja A1 - Stephan, Ina T1 - Mildew growth on automotive coatings influencing the results of outdoor weathering N2 - As the results of a 14 weeks outdoor exposure of a series of automotive coatings in South Florida, the panels were found to be overgrown with an almost closed layer of mildew. Pinholes remained as permanent surface damage after removing the mildew mycelium. The extent of the damage differed in dependence of the kind of the coating. By tracing the images and profiles of the coating surfaces systematically over all phases of weathering and the subsequent cleaning procedure, a connection between formation of pinholes and mildew growth could be found. Outdoor weathering tests in other regions of Florida as well as in Europe and Australia showed that pinholes caused by mildew attack could also be found in all other locations, but always to a lower extent than in South Florida. The standardised mildew tests EN ISO 846 and MIL-STD 810F for laboratory exposure failed to reproduce the formation of pinholes. KW - Coatings KW - Mildew KW - Weathering KW - South Florida PY - 2012 DO - https://doi.org/10.1002/maco.201005784 SN - 0947-5117 SN - 1521-4176 VL - 63 IS - 2 SP - 140 EP - 147 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-25467 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröter, Maria-Astrid A1 - Holschneider, M. A1 - Sturm, Heinz T1 - Analytical and numerical analysis of imaging mechanism of dynamic scanning electron microscopy N2 - The direct observation of small oscillating structures with the help of a scanning electron beam is a new approach to study the vibrational dynamics of cantilevers and microelectromechanical systems. In the scanning electron microscope, the conventional signal of secondary electrons (SE, dc part) is separated from the signal response of the SE detector, which is correlated to the respective excitation frequency for vibration by means of a lock-in amplifier. The dynamic response is separated either into images of amplitude and phase shift or into real and imaginary parts. Spatial resolution is limited to the diameter of the electron beam. The sensitivity limit to vibrational motion is estimated to be sub-nanometer for high integration times. Due to complex imaging mechanisms, a theoretical model was developed for the interpretation of the obtained measurements, relating cantilever shapes to interaction processes consisting of incident electron beam, electron–lever interaction, emitted electrons and detector response. Conclusions drawn from this new model are compared with numerical results based on the Euler–Bernoulli equation. KW - Electron microscopy KW - Scanning force microscopy KW - Cantilever motion KW - Modes KW - Harmonics KW - Mathematical model KW - Imaging theory PY - 2012 DO - https://doi.org/10.1088/0957-4484/23/43/435501 SN - 0957-4484 SN - 1361-6528 VL - 23 IS - 43 SP - 1 EP - 10 PB - IOP Publishing Ltd. CY - Bristol AN - OPUS4-27642 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sturm, Heinz A1 - Schartel, Bernhard A1 - Weiß, André A1 - Braun, Ulrike T1 - SEM/EDX: Advanced investigation of structured fire residues and residue formation N2 - Heterogeneous, gradual or structured morphology of fire residues plays an important role in fire retardancy of polymers. A scanning electron microscope with an attached energy dispersive X-ray spectrometer (SEM/EDX) is highlighted as a powerful tool for the advanced characterization of such complex fire residues, since it offers high resolution in combination with both good depth of field and analysis of chemical composition. Two examples are presented: First, comprehensive SEM/EDX investigation on a complex structured fire residue of glass fibre reinforced polyamide 6,6 (PA 66-GF) flame retarded by diethylaluminium phosphinate, melamine polyphosphate and some zinc borate. A multilayered surface crust (thickness ~ 24 µm) covers a rather hollow area stabilized by GF glued together. The resulting efficient thermal insulation results in self-extinguishing before pyrolysis is completed, even under forced-flaming combustion. Second, sophisticated, quasi online SEM/EDX imaging of the formation of residual protection layer in layered silicate epoxy resin nanocomposites (LSEC). Burning specimens were quenched in liquid nitrogen for subsequent analyses. Different zones were distinguished in the condensed phase characterized by distinct processes such as melting and ablation of organic material, as well as agglomeration, depletion, exfoliation and reorientation of the LS. KW - Fire residue KW - SEM/EDX KW - Fire retardancy KW - PA 66 KW - Layered silicate KW - Diethylaluminium phosphinate PY - 2012 DO - https://doi.org/10.1016/j.polymertesting.2012.03.005 SN - 0142-9418 VL - 31 IS - 5 SP - 606 EP - 619 PB - Elsevier CY - Amsterdam AN - OPUS4-25802 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stark, Wolfgang A1 - Jaunich, Matthias A1 - Bohmeyer, W. A1 - Lange, K. T1 - Investigation of the crosslinking behaviour of ehtylene vinyl acetate (EVA) for solar cell encapsulation by rheology and ultrasound N2 - EVA is a widely used material for the encapsulation of photovoltaic modules. It melts at elevated temperatures, and seals the module before it is crosslinked at temperatures above 130 °C by a peroxide-initiated crosslinking reaction. EVA has good optical properties necessary for application in solar modules. For process optimization and quality management, a method for the quick and reliable characterization of EVA crosslinking behaviour is of great value. Here, the practicability of ultrasound for online crosslinking monitoring is demonstrated. A sound velocity increase of about 8 m/s during the crosslinking reaction is found. The ultrasound results are compared with rheometer measurements performed with a curemeter typically used for the investigation of rubber crosslinking. KW - Ethylene vinyl acetate KW - EVA KW - Crosslinking KW - Ultrasound KW - Rheology KW - Curemeter KW - DSC PY - 2012 DO - https://doi.org/10.1016/j.polymertesting.2012.07.004 SN - 0142-9418 VL - 31 IS - 7 SP - 904 EP - 908 PB - Elsevier CY - Amsterdam AN - OPUS4-26291 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Razzaq, M. Y. A1 - Behl, M. A1 - Frank, U. A1 - Koetz, J. A1 - Szczerba, Wojciech A1 - Lendlein, A. T1 - Oligo(omega-pentadecalactone) decorated magnetic nanoparticles N2 - Hybrid magnetic nanoparticles (mgNP) with a magnetite core diameter of 10 ± 1 nm surface functionalized with oligo(ω-pentadecalactone) (OPDL) oligomers with Mn between 1300 and 3300 g mol-1 could be successfully prepared having OPDL grafted from 200 mg g-1 to 2170 mg g-1. The particles are dispersible in chloroform resulting in stable suspensions. Magnetic response against an external magnetic field proved the superparamagnetic nature of the particles with a low coercivity (Bc) value of 297 µT. The combination of the advantageous superparamagnetism of the mgNP with the exceptional stability of OPDL makes these novel hybrid mgNP promising candidates as multifunctional building blocks for magnetic nanocomposites with tunable physical properties. KW - PPDL KW - OPDL KW - Magnetic core-shell nanoparticles PY - 2012 DO - https://doi.org/10.1039/c2jm16146j SN - 0959-9428 SN - 1364-5501 VL - 22 IS - 18 SP - 9237 EP - 9243 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-25741 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mandel, K. A1 - Szczerba, Wojciech A1 - Thünemann, Andreas A1 - Riesemeier, Heinrich A1 - Girod, Matthias A1 - Sextl, G. T1 - Nitric acid-stabilized superparamagnetic iron oxide nanoparticles studied with X-rays N2 - Agglomerated superparamagnetic iron oxide nanoparticles can easily and in large scale be precipitated from iron salt solutions. Although the process is well known, it is ambiguously either assumed that magnetite or maghemite is obtained. The first part of our study clarifies this question using X-ray absorption spectroscopy. For further processing of the nanoparticles, i.e., for giving them a surface functionality or incorporating them into composites, it is important to break the agglomerates and individualize the particles at first. This can effectively be done with nitric acid treatment. The influence of this process on the particles chemistry and structure was analyzed in great detail using X-ray diffraction, X-ray absorption, and smallangle X-ray scattering. In contrast to our expectation, no oxidation from magnetite (Fe3O4) to maghemite (γ- Fe2O3) was found; the formal valence of the particles in any case is magnetite (Fe3O4). Instead, an increase in the particles' surface disorder was discovered from X-ray absorption analyses and high-resolution transmission electron microscopy. The acid treatment roughens and distorts the surface of the nanoparticles which is connected with an increased spin disorder. KW - XANES KW - EXAFS KW - SAXS KW - Coprecipitation KW - Iron oxide spectra KW - Ferrofluid PY - 2012 DO - https://doi.org/10.1007/s11051-012-1066-3 SN - 1388-0764 SN - 1572-896X VL - 14 IS - 8 SP - 1 EP - 9 PB - Kluwer CY - Dordrecht AN - OPUS4-26357 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wiegner, Katharina A1 - Hahn, Oliver A1 - Horn, Wolfgang A1 - Farke, M. A1 - Kalus, Sabine A1 - Nohr, Michael A1 - Jann, Oliver T1 - Determination of formic and acetic acid emissions in indoor air or from building products N2 - Several construction and building materials, including wood, glue and coatings, are possible sources of very volatile organic compounds (VVOCs) and volatile organic compounds (VOCs) like formic and acetic acid. Due to very high air tightness and very low air exchange rates in new buildings concentrations of these harmful substances can increase considerably. To minimize the risk, emissions from building products should be identified and quantified. With the common standard method, this means Tenax® sampling followed by thermal desorption and GC-MS analysis, these acids could not be detected sufficiently. The aim oft this study is the comparison of two different methods for the determination of acetic and formic acid. The sampling of method one, which is usually used for identification and quantification of VOCs, is done in accordance with ISO 16000-6 and ISO 16017-1 on Carbotrap® 202 multi-bed thermal desorption tube by subsequent identification and quantification with GC-MS. Method two is based on sampling on 2,4-dinitrophenylhydrazine (DNPH) cartridges, derivatisation, elution, identification and quantification of the derivatives with LC-MS/MS (liquid chromatography – mass spectrometry/mass spectrometry). N2 - Viele Konstruktions- und Baumaterialien, wie Holz, Kleber und Anstriche, sind mögliche Quellen für leicht flüchtige organische Verbindungen (VVOC) und flüchtige organische Verbindungen (VOC), wie Ameisen- und Essigsäure. Bedingt durch die hohe Dichtigkeit und den damit verbundenen niedrigen Luftwechsel in neuen Gebäuden können die Konzentrationen dieser gesundheitsgefährdenden Substanzen beträchtlich ansteigen. Um das Risiko zu minimieren, sollen Emissionen aus Bauprodukten identifiziert und quantifiziert werden. Mit der üblichen Standardmethode, die auf einer Luftprobenahme auf Tenax® und anschließender Analyse mittels GC-MS basiert, können diese Säuren nicht ausreichend detektiert werden. Ziel dieser Arbeit ist der Vergleich von zwei unterschiedlichen Methoden zur Bestimmung von Essig- und Ameisensäure. Die Luftprobenahme der ersten Methode, die üblicherweise zur Identifizierung und Quantifizierung von VOC genutzt wird, wurde gemäß ISO 16000-6 and ISO 16017-1 auf Carbotrap® 202, ein mit mehreren Adsorbentien gepacktes Thermodesorptionsrohr, mit anschließender Identifikation und Quantifizierung mittels GC-MS durchgeführt. Die zweite Methode basiert auf einer Luftprobenahme mittels 2,4-Dinitrophenylhydrazin-(DNPH)-Kartuschen, Derivatisierung, Elution, Identifikation und Quantifizierung der Derivate mit LC-MS/MS (Flüssigkeitschromatographie – Massenspektometrie/Massenspektometrie). KW - Formic acid KW - Acetic acid KW - VVOCs KW - Air sampling KW - DNPH PY - 2012 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-255911 UR - http://www.gefahrstoffe.de/gest/article.php?data[article_id]=65887 SN - 0949-8036 SN - 0039-0771 SN - 1436-4891 VL - 72 IS - 3 SP - 84 EP - 88 PB - Springer-VDI-Verlag CY - Düsseldorf AN - OPUS4-25591 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schartel, Bernhard T1 - Towards evidence-based development of flame retarded polymers N2 - Competence in polymer research and development is founded not only on technical/methodical components such as know-how, knowledge and communication, but also on scientific components. According to many sources the latter can be identified as a) identifying topics, tasks, opportunities, challenges, etc. b) describing /understanding phenomena and c) using evidence. Accepting this Basic background, this contribution demonstrates how a, b and c can be fulfilled in the development of flame retarded polymeric materials. Based on different examples of our work over the last 10 years, it is shown that innovation and co-operation are used to tackle actualtasks and opportunities, and that multi-methodical approaches and key experiments are sufficient to generate a deep understanding of phenomena as well as systematic investigations and comprehensive assessments. What is more, the examples shown demonstrate how guidelines are deduced for future material developments, which is, of course, the ultimate benefit of using evidence in applied polymer Science and engineering. T2 - 243rd National ACS meeting - Spring 2012 CY - San Diego, CA, USA DA - 25.03.2012 KW - Flame retardancy KW - Halogen-free KW - Flame retardancy mechanism KW - Fire property assessment PY - 2012 SN - 978-0-8412-2727-9 SN - 1550-6703 N1 - Serientitel: PMSE Preprints – Series title: PMSE Preprints VL - 243 SP - 38-PMSE PB - Amer Chemical SOC CY - Washington, USA AN - OPUS4-26381 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Schartel, Bernhard A1 - Richter, K. H. A1 - Böhning, Martin ED - Morgan, A. B. ED - Wilkie, C. A. ED - Nelson, G. L. T1 - Synergistic use of talc in halogen-free flame retarded polycarbonate/Acrylonitrile-butadiene-styrene blends N2 - Pyrolysis, flammability, fire behavior, melt viscosity, and gas diffusion of bisphenol A polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) were investigated, with bisphenol A bis(diphenyl phosphate) (BDP), with 10 wt.% talc and with BDP in combination with 5, 10 and 20 wt.% talc, respectively. Compared to PC/ABS, PC/ABS + BDP results in an increased decomposition temperature of PC, a higher char yield, a significantly increased LOI, a V-0 classification in UL 94, a reduced peak heat release rate (pHRR), and a reduced total heat release (THR) in the cone calorimeter. This efficient flame retardancy is due to mechanisms in both the gas and condensed phases. PC/ABS + 10 wt.% talc shows a decrease in the PC decomposition temperature. The fire behavior is improved in part compared to PC/ABS, with an increased LOI and reduced pHRR. PC/ABS + BDP + 10 wt.% talc shows a strong synergism in LOI, a V-0 classification, and a decrease in pHRR, whereas THR is slightly increased compared to PC/ABS + BDP. Talc decreases the gas diffusion and enhances the flow limit for low shear rates, both of which influence the pyrolysis and flammability results. Further, talc improves the protection properties of the fire residues. Nevertheless it also partly suppresses flame inhibition and the charring effect of BDP. The synergism between BDP and talc in LOI is obtained even for low talc loadings in PC/ABS + BDP + talc, whereas for higher loadings saturation is observed. KW - Flame retardancy KW - PC/ABS KW - Aryl phosphate KW - Talc PY - 2012 SN - 978-0-8412-2780-4 DO - https://doi.org/10.1021/bk-2012-1118.ch002 N1 - Serientitel: ACS Symposium Series – Series title: ACS Symposium Series VL - 1118 IS - Chapter 2 SP - 15 EP - 36 PB - Oxford University Press AN - OPUS4-27563 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brice, H. A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Frictional behavior of material couples in superconducting MRI magnet systems at 4.2 K N2 - Windings in superconducting magnets operating at 4.2 K are highly susceptible to quenching caused by small frictional heat inputs. Small movements in the magnet system are inevitable during ramping due to the increasing electromagnetic forces. Friction pairs of polymer based materials have been investigated at 4.2 K to gain an understanding of their sliding behavior in conditions representative of superconducting MRI systems. The results indicate that polymer-polymer pairs experience unstable sliding behavior with repeated stick-slip whereas polymer-aluminum couples have stable sliding behavior up to high contact pressures of 20 MPa. KW - Cryotribology KW - Friction KW - MRI magnets KW - Stick-slip PY - 2012 DO - https://doi.org/10.1109/TASC.2011.2175683 SN - 1051-8223 VL - 22 IS - 3 SP - 4400204-1 EP - 4400204-4 PB - IEEE CY - New York, NY AN - OPUS4-26384 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sterthaus, Jens A1 - Ballheimer, Viktor A1 - Kuschke, Christian A1 - Wille, Frank T1 - Numerical analysis of bolted trunnion systems of packages for radioactive materials N2 - Packages for the transport of radioactive material are generally equipped with particular components for crane operations and supporting the package during transport. As an example of such components the bolted trunnion system of heavy packages are analysed in this paper. According to the German guideline BAM-GGR 012 created by the BAM Federal Institute for Materials Research and Testing for analysis and assessment of bolted lid and trunnion Systems, the finite element (FE) method is to be used preferably in the analysis of such kind of structures to obtain more accurate and detailed Information about their stressing. The FE model of a trunnion System should include the trunnion itself, the bolts and an appropriate part of the packaging wall with necessary contact conditions on all interfaces between these components. The use of solid finite elements, which is generally recommended in the BAM-GGR 012 guideline, leads to local stress and strain fields as a result of the calculation. The modelling strategy, e.g. the way of modelling interaction between the components of the trunnion System, has an essential impact on these local values. The effect of different assumptions in a FE model is demonstrated in this paper using the calculation results for a reference trunnion System. The approaches for preparation and Interpretation of results in connection with local or nominal assessment criteria are discussed as well. T2 - ASME 2012 Pressure Vessels and Piping Division Conference - PVP 2012 CY - Toronto, Ontario, Canada DA - 15.07.2012 KW - Bolted trunnion KW - German guideline BAM-GGR 012 KW - Local stress and strain fields KW - Local and nominal assessment criteria PY - 2012 SP - 1 EP - 6 PB - American Society of Mechanical Engineers (ASME) CY - New York, NY AN - OPUS4-26835 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weidner, Steffen A1 - Falkenhagen, Jana A1 - Bressler, I. T1 - Copolymer composition determined by LC-MALDI-TOF MS coupling and 'MassChrom2D' data analysis N2 - The MALDI-TOF MS analysis of copolymers very often results in complex spectra. A chromatographic separation/fractionation prior to the MALDI investigation can be advantageous since the MALDI mass spectra of fractions very often reveal well-resolved peaks of distinguishable copolymer series. For this purpose, different modes of chromatography have been applied. Chromatographic runs were transferred to MALDI targets utilizing a combined air/electrospray deposition device. Using the new MassChrom2D software, fraction-dependent 2D copolymer compositions plots were obtained providing additional information on the chromatographic mode, and enabling fast modification of conditions to increase separation. KW - Copolymer composition KW - Chromatography KW - Coupling KW - MALDI-TOF mass spectrometry PY - 2012 DO - https://doi.org/10.1002/macp.201200169 SN - 1022-1352 SN - 1521-3935 VL - 213 IS - 22 SP - 2404 EP - 2411 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-27270 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gallo, Emanuela A1 - Sánchez-Olivares, G. A1 - Schartel, Bernhard T1 - Flame retardancy of starch-based biocomposites - aluminium hydroxide-coconut fiber synergy N2 - The use of coconut fiber (CF) agricultural waste was considered as an environmentally friendly and inexpensive alternative in flame retarded biocomposites. To decrease the high content of aluminum trihydrate (ATH) required, the thermal decomposition (thermogravimetry), flammability [oxygen index (LOI) and UL 94 test] and fire behavior (cone calorimeter) of a combination of CF and ATH were investigated in a commercial blend of thermoplastic starch (TPS) and cellulose derivatives. CF induced some charring activity, slightly decreasing the fire load and burning propensity in cone calorimeter test. ATH decomposes endothermically into water and inorganic residue. Significant fuel dilution as well as a pronounced residual protection layer reduces the fire hazards. Replacing a part of ATH with coconut fibers resulted in improved flame retardancy in terms of ignition, reaction to small flame, and flame-spread characteristics [heat release rate (HRR), fire growth rate (FIGRA), etc.]. The observed ATH and CF synergy opens the door to significant reduction of the ATH contents and thus to interesting flame retarded biocomposites. KW - Biocomposites KW - Flammability KW - Starch KW - Aluminium hydroxide KW - Coconut fiber PY - 2013 SN - 0032-2725 VL - 58 IS - 5 SP - 395 EP - 402 PB - Industrial chemistry research inst CY - Warszawa, Poland AN - OPUS4-28513 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gallo, Emanuela A1 - Schartel, Bernhard A1 - Schmaucks, G. A1 - von der Ehe, Kerstin A1 - Böhning, Martin T1 - Effect of well dispersed amorphous silicon dioxide in flame retarded styrene butadiene rubber N2 - Spherically shaped amorphous silicon dioxide with broad size particle distribution was used in combination with aluminium trihydroxide (ATH) in styrene butadiene rubber composites. The pyrolysis, flammability, fire properties, flame spread and gas diffusion were investigated. The kind and amount of ATH, but in particular the fine silicon dioxide chosen as an additive, influenced the thermal decomposition and fire behaviour of styrene butadiene rubber composites. Gravimetric gas sorption measurements showed that the gas diffusion was systematically lower with silicon dioxide. The initial pyrolysis gas release was hindered, increasing the temperature at which decomposition begins as well as the ignition time in fire tests. During combustion, ATH and silicon dioxide accumulate on the surface of the specimen, forming a residual protective layer. A reduced peak heat release rate and fire spread were observed. The addition of a special kind of silicon dioxide is proposed to play a key role in optimising fire retardancy. KW - Flame retardancy KW - Styrene butadiene rubber KW - SBR KW - Silicon dioxide KW - Aluminium trihydroxide KW - ATH PY - 2013 DO - https://doi.org/10.1179/1743289812Y.0000000012 SN - 1465-8011 SN - 1743-2898 VL - 42 IS - 1 SP - 34 EP - 42 PB - IOM Communications CY - London, UK AN - OPUS4-27626 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brosig, Laura A1 - Horn, Wolfgang A1 - Pyza, Lars A1 - Jann, Oliver A1 - Plehn, W. T1 - Round robin test for the implementation of odour measurements according to DIN ISO 16000-28 into the assessment of emissions from building products N2 - Odour measurements become increasingly important in view of the assessment of indoor air quality and the emissions of building products. Hence they need to be implemented into evaluation schemes such as the AgBB scheme. While there are already standards like DIN ISO 16000-28 and VDI 4302 Part 1 specifying the procedure of odour measurements using a comparison scale, no final validation of the method has been carried out so far. Therefore, a round robin test was conducted in 2012 with 12 participating laboratories that mainly consisted of the following two parts: 1) testing of the available comparison scales with respect to their operational performance and 2) execution of an odour assessment of an acrylic sealant using emission test chambers. Part one included the measurement of the air flow rates and the provided concentrations of the reference substance (acetone). Part two was conducted to test the performance of the laboratories and the applicability of DIN ISO 16000-28 and supplementary VDI 4302 Part 1 by assessing the perceived intensity and the hedonic tone of the air samples. Moreover, samples for VOC analysis were taken from the air in the emission test chamber on the 7th day of testing to allow for quality control. Resulting from this round robin test main deficits were detected and suggestions for the improvement of the odour measurement procedure were made. N2 - Im Rahmen der Bewertung von Innenraumluftqualität und von Emissionen aus Bauprodukten gewinnt auch die Beurteilung entstehender Gerüche zunehmend an Bedeutung. Um der daraus resultierenden Forderung nach Geruchsbewertungen gerecht zu werden, müssen entsprechende Methoden in bestehende Bewertungssysteme, wie z. B. das AgBB-Schema, aufgenommen werden. Als Grundlage hierfür bieten sich die bereits bestehenden Regelwerke DIN ISO 16000-28 und VDI 4302 Blatt 1 an, die das Vorgehen bei Geruchsmessungen unter Verwendung eines Vergleichsmaßstabes vorgeben. Da für die beschriebene Methode bisher keine Validierung vorliegt, wurde 2012 ein Ringversuch mit zwölf Instituten durchgeführt, der sich hauptsächlich aus zwei Teilen zusammensetzte: 1) Überprüfung der technischen Funktionsfähigkeit der verwendeten Vergleichsmaßstäbe und 2) Durchführung einer Geruchsbewertung für eine Acryldichtmasse mithilfe von Emissionsprüfkammern. Im ersten Teil wurden sowohl die Volumenströme als auch die bereitgestellten Konzentrationen der Referenzsubstanz Aceton bestimmt. Der zweite Teil diente neben der Ermittlung der Leistungsfähigkeit der Laboratorien vor allem der Feststellung, inwieweit eine Bestimmung der empfundenen Intensität und der Hedonik nach DIN ISO 16000-28, ergänzt durch VDI 4302 Blatt 1, einheitlich möglich ist. Aus Gründen der Vergleichbarkeit und der Qualitätskontrolle wurden am siebten Tag der Messungen zusätzlich Proben der Prüfkammerluft zur VOC-Bestimmung genommen. Mithilfe des Ringversuchs konnten Defizite sowohl technischer als auch methodischer Art festgestellt und Vorschläge für die Verbesserung des Vorgehens bei Geruchsbewertungen erarbeitet werden. PY - 2013 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-293110 UR - http://www.gefahrstoffe.de/gest/article.php?data[article_id]=75118 SN - 0949-8036 SN - 0039-0771 SN - 1436-4891 VL - 73 IS - 10 SP - 441 EP - 445 PB - Springer-VDI-Verlag CY - Düsseldorf AN - OPUS4-29311 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pech, Anja A1 - Wilke, Olaf A1 - Mull, Birte A1 - Horn, Wolfgang A1 - Jann, Oliver T1 - Development of a TDS-GC-FID method for the determination of methanol and ethanol in air N2 - A method for the determination of very volatile organic compounds (VVOC) in air was developed and successfully tested for methanol and ethanol. Carbotrap300® (a multi-bed tube using Carbopack C®, Carbopack B® and Carbosive SIII®) was selected as sorption material for thermal desorption and tested for its suitability for emission test chamber measurements. The adsorption behaviour and the chromatographic results are influenced negatively by spiking aqueous solutions on the adsorption medium for calibration purposes. The latter effect can be reduced by blowing dry air across the adsorbent to remove the adsorbed water. Detection and quantification limits were determined for a GC-FID system and compared to GC-MS. The applicability of the method was tested with a methanol eliminating silane modified polymeric adhesive (SMP-adhesive for parquet) in an emission test chamber N2 - Eine Methode zur Bestimmung von sehr leicht flüchtigen Verbindungen in Luft wurde für Methanol und Ethanol entwickelt und erfolgreich getestet. Dafür wurde Carbotrap300® (Multibettrohr aus Carbopack C®, Carbopack B® und Carbosive SIII®) als Sorptionsmedium für die Thermodesorption ausgewählt und dessen Eignung für Emissionskammermessungen untersucht. Das Adsorptionsverhalten und die chromatographischen Ergebnisse werden negativ durch die Aufgabe von wässrigen Kalibrierlösungen auf das Adsorptionsmedium beeinflusst. Durch das Überleiten von trockener Luft kann dieser Effekt verringert werden, da so das adsorbierte Wasser entfernt wird. Die Nachweis- und Bestimmungsgrenzen wurden für ein eingesetztes GC- FID-System ermittelt und mit einem GC-MS verglichen. Mit einem methanolabspaltenden silanmodifizierten Polymerklebstoff (SMP-Parkettkleber), der in eine Emissionskammer eingebracht wurde, konnte die Tauglichkeit der Methode überprüft werden. PY - 2013 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-297020 UR - http://www.gefahrstoffe.de/gest/article.php?data[article_id]=76019 SN - 0949-8036 SN - 0039-0771 SN - 1436-4891 VL - 73 IS - 11/12 SP - 477 EP - 482 PB - Springer-VDI-Verlag CY - Düsseldorf AN - OPUS4-29702 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stindt, Arne A1 - Buurman, Merwe A1 - Panne, Ulrich A1 - Riedel, Jens T1 - CO2 laser ionization of acoustically levitated droplets N2 - For many analytical purposes, direct laser ionization of liquids is desirable. Several studies on supported droplets, free liquid jets, and ballistically dispensed microdroplets have been conducted, yet detailed knowledge of the underlying mechanistics in ion formation is still missing. This contribution introduces a simple combination of IR-MALDI mass spectrometry and an acoustical levitation device for contactless confinement of the liquid sample. The homebuilt ultrasonic levitator supports droplets of several millimeters in diameter. These droplets are vaporized by a carbon dioxide laser in the vicinity of the atmospheric pressure interface of a time of flight mass spectrometer. The evaporation process is studied by high repetition rate shadowgraphy experiments elucidating the ballistic evaporation of the sample and revealing strong confinement of the vapor by the ultrasonic field of the trap. Finally, typical mass spectra for pure glycerol/water matrix and lysine as an analyte are presented with and without the addition of trifluoracetic acid, and the ionization mechanism is briefly discussed. The technique is a promising candidate for a reproducible mass spectrometric detection scheme for the field of microfluidics. KW - Ambient mass spectrometry KW - Levitated droplets KW - IR-MALDI PY - 2013 DO - https://doi.org/10.1007/s00216-012-6500-y SN - 1618-2642 SN - 1618-2650 N1 - Geburtsname von Buurman, Merwe: Albrecht, M. - Birth name of Buurman, Merwe: Albrecht, M. VL - 405 SP - 7005 EP - 7010 PB - Springer CY - Berlin AN - OPUS4-27429 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröter, Maria-Astrid A1 - Sturm, Heinz A1 - Holschneider, M. T1 - Phase and amplitude patterns in DySEM mappings of vibrating microstructures N2 - We use a dynamic scanning electron microscope (DySEM) to analyze the movement of oscillating micromechanical structures. A dynamic secondary electron (SE) signal is recorded and correlated to the oscillatory excitation of scanning force microscope (SFM) cantilever by means of lock-in amplifiers. We show, how the relative phase of the oscillations modulate the resulting real part and phase pictures of the DySEM mapping. This can be used to obtain information about the underlying oscillatory dynamics. We apply the theory to the case of a cantilever in oscillation, driven at different flexural and torsional resonance modes. This is an extension of a recent work (Schr¨oter et al 2012 Nanotechnology 23 435501), where we reported on a general methodology to distinguish nonlinear features caused by the Imaging process from those caused by cantilever motion. KW - DySEM KW - mechanical nonlinearity KW - vibration KW - DySEM KW - mechanische Nichtlinearitäten KW - Vibration PY - 2013 DO - https://doi.org/doi:10.1088/0957-4484/24/21/215701 VL - 24 IS - 21 SP - 215701-1 EP - 215701-10 PB - IOP PUBLISHING LTD CY - Bristol, UK AN - OPUS4-35396 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gebhardt, M.O. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Numerical analysis of hot cracking in laser-hybrid welded tubes N2 - In welding experiments conducted on heavy wall pipes, the penetration mode (full or partial penetration) occurred to be a significant factor influencing appearance of solidification cracks. To explain the observed phenomena and support further optimization of manufacturing processes, a computational model was developed, which used a sophisticated strategy to model the material. High stresses emerged in the models in regions which showed cracking during experiments. In partial penetration welding, they were caused by the prevention of weld shrinkage due to the cold and strong material below the joint. Another identified factor having an influence on high stress localization is bulging of the weld. PY - 2013 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-302961 DO - https://doi.org/10.1155/2013/520786 SN - 1687-8442 SN - 1687-8434 IS - Article ID 520786 SP - 1 EP - 8 PB - Hindawi Publishing Corporation CY - New York, NY, USA AN - OPUS4-30296 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schartel, Bernhard ED - D'Amore, A. ED - Acierno, Domenico ED - Grassia, L. T1 - Nanotechnology finding its way into flame retardancy N2 - Nanotechnology is one of the key technologies of the 21st century. The exploitation of 'new' effects that arise from materials structured on the nano-scale has also been proposed successfully for flame retardancy of polymers since the end of the 90s. Of all of the approaches these include, at this time the use of nanocomposites offers the best potential for industrial application, also some other ideas are sketched, such as using electrospun nanofibers mats or layer-by-layer deposits as protection coatings, as well as sub-micrometer multilayer coatings as effective IR-mirrors. The general phenomena, inducing a flow limit in the pyrolysing melt and changing the fire residue, are identified in nanocomposites. Key experiments are performed such as quasi online investigation of the protection layer formation to understand what is going on in detail. The flame retardancy mechanisms are discussed and their impact on fire behaviour quantified. With the latter, the presentation pushes forward the state of the art. For instance, the heat shielding is experimentally quantified for a layered silicate epoxy resin nanocomposite proving that it is the only import mechanism controlling the reduction in peak heat release rate in the investigated system for different irradiations. The flame retardancy performance is assessed comprehensively illuminating not only the strengths but also the weak points of the concepts. Guidelines for materials development are deduced and discussed. Apart from inorganic fillers (layered silicate, boehmite, etc.) not only carbon nanoobjects such as multiwall carbon nanotubes, multilayer graphene and graphene are investigated, but also nanoparticles that are more reactive and harbor the potential for more beneficial interactions with the polymer matrix. T2 - Times of polymers (TOP) and composites 2014 - 7th international conference on times of polymers (TOP) and composites CY - Ischia, Italy DA - 22.06.2014 KW - Nanotechnology KW - Flame retardancy KW - Nanocomposites KW - Fire behavior KW - Layered silicate KW - Graphene KW - Nanotubes KW - Nanofibers KW - Flammability KW - Cone calorimeter PY - 2014 SN - 978-0-7354-1233-0 DO - https://doi.org/10.1063/1.4876766 SN - 0094-243X N1 - Serientitel: AIP conference proceedings – Series title: AIP conference proceedings VL - 1599 SP - 14 EP - 17 PB - AIP Publishing CY - Melville, New York AN - OPUS4-30994 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schoknecht, Ute A1 - Kalbe, Ute A1 - Van Zomeren, A. A1 - Hjelmar, O. T1 - Laboratory leaching tests on treated wood according to different harmonised test procedures N2 - -Background- Laboratory leaching tests on treated wood were performed during a European robustness study in the framework of the validation of a tank leaching test procedure that has been proposed for construction products in order to determine the potential release of dangerous substances which can be transferred to soil and groundwater. The release of substances has to be determined also for materials treated with biocidal products according to the requirements of the European Biocidal Products Regulation. A similar leaching test procedure was already harmonised for treated wood for this purpose. Both test procedures were applied in parallel to wood treated with the same preservative to investigate whether the results of these tests can replace each other. Additional experiments were performed to further investigate unexpected effects of L/A ratio on leaching of copper and duration of storage of treated test specimens. -Results- Both procedures generate similar results concerning cumulative emissions of tebuconazole, copper, dissolved organic carbon and total nitrogen. The emission rates with time are in comparable ranges for both leaching protocols. Emissions of copper increased with decreasing L/A ratios. Strong correlation of copper concentrations and dissolved organic carbon as well as total nitrogen concentrations in eluates indicates that this observation is caused by co-elution of copper with organic substances. Duration of storage of treated test specimens affected emissions for the investigated wood preservative. -Conclusions- Based on these findings, results from both test procedures can be used to describe leaching characteristics and avoid double testing of treated wood to fulfil the requirements of the European regulations for either biocides or construction products. Leaching of substances from treated wood is a complex process that depends on its chemical composition and ageing processes. KW - Construction products KW - Biocidal product KW - Emission KW - Leaching KW - Tank leaching test KW - Treated wood KW - European regulation PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-317320 UR - http://www.enveurope.com/content/26/1/25 SN - 2190-4715 SN - 2190-4707 VL - 26 SP - 25, 1 EP - 10 PB - Springer CY - Berlin ; Heidelberg AN - OPUS4-31732 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Wirth, Cynthia A1 - Mühler, T. A1 - Günster, Jens T1 - Powder-bed stabilization for powder-based additive manufacturing N2 - The most successful additive manufacturing (AM) technologies are based on the layer-by-layer deposition of a flowable powder. Although considered as the third industrial revolution, one factor still limiting these processes to become completely autonomous is the often necessary build-up of support structures. Besides the prevention of lateral shifts of the part during the deposition of layers, the support assures quality and stability to the built process. The loose powder itself surrounding the built object, or so-called powder-bed, does not provide this sustenance in most existent technology available. Here we present a simple but effective and economical method for stabilizing the powder-bed, preventing distortions in the geometry with no need for support structures. This effect, achieved by applying an air flow through the powder-bed, is enabling an entirely autonomous generation of parts and is a major contribution to all powder-based additive manufacturing technologies. Moreover, it makes powder-based AM independent of gravitational forces, which will facilitate crafting items in space from a variety of powdery materials. KW - Additive manufacturing KW - Powder bed PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-314244 DO - https://doi.org/10.1155/2014/491581 SN - 1687-8132 SN - 1687-8140 N1 - Geburtsname von Wirth, Cynthia: Gomes, C. M. - Birth name of Wirth, Cynthia: Gomes, C. M. VL - 2014 SP - 491581-1 - 491581-6 PB - Hindawi Publishing Corporation CY - New York, NY ; Cairo AN - OPUS4-31424 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dittrich, Bettina A1 - Wartig, K.-A. A1 - Mülhaupt, R. A1 - Schartel, Bernhard T1 - Flame-retardancy properties of intumescent ammonium poly(phosphate) and mineral filler magnesium hydroxide in combination with graphene N2 - Thermally reduced graphite oxide (TRGO), containing only four single carbon layers on average, was combined with ammonium polyphosphate (APP) and magnesium hydroxide (MH), respectively, in polypropylene (PP). The nanoparticle's influence on different flame-retarding systems and possible synergisms in pyrolysis, reaction to small flame, fire behavior and mechanical properties were determined. TRGO has a positive effect on the yield stress, which is decreased by both flame-retardants and acts as a synergist with regard to Young's modulus. The applicability and effects of TRGO as an adjuvant in combination with conventional flame-retardants depends strongly on the particular flame-retardancy mechanism. In the intumescent system, even small concentrations of TRGO change the viscosity of the pyrolysing melt crucially. In case of oxygen index (OI) and UL 94 test, the addition of increasing amounts of TRGO to PP/APP had a negative impact on the oxygen index and the UL 94 classification. Nevertheless, systems with only low amounts (≤1 wt%) of TRGO achieved V-0 classification in the UL 94 test and high oxygen indices (>31 vol%). TRGO strengthens the residue structure of MH and therefore functions as a strong synergist in terms of OI and UL 94 classification (from HB to V-0). KW - Graphene KW - Intumescence KW - Ammonium polyphosphate KW - Magnesium hydroxide KW - Synergy KW - Polypropylene PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-320685 DO - https://doi.org/10.3390/polym6112875 SN - 2073-4360 VL - 6 IS - 11 SP - 2875 EP - 2895 PB - MDPI CY - Basel AN - OPUS4-32068 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Adhami, Forogh A1 - Safavi, Maliheh A1 - Ehsani, Maryam A1 - Ardestani, Sussan K. A1 - Emmerling, Franziska A1 - Simyari, Farzaneh T1 - Synthesis, crystal structure, and cytotoxic activity of novel cyclic systems in [1,2,4]thiadiazolo[2,3-a]pyridine benzamide derivatives and their copper(ii) complexes N2 - Three N-(pyridine-2-ylcarbamothioyl)benzamide derivatives were synthesized by the reaction of potassium thiocyanate, benzoyl chloride, and 2-amino pyridine derivatives in one pot. The obtained derivatives were oxidized using copper(II) chloride. During the oxidation, two hydrogen atoms were removed, cyclization of the derivatives occurred, and finally, three new N-(2H-[1,2,4]thiadiazolo[2,3-a]pyridine-2-ylidene)benzamide derivatives were produced. Coordination of these three new derivative ligands to the copper(II) ion resulted in the formation of three new complexes: dichlorobis(N-(2H-[1,2,4]thiadiazolo[2,3-a]pyridine-2-ylidene)benzamide)copper(II), dichlorobis(N-(7-methyl-2H-[1,2,4]thiadiazolo[2,3-a]pyridine-2ylidene)benzamide)copper(II), and dichlorobis(N-(5-methyl-2H-[1,2,4]thiadiazolo[2,3-a]pyridine-2-ylidene)benzamide)copper(II). All the synthesized products were characterized by IR, 1H NMR, and 13C NMR spectroscopies. Crystal structures of the obtained N-(pyridine-2-ylcarbamothioyl)benzamide derivatives, N-(2H-[1,2,4]thiadiazolo[2,3-a]pyridine-2-ylidene)benzamide derivatives, and complexes were determined using X-ray single-crystal diffraction; the positions of atoms, bond lengths, bond angles, and dihedral angles were also determined. In all complexes, the coordination of two large monodentate ligands and two chloride anions to the copper(II) ion resulted in the formation of a stable planar geometry around the central ion. Three N-(pyridine-2-ylcarbamothioyl)benzamide derivatives, three N-(2H-[1,2,4]thiadiazolo[2,3-a]pyridine-2-ylidene)benzamide derivatives, and three complexes were evaluated for their cytotoxicity against five human cancer cell lines (breast cancer cell line MDA-MB-231, neuroblastoma cell line SK-N-MC, prostate adenocarcinoma cell line LNCap, nasopharyngeal epidermoid carcinoma cell line KB, and liver cancer cell line HEPG-2) using an in vitro analysis. The N-(pyridine-2-ylcarbamothioyl)benzamide derivatives showed no cytotoxic activity, whereas the N-(2H-[1,2,4]thiadiazolo[2,3-a]pyridine-2-ylidene)benzamide derivatives and their complexes showed significant cytotoxicity, especially against MDA-MB-231 and LNCap cell lines. The complexes demonstrated smaller IC50 values than N-(2H-[1,2,4]thiadiazolo[2,3-a]pyridine-2-ylidene)benzamide derivatives. KW - Copper complexes PY - 2014 DO - https://doi.org/10.1039/c3dt52905c SN - 1477-9226 VL - 43 IS - 21 SP - 7945 EP - 7957 PB - Royal Society of Chemistry (RSC) AN - OPUS4-65449 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tschirschwitz, Rico A1 - Schröder, Volkmar A1 - Brandes, E. A1 - Krause, U. T1 - Determination of explosion limits - Criterion for ignition under non-atmospheric conditions N2 - Many industrial processes are run at non-atmospheric conditions (elevated temperatures and pressures, other oxidizers than air). To judge whether and if yes to what extent explosive gas(vapor)/air mixtures will occur or may be generated during malfunction it is necessary to know the safety characteristic data at the respective conditions. Safety characteristic data like Explosion limits, are depending on pressure, temperature and the oxidizer. Most of the determination methods are standardized for ambient conditions. In order to obtain determination methods for non-atmospheric conditions, particularly for higher initial pressures, reliable ignition criteria were investigated. Ignition tests at the explosion Limits were carried out for mixtures of methane, propane, n-butane, n-hexane, hydrogen, ammonia and acetone in air at initial pressures up to 20 bar. The tests have been evaluated according to different ignition criteria: visual flame propagation, temperature and pressure rising. It could be shown that flame propagation and occasionally self-sustained combustion for several seconds occurred together with remarkable temperature rise, although the pressure rise was below 3%. The results showed that the combination of a pressure rise criterion of 2% and a temperature rise criterion of 100 K seems to be a suitable ignition criterion for the determination of explosion limits and limiting oxidizer concentration at higher initial pressures and elevated temperatures. The tests were carried out within the framework of a R&D project founded by the German Ministry of Economics and Technology. KW - Explosion limits KW - Ignition criterion KW - Standardization KW - Non-atmospheric conditions PY - 2015 DO - https://doi.org/10.1016/j.jlp.2015.01.012 SN - 0950-4230 VL - 36 SP - 562 EP - 568 PB - Elsevier CY - Amsterdam AN - OPUS4-36954 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hernández-Nava, E. A1 - Smith, C.J. A1 - Derguti, F. A1 - Tammas-Williams, S. A1 - Léonard, Fabien A1 - Withers, P. J. A1 - Todd, I. A1 - Goodall, R. T1 - The effect of density and feature size on mechanical properties of isostructural metallic foams produced by additive manufacturing N2 - Simple models describing the relationship between basic mechanical properties and the relative density of various types of porous metals (such as foams, sponges and lattice structures) are well established. Carefully evaluating these relationships experimentally is challenging, however, because of the stochastic structure of foams and the fact that it is difficult to systematically isolate density changes from variations in other factors, such as pore size and pore distribution. Here a new method for producing systematic sets of stochastic foams is employed based on electron beam melting (EBM) additive manufacturing (AM). To create idealised structures, structural blueprints were reverse-engineered by inverting X-ray computed tomographs of a randomly packed bed of glass beads. This three-dimensional structure was then modified by computer to create five foams of different relative density ρr, but otherwise consistent structure. Yield strength and Young’s modulus have been evaluated in compression tests and compared to existing models for foams. A power of 3 rather than a squared dependence of stiffness on relative density is found, which agrees with a recent model derived for replicated foams. A similar power of 3 relation was found for yield strength. Further analysis of the strength of nominally fully dense rods of different diameters built by EBM AM suggest that surface defects mean that the minimum size of features that can be created by EBM with similar strengths to machined samples is ∼1 mm. KW - Metal foam KW - Cellular solids KW - Reverse engineering KW - Open-cell foam KW - X-ray computed tomography PY - 2015 DO - https://doi.org/10.1016/j.actamat.2014.10.058 SN - 1359-6462 VL - 85 SP - 387 EP - 395 AN - OPUS4-39071 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kardjilov, N. A1 - Hilger, A. A1 - Manke, I. A1 - Banhart, J. A1 - Griesche, Axel T1 - Imaging with Cold Neutrons at the CONRAD-2 Facility N2 - CONRAD-2 is an imaging instrument using low-energy (cold) neutrons. The instrument is installed at the end of a curved neutron guide which avoids the direct line of sight towards the reactor core. This ensures a very low background of high-energy neutrons and. photons at the sample position. The cold neutron beam provides a wavelength range which is suitable for phase-and diffraction-contrast imaging such as grating interferometry and Bragg edge mapping. The instrument is well suited for high resolution imaging due to the high efficiency of the very thin scintillators that can be used for the detection of cold neutrons. An instrument upgrade was performed recently as a part of an upgrade program for the cold neutron instrumentation at HZB. The parameters of the instrument as well as some research highlights will be presented. T2 - 10th World Conference on Neutron Radiography (WCNR) CY - Grindelwald, SWITZERLAND DA - 05.10.2014 KW - iron embrittlement KW - neutron imaging KW - neutron instrumentation KW - cold neutrons PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-373239 DO - https://doi.org/10.1016/j.phpro.2015.07.008 SN - 1875-3892 VL - 69 SP - 60 EP - 66 PB - Elsevier B.V. CY - Amsterdam, NL AN - OPUS4-37323 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tammas-Williams, S. A1 - Zhao, H. A1 - Léonard, Fabien A1 - Derguti, F. A1 - Todd, I. A1 - Prangnell, P.B. T1 - XCT analysis of the influence of melt strategies on defect population in Ti-6Al-4V components manufactured by Selective Electron Beam Melting N2 - Selective Electron Beam Melting (SEBM) is a promising powder bed Additive Manufacturing technique for near-net-shape manufacture of high-value titanium components. However without post-manufacture HIPing the fatigue life of SEBM parts is currently dominated by the presence of porosity. In this study, the size, volume fraction, and spatial distribution of the pores in model samples have been characterised in 3D, using X-ray Computed Tomography, and correlated to the process variables. The average volume fraction of the pores (b0.2%) was measured to be lower than that usually observed in competing processes, such as selective laser melting, but a strong relationship was found with the differentbeamstrategies used to contour ,and infill by hatching, a part section. The majority of pores were found to be small spherical gas pores, concentrated in the infill hatched region; this was attributed to the lower energy density and less focused beam used in the infill strategy allowing less opportunity for gas bubbles to escape the melt pool. Overall, increasing the energy density or focus of the beam was found to correlate strongly to a reduction in the level of gas porosity. Rarer irregular shaped pores were mostly located in the contour region and have been attributed to a lack of fusion between powder particles. KW - Titanium KW - Additive Manufacture KW - Selective Electron Beam Melting KW - Pores KW - X-ray computed tomography PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-416577 UR - http://www.sciencedirect.com/science/article/pii/S104458031500039X?via%3Dihub DO - https://doi.org/10.1016/j.matchar.2015.02.008 VL - 102 SP - 47 EP - 61 CY - Materials Characterization AN - OPUS4-41657 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hartmann, S. A1 - Shaporin, A. A1 - Hermann, S. A1 - Bonitz, J. A1 - Heggen, M. A1 - Meszmer, P. A1 - Sturm, Heinz A1 - Hölck, O. A1 - Blaudeck, T. A1 - Schulz, S. E. A1 - Mehner, J. A1 - Gessner, T. A1 - Wunderle, B. T1 - Towards nanoreliability of CNT-based sensor applications: Investigations of CNT-metal interfaces combining molecular dynamics simulations, advanced in situ experiments and analytics N2 - In this paper we present results of our recent efforts to understand the mechanical interface behaviour of single-walled carbon nanotubes (CNTs) embedded in metal matrices. We conducted experimental pull-out tests of CNTs embedded in Pd or Au and found Maximum forces in the range 10 - 102 nN. These values are in good agreement with forces obtained from molecular Dynamics simulations taking into account surface functional Groups (SFGs) covalently linked to the CNT material. The dominant failure mode in experiment is a CNT rupture, which can be explained with the presence of SFGs. To qualify the existence of SFGs on our used CNT material, we pursue investigations by means of fluorescence labeling of surface species in combination with Raman imaging. We also report of a tensile test system to perform pull-out tests inside a transmission electron microscope to obtain in situ images of CNT-metal interfaces under mechanical loads at the atomic scale. T2 - 2015 16th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems CY - Budapest, Hungary DA - 20.4.2015 KW - Carbon nanotube CNT KW - Metal matrix KW - Pull-out test KW - Molecular dynamics simulation KW - Surface functional groups KW - Fluorescence labeling KW - Raman imaging KW - Tensile test inside a TEM PY - 2015 SN - 978-1-4799-9950-7 VL - 2015 SP - 1 EP - 8 PB - IEEE AN - OPUS4-37625 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hahn, Marc Benjamin A1 - Solomun, Tihomir A1 - Wellhausen, Robert A1 - Herrmann, S A1 - Seitz, H A1 - Meyer, Susann A1 - Kunte, Hans-Jörg A1 - Zeman, J. A1 - Uhlig, F A1 - Smiatek, J A1 - Sturm, Heinz T1 - Influence of the Compatible Solute Ectoine on the Local Water Structure: Implications for the Binding of the Protein G5P to DNA N2 - Microorganisms accumulate molar concentrations of compatible solutes like ectoine to prevent proteins from denaturation. Direct structural or spectroscopic information on the mechanism and about the hydration shell around ectoine are scarce. We combined surface plasmon resonance (SPR), confocal Raman spectroscopy, molecular dynamics simulations, and density functional theory (DFT) calculations to study the local hydration shell around ectoine and its influence on the binding of a gene-S-protein (G5P) to a single-stranded DNA (dT(25)). Due to the very high hygroscopicity of ectoine, it was possible to analyze the highly stable hydration shell by confocal Raman spectroscopy. Corresponding molecular dynamics simulation results revealed a significant change of the water dielectric constant in the presence of a high molar ectoine concentration as compared to pure water. The SPR data showed that the amount of protein bound to DNA decreases in the presence of ectoine, and hence, the protein-DNA dissociation constant increases in a concentration-dependent manner. Concomitantly, the Raman spectra in terms of the amide I region revealed large changes in the protein secondary structure. Our results indicate that ectoine strongly affects the molecular recognition between the protein and the oligonudeotide, which has important consequences for osmotic regulation mechanisms. KW - Aqueous solution KW - Biological structure KW - Raman spectroscopy KW - Organic osmolytes KW - High throughput KW - Gene-5 protein KW - Amino acid KW - Water structure PY - 2015 DO - https://doi.org/10.1021/acs.jpcb.5b09506 SN - 1520-6106 SN - 1089-5647 SN - 1520-5207 VL - 119 IS - 49 SP - 15212 EP - 15220 AN - OPUS4-35800 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wäsche, Rolf A1 - Hartelt, Manfred A1 - Hodoroaba, Vasile-Dan T1 - Analysis of nanoscale wear particles from lubricated steel-steel contacts N2 - A new method for sampling wear particles directly from the lubricant reservoir has been developed and applied successfully for analyzing wear particles by high-resolution scanning electron microscopy in transmission mode having coupled energy-dispersive X-ray spectroscopy. The lubricated tribological testing was carried out with fully formulated as well as with non-formulated synthetic base oil. It was possible to analyze individual particles with dimensions as small as about 5–30 nm which are likely the 'primary' wear particles. A majority of the particles, however, are agglomerated and, thus, lead to the formation of larger agglomerates of up to a few micrometers. Chemical analysis led to the conclusion that most of the observed particles generated in formulated oil, especially the larger ones, are composed of the additives of the lubricant oil. In non-formulated base oil, the primary particles are of similar dimensions but contain only iron, chromium and oxygen, but most likely stem from the mating materials. This finding points to the fact that the main wear mechanism under lubricated conditions with fully formulated oil is more like a continuous shearing process rather than a catastrophic failure with the generation of larger primary particles. When the oil is non-formulated, however, several wear mechanisms act simultaneously and the wear rate is increased significantly. Generated larger primary particles are milled down to the nanoscale. When the oil is fully formulated, wear mainly takes places at the additive layer or tribofilm; thus, the steel surface is protected. KW - Particle KW - Wear particle analysis KW - Lubricated contact KW - Bearing steel KW - Nanoscale T-SEM KW - Nanoscale EDX analysis PY - 2015 DO - https://doi.org/10.1007/s11249-015-0534-1 SN - 1023-8883 SN - 1573-2711 VL - 58 IS - 3 SP - 49-1 - 49-10 PB - Springer Science Business Media B.V. CY - Dordrecht AN - OPUS4-33525 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Matzen, Melissa A1 - Kandola, B. A1 - Huth, Christian A1 - Schartel, Bernhard T1 - Influence of flame retardants on the melt dripping behaviour of thermoplastic polymers N2 - Melt flow and dripping of the pyrolysing polymer melt can be both a benefit and a detriment during a fire. In several small-scale fire tests addressing the ignition of a defined specimen with a small ignition source, well-adjusted melt flow and dripping are usually beneficial to pass the test. The presence of flame retardants often changes the melt viscosity crucially. The influence of certain flame retardants on the dripping behaviour of four commercial polymers, poly(butylene terephthalate) (PBT), polypropylene (PP), polypropylene modified with ethylene-propylene rubber (PP-EP) and polyamide 6 (PA 6), is analysed based on an experimental monitoring of the mass loss due to melt dripping, drop size and drop temperature as a function of the furnace temperature applied to a rod-shaped specimen. Investigating the thermal transition (DSC), thermal and thermo-oxidative decomposition, as well as the viscosity of the polymer and collected drops completes the investigation. Different mechanisms of the flame retardants are associated with their influence on the dripping behaviour in the UL 94 test. Reduction in decomposition temperature and changed viscosity play a major role. A flow limit in flame-retarded PBT, enhanced decomposition of flame-retarded PP and PP-EP and the promotion of dripping in PA 6 are the salient features discussed. KW - Fire retardant KW - Viscosity KW - Melt dripping KW - Reaction-to-small-flame KW - UL 94 PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-338941 DO - https://doi.org/10.3390/ma8095267 SN - 1996-1944 VL - 8 IS - 9 SP - 5621 EP - 5646 PB - MDPI CY - Basel AN - OPUS4-33894 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Breßler, Ingo A1 - Kohlbrecher, J. A1 - Thünemann, Andreas T1 - SASfit: a tool for small-angle scattering data analysis using a library of analytical expressions N2 - SASfit is one of the mature programs for small-angle scattering data analysis and has been available for many years. This article describes the basic data processing and analysis workflow along with recent developments in the SASfit program package (version 0.94.6). They include (i) advanced algorithms for reduction of oversampled data sets, (ii) improved confidence assessment in the optimized model parameters and (iii) a flexible plug-in system for custom user-provided models. A scattering function of a mass fractal model of branched polymers in solution is provided as an example for implementing a plug-in. The new SASfit release is available for major platforms such as Windows, Linux and MacOS. To facilitate usage, it includes comprehensive indexed documentation as well as a web-based wiki for peer collaboration and online videos demonstrating basic usage. The use of SASfit is illustrated by interpretation of the small-angle X-ray scattering curves of monomodal gold nanoparticles (NIST reference material 8011) and bimodal silica nanoparticles (EU reference material ERM-FD-102). KW - Small-angle X-ray scattering KW - Small-angle neutron scattering KW - Curve fitting KW - Nanotechnology KW - Nanoparticles KW - Polymers KW - SAXS PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-343348 DO - https://doi.org/10.1107/S1600576715016544 SN - 0021-8898 SN - 1600-5767 VL - 48 SP - 1587 EP - 1598 PB - Blackwell CY - Oxford AN - OPUS4-34334 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Breßler, Ingo A1 - Pauw, Brian Richard A1 - Thünemann, Andreas T1 - McSAS: software for the retrieval of model parameter distributions from scattering patterns N2 - A user-friendly open-source Monte Carlo regression package (McSAS) is presented, which structures the analysis of small-angle scattering (SAS) using uncorrelated shape-similar particles (or scattering contributions). The underdetermined problem is solvable, provided that sufficient external information is available. Based on this, the user picks a scatterer contribution model (or 'shape') from a comprehensive library and defines variation intervals of its model parameters. A multitude of scattering contribution models are included, including prolate and oblate nanoparticles, core-shell objects, several polymer models, and a model for densely packed spheres. Most importantly, the form-free Monte Carlo nature of McSAS means it is not necessary to provide further restrictions on the mathematical form of the parameter distribution; without prior knowledge, McSAS is able to extract complex multimodal or odd-shaped parameter distributions from SAS data. When provided with data on an absolute scale with reasonable uncertainty estimates, the software outputs model parameter distributions in absolute volume fraction, and provides the modes of the distribution (e.g. mean, variance etc.). In addition to facilitating the evaluation of (series of) SAS curves, McSAS also helps in assessing the significance of the results through the addition of uncertainty estimates to the result. The McSAS software can be integrated as part of an automated reduction and analysis procedure in laboratory instruments or at synchrotron beamlines. KW - Nanotechnology KW - Nanoparticles KW - Small-angle X-ray scattering KW - SAXS PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-334396 DO - https://doi.org/10.1107/S1600576715007347 SN - 0021-8898 SN - 1600-5767 VL - 48 IS - 3 SP - 962 EP - 969 PB - Blackwell CY - Oxford AN - OPUS4-33439 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dmitriev, A. I. A1 - Häusler, Ines A1 - Wetzel, B. A1 - Zhang, G. A1 - Österle, Werner T1 - Modeling of the stress-strain behavior of an epoxy-based nanocomposite filled with silica nanoparticles N2 - The method of movable cellular automata (MCA) was applied to simulate the stress-strain behavior of a nano composite consisting of an epoxy matrix and 6 vol. % silica nano particles. The size of the elements used for modelling was fixed at 10 nm, corresponding approximately to the diameter of the filler particles. Since not only the stress-strain response of the two constituents but also debonding of neighboring particles and granular flow was taken into account, plastic deformation as well as crack initiation and propagation could be simulated with the model. Modelling results were compared with tensile test results of both, pure epoxy as well as the epoxy-6 vol. % SiO2 composite. Since assuming bulk properties of the two constituents did not yield satisfactory results, slight modifications of the nanoparticle response functions and nanostructures were tested numerically. Finally, it was observed that only the assumption of slightly increased strength properties of the epoxy yielded good correlation between experimental and modelling results. This was attributed to an increased cross linking of the epoxy caused by the presence of silica nano particles. KW - Nanocomposite KW - Polymer matrix composite KW - Stress-strain behavior KW - Modeling KW - Computational mechanics PY - 2016 DO - https://doi.org/http://dx.doi.org/10.1016/j.matdes.2015.10.038 SN - 0264-1275 VL - 89 SP - 950 EP - 956 PB - Elsevier AN - OPUS4-35596 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Österle, Werner A1 - Dmitriev, A. I. A1 - Wetzel, B. A1 - Zhang, G. A1 - Häusler, Ines A1 - Jim, B.C. T1 - The role of carbon fibers and silica nanoparticles on friction and wear reduction of an advanced polymer matrix composite N2 - Excellent tribological properties of an advanced polymer matrix composite were obtained by a combination of micro- and nano-sized fillers. Surface features and the nanostructure of tribofilms were characterized by advanced microscopic techniques, and correlated with the macroscopic behavior in terms of wear rate and friction evolution. A model based on movable cellular automata was applied for obtaining a better understanding of the sliding behavior of the nanostructured tribofilms. The failure of the conventional composite without silica nanoparticles could be attributed to severe oxidational wear after degradation of an initially formed polymer transfer film. The hybrid composite preserves its antiwear and antifriction properties because flash temperatures at micron-sized carbon fibers, lead to polymer degradation and subsequent release of nanoparticles. It has been shown that the released particles are mixed with other wear products and form stable films at the disc surface thus preventing further severe oxidational wear. Furthermore, the released wear product also is embedding carbon fibers at the composite surface thus preventing fiber fragmentation and subsequent third body abrasion. With nanoscale modelling we were able to show that low friction and wear can be expected if the nanostructured silica films contain at least 10 vol.% of a soft ingredient. KW - Carbon fibers KW - Silica nanoparticles KW - Hybrid composite KW - Tribological properties KW - Tribofilm KW - Sliding simulation PY - 2016 DO - https://doi.org/10.1016/j.matdes.2015.12.175 SN - 0264-1275 VL - 93 SP - 474 EP - 484 PB - Elsevier AN - OPUS4-35598 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lehmann, Jens A1 - Burkert, Andreas A1 - Mietz, Jürgen T1 - Investigations proofing the passive layer stability of stainless steels N2 - The presented investigations have proved the principal suitability of the KorroPad method to assess the passive layer stability of stainless steels. The electrochemical mode of action could be described in detail and limitations of the applicability have been demonstrated. The influence of different surface finishes has been investigated and verified by known methods for describing corrosion resistances. As a result, the increased corrosion susceptibility of two ground surfaces has been detected, but also the corrosion resistance of further surface finishes could be confirmed. KW - Stainless steel KW - KorroPad KW - Passive layer PY - 2016 DO - https://doi.org/10.1002/maco.201408202 VL - 1 IS - 67 SP - 84 EP - 91 PB - WILEY-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-35545 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Burbank, John A1 - Woydt, Mathias T1 - Optimization of pre-conditioned cold work hardening of steel alloys for friction and wear reductions under slip-rolling contact N2 - The goal of reducing CO2 emissions in the automobile industry has led to the development of increasingly efficient lightweight material solutions that yield enhanced performance. In light of this goal, this current work involves the optimization of the pre-conditioning of novel, high toughness steel bearings without thermo-chemical treatment, with the aim of transferring the running-in phase into the final step of the mechanical finishing process. A case-hardened gear steel and two novel non-case-hardened steels were evaluated. KW - Work hardening KW - Steel KW - Gear KW - Bearing KW - Residual stress KW - Hardness PY - 2016 DO - https://doi.org/10.1016/j.wear.2016.01.011 SN - 0043-1648 VL - 350-351 SP - 141 EP - 154 PB - Elsevier B.V. CY - Amsterdam, u.a. AN - OPUS4-35665 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bachmann, Marcel A1 - Kunze, R. A1 - Avilov, Vjaceslav A1 - Rethmeier, Michael T1 - Finite element modeling of an alternating current electromagnetic weld pool support in full penetration laser beam welding of thick duplex stainless steel plates N2 - An electromagnetic weld pool support system for 20 mm thick duplex stainless steel AISI 2205 was investigated numerically and compared to experiments. In our former publications, it was shown how an alternating current (AC) magnetic field below the process zone directed perpendicular to the welding direction can induce vertically directed Lorentz forces. These can counteract the gravitational forces and allow for a suppression of material drop-out for austenitic stainless steels and aluminum alloys. In this investigation, we additionally adopted a steady-state complex magnetic permeability model for the consideration of the magnetic hysteresis behavior due to the ferritic characteristics of the material. The model was calibrated against the Jiles–Atherton model. The material model was also successfully tested against an experimental configuration before welding with a 30 mm diameter cylinder of austenitic stainless steel sur-rounded by duplex stainless steel. Thereby, the effects of the Curie temperature on the magnetic characteristics in the vicinity of the later welding zone were simulated. The welding process was modeled with a three-dimensional turbulent steady-state model including heat transfer and fluid dy-namics as well as the electromagnetic field equations. Main physical effects, the thermo-capillary (Marangoni) convection at the weld pool boundaries, the natural convection due to gravity as well as latent heat of solid–liquid phase transitions at the phase boundaries were accounted for in the model. The feedback of the electromagnetic forces on the weld pool was described in terms of the electromagnetic-induced pressure. The finite element software COMSOL Multiphysics 4.2 was used in this investigation. It is shown that the gravity drop-out associated with the welding of 20 mm thick duplex stainless steel plates due to the hydrostatic pressure can be prevented by the application of AC magnetic fields between around 70 and 90 mT. The corresponding oscillation frequencies were between 1 and 10 kHz and the electromagnetic AC powers were between 1 and 2.3 kW. In the experiments, values of the electromagnetic AC power between 1.6 and 2.4 kW at os-cillation frequencies between 1.2 and 2.5 kHz were found to be optimal to avoid melt sagging or drop-out of melt in single pass full-penetration laser beam welding of 15 and 20 mm thick AISI 2205. KW - Laser KW - Numerical simulation KW - Laser beam welding KW - Electromagnetic weld pool support KW - Duplex stainless steel PY - 2016 DO - https://doi.org/10.2351/1.4943906 VL - 28 IS - 2 SP - 022404-1 EP - 022404-9 PB - AIP Publishing AN - OPUS4-35676 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Javdanitehran, M. A1 - Berg, D. Ch. A1 - Dümichen, Erik A1 - Ziegmann, G. ED - Javdanitehran, M. T1 - An iterative approach for isothermal curing kinetics modelling of an epoxy resin system N2 - In this work a novel iterative method for isothermal cure kinetic modelling of an epoxy resin system using differential scanning calorimetry (DSC) technique is presented. To reach the isothermal cure temperature, the sample has to be heated up from ambient temperature. This is commonly done with very high heat-up rates to minimise the time the sample reacts at temperatures other than the desired one. However, during heat up with high heating the amount of released energy rates cannot be measured directly because the shape of baseline is unknown. This means that the cure state at the beginning of the isothermal stage is unknown. For fast curing systems this unknown cure state causes significant inaccuracies in cure kinetics modelling. The presented iterative approach attempts to estimate the released enthalpy during heat-up of an isothermal run through an iterative numerical modelling of the heat-up phase. In each iteration the algorithm starts by estimating the enthalpy released during heat-up based on the recorded temperature profile and the calibrated model of the previous iteration. At the same time, it estimates the degree of cure at the end of the heat-up phase. Once the initial cure state is known the total heat of enthalpy can be recalculated for the current iteration. Subsequently the degree of cure and curing rate are re-evaluated with the newly estimated total enthalpy and used for determining the kinetics parameters. This is done by simultaneous fitting of the selected model to all experimental heat flow curves using a non-linear nonrestricted multivariable fitting method. The model with these new parameters is used again to estimate the released enthalpy and cure degree during the heat-up phase. The described loop is repeated until a predefined convergence criterion is satisfied. For modelling the reaction kinetics, the Kamal–Sourour equation accompanied with Rabinowitch approach to consider the diffusion effects is used. The diffusion reaction rate is modelled by the free volume model proposed by Huguenin and Klein. DiBenedetto model is applied to predict the Evolution of glass transition temperature against the degree of cure. In order to compensate the effect of the Initial values in the model’s calibration, the algorithm is implemented in a routine, which assesses the quality of the fitting and consequently selects the cure kinetics parameter. The described algorithm and the Routine are implemented in MATLAB. This paper demonstrates the application of this approach for using cure kinetics modelling to predict the degree of cure and the glass transition temperature. It supports the obtained results with validation tests using isothermal, dynamic and combined temperature profiles. KW - Epoxy resins KW - Curing kinetics KW - DSC KW - Isothermal PY - 2016 DO - https://doi.org/10.1016/j.tca.2015.11.014 VL - 2016 IS - 623 SP - 72 EP - 79 PB - Elsevier B.V. AN - OPUS4-35719 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fischer, Franziska A1 - Schmidt, M. U. A1 - Greiser, Sebastian A1 - Emmerling, Franziska T1 - The challenging case of the theophylline–benzamide cocrystal N2 - Theophylline has been used as an active pharmaceutical ingredient (API) in the treatment of pulmonary diseases, but due to its low water solubility reveals very poor bioavailability. Based on its different hydrogen-bond donor and acceptor groups, theophylline is an ideal candidate for the formation of cocrystals. The crystal structure of the 1:1 benzamide cocrystal of theophylline, C7H8N4O2·-C7H7NO, was determined from synchrotron X-ray powder diffraction data. The compound crystallizes in the tetragonal space group P41 with four Independent molecules in the asymmetric unit. The molecules form a hunter’s fence packing. The crystal structure was confirmed by dispersion-corrected DFT calculations. The possibility of salt formation was excluded by the results of Raman and 1H solid-state NMR spectroscopic analyses. KW - powder diffraction KW - theophylline KW - benzamide KW - cocrystal KW - crystal structure KW - active pharmaceutical ingredient KW - dispersion-corrected density-functional theory PY - 2016 DO - https://doi.org/10.1107/S2053229616002643 SN - 2053-2296 VL - 72 IS - 3 SP - 217 EP - 224 AN - OPUS4-35621 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wu, Cheng-Chieh A1 - Weisbrich, S. A1 - Neitzel, F. ED - Nicoletto, G. ED - Pastrama, S. D. ED - Emri, I. T1 - Inverse finite element adjustment of material parameters from integrated analysis of displacement field measurement N2 - The determination of material parameters from displacement field measurement is being examined for linear elastic solid. A frequently used approach to compute material constants can be found in many studies. Even though they presented the approach in many different variations, but in the end they are essentially based on the same algorithm: Parameters are iteratively tuned until the computed results are in accordance with the measurements. The main drawback of this approach is that mainly commercial software is used that hinders us to investigate its inner evaluation process. This leads to the question, how the results from this commercial software can be trusted. On the contrary to these debatable approaches, we present a method that inverts the procedure of finite element method by using the most general model for a least-squares adjustment – the GAUSS-HELMERT Model. T2 - 32nd DANUBIA ADRIA SYMPOSIUM on Advances in Experimental Mechanics CY - Starý Smokovec, Slovakia DA - 22.09.2015 KW - Integrated analysis KW - Inverse problem KW - Finite element method KW - Least-squares adjustment KW - Model and measurement based analysis PY - 2016 UR - http://www.sciencedirect.com/science/article/pii/S2214785316002091 DO - https://doi.org/10.1016/j.matpr.2016.03.004 SN - 2214-7853 VL - 3 IS - 4 SP - 1211 EP - 1215 PB - Elsevier Ltd. AN - OPUS4-35629 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fahmy, Alaa A1 - Schönhals, Andreas T1 - Reaction of CO2 gas with (radicals in) plasma-polymerized acrylic acid (and formation of COOH-rich polymer layers) N2 - In contrast to most of the existing literature on plasma polymerization of acrylic acid (AA), not only the chemical structure and film thickness of the deposits were studied, but also a new way to obtain COOH-rich surfaces. This is an important aspect when applying the obtained coatings for biomedical and electronics applications. Therefore, acrylic acid/CO2 polymer films with a thickness of ca. 150 nm were deposited in the pulsed plasma regime onto polyethylene and aluminium as organic and inorganic substrates. Their structure–property relationships were studied in dependence on the mixture ratio of acrylic acid monomer and CO2 gas. The influence of the CO2 gas on the regularity and functionality of plasma deposited poly(acrylic acid) (PAA) was studied in detail using bulk-sensitive (dielectric spectroscopy and Fourier transforms infrared spectroscopy) as well as surface-sensitive methods such as X-ray photoelectron spectroscopy. For a clear identification of the functionality of the deposited films, the COOH groups were estimated after derivatization with trifluoroethanol by XPS measurement as well as by the quantitative analysis of the FTIR data. Results show, in presence of a small amount of CO2 gas within the acrylic acid plasma, a structure of poly(acrylic acid) with high concentration of COOH groups was obtained. However, the excess of CO2 gas in the plasma chamber leads to fragmentation of the monomer or/and degradation of the layer which is already deposited. A polymer network is obtained with an increasing abundance of branched groups for AA/CO2 with increasing CO2 gas in the mixture. KW - Poly(acrylic acid) KW - Plasma polymerization KW - COOH rich surfaces PY - 2016 DO - https://doi.org/10.1002/ppap.201500128 SN - 1612-8850 VL - 13 IS - 5 SP - 499 EP - 508 PB - Wiley-VCH Verlag CY - Weinheim AN - OPUS4-36058 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Klingbeil, Dietmar A1 - Svendsen, B. A1 - Reusch, F. T1 - Gurson-based modelling of ductile damage and failure during cyclic loading processes at large deformation N2 - Purpose is the formulation, numerical implementation, identification and application of a material model for ductile damage and failure during cyclic and non-proportional loading. The authors combined a hyperelasticity-based elasto-plastic model for non-linear isotropic as well as kinematic hardening with a modified Gurson model. Evolution strategy helped identify the model parameters for the high-strength steel 10MnMoNi5-5. The simulation of ductile failure in fracture mechanics specimens verified the model with respect to cyclic loading at two temperatures. The simulation of additional fracture mechanics applications validated the model as to the development of residual stresses at the crack tip under cyclic loads. KW - Ductile damage KW - Combined non-linear hardening with cyclic loading KW - Finite-element simulation KW - Material parameter identification KW - Residual stresses PY - 2016 UR - http://www.sciencedirect.com/science/article/pii/S0013794416301138 DO - https://doi.org/10.1016/j.engfracmech.2016.03.023 SN - 0013-7944 VL - 160 SP - 95 EP - 123 PB - Pergamon-Elsevier Science Ltd. CY - Oxford, UK AN - OPUS4-36121 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kloß, Heinz A1 - Woydt, Mathias T1 - Prediction of tribological limits in sliding contacts: flash temperature calculations in sliding contacts and material behavior N2 - In order to achieve greater efficiency or to meet light weight requirements, components are downsized. This, however, increases the load, e.g., Hertzian or nominal contact pressures and stresses of tribosystems. This load is expressed as pₐ·v-value, the product of nominal contact pressure and sliding velocity. pₐ·v-values are an effective tool for design engineers for predicting low wear/high wear transitions. Therefore, in the present work, topographical analysis has been combined with the plasticity of micro-asperities and the flash temperatures to estimate the limits of pₐ·v diagrams. The central piece of this set of models presented here is the calculations for flash temperatures and contact mechanics of micro-asperities. This central piece is used to predict the performance of materials in high velocity (turbines, machinery) and low velocity (human joint) applications. It is shown that the model combination suggested here is a useful tool for screening and preselecting a candidate and new materials with respect to tribological requirements before engaging in expensive testing. KW - Hot spot KW - Flash temperature KW - Micro-asperity KW - Abrasive wear KW - Turbine KW - Artificial hip joint KW - Low wear/high wear transition PY - 2016 DO - https://doi.org/10.1115/1.4033132 SN - 0742-4787 SN - 1528-8897 VL - 138 IS - 3 SP - 031403-1 EP - 031403-11 PB - The American Society of Mechanical Engineers AN - OPUS4-36122 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neubert, Sebastian A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Numerical sensitivity analysis of TRIP-parameter K on weld residual stresses for steel S355J2+ N N2 - A combined experimental numerical approach is applied for sensitivity analysis of the transformation induced plasticity (TRIP)-parameter K on weld residual stresses for welding of structural steel of grade S355J2+N. K was determined experimentally using the Gleeble 3500 facility. A thermomechanical FE model of the real welding process was experimentally validated against temperature field and X-ray stress measurements. Within sensitivity analyses K was varied by several orders of magnitude and the influence on the calculated residual stresses is evaluated by performing corresponding FEA. The correct order of magnitude is sufficient to reproduce the residual stresses qualitatively and quantitatively. KW - TRIP - transformation induced plasticity KW - welding residual stresses KW - sensitivity analysis KW - FEA PY - 2016 DO - https://doi.org/10.1080/01495739.2015.1124641 SN - 0149-5739 VL - 2016 IS - 39/2 SP - 201 EP - 219 PB - Journal of Thermal Stresses AN - OPUS4-35880 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Burbank, John A1 - Woydt, Mathias T1 - Friction and wear reductions in slip-rolling steel contacts through pre-conditioned chemical tribofilms from bismuth compounds N2 - Downsizing in mechanical systems requires effective lubrication strategies to ensure that increased contact stresses do not cause critical material failure during operation. Additionally, eco-toxicological consideration are becoming increasingly important. In this regard, the goal of this investigation is to transfer the running-in phase into the final step of the mechanical finishing process through the targeted pre-conditioning of novel, high toughness steel bearings without thermo-chemical treatments and compare these to conventional, case-hardened Steels. Pre-conditioning involved implementation of the ecologically sustainable, bismuth-based additives to generate chemically reactive tribofilms on slip-rolling contacts by using a formulation with a high concentration of tribofilm forming additive. Generated tribofilms were analyzed by Raman spectroscopy to elucidate their molecular composition and, ultimately, determine the reaction mechanisms of bismuth-based tribofilm formation. Tribofilm-protected samples were subjected to slip-rolling endurance testing in a factory fill engine oil without pre-conditioning additives to determine the influence of pre-condition tribofilms on friction behavior and wear performance. It was observed that pre-conditioned tribofilms from the bismuth-based additives were able to yield lower coefficients of friction (COF) and profilometric wear coefficients than for Steels without pre-conditioning. Moreover, COF values under mixed/boundary conditions approaching and even less than 0.04 were achieved, thereby rivaling DLC-coated alloy equivalents. KW - tribofilm KW - bismuth KW - carbamate KW - slip-rolling KW - friction KW - wear PY - 2016 DO - https://doi.org/doi:10.1016/j.wear.2016.04.004 SN - 0043-1648 VL - 360-361 SP - 29 EP - 37 PB - Elsevier B.V. AN - OPUS4-35919 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Madkour, Sherif A1 - Melnichu, I. A1 - Choukourov, A. A1 - Krakovsky, I. A1 - Biedermann, H. A1 - Schönhals, Andreas T1 - In situ nanocalorimetric investigations of plasma assisted deposited poly(ethylene oxide)-like films by specific heat spectroscopy N2 - In the recent years, highly crosslinked plasma polymers have started to unveil their potential in numerous biomedical applications in thin-films form. However, conventional diagnostic methods often fail due to their diverse molecular dynamics conformations. Here, glassy dynamics and the melting transition of thin PEO-like plasma assisted deposited (ppPEO) films (thickness 100 nm) were In situ studied by a combination of specific heat spectroscopy, utilizing pJ/K sensitive AC-calorimeter chip, and composition analytical techniques. Different crosslinking densities were obtained by different plasma powers during the deposition of the films. Glassy dynamics was observed for all values of the plasma power. It was found that the glassy dynamics slows down with increasing the plasma power. Moreover, the underlying relaxation time spectra broaden indicating that the molecular motions become more heterogeneous with increasing plasma power. In a second set of experiment, the melting behavior of the ppPEO films was studied. The melting temperature of ppPEO was found to be decreasing with increasing plasma power. This was explained by a decrease of the order in the crystals due to formation of chemical defects during the plasma process. KW - Plasma deposited polymers KW - Nanocalorimetry KW - Thin polymer films KW - Glass transition PY - 2016 DO - https://doi.org/10.1021/acs.jpcb.6b01355 SN - 1520-6106 SN - 1520-5207 VL - 120 IS - 16 SP - 3954 EP - 3962 PB - American Chemical Society CY - Washington, DC, USA AN - OPUS4-35922 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fasano, A. A1 - Woyessa, G. A1 - Stajanca, Pavol A1 - Markos, C. A1 - Stefani, A. A1 - Nielsen, K. A1 - Rasmussen, H. K. A1 - Krebber, Katerina A1 - Bang, O. ED - Kalli, K. ED - Mendez, A. T1 - Creation of a microstructured polymer optical fiber with UV Bragg grating inscription for the detection of extensions at temperatures up to 125°C N2 - We describe the fabrication of a polycarbonate (PC) micro-structured polymer optical fiber (mPOF) and the writing of fiber Bragg gratings (FBGs) in it to enable strain and temperature measurements. We demonstrate the photosensitivity of a dopant-free PC fiber by grating inscription using a UV laser. We further show that PC Bragg gratings can be extended up to at least 3% without affecting the initial functionality of the micro-structured fiber. The response of PC FBGs to temperature up to 125°C is also investigated. Polycarbonate has good mechanical properties and its high temperatureresistance might extend the range of application of polymeric FBGs. T2 - Photonics Europe 2016, Micro-Structured and Specialty Optical Fibres IV CY - Brussels, Belgium DA - 03.04.2016 KW - fiber Bragg gratings KW - Polycarbonate KW - polymers KW - micro-structured polymer optical fibers KW - UV laser inscription KW - optical fiber sensors PY - 2016 DO - https://doi.org/10.1117/12.2227843 VL - 9886 SP - 988619-1 EP - 988619-6 PB - SPIE AN - OPUS4-35928 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Höhm, S. A1 - Koter, Robert A1 - Hartelt, Manfred A1 - Spaltmann, Dirk A1 - Pentzien, Simone A1 - Rosenfeld, A. A1 - Krüger, Jörg T1 - Tribological performance of sub-100-nm femtosecond laser-induced periodic surface structures on titanium N2 - Sub-100-nm laser-induced periodic surface structures (LIPSS) were processed on bulk titanium (Ti) surfaces by femtosecond laser pulse irradiation in air (30 fs pulse duration, 790 nm wavelength). The laser peak fluence, the spatial spot overlap, and the number of overscans were optimized in a sample-scanning geometry in order to obtain large surface areas (5 mm × 5 mm) covered homogeneously by the LIPSS. The laser-processed regions were characterized by optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM). The friction coefficient of the nanostructured surfaces was tested during 1000 cycles under reciprocal sliding conditions (1 Hz, 1.0 N normal load) against a 10-mm diameter ball of hardened 100Cr6 steel, both in paraffin oil and in engine oil used as lubricants. Subsequently, the corresponding wear tracks were qualified by OM, SEM, and energy dispersive X-ray analyses (EDX). The results of the tribological tests are discussed and compared to that obtained for near wavelength-sized fs-LIPSS, processed under somewhat different irradiation conditions. Some constraints for a beneficial effect of LIPSS on the tribological performance are provided. KW - Femtosecond laser ablation KW - Laser-induced periodic surface structures, LIPSS KW - Friction KW - Wear KW - Nanostructures KW - Surface functionalization PY - 2016 UR - http://www.sciencedirect.com/science/article/pii/S0169433215026987 DO - https://doi.org/10.1016/j.apsusc.2015.11.019 SN - 0169-4332 SN - 1873-5584 VL - 374 SP - 190 EP - 196 PB - Elsevier B.V. CY - Amsterdam, Netherlands AN - OPUS4-35937 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Höhm, S. A1 - Herzlieb, M. A1 - Rosenfeld, A. A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Dynamics of the formation of laser-induced periodic surface structures (LIPSS) upon femtosecond two-color double-pulse irradiation of metals, semiconductors, and dielectrics N2 - In order to address the dynamics and physical mechanisms of LIPSS formation for three different classes of materials (metals, semiconductors, and dielectrics), two-color double-fs-pulse experiments were performed on Titanium, Silicon and Fused Silica. For that purpose a Mach–Zehnder interferometer generated polarization controlled (parallel or cross-polarized) double-pulse sequences at 400 nm and 800 nm wavelength, with inter-pulse delays up to a few picoseconds. Multiple of these two-color double-pulse sequences were collinearly focused by a spherical mirror to the sample surfaces. The fluence of each individual pulse (400 nm and 800 nm) was always kept below its respective ablation threshold and only the joint action of both pulses lead to the formation of LIPSS. Their resulting characteristics (periods, areas) were analyzed by scanning electron microscopy. The periods along with the LIPSS orientation allow a clear identification of the pulse which dominates the energy coupling to the material. For strong absorbing materials (Silicon, Titanium), a wavelength-dependent plasmonic mechanism can explain the delay-dependence of the LIPSS. In contrast, for dielectrics (Fused Silica) the first pulse always dominates the energy deposition and LIPSS orientation, supporting a non-plasmonic formation scenario. For all materials, these two-color experiments confirm the importance of the ultrafast energy deposition stage for LIPSS formation. KW - Femtosecond laser ablation KW - Double-pulse experiments KW - Laser-induced periodic surface structures (LIPSS) KW - Mach-Zehnder interferometer KW - Ultrafast optical techniques PY - 2016 UR - http://www.sciencedirect.com/science/article/pii/S0169433215031347 DO - https://doi.org/10.1016/j.apsusc.2015.12.129 SN - 0169-4332 SN - 1873-5584 VL - 374 SP - 331 EP - 338 PB - Elsevier CY - Amsterdam, Netherlands AN - OPUS4-35938 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Zergioti, I. A1 - Delaporte, P. A1 - Scarisoreanu, N. D. T1 - Preface - E-MRS 2015 Spring Meeting Symposium CC: “Laser and plasma processing for advanced applications in material science”, 11-15 May 2015, Lille (France) N2 - This article represents the editorial preface for the proceedings of the Symposium CC “Laser and plasma processing for advanced applications in material science” held from May 11th to 15th 2015 in the Lille Grand Palais, France, during the annual Spring Meeting of the European Materials Research Society (E-MRS). KW - Laser processing KW - Plasma processing KW - Material sciences KW - Advanced applications PY - 2016 UR - http://www.sciencedirect.com/science/article/pii/S0169433216307243 DO - https://doi.org/10.1016/j.apsusc.2016.03.231 SN - 0169-4332 SN - 1873-5584 VL - 374 SP - 1 EP - 1 PB - Elsevier B.V. CY - Amsterdam, Netherlands AN - OPUS4-35939 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wildgruber, M. A1 - Lueg, C. A1 - Borgmeyer, S. A1 - Karimov, I. A1 - Braun, Ulrike A1 - Kiechle, M. A1 - Meier, R. A1 - Koehler, M. A1 - Ettl, J. A1 - Berger, H. T1 - Polyurethane versus silicone catheters for central venous port devices implanted at the forearm N2 - Purpose: We aimed to analyse short and long-term complications of polyurethane (PU) versus silicone catheters used in totally implantable venous-access ports (TIVAPs) implanted at the forearm. Methods: Retrospective analysis of 698 consecutively implanted TIVAPs was performed. Primary end-points were defined as rates of major complications associated with either type of central venous port catheter. Technical success rate, device service interval as well as minor complications not requiring port explantation were defined as secondary end-points. Results: A total of 698 port devices were implanted in 681 patients, 396 equipped with a PU catheter, 302 with a silicone catheter. The technical success rate was 99.9% with no major periprocedural complications. During follow-up a total of 211 complications in 146 patients were observed (1.0/1000 catheter days), 183 occurred associated with PU catheters (1.8/100 catheter days), 28 (0.3/1000 catheter days) with silicone catheters (log rank test p < 0.0001). Catheter-related bloodstream infections as well as thrombotic complications occurred significantly more frequently with PU catheters, while silicone catheters exhibited a trend towards a higher rate of mechanical failure such as disconnection or catheter rupture. Major complications requiring explantation of the device occurred more frequently with PU-based catheters (10.6%) compared to silicone catheter carrying ports (4.6%, log rank test p < 0.001). KW - Chemotherapy KW - Central venous access port KW - Complication KW - Thrombosis KW - Infection PY - 2016 DO - https://doi.org/10.1016/j.ejca.2016.02.011 SN - 0959-8049 VL - 59 SP - 113 EP - 124 PB - Elsevier Ltd. CY - Oxford, UK AN - OPUS4-36288 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bachmann, Marcel A1 - Rethmeier, Michael A1 - Wu, Chuan Song T1 - Sensitivity analysis of the residual stress state in friction stir welding of high strength aluminium alloy N2 - In this paper, the friction stir welding process was numerically investigated for 6 mm thick aluminum alloy AA2024-T3. The finite element software COMSOL Multiphysics was used to calculate the transient thermal field during welding and the mechanical reaction depending on different mechanical clamping conditions and hardening models subsequently. A thermal pseudo-mechanical (TPM) heat source was implemented. Softening effects of the material due to precipitation hardening dissolution caused by the frictional heat were accounted for. The transient temperature evolution measured by thermocouple elements at various locations was compared to the numerical results. A good agreement was found for the thermal field. A sensitivity study of the mechanical models showed the strong influence of the clamping conditions and the softening model. PY - 2016 DO - https://doi.org/10.3139/120.110809 SN - 0025-5300 VL - 58 IS - 1 SP - 20 EP - 26 PB - Hanser CY - München AN - OPUS4-35269 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schartel, Bernhard A1 - Perret, Birgit A1 - Dittrich, Bettina A1 - Ciesielski, M. A1 - Krämer, J. A1 - Müller, P. A1 - Altstädt, V. A1 - Zang, L. A1 - Döring, M. T1 - Flame retardancy of polymers: the role of specific reactions in the condensed phase N2 - Condensed-phase mechanisms play a major role in fire-retardant polymers. Generations of development have followed the concept of charring to improve fire properties. Whereas the principal reactions are believed to be known, the specific description for multicomponent systems is lacking, as is the picture across different systems. A two-step approach is proposed in general, and also presented in greater detail. The second step covers the specific reactions controlling charring, whereas the actual reactants are provided in the preceding step. This model consistently incorporates the variety of structure–property relationships reported. A comprehensive case study is presented on seven phosphorus flame retardants in two epoxy resins to breathe life into the two-step approach. KW - Charring KW - Epoxy KW - Flame retardancy KW - Pyrolysis KW - Thermogravimetric analysis (TGA) PY - 2016 DO - https://doi.org/10.1002/mame.201500250 SN - 1438-7492 SN - 1439-2054 VL - 301 IS - 1 SP - 9 EP - 35 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-35273 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Madia, Mauro A1 - Zerbst, Uwe T1 - Application of the cyclic R-curve method in notch fatigue analysis N2 - The paper deals with the prediction of the fatigue Limit of notched specimens. Some authors in the literature have shown that this issue can be solved by employing an approach based on critical distances, others used elastic fracture mechanics. In this paper the fatigue limit of notched specimens is given by the non-propagating condition of mechanically small surface cracks. According to the so-called cyclic R-curve method, the crack driving force of a growing small crack is compared to its resistance force, which incorporates the gradual build-up of crack closure. The fatigue limit is determined by that applied nominal stress, for which the tangency condition of crack driving and resistance force is satisfied. The approach has been modified to incorporate plasticity effects in the mechanically short crack Regime and it has been applied to a mild and a high-strength steel, in case of an infinite plate with circular hole under remote tensile stress. The method has been successfully applied to the evaluation of fatigue notch-sensitivity in case of surface roughness. KW - Notch fatigue KW - Notch sensitivity KW - Cyclic R-curve KW - Non-propagating cracks KW - Critical distance PY - 2016 DO - https://doi.org/10.1016/j.ijfatigue.2015.06.015 SN - 0142-1123 VL - 82 IS - 1 SP - 71 EP - 79 PB - Elsevier Ltd. CY - Oxford, UK AN - OPUS4-35298 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Frunza, S. A1 - Frunza, L. A1 - Ganea, C. P. A1 - Zgura, I. A1 - Bras, A. R. A1 - Schönhals, Andreas T1 - Rod-like cyanophenyl probe molecules nanoconfined to oxide particles: Density of adsorbed surface species N2 - Surface layers have already been observed by broadband dielectric spectroscopy for Composite systems formed by adsorption of rod-like cyanophenyl derivates as probe molecules on the surface of oxide particles. In this work, features of the surface layer are reported; samples with different amounts of the probe molecules adsorbed onto oxide (nano) particles were prepared in order to study their interactions with the surface. Thermogravimetric analysis (TGA) was applied to analyze the amount of loaded probe molecules. The density of the surface species ns was introduced and its values were estimated from quantitative Fourier transform infrared spectroscopy (FTIR) coupled with TGA. This parameter allows discriminating the composites into several groups assuming a similar interaction of the probe molecules with the hosts of a given group. An influence factor H is further proposed as the ratio of the number of molecules in the surface layer showing a glassy dynamics and the number of molecules adsorbed tightly on the surface of the support: It was found for aerosil composites and used for calculating the maximum filling degree of partially filled silica MCM-41 composites showing only one dielectric process characteristic for glass-forming liquids and a bulk behavior for higher filling degrees. KW - Cyanophenyl molecules KW - Nanoconfinement KW - Surface Species PY - 2016 DO - https://doi.org/10.1140/epjp/i2016-16027-5 SN - 2190-5444 VL - 131:27 IS - 2 SP - 1 EP - 9 PB - Springer AN - OPUS4-35364 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pérez, P. A1 - Cabeza, Sandra A1 - Garcés, G. A1 - Adeva, Paloma T1 - Influence of long period stacking ordered phase arrangements on thecorrosion behaviour of extruded Mg97Y2Zn1 alloy N2 - The influence of second phase arrangements on the corrosion resistance of extruded Mg97Y2Zn1 alloy has been evaluated in a 0.1 M NaCl solution. The microstructure of the alloy consists of a high volume fraction of coarse elongated particles of a long period stacking ordered phase aligned along the extrusion direction. Corrosion rate of transversal sections is lower than that of longitudinal sections. Such difference is attributed to the different orientation of second phases in longitudinal and transversal sections. The corrosion front advances mainly perpendicular to the surface in transversal samples while perpendicular and lateral growth occur in longitudinal samples KW - passive films KW - Magnesium alloys KW - anodic dissolution PY - 2016 DO - https://doi.org/10.1016/j.corsci.2016.02.024 SN - 0010-938X VL - 107 SP - 107 EP - 112 PB - Elsevier Ltd. CY - Oxford, UK AN - OPUS4-36358 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Griesche, Axel A1 - Große, M. A1 - Schillinger, B. ED - Fritzsche, H. ED - Huot, J. ED - Fruchart, D. T1 - Neutron imaging N2 - Neutron imaging methods are appropriate to investigate hydrogen distributions in several metallic systems. The large total neutron cross section of hydrogen compared to those of elements or isotopes, respectively, in usual structural materials like steels or zirconium alloys allows the detection even of small amounts of hydrogen in such materials. The dependence of the total macroscopic neutron cross section of the sample or component on the hydrogen concentration can be determined experimentally by means of calibration specimens with known hydrogen concentrations. Such a calibration allows for a full quantitative determination of the local hydrogen concentration with a spatial resolution better than 20 μm. Because neutron radiography is fast and non-destructive, in situ investigations of time-dependent processes like hydrogen absorption and release or hydrogen bulk diffusion can be performed. This chapter gives an introduction into the main neutron imaging methods, radiography and tomography, and gives as examples results of neutron imaging investigations of hydrogen in different steels and in zirconium alloys,respectively. KW - Neutron imaging KW - Neutron radiography KW - Hydrogen PY - 2016 SN - 978-3-319-22792-4 SN - 978-3-319-22791-7 DO - https://doi.org/10.1007/978-3-319-22792-4_7 SN - 1868-0380 SN - 1868-0372 SP - Chapter 7, 193 EP - 225 PB - Springer Nature CY - Zurich, Switzerland AN - OPUS4-36365 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Beckmann, Jörg A1 - Marchetti, B. A1 - von Chrzanowski, Lars S. A1 - Ritter, E. A1 - Puskar, L. A1 - Aziz, E. F. A1 - Schade, U. T1 - Optical constants of harmful and highly energetic liquids for application to THz screening systems N2 - The far-infrared (IR) optical constants of a set of hazardous and flammable liquids have been obtained by means of spectroscopic ellipsometry in attenuated total reflection configuration over a broad spectral range. Such liquids recently became of considerable concern for transportation security measures worldwide. Their optical identification at check-in gates can only become possible if the characteristic spectra are already known. The refractive indices and the extinction coefficients reported here contribute to a spectroscopic data base in the far-IR and terahertz (THz) spectral regions and may support modeling the performance of THz screening systems on liquids for airports and other security sensitive areas. Examples of several container material/liquid systems are discussed. From the measured optical constants typical THz waveforms are calculated and discussed. KW - liquids material characterization KW - Ellipsometry KW - FT-IR spectroscopy KW - THz time-domain spectroscopy (THz-TDS) PY - 2016 DO - https://doi.org/10.1109/TTHZ.2016.2547319 SN - 2156-342X VL - 2016 / Vol. PP IS - 99 SP - 1 EP - 12 PB - IEEE - Inst. Electrical Electronics Engineers Inc CY - New York, NY, USA AN - OPUS4-36366 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mangelsdorf, Axel A1 - Blind, K. T1 - Motives to standardize: Empirical evidence from Germany N2 - In this paper, we identify the strategic motives of German manufacturing companies in the electrical engineering and machinery industry to be involved in standards development organizations. First, we present the general motives for the formation of strategic alliances and relate them to specific standardization motives. Then, we identify pursuing specific company interests, solving technical problems, knowledge seeking, influencing regulation, and facilitating market access as motives to standardize by means of factor analysis. In a second step, we test hypotheses on the relationship between the importance of strategic motives and firm level variables, e.g. R&D intensity, innovation activities, and firm size. The results reveal that firms in electric engineering and machinery have a particularly strong interest in ensuring industry-friendly design of regulations, which can be achieved by standards. Moreover, the results confirm that small firms also from these two sectors are active in standardization alliances to access knowledge from other involved stakeholders. KW - Factor analysis KW - Standardization KW - Strategic alliances KW - Knowledge spillovers KW - Market access KW - Regulation KW - Innovation KW - R&D PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-364586 DO - https://doi.org/10.1016/j.technovation.2016.01.001 SN - 0166-4972 VL - 48-49 SP - 13 EP - 24 PB - Elsevier Science B.V. CY - Amsterdam, Netherlands AN - OPUS4-36458 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Erwamati, F. U. A1 - Pratapa, S. A1 - Suasmoro, S. A1 - Hübert, Thomas A1 - Banach, Ulrich T1 - Preparation and structural study of Mg1−xZnxTiO3 ceramics and their dielectric properties from 1 Hz to 7.7 GHz N2 - A series of Mg₁₋ₓZnₓTiO₃, x = 0–0.5 (MZT0–MZT0.5) ceramics was synthesised and characterised. The dielectric properties of the samples in the frequency range of 1 Hz – 7.7 GHz were explored using three different methods: a contacting electrode method, a parallel-plate method and a perturbed resonator method. The electrical properties in the space charge and dipolar polarisation frequency ranges are discussed in relation to the phase composition and microstructure data. Differences in the zinc Substitution divided the dielectrics into two groups, namely MZT0-MZT0.2 and MZT0.3–MZT0.5, each with different amount of a main Mg₁₋ₓZnₓTiO₃ solid solution phase and a secondary solid solution phase. Zinc substitution promoted the density of the ceramics, improved the purity of the main phase and increased the permittivity for frequencies up to 10⁸ Hz, but reduced the permittivity in the microwave range. In the MZT0.3–MZT0.5 samples, for frequencies less than 1 MHz the quality (Q x ƒ) factors were lower and log σ ₐ.c, the AC conductivity, was higher than for the MZT0–MZT0.2 samples. Above 10 MHz, the (Q x ƒ) factors and log σ ₐ.c of the two groups were similar. KW - Mg1-xZnxTiO3 KW - Space charge polarisation KW - Dipole polarisation KW - Microwave frequency KW - Dielectric properties PY - 2016 DO - https://doi.org/10.1007/s10854-016-4610-6 SN - 0957-4522 VL - 27 IS - 7 SP - 6637 EP - 6645 PB - Springer CY - Dordrecht, Netherlands AN - OPUS4-36466 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schönhals, Andreas A1 - Zorn, R. A1 - Frick, B. T1 - Inelastic neutron spectroscopy as a tool to investigate nanoconfined polymer systems N2 - The effect of a nanometer scale confinement (pore sizes 7.5 nm down to 2.5 nm) on the vibrational density of states (VDOS) and on the molecular dynamics of Poly(dimethyl siloxane) (PDMS) and Poly(-methyl phenyl siloxane) (PMPS) is studied by inelastic Neutron scattering. The high penetration depth of neutrons makes neutron scattering a suitable tool for the study of confined systems. Moreover, Neutrons are sensitive to light nuclei therefore the confined polymers can be investigated directly, more or less independently of the confining host. Resulting findings are firstly, a reduction of the low frequency contributions to the VDOS below the Boson Peak frequency for both polymers. Including literature data, this reduction can be regarded as a more general feature for glass-forming systems confined by hard walls. Secondly, clear deviations in the temperature dependence of the mean squared displacement of the confined molecules compared to the bulk were found close to the thermal glass transition temperature, whereas localized methyl group rotations were only weakly influenced. Furthermore, the molecular dynamics is accessed. The combination of neutron Time-of-Flight with neutron backscattering, thus covering a broad dynamical range from sub ps to ns, reveal clear influence from confinement on the intermediate incoherent scattering function S(q,t). The latter was obtained by combining the inverse Fourier transform of the individual dynamical structure factors measured by the both methods. The time and q dependence of S(q,t) are discussed in detail for the local methyl group rotations and the segmental dynamics, considering both the interaction of the segments with the pore walls and possible geometrical confinement effects. KW - Confinement KW - Density of states KW - Dynamic glass transition PY - 2016 DO - https://doi.org/10.1016/j.polymer.2016.06.006 SN - 0032-3861 SN - 1873-2291 VL - 105 SP - 393 EP - 406 PB - Elsevier AN - OPUS4-38256 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hetti, M. A1 - Wei, Q. A1 - Casperson, Ralf A1 - Pohl, Rainer A1 - Bartusch, M. A1 - Neu, V. A1 - Pospiech, D. A1 - Voit, B. T1 - Magnetite core-shell nanoparticles in nondestructive flaw detection of polymeric materials N2 - Nondestructive flaw detection in polymeric materials is important but difficult to achieve. In this research, the application of magnetite nanoparticles (MNPs) in nondestructive flaw detection is studied and realized, to the best of our knowledge, for the first time. Superparamagnetic and highly magnetic (up to 63 emu/g) magnetite core-shell nanoparticles are prepared by grafting bromo-end group-functionalized poly(glycidyl methacrylate) (Br-PGMA) onto surface-modified Fe3O4 NPs. These Fe3O4-PGMA NPs are blended into bisphenol A diglycidylether (BADGE) based epoxy to form homogeneously distributed magnetic epoxy nanocomposites (MENCs) after curing. The core Fe3O4 of the Fe3O4-PGMA NPs endows the MENCs with magnetic property, which is crucial for nondestructive flaw detection of the materials, while the shell PGMA promotes colloidal stability and prevents NP aggregation during curing. The eddy current testing (ET) technique is firstly applied to detect flaws in the MENCs. Through the brightness contrast of the ET image, surficial and sub-surficial flaws in MENCs can be detected, even for MENCs with low content of Fe3O4-PGMA NPs (1 wt %). The incorporation of Fe3O4-PGMA NPs can be easily extended to other polymer and polymer-based composite systems and opens a new and very promising pathway toward MNP-based nondestructive flaw detection in polymeric materials. KW - Magnetite nanoparticles KW - Poly(glycidyl methacrylate) KW - Atom transfer radical polymerization KW - Magnetic nanocomposites KW - Nondestructive flaw detection PY - 2016 DO - https://doi.org/10.1021/acsami.6b09934 SN - 1944-8244 SN - 1944-8252 VL - 8 IS - 41 SP - 28208 EP - 28215 PB - American Chemical Society CY - Washington, DC AN - OPUS4-38300 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Kasch, Thomas A1 - Binder, Christian A1 - Woitzek, Andreas A1 - Szypkowski, Marko A1 - Treisch, N. ED - Davis, S. E. ED - Steinberg, Th. A. T1 - Oxygen endurance testing of oxygen cylinder valves N2 - Cylinder valves for oxygen service that meet the standard DIN EN ISO 10297 should be safe, if properly handled by the user. In the last few years, however, the number of incidents with oxygen valves that has been reported to Federal Institute for Materials Research and Testing (BAM) has increased. According to the incident reports, incorrect handling can be ruled out. People were seriously injured and in most cases, the causes of these incidents were not clear. Very often, such incidents occurred during opening and closing of the valves. Therefore, the technical-scientific community has put the existing test methods for type testing more and more into question. Besides other mandatory tests, the above-mentioned standard allows to perform the endurance test with air or with nitrogen. This is appropriate for all other gases but not for oxygen. Up to now, this test does not consider the fact that cylinder valves also contain nonmetallic seat materials and lubricants that may react with oxygen in a dangerous way. Because of this unsatisfactory situation, BAM initiated a research project to perform endurance testing of cylinder valves for oxygen service much more practice related with oxygen. This test simulates very well real life situations when the cylinder valve is opened or closed. The first part of this project was the development of a new oxygen operated endurance tester in accordance with DIN EN ISO 10297. In a second part, endurance testing of valves with air and with oxygen was performed and the results were compared. In addition, another mandatory test of the standard, the oxygen pressure surge test was carried out on new valves and on valves that had undergone endurance tests with air or oxygen, to see the influence on the burn-out safety of such pre-stressed valves. This paper presents the main results of the project. The findings clearly speak for implementing the oxygen endurance test not only to DIN EN ISO 10297 but also to various other standards to increase the burn-out safety of oxygen cylinder valves. KW - Endurance testing KW - High pressure oxygen KW - Nonmetallic material KW - Lubricant KW - Ignition source KW - Incident research KW - Oxygen pressure surge PY - 2016 SN - 978-0-8031-7637-9 DO - https://doi.org/10.1520/STP1596-EB SN - 0899-6652 SN - 0066-0558 VL - 14 SP - 393 EP - 404 PB - ASTM International CY - West Conshohocken, PA. ET - STP 1596 AN - OPUS4-38243 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Naghib-zadeh, H. A1 - Oder, Gabriele A1 - Hesse, J. A1 - Reimann, T. A1 - Töpfer, J. A1 - Rabe, Torsten T1 - Effect of oxygen partial pressure on co-firing behavior and magnetic properties of LTCC modules with integrated NiCuZn ferrite layers N2 - Low-κ dielectric LTCC was developed, to realize successful co-firing with NiCuZn ferrite tapes. A critical high-temperature process in the production of highly integrated LTCC modules is the migration of silver from inner conductors into the LTCC glass phase. Intensive silver migration causes strong deformation of LTCC multilayers during firing in air. Silver migration into the LTCC glass phase depends on oxygen content of the sintering atmosphere and can be minimized by sintering in nitrogen atmosphere. However, partial decomposition of NiCuZn-ferrite and formation of cuprite was observed during sintering in nitrogen and, consequently, the permeability of the ferrite decreases. As shown by a combined XRD/thermogravimetric study the co-firing of LTCC modules with silver metallization and integrated ferrite layer demands precise adjustment of oxygen partial pressure. KW - Ferrite KW - Silver diffusion KW - Co-firing KW - LTCC PY - 2016 DO - https://doi.org/10.1007/s10832-016-0043-0 SN - 1385-3449 SN - 1573-8663 VL - 37 IS - 1-4 SP - 100 EP - 109 PB - Springer Science+Business Media CY - New York AN - OPUS4-38603 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Abere, M. J. A1 - Zhong, M. A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Ultrafast laser-induced morphological transformations N2 - Ultrafast laser processing can be used to realize various morphological surface transformations, ranging from direct contour shaping to large-area-surface functionalization via the generation of “self-ordered” micro- and nanostructures as well as their hierarchical hybrids. Irradiation with high-intensity laser pulses excites materials into extreme conditions, which then return to equilibrium through these unique surface transformations. In combination with suitable top-down or bottom-up manufacturing strategies, such laser-tailored surface morphologies open up new avenues toward the control of optical, chemical, and mechanical surface properties, featuring various technical applications especially in the fields of photovoltaics, tribology, and medicine. This article reviews recent efforts in the fundamental understanding of the formation of laser-induced surface micro- and nanostructures and discusses some of their emerging capabilities. KW - Laser ablation KW - Laser-induced periodic surface structures (LIPSS) KW - Surface morphology KW - Oxidation KW - Tribology PY - 2016 DO - https://doi.org/10.1557/mrs.2016.271 SN - 0883-7694 SN - 1938-1425 VL - 41 IS - 12 SP - 969 EP - 974 PB - Cambride University Press AN - OPUS4-38637 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Winkelmann, Aimo A1 - Nolze, Gert T1 - Channeling-enhanced EDX for polarity resolved crystal orientation determination N2 - Using channeling-enhanced energy-dispersive X-ray spectroscopy (EDX), we demonstrate polarity sensitive orientation determination of a non-centrosymmetric crystal in the scanning electron microscope. The authors observe a characteristic asymmetry in the channeling-enhanced, angle-dependent EDX data of a GaAs sample, which is in good agreement to simulations using the dynamical theory of diffraction for the incident electron beam. This allows us to assign the orientation of the GaAs crystal according to the non-centrosymmetric point group. The method shown here overcomes the limitation of a reduced point-group sensitivity of electron backscatter diffraction Patterns and electron channeling patterns for crystalline phases that contain atoms of approximately equal electron scattering cross sections. KW - Channeling KW - EDX KW - EDS KW - Composition KW - GaAs KW - GaP PY - 2016 DO - https://doi.org/10.1002/crat.201600258 SN - 0232-1300 SN - 0023-4753 VL - 51 IS - 12 SP - 752 EP - 756 AN - OPUS4-38098 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhao, F. A1 - Li, G. A1 - Österle, Werner A1 - Häusler, Ines A1 - Zhang, G. A1 - Wang, T. A1 - Wang, Q. T1 - Tribological investigations of glass fiber reinforced epoxy composites under oil lubrication conditions N2 - The tribological performance of short glass fibers (SGF),solid lubricants and silica nanoparticles filled epoxy (EP) composites was investigated under oil lubrication conditions. It is demonstrated that the addition of SGF greatly reduces the friction and wear of EP. However, further addition of solid lubricants and silica nanoparticles does not change obviously the friction and wear. It is identified that the high tribological performance of SGF reinforced EP is related to the high load carrying capacity and abrasion resistance of SGF. The nanostructure of the tribofilm was comprehensively characterized. It is deemed that the tribofilm plays an important role in the tribological performance by avoiding the direct rubbing of the sliding pairs exposed to boundary and mixed lubrication conditions. KW - Reinforced epoxy composites KW - Short glass fiber KW - Oil lubrication KW - Tribofilm PY - 2016 DO - https://doi.org/10.1016/j.triboint.2016.07.002 SN - 0301-679X VL - 103 SP - 208 EP - 217 PB - Elsevier Ltd. AN - OPUS4-38145 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zerbst, Uwe A1 - S., Romano A1 - D., Manenti A1 - S., Beretta T1 - Semi-probabilistic method for residual lifetime of aluminothermic welded rails with foot cracks N2 - One of the most frequent and dangerous failure modes in continuous welded rails is fatigue crack Propagation terminated by brittle fracture. Due to the brittleness of the weld material and HAZ and the scatter in its mechanical properties, a statistical approach is necessary. The paper deals with surface cracks at the foot base of aluminothermic welded rails, developing a probabilistic methodology for determining the day by day prospective failure probability. The investigations presented here comprise weld material characterization, simulation of fatigue crack propagation and finally the determination of the failure probability using the Monte Carlo method. The effect of various parameters, such as axle weight, Initial crack size, residual stresses, fatigue crack propagation threshold and date of inspection were analyzed. The results show that, independent of the date of the last inspection, almost any failure event happens in wintertime. This is in accordance with practical experience. However, from the proposed analysis it is evident that the main parameter controlling rail fracture is not only the minimum local temperature, but the temperature range over the whole year. Finally, the results are compared to the standard rail classification method. KW - Railway rails KW - Foot crack KW - Fatigue crack KW - Failure probability KW - Residual lifetime PY - 2016 DO - https://doi.org/10.1016/j.tafmec.2016.05.002 SN - 0167-8442 VL - 85 IS - Part B SP - 398 EP - 411 PB - Elsevier AN - OPUS4-38156 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nagelschmidt, Sven A1 - Probst, Ulrich A1 - Völzke, Holger A1 - Wolff, Dietmar T1 - Long-term investigations of metal seals for storage casks of radioctive materials N2 - The Bundesanstalt für Materialforschung und –prüfung (BAM) is a federal institute for materials research and testing in Germany and has been involved in the qualification and safety evaluation procedures of metal seals from the early beginning of the interim storage licensing procedures for radioactive materials, stored in dual purpose casks. Regarding this subject, BAM investigates the long-term behavior of metal seals under the influence of temperature using experimental data and analytical approaches. The development of numerical models is in progress as well. Systematic experimental investigations performed by BAM indicate a continuous decrease of the remaining seal force and the usable resilience considering the leak tightness. Hence, there is a fundamental interest of describing time and temperature dependency to gain predictable values for the long-term behavior and to achieve reliable results with help of short-term tests. The paper gives an overview about the sealing principle, test program and test results of metal seals of the type HELICOFLEX® HN200. The aging effect, respectively the long-term behavior in dependency of time and temperature, are introduced for two different outer liner materials, aluminum and silver. T2 - PVP ASME Conference CY - Vancouver, Canada DA - 17.07.2016 KW - Long-Term Behaviour KW - Metal Seal KW - Metal Gasket PY - 2016 SN - 978-0-7918-5045-9 VL - 7 SP - 63596-1 EP - 63596-5 AN - OPUS4-38039 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kormunda, M. A1 - Fischer, Daniel A1 - Hertwig, Andreas A1 - Beck, Uwe A1 - Sebik, M. A1 - Esser, N. T1 - Preparation of pulsed DC magnetron deposited Fe-doped SnO2 coatings N2 - Iron-doped SnO2 coatings were deposited in a 50 kHz DC-pulsed magnetron sputtering discharge. The pulses had a duration of 4 µs in selected gas mixtures from pure argon up to 60% of oxygen at a constant total pressure of 0.2 Pa. A single target of SnO2 with Fe inset was used. The mass spectrometry study detected the gas-related ions Ar+, O2+ and O+, where the last one becomes the dominant positive ion at higher oxygen contents. Atomic oxygen ions had a higher energy as it resulted from the collision-caused dissociation on the target surface. The tin-related species were detected as Sn+ and SnO+. SnO2+ species were not detected. The deposition rate decreased by using gas mixtures with oxygen as well as the corresponding amount of Sn-related species in the plasma. The increase of oxygen also increased significantly the sheet resistance of the films. The XPS study showed that the iron concentration decreased by using additional oxygen. But the O/Sn ratio in the coatings was constant, contrary to the increased FeO/Fe ratio in the films. An additional analysis of the coatings by spectroscopic ellipsometry has shown a dependence of the polarizability and the permittivity on the amount of oxygen used during the deposition. In contrast, the study has found no such dependence for the absorption of the layers. KW - Coatings KW - Magnetron sputtering KW - Optical properties KW - Sheet resistivity KW - SnO2 PY - 2016 UR - http://onlinelibrary.wiley.com/doi/10.1002/pssa.201532882/full DO - https://doi.org/10.1002/pssa.201532882 SN - 0031-8965 SN - 1862-6300 VL - 213 IS - 9 SP - 2303 EP - 2309 PB - WILEY-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-38106 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -