TY - JOUR A1 - Vöse, Markus A1 - Fedelich, Bernard A1 - Otto, F. A1 - Eggeler, G. T1 - Micromechanical modeling of creep damage in a copper-antimony alloy N2 - A micromechanical model of creep induced grain boundary damage is proposed, which allows for the simulation of creep damage in a polycrystal with the finite element method. Grain boundary cavitation and sliding are considered via a micromechanically motivated cohesive zone model, while the grains creep following the slip system theory. The model has been calibrated with creep test data from pure Cu single crystals and a coarse-grained polycrystalline Cu-Sb alloy. The test data includes porosity measurements and estimates of grain boundary sliding. Finally, the model has been applied to Voronoi models of polycrystalline structures. In particular the influence of grain boundary sliding on the overall creep rate is demonstrated. T2 - ECF20 - 20th European conference on fracture CY - Trondheim, Norway DA - 28.06.2014 KW - Creep damage KW - Grain boundary sliding KW - Cohesive zone KW - Micromechanical model KW - Polycrystal PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-309914 DO - https://doi.org/10.1016/j.mspro.2014.06.006 SN - 2211-8128 VL - 3 SP - 21 EP - 26 PB - Curran CY - Red Hook, NY, USA AN - OPUS4-30991 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kreutzbruck, Marc A1 - Bauer, P. A1 - Caspers, F. A1 - Heck, S. A1 - Müller, F. A1 - Pohl, Rainer A1 - Scheuerlein, C. A1 - Sickert, Roland A1 - Maierhofer, Christiane A1 - Brackrock, Daniel T1 - Sensoren für Verbunddrähte aus Niob-Titan und Kupfer N2 - Der Large Hadron Collider (LHC) des europäischen Kernforschungszentrums CERN ist einer der weltweit größten und leistungsfähigsten Teilchenbeschleuniger. Um den Teilchenstrahl auf seiner Kreisbahn zu halten, werden mit Hilfe supraleitender Spulen sehr starke Magnetfelder erzeugt. Die hierzu benötigten hohen Ströme werden über Verbunddrähte aus Niob-Titan und Kupfer geleitet. Die Drähte werden u.a. durch Ultraschallschweißungen miteinander verbunden. Eine mangelhafte Verbindung kann zur Erwärmung der Kontaktstelle und in Folge davon zum Zusammenbruch der Supraleitung führen. Auf Anfrage des CERN wurden an der BAM Untersuchungen zur Prüfbarkeit solcher Verbindungen bei Umgebungstemperatur durchgeführt. Es gelang, für einen Verbindungstypen einen Wirbelstromsensor für eine manuelle Prüfung zu entwickeln. Ein Prototyp des Sensors befindet sich beim CERN in der praktischen Erprobung. Das Sensorprinzip sowie Prüfergebnisse aus Labor und Praxis werden vorgestellt. T2 - DGZfP-Jahrestagung 2014 CY - Potsdam, Germany DA - 26.05.2014 KW - Ultraschallprüfung mit Matrix-Sensoren KW - Aktive Thermografie KW - Gabelsensor PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-319785 SN - 978-3-940283-61-0 VL - 148 SP - 1 EP - 12 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) CY - Berlin AN - OPUS4-31978 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ritter, B. A1 - Krahl, T. A1 - Rurack, Knut A1 - Kemnitz, E. T1 - Nanoscale CaF2 doped with Eu3+ and Tb3+ through fluorolytic sol-gel synthesis N2 - In this article, the high potential of the fluorolytic sol–gel process to synthesize nanoscopic rare earth-doped calcium fluoride sols is shown. Through a fluorolytic sol–gel process we manage to achieve spherical monodisperse ~5 nm sized nanoparticles using a simple and reproducible one-pot-wet chemical route at room temperature. The as-synthesized clear sols exhibit an intense red and green luminescence under UV excitation at room temperature. A spectroscopic study of the sols revealed the characteristic transitions 5D0 → 7FJ of Eu3+ and 5D4 → 7FJ of Tb3+, with 5D0 → 7F2 (611 nm) of Eu3+ and 5D4 → 7F4 (581 nm) of Tb3+ as the most prominent transitions. This facile synthetic strategy is also valuable for developing other luminescent nanoparticles. KW - Calciumfluorid KW - Europium KW - Lumineszenz KW - Nanopartikel KW - Sol-Gel-Synthese KW - Terbium PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-320120 DO - https://doi.org/10.1039/c4tc01073f SN - 2050-7526 SN - 2050-7534 VL - 2 IS - 40 SP - 8607 EP - 8613 PB - Royal Soc. of Chemistry CY - Cambridge AN - OPUS4-32012 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ressnig, A. A1 - Corbiere, T. A1 - Lunkenbein, T. A1 - Braun, Ulrike A1 - Willinger, M. G. A1 - Antonietti, M. T1 - Decomposition synthesis of tuneable, macroporous carbon foams from crystalline precursors via in situ templating N2 - A flexible, sustainable, one-step thermal decomposition route for the synthesis of hierarchical, heteroatom doped carbon foams is presented. Task-specific semi-organic crystals combine functions for three different purposes: the carbon and heteroatom source, a foaming agent (CO2) and an in situ generable template (NaCl). Insights to the decomposition pathway were gained through FTIR/MS coupled TGA and an ultrafast out-of-furnace heating procedure and the products were analysed with (HR)SEM/TEM, EELS, FTIR, and N2 sorption. The resulting macroporous carbon foams are excellent supports for metallic nanoparticles due to their hierarchical structure, high surface area and tuneable heteroatom contents. This was demonstrated for catalytically active copper or the magnetic CoNi alloy for water purification. KW - macroporous carbon KW - thermal decomposition KW - synthesize heteroatom KW - in situ template (NaCl) PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-318641 DO - https://doi.org/10.1039/c4ta03646h SN - 2050-7496 SN - 2050-7488 VL - 2 IS - 42 SP - 18076 EP - 18081 PB - RSC CY - London [u.a.] AN - OPUS4-31864 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Sabine A1 - Niederleithinger, Ernst T1 - Anwendung der Reverse Time Migration auf Ultraschall-Echo-Messungen in der zerstörungsfreien Prüfung im Bauwesen N2 - Ultraschall-Echo-Messungen dienen im Bauwesen zur Dickenbestimmung von Bauteilen sowie der Lokalisierung und Charakterisierung von Einbauteilen, Einlagerungen und anderen Inhomogenitäten. Zur Rekonstruktion werden bisher Abbildungsverfahren wie z.B. 3D-SAFT genutzt. Diese setzen aber voraus, dass direkte Reflexionen am Abbildungsobjekt erfolgen. Deshalb können keine zuverlässigen Aussagen über den Durchmesser von eingebauten Spannkanälen oder z. B. Seitenkanten von Objekten getroffen werden. Ziel laufender Forschungsarbeiten ist es, die Abbildungsqualität zu verbessern. Mit der aus der Geophysik stammenden Reverse Time Migration, die bereits häufig in der Erdölexploration genutzt wird, lassen sich auch steilere Strukturen über 70° abbilden und somit auch die Unterseite von Einbauten oder Stufen in Bauteilen darstellen. Um die Leistungsfähigkeit des Algorithmus für die zerstörungsfreie Prüfung zu untersuchen, wurden verschiedene Simulationsrechnungen durchgeführt. Dabei wurden typische Prüfprobleme unterschiedlicher Komplexität zunächst in Polyamid nachgestellt. Die Schwerpunkte lagen bei der Darstellung senkrechter Grenzflächen und Hohlstellen. Die Rechnungen dienten neben der Evaluierung und Optimierung des Verfahrens auch der Planung von Experimenten an Probekörpern mit verschiedenen Einbauten. Die Simulationsergebnisse wurden an einem dem synthetischen Modell entsprechenden Polyamidprobekörper überprüft, an dem rauscharme Ultraschalldaten aufgenommen werden konnten. In einer Messreihe wurde in den Probekörper eine Bohrung eingebracht und schrittweise vergrößert. Mit diesen Messungen konnte die Leistungsfähigkeit der Reverse Time Migration auch an realen Ultraschalldaten nachgewiesen werden. Untersuchungen mit an Beton aufgenommenen Ultraschalldaten werden folgen. T2 - DGZfP-Jahrestagung 2014 CY - Potsdam, Germany DA - 26.05.2014 KW - Ultraschall KW - Reverse Time Migration KW - Zerstörungsfreie Prüfung PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-319311 SN - 978-3-940283-61-0 IS - DGZfP-BB 148 SP - Di.1.C.4, 1 EP - 8 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) AN - OPUS4-31931 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mozetic, M. A1 - Ostrikov, K. A1 - Ruzic, D.N. A1 - Curreli, D. A1 - Cvelbar, U. A1 - Vesel, A. A1 - Primc, G. A1 - Leisch, M. A1 - Jousten, K. A1 - Malyshev, O.B. A1 - Hendricks, J.H. A1 - Kövér, L. A1 - Tagliaferro, A. A1 - Conde, O. A1 - Silvestre, A.J. A1 - Giapintzakis, J. A1 - Buljan, M. A1 - Radic, N. A1 - Drazic, G. A1 - Bernstorff, S. A1 - Biedermann, H. A1 - Kylián, O. A1 - Hanus, J. A1 - Milosevic, S. A1 - Galtayries, A. A1 - Dietrich, Paul A1 - Unger, Wolfgang A1 - Lehocky, M. A1 - Sedlarik, V. A1 - Stana-Kleinschek, K. A1 - Drmota-Petric, A. A1 - Pireaux, J.J. A1 - Rogers, J.W. A1 - Anderle, M. T1 - Recent advances in vacuum sciences and applications N2 - Recent advances in vacuum sciences and applications are reviewed. Novel optical interferometer cavity devices enable pressure measurements with ppm accuracy. The innovative dynamic vacuum standard allows for pressure measurements with temporal resolution of 2 ms. Vacuum issues in the construction of huge ultra-high vacuum devices worldwide are reviewed. Recent advances in surface science and thin films include new phenomena observed in electron transport near solid surfaces as well as novel results on the properties of carbon nanomaterials. Precise techniques for surface and thin-film characterization have been applied in the conservation technology of cultural heritage objects and recent advances in the characterization of biointerfaces are presented. The combination of various vacuum and atmospheric-pressure techniques enables an insight into the complex phenomena of protein and other biomolecule conformations on solid surfaces. Studying these phenomena at solid–liquid interfaces is regarded as the main issue in the development of alternative techniques for drug delivery, tissue engineering and thus the development of innovative techniques for curing cancer and cardiovascular diseases. A review on recent advances in plasma medicine is presented as well as novel hypotheses on cell apoptosis upon treatment with gaseous plasma. Finally, recent advances in plasma nanoscience are illustrated with several examples and a roadmap for future activities is presented. KW - Vacuum KW - Surface KW - Plasma KW - Interface KW - Nanoscience PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-304884 DO - https://doi.org/10.1088/0022-3727/47/15/153001 SN - 0022-3727 SN - 1361-6463 VL - 47 IS - 15 SP - 153001-1 EP - 153001-23 PB - IOP Publ. CY - Bristol AN - OPUS4-30488 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Myrach, Philipp A1 - Maierhofer, Christiane A1 - Reischel, Mercedes A1 - Rahammer, M. A1 - Holtmann, N. T1 - Untersuchung der Auflösungsgrenzen der Lockin-Thermografie zur Prüfung von Faserverbundwerkstoffen N2 - Aktive Thermografie mit Lockin-Anregung stellt ein berührungsfreies und zerstörungsfreies Prüfverfahren dar, welches insbesondere auch die Prüfung von kohlenstofffaserverstärkten Kunststoffen ermöglicht. Um eine Standardisierung dieses Verfahrens voranzubringen, wurden im Rahmen eines Forschungsprojektes umfangreiche Untersuchungen zur Validierung des Verfahrens durchgeführt. Dabei wurden unter anderem der Einfluss der spektralen Empfindlichkeit verschiedener Kamerasysteme, unterschiedlicher Lagenaufbauten bei CFK-Probekörpern und der Einfluss einer Phasenverschiebung zwischen dem Anregungssignal und der Detektion der Thermografiebilder untersucht. T2 - DGZfP-Jahrestagung 2014 CY - Potsdam, Germany DA - 26.05.2014 KW - Aktive Thermografie KW - Lockin-Thermografie KW - CFK PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-309259 SN - 978-3-940283-61-0 IS - DGZfP-BB 148 SP - Di.3.C.3, 1 EP - 10 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) AN - OPUS4-30925 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ecker, Melanie A1 - Pretsch, Thorsten T1 - Novel design approaches for multifunctional information carriers N2 - Two design approaches for multifunctional information carriers are introduced. In the first one, quick response (QR) code carriers, which were composed of poly(ester urethane) (PEU) and microencapsulated thermochromic pigments (T-PIGs), differing in color and color switching temperature (CST), were prepared. The obtained material systems exhibited machine-readable QR codes at 23 °C and a two-stage decolorization when heated, culminating in unreadable QR codes at temperatures above the highest CST of the employed T-PIGs. In the second scenario, information carriers were sealed with a dark, thermochromic PEU layer. As a result, the QR codes were hidden at 23 °C and became readable upon heating due to color fading. Beyond the characterization of the employed components, preparation methods, functionality analyses and durability investigations are reported. When heated after thermo-mechanical programming, pronounced shape memory properties could be verified. The thermo-responsiveness of such multifunctional material systems may qualify them for usage in anti-counterfeiting applications. KW - Poly(ester urethane) KW - Shape memory polymer KW - Thermo-responsiveness KW - Information carrier KW - QR code carrier KW - Thermochromic properties KW - Microencapsulated thermochromic pigments KW - Anti-counterfeiting KW - Smart label KW - Difficult-to-copy KW - Durability KW - Multifuncitonal material systems PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-315176 DO - https://doi.org/10.1039/c4ra08977d SN - 2046-2069 VL - 4 IS - 87 SP - 46680 EP - 46688 PB - RSC Publishing CY - London AN - OPUS4-31517 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Batzdorf, Lisa A1 - Emmerling, Franziska T1 - Mechanochemical synthesis and characterisation of cocrystals and metal-organic compounds N2 - The mechanochemical synthesis of two model compounds, a metal organic framework ([Bi(1,4-bdc)2]*(Im) (bdc = benzene dicarboxylate, Im = imidazole cation)) and a cocrystal (Carbamazepine:Indometacin 1:1) were followed ex situ by combined analytical methods. Powder X-ray diffraction (XRD) and Raman spectroscopy data were evaluated for the synthesis of the metal organic framework. XRD measurements and REM images were analysed for the synthesis of the cocrystal. The measurements revealed that both model compounds were synthesised within minutes. The metal organic framework [Bi(1,4-bdc)2]*(Im) is synthesised via an intermediate structure. The cocrystal Carbamazepine:Indometacin 1:1 is formed within few seconds and afterwards the crystallite size decreases extremely. KW - Powder X-ray diffraction (XRD) KW - Raman spectroscopy KW - mechanochemical synthesis PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-306305 UR - http://pubs.rsc.org/en/content/articlepdf/2014/fd/c3fd00163f DO - https://doi.org/10.1039/C3FD00163F SN - 1359-6640 SN - 1364-5498 N1 - Geburtsname von Batzdorf, Lisa: Tröbs, L. - Birth name of Batzdorf, Lisa: Tröbs, L. SP - 109 EP - 119 PB - RSC CY - Cambridge [u.a.] AN - OPUS4-30630 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinrich, Thomas A1 - Traulsen, Christoph Hans-Henning A1 - Darlatt, Erik A1 - Richter, S. A1 - Poppenberg, J. A1 - Traulsen, N.L. A1 - Linder, I. A1 - Lippitz, Andreas A1 - Dietrich, Paul A1 - Dib, B. A1 - Unger, Wolfgang A1 - Schalley, C.A. T1 - The versatility of 'Click' reactions at surfaces: Molecular recognition at interfaces N2 - In order to investigate molecular recognition on surfaces, an azide-functionalized monolayer was deposited on gold. The monolayer was characterized by X-ray photoelectron spectroscopy (XPS) and angle-resolved near-edge X-ray absorption fine structure (NEXAFS) experiments and the decomposition of the azide upon irradiation with X-ray beams was investigated. Subsequently, various alkyne-functionalized host and guest molecules were attached to the azide by 1,3-dipolar cycloaddition. These modified surfaces and their host–guest chemistry were analysed by XPS and angle-resolved NEXAFS. The reversibility of guest binding was shown for one example as a proof of principle. KW - 'Click' reaction KW - Azide-terminated surfaces KW - SAMs KW - Host guest molecules KW - Molecular recognition at interfaces PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-306463 DO - https://doi.org/10.1039/C4RA01730G SN - 2046-2069 VL - 4 IS - 34 SP - 17694 EP - 17702 PB - RSC Publishing CY - London AN - OPUS4-30646 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bald, Ilko A1 - Keller, A. T1 - Molecular processes studied at a single-molecule level using DNA origami nanostructures and atomic force microscopy N2 - DNA origami nanostructures allow for the arrangement of different functionalities such as proteins, specific DNA structures, nanoparticles, and various chemical modifications with unprecedented precision. The arranged functional entities can be visualized by atomic force microscopy (AFM) which enables the study of molecular processes at a single-molecular level. Examples comprise the investigation of chemical reactions, electron-induced bond breaking, enzymatic binding and cleavage events, and conformational transitions in DNA. In this paper, we provide an overview of the advances achieved in the field of single-molecule investigations by applying atomic force microscopy to functionalized DNA origami substrates. KW - DNA origami KW - atomic force microscopy KW - single-molecule analysis KW - DNA radiation damage KW - protein binding KW - enzyme reactions KW - G quadruplexes PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-314343 DO - https://doi.org/10.3390/molecules190913803 SN - 1420-3049 VL - 19 IS - 9 SP - 13803 EP - 13823 PB - MDPI CY - Basel AN - OPUS4-31434 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bachmann, Marcel A1 - Avilov, Vjaceslav A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Experimental and numerical investigation of an electromagnetic weld pool control for laser beam welding N2 - The objective of this study was to investigate the influence of externally applied magnetic fields on the weld quality in laser beam welding. The optimization of the process parameters was performed using the results of computer simulations. Welding tests were performed with up to 20 kW laser beam power. It was shown that the AC magnet with 3 kW power supply allows for a prevention of the gravity drop-out for full penetration welding of 20 mm thick stainless steel plates. For partial penetration welding it was shown that an0.5 T DC magnetic field is enough for a suppression of convective flows in the weld pool. Partial penetration welding tests with 4 kW beam power showed that the application of AC magnetic fields can reduce weld porosity by a factor of 10 compared to the reference joints. The weld surface roughness was improved by 50%. KW - Laser beam welding KW - Electromagnetic weld pool support KW - Hartmann effect KW - Electromagnetic rectification PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-314405 DO - https://doi.org/10.1016/j.phpro.2014.08.006 SN - 1875-3892 VL - 56 SP - 515 EP - 524 PB - Elsevier B.V. CY - Amsterdam [u.a.] AN - OPUS4-31440 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 - Nariaki, D. A1 - Lekovic, F. A1 - Homenya, P. A1 - Costa, B. F. O. A1 - Menzel, Michael A1 - Boca, R. A1 - Blumers, M. A1 - Klingelhöfer, G. A1 - Renz, F. T1 - Iron(III) complexes on a dendrimeric basis and various amine core investigated by Mössbauer spectroscopy N2 - Dendrimers of various generations were synthesized by the divergent method. Starting from various amine cores (G0a, G0b, G0c) the generations were built by reaction of the amine with acrylnitrile followed by hydrogenation with DIBAL-H. Treatment with salicylaldehyde creates a fivefold coordination sphere for iron in the molecular periphery. The resulting multinuclear coordination compounds are investigated by Mossbauer spectroscopy. T2 - ICRTP 2014 - International conference on recent trends in physics CY - Indore, India DA - 22.02.2014 PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-316331 DO - https://doi.org/10.1088/1742-6596/534/1/012003 SN - 1742-6588 SN - 1742-6596 VL - 534 IS - 1 SP - 012003-1 EP - 012003-8 PB - IOP Publ. CY - Bristol, UK AN - OPUS4-31633 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Epishin, A.I. A1 - Link, T. A1 - Fedelich, Bernard A1 - Svetlov, I.L. A1 - Golubovskiy, E.R. T1 - Hot isostatic pressing of single-crystal nickel-base superalloys: mechanism of pore closure and effect on mechanical properties N2 - Pore annihilation was investigated in the single-crystal nickel-base superalloy CMSX-4. HIP tests at 1288 °C/103 MPa were interrupted at different times, then the specimens were investigated by TEM, metallography and density measurements. The kinetics of pore annihilation was determined. The pore closure mechanism was identified as plastic deformation on the octahedral slip systems. A model describing the kinetics of pore closure has been developed on the base of crystal plasticity and large strain theory. Mechanical tests with the superalloy CMSX-4 and the Ru-containing superalloy VGM4 showed, that HIP significantly increases the fatigue life at low temperatures but has no effect on creep strength. T2 - Eurosuperalloys 2014 - 2nd European symposium on superalloys and their applications CY - Giens, France DA - 12.05.2014 PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-316410 DO - https://doi.org/10.1051/matecconf/20141408003 N1 - Serientitel: MATEC Web of conferences – Series title: MATEC Web of conferences VL - 14 SP - 08003-1 EP - 08003-6 PB - EDP Sciences AN - OPUS4-31641 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rades, Steffi A1 - Hodoroaba, Vasile-Dan A1 - Salge, T. A1 - Wirth, Thomas A1 - Lobera, M.P. A1 - Labrador, R.H. A1 - Natte, Kishore A1 - Behnke, Thomas A1 - Gross, Thomas A1 - Unger, Wolfgang T1 - High-resolution imaging with SEM/T-SEM, EDX and SAM as a combined methodical approach for morphological and elemental analyses of single engineered nanoparticles N2 - The combination of complementary characterization techniques such as SEM (Scanning Electron Microscopy), T-SEM (Scanning Electron Microscopy in Transmission Mode), EDX (Energy Dispersive X-ray Spectroscopy) and SAM (Scanning Auger Microscopy) has been proven to be a powerful and relatively quick characterization strategy for comprehensive morphological and chemical characterization of individual silica and titania nanoparticles. The selected “real life” test materials, silica and titania, are listed in the OECD guidance manual as representative examples because they are often used as commercial nanomaterials. Imaging by high resolution SEM and in the transmission mode by T-SEM allows almost simultaneous surface and in-depth inspection of the same particle using the same instrument. EDX and SAM enable the chemical characterization of bulk and surface of individual nanoparticles. The core–shell properties of silica based materials are addressed as well. Titania nominally coated by silane purchased from an industrial source has been found to be inhomogeneous in terms of chemical composition. KW - surface and in-depth inspection KW - silica nanoparticles KW - titania nanoparticles PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-316296 DO - https://doi.org/10.1039/c4ra05092d SN - 2046-2069 VL - 4 IS - 91 SP - 49577 EP - 49587 PB - RSC Publishing CY - London AN - OPUS4-31629 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Woydt, Mathias A1 - Mohrbacher, H. T1 - The tribological and mechanical properties of niobium carbides (NbC) bonded with cobalt of Fe3Al N2 - The tribological and mechanical properties of niobium carbide bonded with 8 vol.-% (NbC-8Co), 12 vol.-% of cobalt (NbC-12Co) or 12 vol.-% of Fe3Al (NbC-12Fe3Al) are presented. Rotating discs made of metal-bonded niobium carbide were mated against alumina (99.7%) under unlubricated (dry) unidirectional sliding tests (0.1 m/s to 12.0 m/s; 22 °C and 400 C) as well as in oscillation tests (f=20 Hz, Δx=0.2 mm, 2/50/98% rel. humidity, n=105/106 cycles). Microstructure and phase compositions were determined as well. The tribological data obtained were benchmarked with different ceramics, cermets, hard metals and thermally sprayed coatings, where NbC bonded with 8% and 12% Co presented above 7 m/s the lowest wear rates so far in such a benchmark. Binderless NbC (HP-NbC1) and the metal-bonded NbCs exhibited low wear rates under dry sliding associated with P·V high load carrying capacities. NbC-based hard metal bonded with 12 vol.-% of Fe3Al resulted in a higher hardness level than for 12 vol.-% cobalt. The tribological profile established revealed a strong position of NbC-bearing materials under tribological considerations and for closed tribosystems against established reference tribo-couples. KW - Sliding KW - Ceramic KW - Oscillation KW - Strength KW - Modulus KW - High temperatures KW - Friction KW - Wear KW - NbC KW - Niobium carbide KW - Cobalt KW - Fe3Al KW - Hard metal PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-316129 DO - https://doi.org/10.1016/j.wear.2014.09.007 SN - 0043-1648 VL - 321 SP - 1 EP - 7 PB - Elsevier CY - Amsterdam AN - OPUS4-31612 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gaal, Mate A1 - Dohse, Elmar A1 - Bartusch, Jürgen A1 - Köppe, Enrico A1 - Kreutzbruck, Marc A1 - Hillger, W. A1 - Amos, J. M. T1 - Ultrasonic testing of adhesively bonded joints using air-coupled cellular polypropylene transducers N2 - In air-coupled ultrasonic testing, the impedance mismatch between the transducer and the air is commonly being solved by adding matching layers to composite transducers. To avoid the difficult technological procedure regarding matching layers, some new piezoelectric materials have been proposed. Most promising are ferroelectrets, which are charged cellular polymers, having ferroelectric and consequently piezoelectric properties. In particular, the extreme softness of cellular polypropylene (cPP) leads to a high piezoelectric constant and to a good impedance match with the air, making matching layers redundant. Its elasticity modulus below 1 MPa causes an additional effect not observed with common piezoelectric materials: that is the electrostrictive effect, here defined as the thickness change due to the attractive force between the transducer electrodes. This effect exceeds the piezoelectric effect at excitation voltages over 1 kV. The extreme softness of cPP leads also to high flexibility, enabling easy focusing by bending the transducer. We have developed air-coupled ultrasonic transducers based on cPP. This includes the electrical matching networks for the transmitter and for the receiver. The transmitter is excited with voltages up to 2.5 kV, so that the electrostrictive effect dominates, leading to sound pressure around 145dB at the transducer surface. These transducers have been applied for testing carbon-fiber-reinforced polymer plates, adhesive joints and other composite structures. Here we report about ultrasonic transmission of two types of adhesive joints. The first one is multi-layer aluminium components with some artificial disbonds, which are common in aerospace industry, and the second one is an aluminium-steel joint with polyurethane adhesive, which is used in automotive industry. T2 - ECNDT 2014 - 11th European conference on non-destructive testing CY - Prague, Czech Republic DA - 06.10.2014 KW - Air-coupled KW - Ultrasonic testing KW - Ferroelectret KW - Cellular polypropylene KW - Transducer KW - Adhesive joint PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-317204 SN - 978-80-214-5018-9 SP - 1 EP - 8 PB - Brno University of Technology AN - OPUS4-31720 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 - Stoch, P. A1 - Szczerba, Wojciech A1 - Bodnar, W. A1 - Ciecinska, M. A1 - Stoch, A. A1 - Burkel, E. T1 - Structural properties of iron-phosphate glasses: spectroscopic studies and ab initio simulations N2 - Vitrification is the most effective method for the immobilization of hazardous waste by incorporating toxic elements into a glass structure. Iron phosphate glasses are presently being considered as matrices for the storage of radioactive waste, even of those which cannot be vitrified using conventional borosilicate waste glass. In this study, a structural model of 60P2O5–40Fe2O3 glass is proposed. The model is based on the crystal structure of FePO4 which is composed of [FeO4][PO4] tetrahedral rings. The rings are optimized using the DFT method and the obtained theoretical FTIR and Raman spectra are being compared with their experimental counterparts. Moreover, the proposed model is in very good agreement with X-ray absorption fine structure spectroscopy (XANES/EXAFS) and Mössbauer spectroscopy measurements. According to the calculations the Fe3+ is in tetrahedral and five-fold coordination. The maximal predicted load of waste constituents into the glass without rebuilding of the structure is 30 mol%. Below this content, waste constituents balance the charge of [FeO4]- tetrahedra which leads to their strong bonding to the glass resulting in an increase of the chemical durability, transformation and melting temperatures and density. KW - Glass KW - Iron KW - DFT simulations KW - Mössbauer spectroscopy KW - XANES/EXAFS KW - FTIR spectroscopy KW - Raman spectroscopy KW - Coordination PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-317351 DO - https://doi.org/10.1039/c4cp03113j SN - 1463-9076 SN - 1463-9084 VL - 16 IS - 37 SP - 19917 EP - 19927 PB - The Royal Soc. of Chemistry CY - Cambridge AN - OPUS4-31735 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -