TY - JOUR A1 - Asadujjaman, Asad A1 - Ahmadi, Vahid A1 - Franc, Antoine Michel Claude A1 - Bertin, Annabelle T1 - 2,6-Diaminopyridine and Acrylamide-Based Copolymers with Upper Critical Solution Temperature-type Behavior in Aqueous Solution N2 - A novel cop olyme r based on supramolecular motif2,6-diaminopyridin e and water-soluble acrylamide, poly[N-(6-ace tamidopyridin-2-yl) acrylamide-co-acrylamide], was synthe-size d via rev ersible addi tion–fragmentation chain transfer (RAFT)polymerization with various monomer compositions. The thermo-respon sive behavior of the copolymers was studied by turbidime-try and dynamic light scattering (DLS). The obtained copolymersshowed an upper critical solution temperature (UCST)-typ e phasetransition behavior in water and electrolyte solution. The phasetransition temperature was found to increase with decreasingam ount of acrylamide in the copolymer and increasing concentra-tion of the solution. Furth ermore, the phase transition temperatureva ried in aqueous solutions of electrolytes according to the naturean d concentration of the electrolyte in accordance with theHoffmeister series. A dramatic solvent isotope effect on thetransition temperature was o bserved in this study, as the transitiontemperature was almost 10–12C higher in D2OthaninH2Oatthesame concentration and acrylamide co mposition. The size of theaggregates below the transition temperature was larger in D2Ocompared to that in H2O that can be explained by deuterium iso-tope effect. The thermoresponsive behavior of the copolymers wasalso investigated in different cell medium and found to be exhibitedUCST-type phase transition behavior in different cell medium.Such behavior of the copo lyme rs can be useful in many a pplica-tions including biomedical, microfluidics, optical materials, and indrug delivery. KW - 2,6-diaminopyridine KW - Acrylamide KW - Stimuli-responsive polymers KW - Thermo-responsive polymers KW - UCST polymers PY - 2019 U6 - https://doi.org/10.1002/pola.29474 SN - 0887-624X VL - 57 IS - 19 SP - 2064 EP - 2073 PB - Wiley AN - OPUS4-49297 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rahrig, M. A1 - Torge, Manfred T1 - 3D Inspection of the restoration and conservation of stained glass N2 - The initial focus of this research was on the development of a general workflow for the documentation and monitoring of historical stained glass windows using structured light scanning. Therefore windows from different churches, time periods and with different corrosion and damage phenomena were scanned before and after conservation measures. T2 - 27th CIPA International Symposium “Documenting the past for a better future” CY - Ávila, Spain DA - 01.09.2019 KW - Stained glass KW - Restoration and conservation KW - Structured light scanning KW - 3D inspection KW - Glass scanning PY - 2019 AN - OPUS4-49600 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thiede, Tobias A1 - Mishurova, Tatiana A1 - Evsevleev, Sergei A1 - Serrano Munoz, Itziar A1 - Gollwitzer, Christian A1 - Bruno, Giovanni T1 - 3D shape analysis of powder for laser beam melting by synchrotron X-ray CT N2 - The quality of components made by laser beam melting (LBM) additive manufacturing is naturally influenced by the quality of the powder bed. A packing density <1 and porosity inside the powder particles lead to intrinsic voids in the powder bed. Since the packing density is determined by the particle size and shape distribution, the determination of these properties is of significant interest to assess the printing process. In this work, the size and shape distribution, the amount of the particle’s intrinsic porosity, as well as the packing density of micrometric powder used for LBM, have been investigated by means of synchrotron X-ray computed tomography (CT). Two different powder batches were investigated: Ti–6Al–4V produced by plasma atomization and stainless steel 316L produced by gas atomization. Plasma atomization particles were observed to be more spherical in terms of the mean anisotropy compared to particles produced by gas atomization. The two kinds of particles were comparable in size according to the equivalent diameter. The packing density was lower (i.e., the powder bed contained more voids in between particles) for the Ti–6Al–4V particles. The comparison of the tomographic results with laser diffraction, as another particle size measurement technique, proved to be in agreement. KW - Additive manufacturing KW - Laser beam melting KW - Synchrotron computed tomography KW - Powder analysis KW - Imaging PY - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-474070 SN - 2412-382X VL - 3 IS - 1 SP - 3, 1 EP - 12 PB - MDPI AN - OPUS4-47407 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Colini, Claudia ED - Hahn, Oliver ED - Rabin, Ira T1 - A black ink by any other name... Typologies of Arabic inks and their detection limits N2 - In this poster we will present some results of a research projects dealing with Arabic recipes of black inks. To improve conservation practices of Arabic manuscripts we have assessed the feasibility of the recipes collected from many Arabic sources on bookmaking and reproduced the most common inks. Ink samples were then artificially aged and analysed using an array of analytical techniques, mostly non-invasive, in order to build a database of Arabic inks and their ingredients and also to verify the detection limits of the portable equipment employed. We will show procedures and problems concerning the identification of ink types and ingredients using reflectography (in Vis, IR and UV), X-Ray Fluorescence, Infrared and Raman spectroscopy. The focus will be in particular on squid ink and mixed inks – both in the form of carbon inks with the addition of tannins and of a mixture of carbon and iron gall inks – which are particularly difficult to detect. We will also examine the results of iron gall inks made with iron filings or nails instead of vitriol, the various precursor used to extract gallic acid that are mentioned in the sources as surrogates of gall nuts. T2 - Jahrestagung „Archäometrie und Denkmalpflege 2019“ CY - Vienna, Austria DA - 11.09.2019 KW - Inks KW - Reflectography KW - XRF KW - Raman Spectroscopy KW - ATR PY - 2019 SN - 0947-6229 VL - Sonderheft 9 SP - 93 EP - 96 PB - Deutsches Bergbau-Museum Bochum CY - Bochum AN - OPUS4-50163 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Colini, Claudia A1 - Hahn, Oliver A1 - Rabin, Ira T1 - A black ink by any other name...: Typologies of arabic inks and their detection limits N2 - In this poster we will present some results of a research projects dealing with Arabic recipes of black inks [1-2]. To improve conservation practices of Arabic manuscripts we have assessed the feasibility of the recipes collected from many Arabic sources on bookmaking and reproduced the most common inks. Ink samples were then artificially aged and analysed using an array of analytical techniques, mostly non-invasive, in order to build a database of Arabic inks and their ingredients and also to verify the detection limits of the portable equipment employed. We will show procedures and problems concerning the identification of ink types and ingredients using reflectography (in Vis, IR and UV), X-Ray Fluorescence, Infrared and Raman spectroscopy. The focus will be in particular on squid ink [3] and mixed inks – both in the form of carbon inks with the addition of tannins and of a mixture of carbon and iron gall inks – which are particularly difficult to detect [4]. We will also examine the results of iron gall inks made with iron filings or nails instead of vitriol, the various precursor used to extract gallic acid that are mentioned in the sources as surrogates of gall nuts. [1] A. Schopen, Tinten und Tuschen des arabisch-islamischen Mittelalters, Göttingen: Vandenhoeck & Ruprecht, 2004 [2] S. Fani, Le arti del libro secondo le fonti arabe originali. I ricettari arabi per la fabbricazione degli inchiostri (sec. IX-XIII): loro importanza per una corretta valutazione e conservazione del patrimonio manoscritto, PhD thesis, Napoli: Università L’Orientale, 2013 [3] S. Centeno, J. Shamir Journal of Molecular Structure, 873 (2008), 149-159 [4] C. Colini et. al, Manuscript cultures, 11 (2018) 43-50 T2 - Jahrestagung „Archäometrie und Denkmalpflege 2019“ CY - Vienna, Austria DA - 11.09.2019 KW - Inks KW - Reflectography KW - XRF KW - Raman Spectroscopy KW - ATR PY - 2019 AN - OPUS4-50162 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Colini, Claudia A1 - Hahn, Oliver A1 - Rabin, Ira T1 - A black ink by any other name...: Typologies of Arabic inks and their detection limits N2 - In this poster we will present some results of a research projects dealing with Arabic recipes of black inks. To improve conservation practices of Arabic manuscripts we have assessed the feasibility of the recipes collected from many Arabic sources on bookmaking and reproduced the most common inks. Ink samples were then artificially aged and analysed using an array of analytical techniques, mostly non-invasive, in order to build a database of Arabic inks and their ingredients and also to verify the detection limits of the portable equipment employed. First, we will provide an overview of the sources [1-2] employed in the study – dating from 9th to 14th century, although the manuscripts in which they can be found dates up to the 20th century – with an eye on the ink typologies (real and perceived by the compilers). Then we will show how, by reproducing the recipes, it was possible to shed light on some oddities in the procedures and the choice of ingredients. In the end we will discuss problems concerning the identification of ink types and ingredients using reflectography (in Vis, IR and UV), X-Ray Fluorescence, Infrared and Raman spectroscopy. The focus will be in particular on mixed inks – both in the form of carbon inks with the addition of tannins and of a mixture of carbon and iron gall inks – which are particularly difficult to detect [3]. We will also examine the results of iron gall inks made with iron filings or nails instead of vitriol and the various precursor used to extract gallic acid that are mentioned in the sources as surrogates of gall nuts. [1] A. Schopen, Tinten und Tuschen des arabisch-islamischen Mittelalters, Göttingen: Vandenhoeck & Ruprecht, 2004 [2] S. Fani, Le arti del libro secondo le fonti arabe originali. I ricettari arabi per la fabbricazione degli inchiostri (sec. IX-XIII): loro importanza per una corretta valutazione e conservazione del patrimonio manoscritto, PhD thesis, Napoli: Università L’Orientale, 2013 [3] C. Colini et. al, Manuscript cultures, 11 (2018) 43-50 T2 - Technart 2019 CY - Bruges, Belgium DA - 07.05.2019 KW - Inks KW - Reflectography KW - XRF KW - Raman Spectroscopy KW - ATR PY - 2019 AN - OPUS4-50112 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Linberg, Kevin A1 - Ali, Naveed Zafar A1 - Etter, M. A1 - Michalchuk, Adam A1 - Rademann, K. A1 - Emmerling, Franziska T1 - A Comparative Study of the Ionic Cocrystals NaX (α-d-Glucose)2 (X = Cl, Br, I) N2 - The mechanochemical formation of the ionic cocrystals of glucose (Glc) and sodium salts Glc2NaCl·H2O (1) and Glc2NaX (X = Br (2), I (3)) is presented. Products are formed by co-milling Glc with three sodium salts (NaCl, NaBr, NaI). The ionic cocrystals were obtained under both neat grinding and liquid-assisted grinding conditions, the later found to accelerate the reaction kinetics. The crystal structures of the ionic cocrystals (2) and (3) were solved from powder X-ray diffraction data. The structure solution contrasts with the structure of Glc2NaCl·H2O (1) where the electron density at three halide crystallographic sites is modeled as of being the intermediate between water molecule and a chloride ion. The reaction pathways of the three ionic cocrystals were investigated in real time using our tandem approach comprising a combination of in situ synchrotron powder X-ray diffraction and Raman spectroscopy. The results indicate the rapid formation of each cocrystal directly from their respective starting materials without any intermediate moiety formation. The products were further characterized by DTA-TG and elemental analysis. KW - In situ KW - Co-crystal KW - Mechanochemistry KW - Glucose PY - 2019 U6 - https://doi.org/10.1021/acs.cgd.8b01929 VL - 19 IS - 8 SP - 4293 EP - 4299 PB - ACS Publications AN - OPUS4-48781 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Artinov, Antoni A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - A decoupling numerical approach for the study of hot cracking formation during high power keyhole mode welding of steel plates with a high sheet thickness N2 - The weld pool dynamics and shape play a fundamental role in keyhole mode welding. The presented work aims the experimental and numerical investigation of the influence of the weld pool characteristics on the formation of hot cracking. The experimental procedure allows recording the molten pool in the longitudinal section of a butt joint configuration of 15 mm thick structural steel and transparent quartz glass by using a high-speed video camera and two thermal imaging cameras. The observations show that the dimensions of the weld pool vary depending on the depth. The regions close to the surface form a teardrop-shaped weld pool. A bulge-region and its temporal evolution are observed approximately in the middle of the depth of the weld pool, where hot cracking appears. A numerical framework including models for the weld pool dynamics, global temperature field, transient stress state, crystal growth, diffusion and macro-segregation and subroutines for their one-way couplings is developed. The numerically obtained and experimentally observed results are in a good agreement. It is shown that the bulge-region leads to a delay in the solidification behavior, increased temporal tensile stresses and accumulation of impurities in the defect region and hence enhance the probability of hot cracking formation. T2 - Colloquium, Dept. Materials Science & Engineering, The Ohio State University CY - Columbus, Ohio, USA DA - 18.10.2019 KW - Keyhole mode welding KW - Weld pool shape KW - Bulge KW - Hot cracking PY - 2019 AN - OPUS4-49339 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wu, Cheng-Chieh A1 - Weisbrich, S. A1 - Burger, M. A1 - Neitzel, F. T1 - A Four-Point Bending Test Apparatus for Measurement- and Model-based Structural Analysis N2 - By means of a small-scale truss bridge, the ability of the Measurement- and Model-based Structural Analysis to detect and localize damage was examined. Although there was no noteworthy difficulty in detecting damage, it turned out that damage localization responds sensitively to systematic influences, i.e. non-modelled properties of the mechanical model. Therefore, another experiment is being conducted to re-examine the Measurement- and Model-based Structural Analysis. For this purpose, the bending test is carried out as it has been already theoretically respectively numerically discussed. In this attempt, the systematic influences such as residual stress are kept as low as possible. T2 - 36th Danubia Adria Symposium on Advances in Experimental Mechanics CY - Pilsen, Czech Republic DA - 24.09.2019 KW - Damage detection KW - Adjustment calculation KW - Finite element method PY - 2019 SN - 978-80-261-0876-4 SP - 63 EP - 64 CY - Pilsen, Czech Republic AN - OPUS4-49290 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thünemann, Andreas T1 - A look inside nanoparticles N2 - Small-angle scattering is the method of choice when it comes to obtaining information about the interior of nanoparticles. The aim is to make nanotechnology safer. While the use of small-angle neutron scattering (SANS) is limited to a few instruments in the world, small-angle X-ray scattering (SAXS) is widely accessible, with an upward trend. The example of core-shell particles shows how simple their analysis is with data from an Anton Paar laboratory system. Here, SAXS is a central tool for the development of new reference materials based on poly(methyl) acrylate-PVDF core-shell particles. The dimensions of the cores and shells can be precisely determined. A detailed analysis makes it possible to show that the cores contain fluorinated and nonfluorinated polymers, whereas the shell consist only of PVDF. This core-shell particles with a diameter around 40 nm show a significantly higher PVDF beta phase content than the PVDF homopolymer when using an emulsion polymerization technique. This finding is of importance with respect to applications in electroactive devices. T2 - SAXS excites: International SAXS Symposium 2019 CY - Graz, Austria DA - 24.09.2019 KW - Small-angle X-ray scattering KW - SAXS KW - Nanoplastics PY - 2019 AN - OPUS4-49126 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - THES A1 - Fritsch, Tobias T1 - A Multiscale Analysis of Additively Manufactured Lattice Structures N2 - Additive Manufacturing (AM) in terms of laser powder-bed fusion (L-PBF) offers new prospects regarding the design of parts and enables therefore the production of lattice structures. These lattice structures shall be implemented in various industrial applications (e.g. gas turbines) for reasons of material savings or cooling channels. However, internal defects, residual stress, and structural deviations from the nominal geometry are unavoidable. In this work, the structural integrity of lattice structures manufactured by means of L-PBF was non-destructively investigated on a multiscale approach. A workflow for quantitative 3D powder analysis in terms of particle size, particle shape, particle porosity, inter-particle distance and packing density was established. Synchrotron computed tomography (CT) was used to correlate the packing density with the particle size and particle shape. It was also observed that at least about 50% of the powder porosity was released during production of the struts. Struts are the component of lattice structures and were investigated by means of laboratory CT. The focus was on the influence of the build angle on part porosity and surface quality. The surface topography analysis was advanced by the quantitative characterisation of re-entrant surface features. This characterisation was compared with conventional surface parameters showing their complementary information, but also the need for AM specific surface parameters. The mechanical behaviour of the lattice structure was investigated with in-situ CT under compression and successive digital volume correlation (DVC). The Deformation was found to be knot-dominated, and therefore the lattice folds unit cell layer wise. The residual stress was determined experimentally for the first time in such lattice structures. Neutron diffraction was used for the non-destructive 3D stress investigation. The principal stress directions and values were determined in dependence of the number of measured directions. While a significant uni-axial stress state was found in the strut, a more hydrostatic stress state was found in the knot. In both cases, strut and knot, seven directions were at least needed to find reliable principal stress directions. KW - Additive manufacturing KW - Laser powder bed fusion KW - Residual stress KW - Surface roughness analysis KW - Computed tomography PY - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-470418 SP - 1 EP - 97 PB - Universitätsbibliothek Potsdam CY - Potsdam AN - OPUS4-53476 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Erning, Johann Wilhelm T1 - A new type of copper pitting corrosion in german tap waters N2 - Half-hard copper pipes show pitting corosion under conditions until now seen as uncritical. Examples are discussed, possible causes described. T2 - MTECH 2019 CY - Porec, Croatia DA - 09.10.2019 KW - Drinking KW - Pitting KW - Corrosion KW - Copper KW - Water PY - 2019 AN - OPUS4-49283 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Artinov, Antoni A1 - Bachmann, Marcel A1 - Karkhin, Victor A1 - Rethmeier, Michael ED - Sommertisch, C. ED - Enzinger, N. ED - Mayr, P. T1 - A novel approach for calculating the thermal cycle of a laser beam welding process using a stationary CFD model N2 - This work aims to find the thermal cycles during and after fusion welding through simulation by first calculating the resulting local temperature field in the quasi-stationary part of the process. Here complete-penetration keyhole laser beam welding with a laser power of 18 kW on a 15 mm thick slab of a low-alloyed steel at a welding speed of 2 m/min is considered. In order to physically depict the laser material interaction a multi-physics numerical model including the effects of phase transformation, thermo-capillary convection, natural convection and temperature-dependent material properties up to evaporation temperature is developed. It uses a fixed keyhole geometry with a right truncated circular cone shape to introduce the laser beam energy to the workpiece. In a subsequent study, the resulting local temperature field is then used as an equivalent heat source in order to predict the unsteady thermal cycle during and after fusion welding. The translational movement of the laser beam through the workpiece is represented by a moving mesh approach. For the simulation, stationary heat transfer and fluid dynamics are described by a system of strongly coupled partial differential equations. These are solved with the commercial finite element software COMSOL Multiphysics 5.0. The results of the numerical simulation are validated by experiments, where the weld bead shapes and the thermal cycles show good correlation. T2 - 12th International Seminar "Numerical Analysis of Weldability" CY - Graz, Austria DA - 24.09.2018 KW - Equivalent heat source KW - Process simulation KW - Laser beam welding KW - Transient heat transfer KW - Moving mesh PY - 2019 SN - 978-3-85125-616-1 VL - 12 SP - Chapt. VI, 694 EP - 710 PB - Verlag der Technischen Universität Graz AN - OPUS4-48817 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hlavacek, Petr A1 - Gluth, Gregor A1 - Lüchtenborg, Jörg A1 - Sturm, Patrick A1 - Mühler, T. A1 - Kühne, Hans-Carsten A1 - Günster, Jens T1 - A Novel Approach to Additive Manufacturing of Alkali-activated Materials: Laser-induced Slip Casting (LIS) of Lithium Aluminate/Silica Slurries N2 - Additive manufacturing of alkali-activated materials currently attracts a lot of attention, because of the possibility to produce customized high-performance elements for a range of applications, potentially being more resource-efficient than conventionally produced parts. Here, we describe a new additive manufacturing process for alkali-activated materials that is based on selective laser-heating of lithium aluminate/microsilica slurries. The new process-material combination allows to manufacture elements with complex geometries at high building rates and high accuracy. The process is versatile and transferrable to structures of sizes differing by orders of magnitude. The mechanical strength of the obtained materials was in the range of values reported for conventional metakaolin-based geopolymers, and superior to what has been hitherto reported for alkali-activated materials produced by additive manufacturing. This mechanical performance was obtained despite the fact that the degree of reaction of the lithium aluminate and the microsilica was low, suggesting that significant reactions took place only at the surface of the microsilica particles. KW - Laser-induced slip casting KW - Alkali-activated materials KW - Additive manufacturing PY - 2019 U6 - https://doi.org/10.29272/cmt.2018.0011 SN - 2612-4882 VL - 1 IS - 2 SP - 138 EP - 144 PB - Techna Group AN - OPUS4-49142 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wu, Cheng-Chieh A1 - Weisbrich, S. A1 - Neitzel, F. A1 - Kadoke, Daniel A1 - Fischer, Michael A1 - Kohlhoff, Harald ED - Pastramă, Ştefan Dan ED - Constantinescu, Dan Mihai T1 - A Small-Scale Test Bridge for Measurement and Model-based Structural Analysis N2 - The Measurement- and Model-based Structural Analysis (MeMoS) integrates a finite element model into least squares adjustment and thus allows to evaluate a mechanical model and measurements in a combined analysis. To examine the capability to detect and localise damage using this integrated analysis MeMoS, a small-scale truss bridge made of aluminium profiles is built as a test specimen for this purpose. T2 - 35th Danubia Adria Symposium on Advances in Experimental Mechanics CY - Sinaia, Romania DA - 25.09.2018 KW - Structural analysis KW - Damage detection and localisation KW - Finite element method KW - Photogrammetry KW - Adjustment calculation PY - 2019 UR - http://www.sciencedirect.com/science/article/pii/S2214785319304894 U6 - https://doi.org/10.1016/j.matpr.2019.03.130 SN - 2214-7853 VL - 12 IS - 2 SP - 319 EP - 328 PB - Elsevier Ltd. AN - OPUS4-48053 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn T1 - A survey of surface functionalization through laser-induced periodic surface structures N2 - Laser-induced periodic surface structures (LIPSS, ripples) are a universal phenomenon that can be observed on almost any material after the irradiation by linearly polarized laser beams, particularly when using ultrashort laser pulses with durations in the femtosecond to picosecond range. During the past few years significantly increasing research activities have been reported in the field of LIPSS, since their generation in a single-step process provides a simple way of nanostructuring and surface functionalization towards the control of optical, mechanical, biological, or chemical surface properties. In this contribution the mechanisms of formation and current applications of LIPSS are reviewed, including the colorization of technical surfaces, the control of surface wetting properties, the mimicry of the natural texture of animal integuments, the tailoring of surface colonization by bacterial biofilms, the advancement of medical pacemakers, and the improvement of the tribological performance of nanostructured metal surfaces. T2 - Seminar, ALPhANOV - Centre Technologique Optique et Lasers CY - Talence, France DA - 07.06.2019 KW - Laser-induced periodic surface structures, LIPSS KW - Surface functionalization KW - Applications KW - Femtosecond laser PY - 2019 AN - OPUS4-48199 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hoevelmann, J. A1 - Stawski, T. M. A1 - Besselink, R. A1 - Freeman, H. M. A1 - Dietmann, K. M. A1 - Mayanna, S. A1 - Pauw, Brian Richard A1 - Benning, L. G. T1 - A template-free and low temperature method for the synthesis of mesoporous magnesium phosphate with uniform pore structure and high surface area N2 - Mesoporous phosphates are a group of nanostructured materials with promising applications, particularly in biomedicine and catalysis. However, their controlled synthesis via conventional template-based routes presents a number of challenges and limitations. Here, we show how to synthesize a mesoporous Magnesium phosphate with a high surface area and a well-defined pore structure through thermal decomposition of a crystalline struvite (MgNH4PO4·6H2O) precursor. In a first step, struvite crystals with various morphologies and sizes, ranging from a few micrometers to several millimeters, had been synthesized from supersaturated aqueous solutions (saturation index (SI) between 0.5 and 4) at ambient pressure and temperature conditions. Afterwards, the crystals were thermally treated at 70–250 °C leading to the release of structurally bound water (H2O) and ammonia (NH3). By combining thermogravimetric analyses (TGA), scanning and transmission electron microscopy (SEM, TEM), N2 sorption analyses and small- and wide-angle X-ray scattering (SAXS/WAXS) we show that this decomposition process results in a pseudomorphic transformation of the original struvite into an amorphous Mg-phosphate. Of particular importance is the fact that the final material is characterized by a very uniform mesoporous structure with 2–5 nm wide pore channels, a large specific surface area of up to 300 m2 g−1 and a total pore volume of up to 0.28 cm3 g−1. Our struvite decomposition method is well controllable and reproducible and can be easily extended to the synthesis of other mesoporous phosphates. In addition, the so produced mesoporous material is a prime candidate for use in biomedical applications considering that Magnesium phosphate is a widely used, non-toxic substance that has already shown excellent biocompatibility and biodegradability. KW - Struvite KW - SAXS KW - Scattering KW - Nanoporous KW - Geology PY - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-477130 VL - 11 IS - 14 SP - 6939 EP - 6951 PB - Royal Society of Chemistry AN - OPUS4-47713 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meng, Xiangmeng A1 - Artinov, Antoni A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - A theoretical study of influence o f electromagnetic stirring on transport phenomena in wire feed laser beam welding N2 - The additional element from the filler wire in the laser beam welding is usually distributed inhomogeneously in the final weld due to the high solidification rate of weld pool. It has been found that the electromagnetic stirring produced by an external oscillating magnetic field can enhance the material mixing in the weld pool to achieve a more uniform element distribution. However, the magnetic field has a highly non-linear and multi-coupled interaction with the weld pool behavior, which makes the quantitative explanation of the physical mechanism difficult. In this study, the effect of electromagnetic stirring on the transport phenomena in the wire feed laser beam welding is investigated by a numerical modelling. A 3D transient multi-physical model considering the magnetohydrodynamics, heat transfer, fluid flow, keyhole dynamics and element transport is developed. The multiple reflections and the Fresnel absorption of the laser on the keyhole wall are calculated using the ray tracing method. The numerical results show that a Lorentz force produced by the oscillating magnetic field and its induced eddy current gives significant influence on the transport phenomena in the molten pool. The forward and downward flow is enhanced by the electromagnetic stirring, which homogenizes the distribution of the additional elements from a nickel-based filler wire in a steel weld pool. The numerical results show a good agreement with the high-speed images of the molten pool, the fusion line from the optical micrograph and the element distribution from the energy dispersive X-ray spectroscopy. This work provides a physical base for the electromagnetic-controlled laser beam welding and some guidance for the selection of electromagnetic parameters. T2 - ICALEO 2019 - 38th International congress on applications of lasers & electro-optics CY - Orlando, FL, USA DA - 07.10.2019 KW - Magnetohydrodynamics KW - Molten pool dynamics KW - Element transport KW - Laser beam welding PY - 2019 SN - 978-1-940168-1-42 SP - Paper # Macro 403 AN - OPUS4-49664 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meng, Xiangmeng A1 - Artinov, Antoni A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - A theoretical study of influence of electromagnetic stirring on transport phenomena in wire feed laser beam welding N2 - The additional element from the filler wire in the laser beam welding is usually distributed inhomogeneously in the final weld due to the high solidification rate of weld pool. It has been found that the electromagnetic stirring produced by an external oscillating magnetic field can enhance the material mixing in the weld pool to achieve a more uniform element distribution. However, the magnetic field has a highly non-linear and multi-coupled interaction with the weld pool behavior, which makes the quantitative explanation of the physical mechanism difficult. In this study, the effect of electromagnetic stirring on the transport phenomena in the wire feed laser beam welding is investigated by a numerical modelling. A 3D transient multi-physical model considering the magnetohydrodynamics, heat transfer, fluid flow, keyhole dynamics and element transport is developed. The multiple reflections and the Fresnel absorption of the laser on the keyhole wall are calculated using the ray tracing method. The numerical results show that a Lorentz force produced by the oscillating magnetic field and its induced eddy current gives significant influence on the transport phenomena in the molten pool. The forward and downward flow is enhanced by the electromagnetic stirring, which homogenizes the distribution of the additional elements from a nickel-based filler wire in a steel weld pool. The numerical results show a good agreement with the high-speed images of the molten pool, the fusion line from the optical micrograph and the element distribution from the energy dispersive X-ray spectroscopy. This work provides a physical base for the electromagnetic-controlled laser beam welding and some guidance for the selection of electromagnetic parameters. T2 - ICALEO 2019 CY - Orlando, US DA - 07.10.2019 KW - Magnetohydrodynamics KW - Molten pool dynamics KW - Element transport KW - Laser beam welding PY - 2019 AN - OPUS4-49300 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waske, Anja T1 - A thermomagnetic generator for harvesting low-grade waste heat N2 - To date, there are only very few technologies available for the conversion of low temperature waste heat to electricity. In this talk, we first describe the principle of thermomagnetic generators. Then we focus on the impact of topology of the magnetic circuit within thermomagnetic generators. We demonstrate that the key operational parameters strongly depend on the genus, i.e. the number of holes within the magnetic circuit. T2 - Eingeladener Vortrag / Symposiumsorganisation und Vortrag CY - Uppsala, Sweden DA - 28.08.2019 KW - Energy harvesting KW - Magnetocaloric KW - Material Science KW - Non-Destructive testing PY - 2019 AN - OPUS4-50179 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -