Inst. Werkstoffwissenschaften und -technologien

235 Items

Recent Submissions
Synchrotron Radiography for a Proton Exchange Membrane (PEM) Electrolyzer

Panchenko, U. ; Arlt, Thomas ; Manke, I. ; Müller, M. ; Stolten, D. ; Lehnert, W. (2020-02-17)

In‐plane synchrotron radiography with a resolution of a few micrometers was applied to study transport processes within a Proton Exchange Membrane (PEM) electrolyzer cell. The degradation process of the catalyst layer, gas production with bubble formation at the catalyst layer and in the porous transport layer (PTL) was analyzed. From this, a new cell design was developed that allows for high X...

Optimization of the Indirect Extrusion Process of Copper-Clad Aluminum Rods by Methods of Statistical Experimental Designs and Numerical Analyses

Lechner, Stefan ; Rœmisch, Ute ; Nitschke, René ; Gensch, Felix ; Mueller, Soeren (2021-05-13)

The success of composite extrusion is influenced by multiple process parameters. In order to investigate the significance of specific parameters during indirect extrusion of copper-clad aluminum (CCA) rods, statistical methods were applied and a central composite experimental design was implemented. The runs of the experimental design were modeled with the finite element method based software D...

Bracket fungi, natural lightweight construction materials: hierarchical microstructure and compressive behavior of Fomes fomentarius fruit bodies

Müller, Cecilia ; Klemm, Sophie ; Fleck, Claudia (2021-02-10)

Bracket fungi such as Fomes fomentarius (“tinder fungus”), have strong, light and tough fruit bodies that make them interesting role-models for bio-inspired, biodegradable applications. So far, little is known about the relation between their microstructure and mechanical properties, information needed for designing novel composites. The fruit bodies (mycelia) of tinder fungus are hierarchicall...

Synchrotron Sub‐μ X‐ray Tomography of Kirkendall Porosity in a Diffusion Couple of Nickel‐Base Superalloy and Nickel after Annealing at 1250 °C

Epishin, Alexander ; Camin, Bettina ; Hansen, Lennart ; Chyrkin, Anton ; Nolze, Gert (2021-01-21)

Kirkendall porosity that forms during interdiffusion in a diffusion couple of nickel‐base superalloy CMSX‐10 with pure nickel is investigated. The diffusion experiments are conducted at a temperature of 1250 °C, where the strengthening γ′‐phase is partially dissolved. The porosity is studied by X‐ray sub‐μ tomography with a spatial resolution of about 0.353 μm3 at the European Synchrotron Radia...

Quantifizierung von Fehlstellen in teiltransparenten Festkörpern mittels der Impulsthermografie

Bernegger, Raphael Kim (2021)

Die Impulsthermografie (PT) gehört zu den zerstörungsfreien Prüfverfahren und wird für die Detektion und Quantifizierung von verdeckten Fehlstellen in einem Bauteil eingesetzt. Bei Materialien, die im Wellenlängenbereich der optischen Anregungsquelle und der Infrarot(IR)-Kamera teiltransparent sind, z.B. glasfaserverstärkter Kunststoff (GFK), können die bestehenden Auswertemethoden der PT nicht...

3D Printing for Soft Tissue Regeneration and Applications in Medicine

Pantermehl, Sven ; Emmert, Steffen ; Foth, Aenne ; Grabow, Niels ; Alkildani, Said ; Bader, Rainer ; Barbeck, Mike ; Jung, Ole (2021-03-26)

The use of additive manufacturing (AM) technologies is a relatively young research area in modern medicine. This technology offers a fast and effective way of producing implants, tissues, or entire organs individually adapted to the needs of a patient. Today, a large number of different 3D printing technologies with individual application areas are available. This review is intended to provide ...

Microstructural Stability of Extruded Mg-Mn-Ce Hollow Profiles with Weld Seams

Gensch, Felix ; Gall, Sven ; Lechner, Stefan ; Fahrenson, Christoph ; Müller, Sören (2021-03-27)

Despite aluminum profiles, magnesium profiles have not been well developed due to the low formability. Furthermore, extruded magnesium profiles show a strong dependence on the mechanical properties, according to the loading direction. This is caused by a strong basal texture, which is directly dependent on the process parameters during the extrusion and the subsequent aging. Thus, the present p...

The Early Fragmentation of a Bovine Dermis-Derived Collagen Barrier Membrane Contributes to Transmembraneous Vascularization—A Possible Paradigm Shift for Guided Bone Regeneration

Kapogianni, Eleni ; Alkildani, Said ; Radenkovic, Milena ; Xiong, Xin ; Krastev, Rumen ; Stöwe, Ignacio ; Bielenstein, James ; Jung, Ole ; Najman, Stevo ; Barbeck, Mike ; Rothamel, Daniel (2021-03-09)

Collagen-based barrier membranes are an essential component in Guided Bone Regeneration (GBR) procedures. They act as cell-occlusive devices that should maintain a micromilieu where bone tissue can grow, which in turn provides a stable bed for prosthetic implantation. However, the standing time of collagen membranes has been a challenging area, as native membranes are often prematurely resorbed...

Theoretical Prediction of P-Triphenylene-Graphdiyne as an Excellent Anode Material for Li, Na, K, Mg, and Ca Batteries

Salavati, Mohammad ; Alajlan, Naif ; Rabczuk, Timon (2021-03-05)

The efficient performance of metal-ion batteries strongly depends on electrode materials characteristics. Two-dimensional (2D) materials are among promising electrode materials for metal-ion battery cells, owing to their excellent structural and electronic properties. Two-dimensional graphdiyne has been recently fabricated and revealed unique storage capacities and fast charging rates. The curr...

Silicate dielectric ceramics for millimetre wave applications

Kamutzki, Franz ; Schneider, Sven ; Barowski, Jan ; Gurlo, Aleksander ; Hanaor, Dorian A.H. (2021-03-02)

Silicate ceramics are of considerable promise as high frequency dielectrics in emerging millimetre wave applications including high bandwidth wireless communication and sensing. In this review, we show how high quality factors and low, thermally stable permittivities arise in ordered silicate structures. On the basis of a large number of existing studies, the dielectric performance of silicate ...

Cu-modified SrTiO3 perovskites toward enhanced water–gas shift catalysis: A combined experimental and computational study

Coletta, Vitor C. ; Gonçalves, Renato V. ; Bernardi, Maria I. B. ; Hanaor, Dorian A. H. ; Assadi, M. Hussein N. ; Marcos, Francielle C. F. ; Nogueira, Francisco G. E. ; Assaf, Elisabete M. ; Mastelaro, Valmor R. (2020-12-23)

A water–gas shift reaction (WGS) is important and widely applied in the production of H2. Cu-modified perovskites are promising catalysts for WGS reactions in hydrogen generation. However, the structure-dependent stability and reaction pathways of such materials remain unclear. Herein, we report catalytically active Cu-modified SrTiO3 (nominally SrTi1–xCuxO3) prepared by a modified polymeric pr...

A constitutive analysis of nonlinear shear flow

Narimissa, Esmaeil ; Schweizer, Thomas ; Wagner, Manfred H. (2020-06-03)

We analyse shear stress and normal stress data obtained by cone-partitioned-plate (CPP) shear rheometry in recent years. The data sets of Schweizer et al. (Rheol. Acta 47, 943–957, 2008 ) and Costanzo et al. (Macromolecules 49, 3925–3935, 2016; & Fluids 4, 28, 2019 ) on nearly monodisperse polystyrene melts and solutions are considered to be among the most reliable shear data available. The Doi...

Effect of hot isostatic pressing on densification, microstructure and nanoindentation behaviour of Mg–SiC nanocomposites

Hübler, Daniela ; Ghasemi, Alireza ; Riedel, Ralf ; Fleck, Claudia ; Kamrani, Sepideh (2020-05-13)

The production of fully dense nanocomposites with a homogeneous distribution of nanoparticles through powder metallurgy (PM) techniques is challenging. Additionally to mechanical milling, pressing and sintering, a final consolidation process is needed to fully densify the nanocomposite. Hot isostatic pressing (HIP) is a promising alternative method to other hot forming processes to eliminate po...

Adjustment of the Mechanical Properties of Mg2Nd and Mg2Yb by Optimizing Their Microstructures

Schmidt, Jonas ; Beyerlein, Irene J. ; Knezevic, Marko ; Reimers, Walter (2021-02-25)

The deformation behavior of the extruded magnesium alloys Mg2Nd and Mg2Yb was investigated at room temperature. By using in situ energy-dispersive synchrotron X-ray diffraction compression and tensile tests, accompanied by Elasto-Plastic Self-Consistent (EPSC) modeling, the differences in the active deformation systems were analyzed. Both alloying elements change and weaken the extrusion textur...

Investigation of Elastic Properties of the Single-Crystal Nickel-Base Superalloy CMSX-4 in the Temperature Interval between Room Temperature and 1300 °C

Epishin, Alexander ; Fedelich, Bernard ; Finn, Monika ; Künecke, Georgia ; Rehmer, Birgit ; Nolze, Gert ; Leistner, Claudia ; Petrushin, Nikolay ; Svetlov, Igor (2021-02-02)

The elastic properties of the single-crystal nickel-base superalloy CMSX-4 used as a blade material in gas turbines were investigated by the sonic resonance method in the temperature interval between room temperature and 1300 °C. Elastic constants at such high temperatures are needed to model the mechanical behavior of blade material during manufacturing (hot isostatic pressing) as well as duri...

Universality of steady shear flow of Rouse melts

Poh, Leslie ; Narimissa, Esmaeil ; Wagner, Manfred H. (2020-08-29)

The data set of steady and transient shear data reported by Santangelo and Roland Journal of Rheology 45: 583–594, (2001) in the nonlinear range of shear rates of an unentangled polystyrene melt PS13K with a molar mass of 13.7 kDa is analysed by using the single integral constitutive equation approach developed by Narimissa and Wagner Journal of Rheology 64:129–140, (2020) for elongational and ...

Transitions of electrons and holes drive diffusion in crystals, glasses and melts

Hoffmann, H.‐J. (2020-12-17)

Diffusion of atoms or molecules (generally: particles) is driven by differences and gradients of the chemical potential of the particles in their accessible space. If the difference of the chemical potential is due to differences of concentrations alone, one arrives at the diffusion equations of Fick. The diffusion coefficients are described in known models by vibrations of atoms in condensed m...

The Neutron Imaging Instrument CONRAD—Post-Operational Review

Kardjilov, Nikolay ; Manke, Ingo ; Hilger, André ; Arlt, Tobias ; Bradbury, Robert ; Markötter, Henning ; Woracek, Robin ; Strobl, Markus ; Treimer, Wolfgang ; Banhart, John (2021-01-19)

The neutron imaging instrument CONRAD was operated as a part of the user program of the research reactor BER-II at Helmholtz-Zentrum Berlin (HZB) from 2005 to 2020. The instrument was designed to use the neutron flux from the cold source of the reactor, transported by a curved neutron guide. The pure cold neutron spectrum provided a great advantage in the use of different neutron optical compon...

Biocompatibility and Immune Response of a Newly Developed Volume-Stable Magnesium-Based Barrier Membrane in Combination with a PVD Coating for Guided Bone Regeneration (GBR)

Steigmann, Larissa ; Jung, Ole ; Kieferle, Wolfgang ; Stojanovic, Sanja ; Proehl, Annica ; Görke, Oliver ; Emmert, Steffen ; Najman, Stevo ; Barbeck, Mike ; Rothamel, Daniel (2020-12-20)

To date, there are no bioresorbable alternatives to non-resorbable and volume-stable membranes in the field of dentistry for guided bone or tissue regeneration (GBR/GTR). Even magnesium (Mg) has been shown to constitute a favorable biomaterial for the development of stabilizing structures. However, it has been described that it is necessary to prevent premature degradation to ensure both the fu...

From heat to entropy

Hoffmann, Hans‐Jürgen (2020-09-18)

Milestones in the development of thermodynamics are the discovery of the absolute temperature scale and the recognition that differential “heat” is a form of energy given as the product of absolute temperature and differential entropy. Following a new path, the last statement results from a careful analysis of the heat transfer applying the first theorem without reference to the usual cycles in...