Inst. Werkstoffwissenschaften und -technologien

172 Items

Recent Submissions
Ceria-Based Dual-Phase Membranes for High-Temperature Carbon Dioxide Separation: Effect of Iron Doping and Pore Generation with MgO Template

Gili, Albert ; Bischoff, Benjamin ; Simon, Ulla ; Schmidt, Franziska ; Kober, Delf ; Görke, Oliver ; Bekheet, Maged F. ; Gurlo, Aleksander (2019-08-26)

Dual-phase membranes for high-temperature carbon dioxide separation have emerged as promising technology to mitigate anthropogenic greenhouse gases emissions, especially as a pre- and post-combustion separation technique in coal burning power plants. To implement these membranes industrially, the carbon dioxide permeability must be improved. In this study, Ce0.8Sm0.2O2−δ (SDC) and Ce0.8Sm0.19Fe...

Characterization of battery anode materials by X-ray and electron-based imaging techniques

Dong, Kang (2020)

To tackle the problem of increasing carbon dioxide emissions, Li batteries have been proposed as a promising storage medium of electricity harvested from renewable clean energy sources. In addition, Li batteries are the predominant power sources in cell phones, laptops and electric vehicles. However, state-of-art Li-ion batteries with an energy density below 300 Wh kg-1 cannot meet the ever-inc...

High-temperature separation and activation of carbon dioxide by dual-phase membranes and nickel catalysts

Gili de Villasante, Albert (2020)

Carbon dioxide emission mitigation arises as one of the critical challenges for sustainable development and to minimize the negative effects of climate change. Dual-phase (DP) membranes for high-temperature separation of carbon dioxide have been suggested as potential post-combustion capture technology in fossil fuel power plants. Once separated, carbon dioxide can be converted to valuable chem...

Rheological and Mechanical Gradient Properties of Polyurethane Elastomers for 3D-Printing with Reactive Additives

Wang, Peng ; Auhl, Dietmar ; Uhlmann, Eckart ; Gerlitzky, Georg ; Wagner, Manfred H. (2019-12-31)

Polyurethane (PU) elastomers with their broad range of strength and elasticity are ideal materials for additive manufacturing of shapes with gradients of mechanical properties. By adjusting the mixing ratio of different polyurethane reactants during 3D-printing it is possible to change the mechanical properties. However, to guarantee intra- and inter-layer adhesion, it is essential to know the ...

Enhanced Strength and Ductility in Magnesium Matrix Composites Reinforced by a High Volume Fraction of Nano- and Submicron-Sized SiC Particles Produced by Mechanical Milling and Hot Extrusion

Kamrani, Sepideh ; Hübler, Daniela ; Ghasemi, Alireza ; Fleck, Claudia (2019-10-21)

In the present study, Mg nanocomposites with a high volume fraction (10 vol %) of SiC particles were fabricated by two approaches: mechanical milling and mixing, followed by the powder consolidation steps, including isostatic cold pressing, sintering, and extrusion. A uniform distribution of the high content SiC particles in a fully dense Mg matrix with ultrafine microstructure was successfully...

Electrochemical performance and structural changes of Na0.67Mn0.67Ni0.33O2 as cathode for sodium ion batteries

Zhang, Li (2019)

P2- and P3-type Na0.67Mn0.67Ni0.33O2 materials are potential cathodes for sodium ion batteries. P3-type Na0.67Mn0.67Ni0.33O2 demonstrates higher initial discharge capacity (233 mAh∙g-1) in the voltage range 1.5 - 4.5 V than P2-type Na0.67Mn0.67Ni0.33O2. However, the severe capacity fading in P3-type Na0.67Mn0.67Ni0.33O2 hinders its practical utilization as cathode for sodium ion batteries. Usin...

Development of cortical bone biomarkers for the prediction of femur strength

Iori, Gianluca (2019)

Osteoporosis is a skeletal disease caused by the imbalance between bone resorption and formation. In osteoporosis, the risk of fracture increases due to the structural deterioration of the bone. Hip fractures are associated with increased mortality and morbidity and lead to a decline in the quality of life. Due to these reasons, hip fractures represent a principal component of the total social ...

Grafting and stabilization of ordered mesoporous silica COK-12 with graphene oxide for enhanced removal of methylene blue

Henning, Laura M. ; Simon, Ulla ; Gurlo, Aleksander ; Smales, Glen J. ; Bekheet, Maged F. (2019-11-07)

Large-pore ordered mesoporous silica (OMS) COK-12, analogous to the well-known SBA-15, but synthesized in a more environmentally friendly way and exhibiting a shorter plate-like structure, was grafted with different amounts of graphene oxide (GO) for the first time in an inexpensive and rapid process, that was successfully upscaled. Samples were examined with nitrogen sorption analysis, SAXS, R...

Influence of Sn addition on the ageing behavior of Al-Mg-Si alloys

Zhang, Xingpu (2019)

In this work, the ageing behavior of age hardenable Al-Mg-Si(Sn) alloys has been systematically studied by positron annihilation lifetime spectroscopy (PALS), hardness measurements, differential scanning dilatometry (DSC), electrical resistivity measurements and transmission electron microscopy (TEM). At room temperature, i.e. around 20 °C, vacancies, which can assist the diffusion of solute a...

Influence of the Microstructure and Silver Content on Degradation, Cytocompatibility, and Antibacterial Properties of Magnesium-Silver Alloys In Vitro

Liu, Zhidan ; Schade, Ronald ; Luthringer, Bérengère ; Hort, Norbert ; Rothe, Holger ; Müller, Sören ; Liefeith, Klaus ; Willumeit-Römer, Regine ; Feyerabend, Frank (2017-06-22)

Implantation is a frequent procedure in orthopedic surgery, particularly in the aging population. However, it possesses the risk of infection and biofilm formation at the surgical site. This can cause unnecessary suffering to patients and burden on the healthcare system. Pure Mg, as a promising metal for biodegradable orthopedic implants, exhibits some antibacterial effects due to the alkaline ...

Development and Application of a Statistically-Based Quality Control for Crowdsourced Air Temperature Data

Napoly, Adrien ; Grassmann, Tom ; Meier, Fred ; Fenner, Daniel (2018-08-29)

In urban areas, dense atmospheric observational networks with high-quality data are still a challenge due to high costs for installation and maintenance over time. Citizen weather stations (CWS) could be one answer to that issue. Since more and more owners of CWS share their measurement data publicly, crowdsourcing, i.e., the automated collection of large amounts of data from an undefined crowd...

Photoinduced thiol-ene click chemistry assisted additive manufacturing and freeze casting of polymer-derived ceramics

Wang, Xifan (2019)

Polymer-derived ceramics possess great advantages in the view of cellular ceramic processing compared to traditional powder-based technologies, as the polymeric nature of ceramic precursors allows the utilization of various shaping approaches. Amongst them, Additive Manufacturing and Freeze Casting are two novel shaping methods, which are capable of producing three-dimensional complex architect...

Processing Effects on the Formability of Magnesium Alloy Sheets

Bohlen, Jan ; Cano, Guadalupe ; Drozdenko, Daria ; Dobron, Patrik ; Kainer, Karl ; Gall, Sven ; Müller, Sören ; Letzig, Dietmar (2018-02-23)

As a generalized semi-finished product, the use of magnesium sheets requires addressing two major aspects of their processing: their microstructure and texture control, which are both essential for the forming behavior of such sheets during their forming to parts. Further, the processing of such sheets is complex, and therefore expensive, and requires simplification. In this work, magnesium all...

Imaging with Polarized Neutrons

Kardjilov, Nikolay ; Hilger, André ; Manke, Ingo ; Strobl, Markus ; Banhart, John (2018-01-16)

Owing to their zero charge, neutrons are able to pass through thick layers of matter (typically several centimeters) while being sensitive to magnetic fields due to their intrinsic magnetic moment. Therefore, in addition to the conventional attenuation contrast image, the magnetic field inside and around a sample can be visualized by detecting changes of polarization in a transmitted beam. The ...

In Operando Neutron Radiography Analysis of a High-Temperature Polymer Electrolyte Fuel Cell Based on a Phosphoric Acid-Doped Polybenzimidazole Membrane Using the Hydrogen-Deuterium Contrast Method

Lin, Yu ; Arlt, Tobias ; Kardjilov, Nikolay ; Manke, Ingo ; Lehnert, Werner (2018-08-24)

In order to characterize high temperature polymer electrolyte fuel cells (HT-PEFCs) in operando, neutron radiography imaging, in combination with the deuterium contrast method, was used to analyze the hydrogen distribution and proton exchange processes in operando. These measurements were then combined with the electrochemical impedance spectroscopy measurements. The cell was operated under dif...

Influence of the Heating Rate on the Foaming Behavior of Various Aluminium Alloys

Neu, Tillmann Robert ; Pfretzschner, Beate ; García-Moreno, Francisco ; Banhart, John (2017-08-23)

Powders of metallurgically prepared precursors expand to a foam differently depending on how fast they are heated to their foaming temperature. The foaming behavior of four alloys was studied with heating rates varying from 0.1 K/s to 18 K/s. It was found that each alloy shows its own non-linear behavior of expansion values. Alloys not containing magnesium exhibit a maximum at intermediate heat...

Influence of Stoichiometry on the Two-Phase Flow Behavior of Proton Exchange Membrane Electrolyzers

Panchenko, Olha ; Giesenberg, Lennard ; Borgardt, Elena ; Zwaygardt, Walter ; Kardjilov, Nikolay ; Markötter, Henning ; Arlt, Tobias ; Manke, Ingo ; Müller, Martin ; Stolten, Detlef ; Lehnert, Werner (2019-01-23)

In order for electrolysis cells to operate optimally, mass transport must be improved. The key initial component for optimal operation is the current collector, which is also essential for mass transport. Water as an educt of the reaction must be evenly distributed by the current collector to the membrane electrode assembly. As products of the reaction, hydrogen and oxygen must also be directed...

Piezo-Plunger Jetting Technology: An Experimental Study on Jetting Characteristics of Filled Epoxy Polymers

Kurz, Alexander ; Bauer, Jörg ; Wagner, Manfred (2019-02-01)

The droplet formation of Newtonian fluids and suspensions modified by spherical, non-colloidal particles has attracted much interest in practical and theoretical research. For the present study, a jetting technique was used which accelerates a geometrically defined plunger by a piezoelectric actuator. Changing rheological properties of materials and extending deformation rates towards nonlinear...

Short- and Long-Range Mechanical and Chemical Interphases Caused by Interaction of Boehmite (γ-AlOOH) with Anhydride-Cured Epoxy Resins

Ghasem Zadeh Khorasani, Media ; Elert, Anna-Maria ; Hodoroaba, Vasile-Dan ; Agudo Jácome, Leonardo ; Altmann, Korinna ; Silbernagl, Dorothee ; Sturm, Heinz (2019-06-04)

Understanding the interaction between boehmite and epoxy and the formation of their interphases with different mechanical and chemical structures is crucial to predict and optimize the properties of epoxy-boehmite nanocomposites. Probing the interfacial properties with atomic force microscopy (AFM)-based methods, especially particle-matrix long-range interactions, is challenging. This is due to...

Effect of Shear Rate on the Orientation and Relaxation of a Vanillic Acid Based Liquid Crystalline Polymer

De Kort, Gijs W. ; Leoné, Nils ; Stellamanns, Eric ; Auhl, Dietmar ; Wilsens, Carolus H. R. M. ; Rastogi, Sanjay (2018-08-22)

In this study, we report on the visco-elastic response during start-up and cessation of shear of a novel bio-based liquid crystal polymer. The ensuing morphological changes are analyzed at different length scales by in-situ polarized optical microscopy and wide-angle X-ray diffraction. Upon inception of shear, the polydomain texture is initially stretched, at larger strain break up processes be...