Inst. Werkstoffwissenschaften und -technologien

163 Items

Recent Submissions
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...

Coalescence Avalanches in Liquid Aluminum Foams

Paeplow, Marlen ; García-Moreno, Francisco ; Meagher, Aaron Joseph ; Rack, Alexander ; Banhart, John (2017-08-04)

Coalescence is the rupture of a film between two adjacent bubbles in any type of liquid foam and has pronounced influence on the development of its macrostructure after solidification, mostly leading to larger pores and a wider size distribution. Foamable AlSi6Cu4 + 0.5 wt % TiH2 precursors made following the powder metallurgical route were foamed in a gas-tight X-ray transparent furnace under ...

Structural characterisation of A-site deficient Pr2-xNiO4+δ by X-ray diffraction, neutron diffraction and X-ray absorption spectroscopy

Ning, De (2019)

The crystal and electronic structures of Pr2-xNiO4+δ (x = 0 - 0.2), as potential materials for solid oxide fuel cell cathodes, are studied by X-ray diffraction, neutron diffraction and X-ray absorption spectroscopy. It turned out that A-site deficiency causes generation of vacancies at equatorial and apical oxygen sites but does not influence the interstitial oxygen content. In-situ X-ray diffr...

Real-time direct transmission electron microscopy imaging of phase and morphology transformation from solid indium oxide hydroxide to hollow corundum-type indium oxide nanocrystallites

Schlicker, Lukas ; Popescu, Radian ; Bekheet, Maged F. ; Doran, Andrew ; Gerthsen, Dagmar ; Gurlo, Aleksander (2019-05-31)

A time-resolved series of high-resolution transmission electron microscopy (HRTEM) images are used to monitor phase and morphology transformation of rod-like and spherical particles with the initial orthorhombic InOOH phase in situ under continuous illumination with high-energy electrons in a transmission electron microscope. For both particle types, the electron-beam irradiation induces a fast...

Optimierung des Eigenschaftsprofils von schmelzgesponnenen Polylactid-Multifilamentgarnen

Tarkhanov, Evgueni (2019)

Die vorliegende Arbeit befasst sich mit der Optimierung des Schmelzspinnverfahrens zur Herstellung von Polylactid (PLA) - Multifilamentgarnen, die ein textil - physikalisches Eigenschaftsprofil aufweisen, das im Bereich von kommerziellen technischen Fasern liegt. Unter Variation des Verstreckprofils, der Temperaturführung (Extrusions- und Galettentemperatur), der Fördermenge, der Düsengeometri...

Untersuchung magnetischer Streufelder in einem inhomogen verformten Baustahl mittels passiv-magnetischer Prüfverfahren

Sonntag, Nadja (2019)

Die Metal Magnetic Memory (MMM) Methode ist ein standardisiertes, zerstörungsfreies Prüfverfahren, das für die Detektion von lokal geschädigten Materialbereichen in ferromagnetischen Bauteilen oder Proben verwendet wird. Es basiert auf der Annahme lokaler magnetoelastischer Wechselwirkungen an Spannungskonzentrationsstellen, die schwache magnetische Streufelder an den geschädigten Prüfkörper¬ob...

Development of in situ methods for process monitoring and control and characterization of Cu-Zn-Sn-S based thin films

van Duren, Stephan (2019)

In recent years, kesterite Cu2ZnSnS4 (CZTS) has become an interesting alternative to copper indium gallium (di)selenide (CIGS) due to its non-toxic and earth abundant constituents. A variety of methods is being used to fabricate kesterite thin films, such as coevaporation, sputtering, electrodeposition, spray pyrolysis and others. Most of them include an annealing step to stimulate elemental mi...

Einfluss der Kompaktierung auf das Schäumverhalten von pulvermetallurgisch hergestellten Metallhalbzeugen

Neu, Tillmann Robert (2019)

Die Herstellung von metallischen Schäumen ist von vielen Einflussfaktoren abhängig. Bei der pulvermetallurgischen Herstellung der Schaumhalbzeuge spielt neben anderen Gegebenheiten auch die Kompaktierung eine wichtige Rolle. Um diesen Einfluss besser zu verstehen, wurden in dieser Arbeit Halbzeuge mit verschiedenen konventionellen Kompaktierungsvarianten (uniaxiales Pressen, Strangpressen und W...

Schädigungscharakterisierung an Faser-Kunststoff-Verbunden im Schwingversuch mittels Röntgenrefraktionstopographie unter Berücksichtigung der Matrixeigenschaften

Müller, Alexander (2019)

In the present thesis different epoxy resin systems were characterized. Two systems with different fracture mechanical properties were selected for the production of equivalent GFRP and CFRP laminates with fiber orientations in 0/90° and ±45°. These laminates were examined for their damage onset and their damage evolution characteristics in tensile tests and fatigue tests with a stress ratio of...

Grundlegende Charakterisierung des Strangpressprozesses pressnahtbehafteter Magnesium - Hohlprofile

Gensch, Felix (2019)

Durch das Strangpressen von Magnesiumwerkstoffen über Kammerwerkzeuge lassen sich komplexere Hohlprofilgeometrien darstellen als durch Verwendung eines Dornes. Jedoch beinhalten so hergestellte Pressprodukte zumeist zwei oder mehrere Längspressnähte, die sich in der Mikrostruktur und daher den mechanischen Eigenschaften lokal vom umgebenden Gefüge unterscheiden können. Daher ist eine Untersuchu...