Inst. Werkstoffwissenschaften und -technologien

143 Items

Recent Submissions
Creep behavior of a γ′-strengthened Co-base alloy with zero γ/γ′-lattice misfit at 800 °C, 196 MPa

Midtlyng, Jan ; Epishin, Alexander I. ; Petrushin, Nikolay V. ; Link, Thomas ; Nolze, Gert ; Svetlov, Igor L. ; Reimers, Walter (2017)

Deformation and structural behavior of an experimental γ′-strengthened Co-base alloy during creep at 800 °C and 196 MPa have been investigated. The characteristic features of this alloy are zero γ/γ′-lattice misfit and a fine γ/γ′-microstructure. In the initial condition, the γ′-precipitates in this alloy are small (size of about 100 nm), have polyhedral morphology, and are separated by the ver...

Verfahrenstechnische Weiterentwicklung des Fused Layer Manufacturing zur Reduzierung der Anisotropie im Bauteil

Butzke, Jens (2019)

Generative Fertigungsverfahren sind im industriellen Umfeld seit mehr als 30 Jahren ein weitverbreitetes Werkzeug zur Herstellung von Prototypen. Das Fused Layer Manufacturing (FLM) generiert im 2½-dimensionalen Strangablageverfahren Anschauungsmuster aus thermoplastischen Filamenten. Dass dieses Verfahren sich nur sehr eingeschränkt für die Herstellung von Funktionsmustern eignet, liegt in der...

Influence of Hydrolytic and Chemical Treatment on the Mechanical Properties of Aramid and Copolyaramid Fibers

Springer, H. ; Abu Obaid, A. ; Prabawa, A.B. ; Hinrichsen, G. (1998)

Commercial PPTA fibers ( Kevlar 49® and Twaron 1055®) and copolyaramid fibers (Trevar®) are subjected to various hydrolytic and chemical treatments. Tensile mod ulus, tensile strength, and elongation at break are measured, and mechanical property deterioration is compared. Copolyaramid fibers show improved hydrolytic stability and chemical resistance compared to PPTA fibers. The time dependence...

Rheological Conditions for the Development of Fibrils in Blends of Liquid Crystalline and Conventional Polymers

Roetting, O. ; Hinrichsen, G. (1997)

In blends of liquid crystalline polymers (LCP) with conventional thermoplastics, the development of infinite, thin and highly oriented LCP-fibrils is very important for a substantial mechanical reinforcement of the blends. Such fibrils can be produced by processing a coarse mixture of LCP and polyethyleneterephthalate (PET) powders in an extrusion apparatus in which preferentially elongational,...

Quasi-Continuous Fibrils in Blends of Liquid Crystalline and Thermoplastic Polymers at Low LCP Concentration

Roetting, O. ; Hinrichsen, G. (1995)

A new technique for blending liquid crystalline polymers (LCPs) with thermoplastic polymers is described. With poly(ethylene terephthalate) as the matrix and Vectra B950 as the LCP, fibers containing quasi-continuous LCP-fibrils can be produced even when the LCP-concentration is very low (1 wt.-% LCP or less). Fragmentation tests show excellent bonding between the components. The elastic modulu...

Effect of Vinyl and Silicon Monomers on Mechanical and Degradation Properties of Bio-Degradable Jute-Biopol® Composite

Khan, M. A. ; Kopp, C. ; Hinrichsen, G. (2001)

Composites of jute fabrics (Hessian cloth) and Biopol® were prepared by compression molding process. Three types of Biopol® (3-hydroxbutyrate-co-3-hydroxyvalarate) such as D300G, D400G and D600G, depending on the concentration of 3-hydroxyvalarate (3HV) in 3-hydroxbutyrate (3HB) were taken for this purpose. Mechanical properties such as tensile strength (TS), bending strength (BS), elongation a...

Exploiting the features of energy-dispersive synchrotron diffraction for advanced residual stress and texture analysis

Genzel, Ch. ; Denks, I. A. ; Coelho, R. ; Thomas, D. ; Mainz, R. ; Apel, D. ; Klaus, M. (2011)

Responding to a growing interest from the materials science community for residual stress, texture, and microstructure analysis, strong efforts are made to enhance existing and develop novel methods that allow for fast in-situ studies at elevated temperature, measurements under external load, or residual strain, and stress scanning with high spatial resolution. In the paper, energy-dispersive d...

Towards the colonization of Mars by in-situ resource utilization: Slip cast ceramics from Martian soil simulant

Karl, David ; Kamutzki, Franz ; Zocca, Andrea ; Görke, Oliver ; Günster, Jens ; Gurlo, Aleksander (2018-10-11)

Here we demonstrate that by applying exclusively Martian resources a processing route involving suspensions of mineral particles called slurries or slips can be established for manufacturing ceramics on Mars. We developed water-based slurries without the use of additives that had a 51 wt. % solid load resembling commercial porcelain slurries in respect to the particle size distribution and rheo...

Innovative Anwendungen von polymeren Werkstoffen in der Medizintechnik

Müller, Th. ; Käufer, H. (1998)

Das bekannte Prinzip des Kunststoff-Schrumpfschlauches, der bei etwa 120°C eine Formänderung vollzieht, wurde vom Fachgebiet Polymertechnik der TU-Berlin in der Art weiterentwickelt, daß es möglich ist, schon eine Formänderung eines Teiles bei Temperaturen zu erreichen, die im menschlichen Organismus vorliegen können.

Einfluß von Sterilisationsverfahren auf thermoplastische Kunststoffe unter spezieller Berücksichtigung modifizierter Oberflächen

Müller, Thomas ; Käufer, Helmut (1999)

Für Werkstoffe für den Einsatz im Medikalbereich ist die Sterilisationsfähigkeit unabdingbare Voraussetzung. Die gängigen Sterilisationsmethoden rufen bei den meisten polymeren Werkstoffen Veränderungen hervor, die bis hin zur Spaltung der Polymerketten führen können. Speziell die in dieser Arbeit untersuchten, zur Verbesserung der Biokompatibilität modifizierten Oberflächen, die durch ihre sta...

An X-ray tomographic study of rechargeable Zn/MnO2 batteries

Osenberg, Markus ; Manke, Ingo ; Hilger, André ; Kardjilov, Nikolay ; Banhart, John (2018-08-21)

We present non-destructive and non-invasive in operando X-ray tomographic investigations of the charge and discharge behavior of rechargeable alkaline-manganese (RAM) batteries (Zn-MnO2 batteries). Changes in the three-dimensional structure of the zinc anode and the MnO2 cathode material after several charge/discharge cycles were analyzed. Battery discharge leads to a decrease in the zinc parti...

Analyse der Mikrostrukturentwicklung von CuInSe2 mittels in-situ Röntgenbeugung

Stange, Anna Helena (2018)

Die Reduzierung der Absorberschichtdicke auf wenige Mikrometer eröffnet neue Anwendungsmöglichkeiten für die Photovoltaik. Der Verbindungshalbleiter Cu(In,Ga)Se2 (CIGSe) hat sich als besonders geeignet für solche Dünnschichtsolarzellen herausgestellt. Mit CIGSe-Absorbern aus einem mehrstufigen Syntheseprozess werden die bisher höchsten Effizienzen im Bereich der Dünnschichttechnologie erreicht....

Preparation, characterization and electrical properties of nanocomposites based on hyperbranched polymers

Omara, Shereen Said Shabaan (2018)

Nanocomposites based on hyperbranched polymers (HBPs) and layered silicates as nanofillers are a relatively new class of nanocomposites. Due to their unique physical/chemical properties, they have attracted scientific interests. This study provides to a better understand the structure-dynamics-properties relationship, for different types of HBP/ kaolinite (Ka) nanocomposites. Two different me...

Microscopic aspects of ageing in Al-Mg-Si alloys

Madanat, Mazen Adel (2018)

Al-Mg-Si alloys with a low solute content (0.4 %Mg, 0.4 %Si) and higher contents (Mg+Si=1.4 %, all in wt.%) were solutionized, quenched and then either artificially aged (AA) at 180 °C or naturally pre-aged (NPA) for 2 weeks at room temperature and then reverse aged (RA) at 250 °C. Subsequently, positron annihilation lifetime spectroscopy was applied with the objective of obtaining information ...

Mechanical properties in crumple-formed paper derived materials subjected to compression

Hanaor, D.A.H. ; Flores Johnson, E.A. ; Wang, S. ; Quach, S. ; Dela-Torre, K.N. ; Gan, Y. ; Shen, L. (2017-06)

The crumpling of precursor materials to form dense three dimensional geometries offers an attractive route towards the utilisation of minor-value waste materials. Crumple-forming results in a mesostructured system in which mechanical properties of the material are governed by complex cross-scale deformation mechanisms. Here we investigate the physical and mechanical properties of dense compacte...

Structure-function relationships in Macadamia integrifolia seed coats – fundamentals of the hierarchical microstructure

Schüler, Paul ; Speck, Thomas ; Bührig-Polaczek, Andreas ; Fleck, Claudia (2014-08-07)

The shells/coats of nuts and seeds are often very hard to crack. This is particularly the case with Macadamia seed coats, known to exhibit astoundingly high strength and toughness. We performed an extensive materials science characterization of the complex hierarchical structure of these coats, using light and scanning electron microscopy in 2D as well as microCT for 3D characterization. We dif...

Analytische Charakterisierung und Modifizierung von Pulverlack-Overspray zum Einsatz als Füllstoff für Polyethylen

John-Müller, Astrid (2018)

In der pulverlackverarbeitenden Industrie fallen erfahrungsgemäß, je nach Beschichtungsanlage, zwischen 0,5 % und 55 % Overspray und überlagerte Gebinde an. Die Entsorgung dieser Pulverlackreste auf Deponien oder durch Verbrennung sind sehr kostenintensiv und belasten die Umwelt. Das Ziel dieser Arbeit beinhaltet, das Recycling von Pulverlackresten als Füllstoffe für Thermoplaste. Die wesentli...

Surface chemistry and stability of metastable corundum-type In2O3

Köck, Eva-Maria ; Kogler, Michaela ; Zhuo, Chen ; Schlicker, Lukas ; Bekheet, Maged F. ; Doran, Andrew ; Gurlo, Aleksander ; Penner, Simon (2017)

To account for the explanation of an eventual sensing and catalytic behavior of rhombohedral In2O3 (rh-In2O3) and the dependence of the metastability of the latter on gas atmospheres, in situ electrochemical impedance spectroscopic (EIS), Fourier-transform infrared spectroscopic (FT-IR), in situ X-ray diffraction and in situ thermogravimetric analyses in inert (helium) and reactive gases (hydro...

High resolution pore size analysis in metallic powders by X-ray tomography

Heim, Korbinian ; Bernier, F. ; Pelletier, R. ; Lefebvre, L.-P. (2016)

The deployment of additive manufacturing processes relies on part quality, specifically the absence of internal defects. Some of those defects have been associated with porosities in the powder feedstock. Since the level of porosity in the powder is generally very low, standard characterisation techniques such as pycnometry and metallography are not suitable for quantification. However, the qua...

Ordered mesoporous silica COK-12: mesoscale tailoring, upscaling, continuous synthesis and application in the oxidative coupling of Methane

Colmenares, Maria (2018)

Ordered mesoporous silica (OMS) materials are a family of silica nanomaterials with pores ranging in size from 2 to 50 nm which are arranged periodically within the silica matrix. They have expanding applications in various fields of research, such as drug delivery, adsorption, separation and catalysis. COK-12 is an OMS produced by the soft-templating method, using the block copolymer P123 as a...