FG Keramische Werkstoffe

12 Items

Recent Submissions
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...

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...

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...

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...

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...

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...

Ultramicroporous silicon nitride ceramics for CO2 capture

Schitco, Cristina ; Seifollahi Bazarjani, Mahdi ; Riedel, Ralf ; Gurlo, Aleksander (2015)

Carbon dioxide (CO2) capture is regarded as one of the biggest challenges of the 21st century; therefore, intense research effort has been dedicated in the area of developing new materials for efficient CO2 capture. Here, we report high CO2 capture capacity in the low region of applied CO2 pressures observed with ultramicroporous silicon nitride-based material. The latter is synthesized by a fa...

A study on the thermal conversion of scheelite-type ABO(4) into perovskite-type AB(O,N)(3)

Li, Wenjie ; Li, Duan ; Gao, Xin ; Gurlo, Aleksander ; Zander, Stefan ; Jones, Philip ; Navrotsky, Alexandra ; Shen, Zhijian ; Riedel, Ralf ; Ionescu, Emanuel (2015)

Phase-pure scheelite AMoO(4) and AWO(4) (A = Ba, Sr, Ca) were thermally treated under an ammonia atmosphere at 400 to 900 degrees C. SrMoO4 and SrWO4 were shown to convert into cubic perovskite SrMoO2N and SrWO1.5N1.5, at 700 degrees C and 900 degrees C respectively, and to form metastable intermediate phases (scheelite SrMoO4-xNx and SrWO4-xNx), as revealed by X-ray diffraction (XRD), elementa...

The contrasting effect of the Ta/Nb ratio in (111)-layered B-site deficient hexagonal perovskite Ba5Nb4-xTaxO15 crystals on visible-light-induced photocatalytic water oxidation activity of their oxynitride derivatives

Hojamberdiev, Mirabbos ; Bekheet, Maged F. ; Zahedi, Ehsan ; Wagata, Hajime ; Vequizo, Junie Jhon M. ; Yamakata, Akira ; Yubuta, Kunio ; Gurlo, Aleksander ; Domen, Kazunari ; Teshima, Katsuya (2016)

The effect of the Ta/Nb ratio in the (111)-layered B-site deficient hexagonal perovskite Ba5Nb4-xTaxO15 (0 <= x <= 4) crystals grown by a KCl flux method on visible-light-induced photocatalytic water oxidation activity of their oxynitride derivatives BaNb1-xTaxO2N (0 <= x <= 1) was investigated. The Rietveld refinement of X-ray data revealed that all Ba5Nb4-xTaxO15 samples were well crystallize...

Enhanced catalytic performance of MnxOy-Na2WO4/SiO2 for the oxidative coupling of methane using an ordered mesoporous silica support

Yildiz, M. ; Aksu, Y. ; Simon, U. ; Kailasam, K. ; Görke, O. ; Rosowski, F. ; Schomäcker, R. ; Thomas, A. ; Arndt, S. (2014)

The oxidative coupling of methane is a highly promising reaction for its direct conversion. Silica supported MnxOy–Na2WO4 is a suitable catalyst for this reaction. In this study, a variety of different SiO2 materials have been tested as supports. Surprisingly, the application of ordered mesoporous silicas, here exemplarily shown for SBA-15 as support materials, greatly enhances the catalytic pe...