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Pfrengle A.,Institute for Materials Research III | Pfrengle A.,Albert Ludwigs University of Freiburg | Binder J.R.,Institute for Materials Research III | Ritzhaupt-Kleissl H.-J.,Institute for Materials Research III | And 4 more authors.
International Journal of Applied Ceramic Technology | Year: 2010

Based on previous work, the material properties of zirconium disilicide containing net-shape ceramic compositions are adjusted to minimize the edge flaking that occurs during micromilling of the green bodies. The material compositions (besides ZrSi 2, also containing ZrO 2, Al 2O 3, MgO, SiO 2, and a polysorbate) are granulated and axially dry pressed to pellets, which are wet milled with a 0.5-mm-diameter tool. The structure's edge flaking is quantitatively determined and compared with previous results. The mechanical properties of the green and sintered bodies are also characterized. The strengths of the green bodies depend on their composition and treatment. Additionally, a correlation between the Weibull moduli of the green compacts and the moduli of the sintered parts is shown. For the sintered ceramics, Weibull strengths of up to 344 MPa can be achieved. It is also shown that the dimensional accuracy of the net-shape material is maintained. © 2009 The American Ceramic Society.

Proll J.,Institute for Materials Research I | Kohler R.,Institute for Materials Research I | Adelhelm C.,Institute for Materials Research I | Bruns M.,Institute for Materials Research III | And 5 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

The development of future battery systems is mainly focused on powerful rechargeable lithium-ion batteries. To satisfy this demand, current studies are focused on cathodes based on nano-composite materials which lead to an increase in power density of the LIB primarily due to large electrochemically active surface areas. Electrode materials made of lithium manganese oxides (Li-Mn-O) are assumed to replace commonly used cathode materials like LiCoO2 due to less toxicity and lower costs. Thin films in the Li-Mn-O system were synthesized by non-reactive r.f. magnetron sputtering of a LiMn 2O4 target on silicon and stainless steel substrates. In order to enhance power density and cycle stability of the cathode material, direct laser structuring methods were investigated using a laser system operating at a wavelength of 248 nm. Therefore, high aspect ratio micro-structures were formed on the thin films. Laser annealing processes were investigated in order to achieve an appropriate crystalline phase for unstructured and structured thin films as well as for an increase in energy density and control of grain size. Laser annealing was realized via a high power diode laser system. The effects of post-thermal treatment on the thin films were studied with Raman spectroscopy, X-ray diffraction and scanning electron microscopy. The formation of electrochemically active and inactive phases was discussed. Surface chemistry was investigated via X-ray photoelectron spectroscopy. Interaction between UV-laser radiation and the thin film material was analyzed through ablation experiments. Finally, to investigate the electrochemical properties, the manufactured thin film cathodes were cycled against a lithium anode. The formation of a solid electrolyte interphase on the cathode side was discussed. © 2011 SPIE.

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