Elastic Tensor of YNi_2B_2C

The complete elastic tensor of YNi_2B_2C was determined by application of the resonant ultrasound spectroscopy technique to a single-crystal sample. Elastic constants were found to be in good agreement with partial results obtained from `time-of-flight' measurements performed on samples cut from the same ingot. From the measured constants, the bulk modulus and Debye temperature are calculated.Comment: 5 pages, 3 figure

Superconductivity in the ternary ZrVGe compound

We report bulk superconductivity in ZrVGe withTc=6K determined by magnetization, electronic transport and specific heat measurements. From the analysis of magnetization and resistivity data we obtain the thermodynamic critical fieldsμ0Hc1andμ0Hc2, respectively. The heat capacity data deviate from conventional BCS theory suggesting possible unconventional superconducting behavior

Thermophysical and microstructural studies on thermally sprayed tungsten carbide-cobalt coatings

The development of new hardmetal coating applications such as fatigue-loaded parts, structural components, and tools for metal forming is connected with improvement of their performance and reliability. For modelling purposes, the knowledge of thermophysical, mechanical, and other material data is required. However, this information is still missing today. In this study, the thermophysical data of a WC-17Co coating sprayed with a liquid-fuelled HVOF-process from a commercial agglomerated and sintered feedstock powder from room temperature up to 700 °C was determined as an example. The dependence of the heat conductivity on temperature was obtained through measurement of the coefficient of thermal expansion, the specific heat capacity, and the thermal diffusivity. Heat conductivities ranging from 29.2 W/(mK) at 50 °C to 35.4 W/(mK) at 700 °C were determined. All measurements were performed twice (as-sprayed and after the first thermal cycle) to take into account the stru ctural and compositional changes. Extensive XRD and FESEM studies were performed to characterize the phase compositions and microstructures in the as-sprayed and heat-treated states. Bulk samples obtained by spark plasma sintering from the feedstock powder were studied for comparison

Entwicklung von Mikrosystemtechniken auf der Basis von AlN-Keramiken. Teilthemen: Wissenschaftliche Grundlagen fuer ein Dickschichtwiderstandspastensystem auf AlN-Keramik und wissenschaftlich-technische Voraussetzungen fuer die Nutzung des Widerstandspastensystems auf AlN-Keramik Abschlussbericht

The scientific and technological bases of a resistance paste system on aluminium nitride as the substrate have been developed including the compatible covering and conductivity pastes. Pb-free, RuO_2-based pastes have been optimized decreasing the chemical reactivity of the system AlN + RuO_2 during the burning-in process by non-crystallizing glasses of modified viscosity-temperature characteristics. The obtained performance parameters are comparable to those of the corresponding Al_2O_3 substrate system. PbO-free modified glasses have been developed for the Ag/Pd-based conductivity paste. The new paste system has been successfully tested on technical AlN substrates (ANCeram, Hoechst). (WEN)SIGLEAvailable from TIB Hannover: F94B2168+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman