Search

ZrB2-SiC-TaC ceramics with different content of TaC were prepared by hot-pressing at 1800°C in vacuum environment. The oxidation behavior of these ceramics was studied in the temperature range of 1200°C-1500°C in air. It was found that low concentration of TaC (10 vol%) deteriorated the oxidation resistance of ZrB2- SiC, while high concentration of TaC (30 vol%) significantly improved the oxidation resistance of the ceramics. Reoxidation experiments indicated that the metallic species (tantalum and/or silicon) diffusing out of the materials into the oxides was initially involved in the controlling process. [ABSTRACT FROM AUTHOR]

Plate-like ZrB2 grains were synthesized at 1550°C by in situ solid/liquid reaction using Zr and B powders mixed with transition metal ( Mo, Nb, Ti, or W) and Si powder. The preferred growth direction of plate grains was along a- or b-axis depending on the initial content of transition metal and silicon in the mixtures. The synthesis mechanism of plate-like grain was possibly related to the catalysis of in situ formed silicides. [ABSTRACT FROM AUTHOR]