Effect of microstructure on mechanical properties of silicon nitride ceramics. Final report for period April 1, 1984 through March 31, 1988.

摘要

The goal of this project was to study the effect of silicon nitride grain morphology and the nature of the grain boundary phase on the mechanical properties of silicon nitride ceramics. A complete study on sintering and grain growth has been conducted in two silicon nitride systems: SiAlON -- Y(sub 3)Al(sub 5)O(sub 12) (YAG) and SiAlON -- Cordierite. The two additives, YAG and cordierite, were selected so that the liquid viscosity during sintering is relatively high in the cordierite system. Extensive kinetic characterization on densification, alpha and beta silicon nitride phase transformation and grain growth has been obtained with respect to sintering temperature and time, sialon composition, and liquid viscosity and content. The growth anisotropy of the (ss) grain has been demonstrated and the possible mechanistic explanation have been addressed.