Influence of Processing Conditions on the Microstructure and Mechanical Properties of Reaction Sintered Silicon Nitride

摘要

The microstructure of reaction bonded silicon nitride (RBSN) was changed in a wide range by varying green density, grain size of the silicon starting powder, nitriding conditions, and by introducing artificial pores. The influence of individual microstructural parameters on mechanical properties such as room temperature strength, creep behavior, and resistance to thermal shock was investigated. The essential factors influencing these properties are total porosity, pore size distribution, and the fractions of alpha and beta Si3N4. In view of high temperature engineering applications of RBSN, possibilities of optimizing the material's properties by controlled processing are discussed.