Sintered body of a silicon nitride with crystalline grain boundaries phases

摘要

A silicon nitride ceramic having crystalline grain boundary phases is prepared by heating a composition comprising silicon nitride, a silicate glass-forming sintering aid and a high metal content transition metal silicide, to a temperature of 1300° to 1800° C. under vacuum until a glass forms, oxygen is removed from the glass, and the glass crystallizes. Alternatively, the grain boundaries of a sintered composition comprising silicon nitride, a silicate glass and a high metal content transition metal silicide can be crystallized by heating to at least 1300° C. under a vacuum.