Microstructure and Mechanical Properties of Sinter-Post-HIPed Si3N4-SiC Composites

Abstract

The microstructural evolution and mechanical properties of Si3N4–SiC composites obtained by the sinter–post‐HIP process were investigated. SiC addition prohibited β‐Si3N4 grain growth; however, the grain growth followed the empirical growth law, with exponents of 3 and 5 for the c‐ and the a‐axis directions, respectively. Mechanical properties were strongly influenced by SiC addition and sintering conditions. Short‐crack propagation behavior was measured and analyzed by the indentation‐strength in‐bending (ISB) method. The present composites had high short‐crack toughness, compared with the values for monolithic Si3N4. The enhanced short‐crack toughness was attributed to crack‐tip bridging by the SiC particles.