Microstructure and Mechanical Properties of Sinter–Post‐HIPed Si 3 N 4 –SiC Composites

The microstructural evolution and mechanical properties of Si 3 N 4 –SiC composites obtained by the sinter–post‐HIP process were investigated. SiC addition prohibited β‐Si 3 N 4 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 Si 3 N 4 . The enhanced short‐crack toughness was attributed to crack‐tip bridging by the SiC particles.