Microstructure and mechanical properties of sinter-post-HIPed Si3N4-SiC composites

The microstructural evolution and mechanical properties of Si3N4-SiC compos ites obtained by the sinter-post-HIP profess were investigated. SiC additio n prohibited beta -Si3N4 grain growth; however, the grain grow-th followed the empirical growth law, with exponents of 3 and 5 for the c- and the alph a -asis directions, respectively. Mechanical properties were strongly influ enced by SiC addition and sintering conditions. Short-crack propagation beh avior was measured and analyzed by the indentation-strength in-bending (ISB ) method, The present composites had high short-crack toughness, compared w ith the values for monolithic Si3N4. The enhanced short-crack toughness was attributed to crack-tip bridging by the SiC particles.