HOT ISOSTATIC PRESSING OF ALPHA-SILICON CARBIDE CERAMICS

A submicron alpha-SiC powder was densified by hot isostatic pressing u sing a Vycor glass container. The effect of different additives such a s B4C, AlN and Al2O3 on densification, mechanical properties and oxida tion behaviour was investigated. The results showed that the densifica tion mechanism was attributed to liquid-phase sintering via the format ion of a eutectic between SiO2 and additive, and Al2O3 was confirmed t o be an effective additive for hot isostatic pressing of SiC. Hot isos tatically pressed, Al2O3-doped SiC had an ultrafine-grained microstruc ture with grain size varying from 0.5 to 2.5 mu m, and exhibited a fle xural strength above 570 MPa and a fracture toughness higher than 5.17 MPa m(1/2).