Improvement Of Creep Resistance Of Sintered Silicon Nitride By Hot Isostatic Extrudation Of Intergranular Glass

Postsintering treatment of pressureless-sintered silicon nitride at 1250 deg C (i.e. above the glass transition temperature of the amorphous phase) by hot isostatic pressing was performed to diminish the quantity of residual intergranular amorphous phase that results from densification aids. The samples were first embedded in a powder, which worked as a diffusion barrier and a pressure transmitter; then, both sample and surrounding powder were encapsulated in evacuated tubes of borosilicate glass or stainless steel.