Influence of Oxygen Content of Silicon Nitride upon Its Sinterability in HIPing without Additives

Two kinds of Si3N4 powders, of which characteristics were similar to each other in morphology, crystallographic phases and chemical contents except for oxygen content, were sintered by HIP using a glass capsule without additives. The amount of oxygen content in Si3N4 powder had influence upon its sinterability without additives. After HIPing, the increase in oxygen content in samples was detected though no penetration of glass through a BN inner capsule into Si3N4 was observed. But the oxygen content in well densified bodies was relatively small.