PHASE RELATIONS IN THE SYSTEM Si-Cr-N-B AT 1600 degree C UNDER 1 ATM N//2.

Metal nitrides and borides are used as structural and mechanical ceramic materials. In particular, Si//3N//4 and BN are important as engineering ceramics and abrasives. Chromium nitrides are also important as cutting tools. Investigation of phase relations of the system Si-Cr-N-B including these materials offers not only basic information, but also useful suggestions in their application to various fields of industries. Phase equilibria and stability of Cr//2N have been discussed in the system Cr-N. The phase relations in the system Si//3N//4-oxides have been extensively studied because many oxides have been effective as sintering aids for Si//3N//4 ceramics. There are, however, very few studies on non-oxide additives to Si//3N//4 as sintering aids. Some nitrides of Mg//3N//2, YN, AlN and ZrN were added to Si//3N//4 in the case of sintering by hot isostatic pressing. However no paper has reported systematic studies on the system Si-Cr-N-B. The present paper summarizes phase relations in the system Cr-B-N and CrSi-N, and compatibility relations in the system Cr-Si-B-N at 1600 degree C under 1 atm N//2.