The Cause of Formation of Pores in Titanium Carbide Based Cermet with the Addition of Zirconium Carbide

Abstract

Formation of micro-pores in TiC-Mo₂C -Ni cermet with the addition of zirconium carbide(ZrC) up to 6 mass% was mainly studied. It was assumed that zirconium oxide(ZrO₂) formed on the surface of ZrC particles during preparation of mixed powder was reduced in the liquid phase which appeared at sintering temperature, resulting in the formation of pores. It was shown that, when the green compact was held under the solid state in a vaccum at temperature of 1250°C before sintering, the tendency of pore-formation was suppressed with increasing holding time and carbon content of the alloy. The well known phenomenon, that is, the increased creep strength of cermet due to ZrC addition was attributed to the decrease of carbon content caused by the reduction of ZrO₂.