Abstract:Ti(C,N)-based cermets were prepared by pressureless sintering method using TiC, TiN, Ni and Co powders as main raw materials and Y₂O₃ as additive. The effects of sintering process and Y₂O₃ content on the microstructure and mechanical properties of Ti(C,N)-based cermet were investigated. The results show that TiC, TiN, WC, Cr₃C₂ and Mo phases disappear gradually and diffuse into hard and rim phases by dissolution-precipitation process with increasing the sintering temperature, finally, new Ti(C,N) hard phases and (Cr,W,Mo,Ti)(C,N) rim phases are formed, while the bonding metals Ni and Co exist mainly in the form of Ni phases and the intermediate phases of TiCo and Co₃W₃C. The phase structure evolution of Ti(C,N)-based cermet almost has no change with adding Y₂O₃ during sintering process. The micro-hardness, bending strength and fracture toughness of Ti(C,N)-based cermet increase first, and then decrease with the increase of Y₂O₃ content. Ti(C,N)-based cermet achieves the best mechanical properties with 0.8% Y₂O₃ (mass fraction) addition, the micro-hardness, flexural strength and fracture toughness are increased by 7.9%, 45.8% and 6.1%, respectively, when compared to those of the sample sintered at 1450 ℃ for 50 min.

Key words: Ti(C,N)-based cermet; Y₂O₃; sintering process; mechanical property