Effect of Si content on microstructure and properties of Ti(C, N)-based cermet

The effects of Si additions (0, 0.5 wt%, 1 wt%, 1.5 wt%) on the microstructure, mechanical properties and oxidation resistance of Ti(C, N)-based cermets were investigated. The results showed that Si additions would combine with Mo, which leaded to the formation of MoSi2. Even though the ceramic black core phase was refined, the increase in Si content decreased the wettability between the binder and hard phases. The bending strength of the cermet grew and subsequently declined as the Si content increased, while the hardness did not change much. The most optimized comprehensive properties of the cermets were achieved with Si addition of 1 wt%, The bending strength, hardness and fracture toughness was 2133.7 MPa, 89.6 HRA and 12.21 MPa m(1/2) respectively. In another side, cermets with 1 wt% Si addition had lower oxidized weight increase and a thinner oxide film than that without Si. A denser oxidation film composed of SiO2 and NiTiO3 was generated during the oxidation process on the surface of the cermets with Si addition, and this would prevent O elements from diffusion into the cermets, thus the oxidation resistance was enhanced.