Effects of TaC addition on microstructure and mechanical properties of SiBCN composite ceramics

In this work, SiBCN-TaC composite ceramics were prepared by a combination of mechanical alloying and reactive hot-pressing sintering techniques. The effects of TaC addition on microstructure, mechanical properties and oxidation resistance of the resulting composite ceramics were studied in detail. Results suggested that the as-sintered SiBCN-TaC composite ceramics composed of three phases: SiC, BN (C) and TaC. Some TaC similar to 10-20 nm dispersed randomly within the ceramic matrix while others similar to 3-5 nm were scattered in turbostratic BN(C). The introduction of nanocrystalline TaC can effectively improve the flexural strength and fracture toughness of SiBCN ceramics. The incorporation of 10 wt% TaC showed the optimized mechanical properties with flexural strength and fracture toughness reaching to 399.5 MPa and 4.26 MPa m(1/2) respectively. The TG-DTA analysis confirmed the oxidation damage of BN (C) phase can be effectively alleviated by the introduction of TaC nanocrystals.