Thermal diffusivity and microstructure of spark plasma sintered TiB2-SiC-Ti composite

This work investigates the microstructural development, thermal properties and phase evolution of spark plasma sintered TiB2-SiC-Ti (TST) ceramic composite. A fully dense TiB2-30 vol% SiC composite, doped with 5 wt% Ti, was sintered by spark plasma at 1900 degrees C for 6 min under 35 MPa pressure in vacuum. The XRD analysis and thermodynamic assessments verified the in-situ synthesis of TiB, TiC and TiSi2 compounds during the sintering process due to the chemical reaction of Ti additive with the SiC reinforcement. The TST composite showed higher thermal conductivity than the monolithic TiB2 at low temperatures, however, a reverse trend was observed at higher temperatures. The governing equation of heat diffusion through a cutting tool, made of monolithic TiB2 and TST, was solved by finite element method and the temperature distribution was obtained. The results showed that TST composite has lower value of maximum temperature compared to the reported values for WC. Cutting tools with lower temperatures result in higher accuracy and more tool lifespan.