Characterization of hot pressed SiC whisker reinforced TiB₂ based composites

TiB₂–SiC ceramic composites, with different contents of SiC whiskers (SiC_w), as a ceramic sinter-additive, were prepared by the hot pressing process at 1850 °C for 2 h under a pressure of 20 MPa. For comparison, a monolithic TiB₂ ceramic was also fabricated under the identical temperature, pressure, atmosphere, and holding time by the hot pressing process. The effects of fabrication process and SiC whiskers on microstructural features, phase evolution and mechanical properties were investigated. Hardness measurements revealed an initial increase in hardness for TiB₂–SiC compared to TiB₂. Also the improvement of the fracture toughness was attributed to the toughening and strengthening effects of SiC whiskers such as crack deflection. The results showed that promoted densification of TiB₂–SiC ceramic composites is due to addition of SiC whiskers and reduction of oxide impurities by reacting with SiC whiskers and removing them from the surface layer of TiB₂ particles. The reaction between TiB₂ particles and SiC whiskers led to in-situ formation of TiC phase in the matrix as well. In general, it is concluded that the sinterability of TiB₂-based composites was remarkably improved by introducing SiC whiskers compared to the single phase TiB₂ ceramic.