Characterization of hot pressed SiC whisker reinforced TiB2 based composites

Abstract

TiB2–SiC ceramic composites, with different contents of SiC whiskers (SiCw), as a ceramic sinter-additive, were prepared by the hot pressing process at 1850°C for 2h under a pressure of 20MPa. 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.