Densification and mechanical properties of CrB₂+MoSi₂ based novel composites

CrB₂+MoSi₂ ceramic composites with different contents of MoSi₂ (5 wt% and 15 wt%) were prepared by pressureless sintering and hot-pressing techniques. For comparison, a monolithic CrB₂ ceramic was also consolidated under the identical temperature, pressure and holding time by both pressureless sintering and hot-pressing techniques. The effects of the fabrication processes on the densification and mechanical properties of the composites were investigated. No improvement in density was observed upon addition of MoSi₂ as sinter additive. The phase analysis and microstructural characterization of the resultant composites indicate that there are no sintering reactions between the matrix (CrB₂) and the additive (MoSi₂). The hardness and fracture toughness of the composites were measured in the range of 17–19 GPa and 3–5 MPa m^1/2 respectively. The hardness was found to decrease (7% to 8%) and fracture toughness was found to increase (60%–90%) with respect to the addition of MoSi₂.