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 m1/2 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.