Thermal shock behavior of ZrB2-MoSi2-SiCw composites

Effect of SiCw volume fraction on thermal shock resistance (TSR) of ZrB2-20 MoSi2 composite has been studied in the present work. Three composites namely ZMSw0 (ZrB2-20 MoSi2-0 SiCw), ZMSw5 (ZrB2-20 MoSi2 - 5SiCw) and ZMSw20 (ZrB2-20 MoSi2-20 SiCw) were prepared by multi-stage spark plasma sintering at 1700 °C. TSR was measured using indentation quench technique. Results indicate that an increase in silicon carbide percentage decrease the crack growth rate and increase the critical temperature differential ΔTc, which in turn continuously raises the TSR of the composites. Development of thermal residual stresses due to thermal shock leads to excellent crack shielding and higher TSR of the ZMSw20 composite. The reduction in hardness and fracture toughness due to thermal shock for the ZMSw20 composite is lesser than that of both the ZMSw0 and ZMSw5 composites.