Enhanced mechanical properties, thermal shock resistance and ablation resistance of Si2BC3N ceramics with nano ZrB2 addition

The mechanical properties, thermal shock resistance, and ablation resistance of nano ZrB2 modified Si2BC3N ceramics were investigated. The results show that ZrB2 stimulated microstructure evolution obviously. Therefore, the maximum strength and fracture toughness reach 559.6 MPa and 6.77 MPa.m(1/2), which are improved by 61.0% and 29.4%, respectively. Furthermore, the residual strengths of 10 wt% ZrB2 containing composites tested at 1000 degrees C retain 363.6 MPa, which is much higher than 97.7 MPa of pristine Si2BC3N ceramics. Besides, the ablation resistance of ZrB2 modified Si2BC3N ceramics at 3000 degrees C is enhanced remarkably and the linear and mass ablation rates of ZrB2-10 are only 0.009 mm/s and 1.91 mg/s, respectively. The ablation in the ultra-high temperature zone is totally dominated by the ZrB2 component, and the thermochemical erosion is determined by the oxidation resistance of ZrB2 in the thermal affected zone.