Abstract
Hot-pressed BN-SiC composites applied for the steel casting application were enhanced using nano Al2O3 and ZrO2 additives. The influences of nano ZrO2 content on the mechanical properties, thermal shock resistance, oxidation resistance, and steel corrosion resistance of BN-SiC composites were investigated. The results showed that the collaborative addition of nano ZrO2 and Al2O3 dominated the densification behavior due to the enhanced solid diffusion and pore filling effects. the improved densification and induced microstructure evelopment contributed to enhanced mechanical properties and thermal shock resistance. Consequently, the flexural strength and fracture toughness of 15 wt% nano ZrO2 containing specimens reached to 334.6 ± 0.1 MPa and 4.60 ± 0.13 MPa m1/2, respectively. Furthermore, no catastrophic fracture was observed during thermal shock tests even under a temperature difference at 1200 °C. In addition, the prepared composites exhibit excellent steel corrosion resistance at 1600 °C, attributing to the much finer grain size and quick formation of protective ZrO2 layer at the interface.
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