Densification mechanism and corrosion resistance of h-BN/ZrO2 ceramics prepared by spark plasma sintering

The dense h-BN/ZrO2(30 wt%) composites without additives were rapidly fabricated by spark plasma sintering. The relative density, apparent porosity, fracture toughness, flexural strength, phase composition and microstructure of h-BN/ZrO2 composites were systematically investigated. Besides, the corrosion resistance of h-BN/ZrO2 composites in molten steel was also studied in detail. Especially, the h-BN/ZrO2 composites were sintered at 1800 °C exhibiting a relative density of 96.6% and the flexural strength of ≈ 157 MPa. The corrosion of h-BN/ZrO2 composites was mainly due to the oxidative decomposition of BN, and the corrosion process was clarified by a parabolic law. The excellent corrosion resistance of the h-BN/ZrO2 composites was attributed to ZrO2 residual layer formed at the interface. The corrosion thickness of h-BN/ZrO2 composites was only ∼116 µm even using the longest corrosion time (80 min). The composites could be a promising candidate material applied to fabricated thin strip continuous casting side sealing plates.