Homogeneous Microstructure of ZrO2-BN Composites with In Situ Synthesized BN

A new process was used to improve microstructure homogeneity of ZrO2-BN composites. Boric acid was deposited on the surface of ZrO2 particles by heterogeneous precipitation method from aqueous solution of boron oxide under the action of heat by evaporation. In order to improve the microstructure homogeneity, the mixture powder was stirred over-vigorously until transforming into the highly viscosity slurry. Subsequently, the obtained mixture powders were dried, nitrided at 900 °C in ammonia and crystallized at 1500 °C in nitrogen atmosphere to obtain in-situ synthesized BN coated on the surface of ZrO2 composite particles. Finally, ZrO2-BN composites incorporated with 30 vol. % BN were prepared by hot-pressing. The SEM microstructure and fracture surface of ZrO2-BN composites revealed that in-situ synthesis BN particles were dispersed in the ZrO2 matrix homogeneously.