Homogeneous microstructure of ZrO₂-BN composites with in-situ synthesized BN

A new process was used to improve microstructure homogeneity of ZrO ₂-BN composites. Boric acid was deposited on the surface of ZrO ₂ 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.