Preparation and Properties of cBN@TiN/β-Sialon Composite Ceramic and Cutting Tool

cBN@TiN/β-Sialon composite ceramic were prepared by in-situ generation of TiN coated cBN (cBN@TiN) particles by discharge plasma sintering technique. The phase composition, micromorphology and mechanical properties of the ceramic were studied. The cutting properties of indexable tool maded by the composite ceramic in continuous dry cutting ductile iron were also studied. The microstructure and propertres of the composite ceramic and cutting tool were compared with those of β-Sialon ceramic and cutting tool. The results show that the cBN@TiN/β-Sialon composite ceramic was composed of β-Sialon, cBN and TiN phases. There were no obvious pores on the polished surface of the ceramic, cBN@TiN particles were evenly distributed and did not fall off obviously. The matrix phase grains were equiaxial and long rod-like. The relative density and grain size of cBN@TiN/β-Sialon composite ceramic were similar to those of the β-Sialon ceramic. The hardness and fracture toughness of the composite ceramic were (17.40±0.11) GPa and (6.19±0.10) MPa · m^1/2, respectively, which were higher than those of the β-Sialon ceramic. Compared with the β-Sialon ceramic cutting tool, the cBN@TiN/β-Sialon composite ceramic cutting tool had better wear resistance and a longer cutting life.