Microstructure and properties of solid PCBN composites with different TiN contents

The solid polycrystalline cubic boron nitride (PCBN) was sintered by CBN powders, TiN and a certain amount of Al. It was investigated that the effect of TiN contents on the microstructure and mechanical properties of the solid PCBN composites under high pressure and high temperature. The phase composition analysis, microstructure observation, density and hardness test of the sintered samples were carried out. The results show that CBN reacts with the binders of TiN and Al to form TiB₂ and AlN. TiN reacts with Al to form Al₃Ti, TiN and AlN. The TiN, AlN, TiB₂ and Al₃Ti are uniformly distributed around the CBN grain boundary and the grains are firmly bonded together, which effectively improves the bonding strength of PCBN composite. The lower content of TiN has a certain increase in the density and hardness of the solid PCBN. When the mass fractions of TiN, Al and CBN are 10%, 10% and 80%, respectively, the solid PCBN composites has the best mechanical properties.