Effect of diamond additive on the properties of cBN composites with Al–Si as binder by HTHP sintering.

In this paper, high thermal conductivity PcBN composites with Al–Si as binder and diamond as additive were prepared by high temperature and high pressure (HTHP) sintering at 5 GPa and 1500 °C. The effects of diamond content on the phase composition, microstructure, density, thermal conductivity, and volume resistivity of PcBN composites were characterized and studied. With the increase of diamond content, the thermal conductivity of PcBN samples increases first and then decreases. When the diamond content is 4 wt%, the thermal conductivity of PcBN composites is the highest, reaching 146.3 W m−1K−1, which is 20.2% higher than the thermal conductivity without diamond. At the same time, the reduction of the residual silicon liquid phase in the sintered body also increases the volume resistivity of the composites. With the increase of diamond content, the volume resistivity of PcBN composites also increases. The volume resistivity of PcBN composite with diamond content of 16 wt% reaches 1.25 * 1010 Ω·cm. [ABSTRACT FROM AUTHOR]