High pressure infiltration sintering of cBN–Si composites

• The cBN-cBN bonding appeared extensively in the sintered samples.
• The cutting performance of our sintered samples is also superior to the commercial PcBN.
• The onset temperature of oxidation can reach to 1300 °C, about 300 °C than that of the commercial PcBN (~ 1000 °C).
• The average Vickers hardness of 43 GPa for the well-sintered samples, which is much higher than the conventional PcBN.

Polycrystalline cubic boron nitride (PcBN) compacts with high hardness, high thermal stability and high cutting performance have been prepared through method of high pressure infiltration of silicon melt. The scanning electron microscopy (SEM) and metallographic observations indicates that cBN–cBN bonding appeared extensively in the sintered samples. The hardness tests give an average Vickers hardness of 43 GPa for the well-sintered cBN–Si compacts, which is much higher than the conventional PcBN composites (~ 30 GPa). The onset temperature of oxidation can reach to 1300 °C, about 300 °C than that of the commercial PcBN (~ 1000 °C). According to the results of turning test, the cutting performance of our sintered samples is also superior to the commercial PcBN.