Densification and phase transformation of β-SiAlON-cubic boron nitride composites prepared by spark plasma sintering

β-SiAlON-cubic boron nitride (cBN) composites were prepared from β-SiAlON and cBN powders at 1600°-1900°C under a pressure of 100 MPa by spark plasma sintering. The effects of cBN content and sintering temperature on densification and phase transformation of the β-SiAlON-cBN composites were studied. When 10-30 vol% cBN was added to β-SiAlON, the shrinkage rate of the compacts increased. The compacts of β-SiAlON-BN composites originally containing 10-30 vol% cBN ceased to shrink at a temperature lower than that of β-SiAlON and the density of the composites increased. The densification of β-SiAlON-BN composites originally containing >40 vol% cBN was suppressed. The phase transformation of cBN to hexagonal BN in the β-SiAlON-BN composite was inhibited to a greater degree than that in the cBN body.