Effect of Sintering Temperature on Microstructure and Performance of High Content Polycrystal Cubic Boron Nitride

By taking cubic boron nitride powder, titanium powder and aluminum powder as raw materials, high content polycrystal cubic boron nitride (PcBN) was prepared by in-situ synthesis method at high temperatures (1 400-1 600℃) and an ultra-high pressure (6.5 GPa). The effects of sintering temperature on the mechanical properties, microstructure and cutting property of PcBN were investigated. The results show that the prepared PcBN all consisted of BN, TiN, TiB₂ and AlN phases. With the increase of sintering temperature, the number of pores in PcBN decreased, the density increased, the microhardness and flexural strength increased first and then decreased, and the flank wear loss of PcBN tool for cutting run length of 10 km decreased first and then increased. At the sintering temperature of 1 550℃, PcBN had the best comprehensive properties with the largest flexural strength of 969 MPa, the largest microhardness of 40.7 GPa, and the smallest flank wear loss of 0.26 μm.