2012 年 59 巻 7 号 p. 410-271
Ni-cubic boron nitride (cBN) composites were prepared using Ni and cBN powders by spark plasma sintering at 1073 to 1473 K for 0.6 ks under a pressure of 100 MPa. Densification, microstructure and hardness of the Ni-cBN composites and the phase transformation of cBN to hexagonal BN (hBN) in the Ni-cBN composite were studied. Ni-cBN composites originally containing 10-30 vol% cBN showed the highest relative density of 98 % at 1373 K for 0.6 ks without the phase transformation to hexagonal BN (hBN). The phase transformation of Ni-20 vol% cBN occurred at 1473 K after 0.6 ks and at 1173 K after 1.2 ks. The maximum hardness of 3.5 GPa was obtained in the Ni-cBN composites originally containing 30 vol% cBN sintered at 1373 K for 0.6 ks.