Spark Plasma Sintering of βSiAlON-cBN Composite
βSiAlON-cubic boron nitride (cBN) composites were prepared from β-SiAlON and cBN powders using spark plasma sintering (SPS) at firing temperature of 1600-1900oC under pressure of 100MPa, and densification, phase transformation and hardness of the composites were investigated. The phase transformation of cBN to hexagonal BN (hBN) was inhibited in βSiAlON-cBN composite. βSiAlON-cBN composites containing 10-30 vol% cBN fired at 1650oC were densified to 95-98% of theoretical density with no transformation of cBN to hBN. Vickers hardness of the βSiAlON-cBN composite containing 20 vol% cBN fired at 1650oC was 17.5 GPa in maximum value, and the hardness significantly decreased as cBN phase was transformed to hBN in the composites.
Young Won Chang, Nack J. Kim and Chong Soo Lee
M. Hotta and T. Goto, "Spark Plasma Sintering of βSiAlON-cBN Composite", Materials Science Forum, Vols. 561-565, pp. 599-602, 2007