Effects of CaB_2O_4 content on the sintering behavior of hexagonal boron nitride

摘要

CaB_2O_4 was added into hexagonal boron nitride (hBN) to improve the sintering behaviors of hBN. CaB_2O_4 and hBN were mixed and then pressed into plates. The plates were sintered at 2000℃ for 5h under a N_2 ambience. The phase compositions with different CaB_2O_4 contents were examined with X-ray diffraction analysis. The fracture cross-sections of the hBN plates were investigated by SEM. The apparent density and Rockwell hardness were also measured. The results show that the hBN particles had a plate-like shape and the grain sizes of hBN increased with increasing CaB_2O_4 contents. The apparent density and Rockwell hardness decreased with increasing CaB_2O_4 contents. When the CaB_2O_4 content was 15(wt) %, the hBN has the average grain sizes of 3μm in diameter and 200nm in thickness, the apparent density of 1.06 g/cm~3 and the Rockwell hardness of 3, respectively.