MIAO Yimin, LIU Liangguang

(School of Materials Science and Engineering, Hainan University, Haikou 570228, Hainan, China)

Abstract: Hexagonal boron nitride (hBN) ceramics have broad application prospects in the fields of chemical industry, metallurgy, aerospace and so on, while the densification of hBN ceramics is still an urgent problem to be solved. With fixed initial particle size distribution and volume fraction of microscale hexagonal boron nitride (hBN) and nanoscale cubic boron nitride (cBN) powders, hNB ceramics were prepared with hot pressing sintering at 1800 °C, where the effect of the content of SiC on densification and mechanical properties of the ceramics were studied. As compared with the introduction of SiC, an increase in sintering pressure (80 MPa) was more significant in improving the densification and mechanical properties of the hBN ceramics. Specifically, the hBN ceramics had a relative density of 93.7%, with flexural and compressive strengths to be 94.90 MPa and 159.32 MPa, respectively. In addition, when the content SiC was 10 wt.%, the exhibited a relative density of 91.1%, with flexural and compressive strengths to be 84.77 MPa and 129.16 MPa. According to the SEM results, it can be concluded that the introduction of SiC can significantly reduce the anisotropic grain growth of the hBN.

Key words: hexagonal boron nitride; cubic boron nitride; silicon carbide; hot press sintering; densification