DING Chao, LIU Liangguang
(School of Materials Science and Engineering, Hainan University, Haikou 570228, Hainan, China)

Abstract: Hexagonal boron nitride ceramics have excellent and stable mechanical properties in thermodynamics, chemistry, electricity, and other fields, with applications in metal smelting, aerospace, high-temperature materials and so on. However, due to their low density, strength and high sintering temperature, they are limited for wider applications. To solve this problem, a phase change sintering method was applied to such ceramics. In this study, spark plasma sintering method was used to introduce different proportions of nano-diamond into hexagonal boron nitride powder. The effect of diamond content on density and mechanical properties of the composite hexagonal boron nitride ceramics was studied. The maximum density of the composite hexagonal boron nitride ceramics is 95%. With increasing content of diamond, compressive strength and bending strength of the composite ceramics gradually increase, with the maximum compressive strength and bending strength to be 189.855 MPa and 136.100 MPa. The composite ceramics exhibited microhardness and Young’s modulus of 0.70 GPa and 10.42 GPa. Compared with the traditional sintering technology, spark plasma sintering method has the advantages of lower sintering temperature and increased density and mechanical properties for hexagonal boron nitride ceramics.
Key words: hexagonal boron nitride; spark plasma sintering; diamond; relative density; mechanical properties