XIAO Fei, XU Zhuangzhi, XUE Jian, ZHANG Wan, YUE Xin
(Liaoning Research Institute of Light Industry, Shenyang 110036, Liaoning, China)
Abstract: In this study, using self-prepared silicon nitride particles as the main material, dense silicon nitride ceramics were prepared by high pressure forming and gas-pressure-sintering. The effects of different sintering temperatures and gas-pressures on the microstructure, relative density and hardness were investigated. The structure was characterized by X-ray diffraction and SEM. The results showed that silicon nitride sintering belongs to liquid phase sintering; the liquid phase began to appear at 1400 ℃, and α-phase began to change to β-phase; the transition was almost completed at 1600 ℃. Within the range of 1-3 MPa, the increase of nitrogen pressure was beneficial to sintering. The relative density of the sample prepared at 1800 ℃ under 3 MPa N2 pressure for 2 hours was 99.41% and the flexural strength was 960 MPa.
Key words: silicon nitride; gas pressure sintering; sintering temperature; gas pressure