Key Words：Fabrication and mechanical properties of boron nitride nanotube reinforced silicon nitride ceramics
Fabrication and mechanical properties of boron nitride nanotube reinforced silicon nitride ceramics
In this study, silicon nitride (Si 3 N 4 ) ceramics added with and without boron nitride nanotubes (BNNTs) were fabricated by hot-pressing method. The influence of sintering temperature and BNNTs content on the microstructures and mechanical properties of Si 3 N 4 ceramics were investigated. It was found that both flexural strength and fracture toughness of Si 3 N 4 were improved when sintering temperature increases. Moreover, α-Si 3 N 4 phase could transform into β-Si 3 N 4 phase completely when sintering temperature rises to 1800 °C and above. BNNTs can enhance the fracture toughness of Si 3 N 4 dramatically, which increases from 7.202MPa·m 1/2 (no BNNTs) to 10.402MPa·m 1/2 (0.802wt.% BNNTs). However, excessive addition of BNNTs would reduce the fracture toughness of Si 3 N 4 . Meanwhile, the flexural strength and relative density of Si 3 N 4 decreased slightly when BNNTs were added. The related toughening mechanism was also discussed.