Study on self-toughening Si₃N₄ ceramics

The relation between the process parameters such as amount of addition, sintering temperature and time of hot-pressed self-toughening Si ₃N₄ ceramics and the microstructure, phase structure as well as mechanical properties was studied. It was found that less amount of addition would be beneficial to microstructure homogenization which relates to better mechanical properties when the densification is well-achieved. On the other hand, due amount of addition and sintering temperature are necessary to the densification of materials and full phase transformation of α-Si ₃N₄ into β-Si₃N₃. The fracture toughness of 9.04MPa-m^1/2 was got with the addition w(Y ₂O₃) +w(Al₂0₃) = 3.5% + 1.5%.