Effects of Ti(C,N) Nanoparticles on Mechanical Properties of the Si₃N₄ Ceramics

Si₃N₄-Ti(C,N) nanocomposites fabricated by vacuum hot pressing with Al₂O₃ and Y₂O₃ as additives were investigated. The results showed that the α-Si₃N₄ phase converted completely into whisker-shaped β-Si₃N₄ grains after vacuum sintering at 1700℃. Suitable addition and well dispersion of the Ti(C,N) particles can restrained the lateral growth of the β-Si₃N₄ grains, increasing aspect ratio of the β-Si₃N₄ grains and improving bending strength of the composites. Fracture toughness of the composites is higher than that of the β-Si₃N₄ ceramics, and the main toughening mechanism is crack bridging due to the higher aspect ratio of the β-Si₃N₄ grains.With the addition of 1vol% of Ti(C,N), the composite has a relative density of 99.31%, Vicker’s hardness of 15.9 GPa, bending strength of 993 MPa, and fracture toughness of 9.9 MPa·m^1/2.