Effect of high-temperature oxidation on Si₃N₄ containing Ti₃AlC₂

In this work, a dense Si₃N₄-based composite was fabricated by spark plasma sintering the mixture of Si₃N₄ and Ti₃AlC₂. The nitrogen atoms of Si₃N₄ diffused into the TiC_x lattice and leaded to the in-situ formation of TiC_0.3N_0.7 and SiC compounds. After annealing in air at 900 °C, TiC_0.3N_0.7 was oxidized to form rutile-TiO₂ particles (about 3–4 μm). Meanwhile, it was found that the oxidized composite displayed superior mechanical and tribological properties, compared to Si₃N₄ and Si₃N₄-based composite before oxidation. Typically, the fracture toughness reached 9.97 MPa m^1/2, which was 59.5% higher than that of Si₃N₄. In addition to cracks branch, bridge and deflection, the surface barrier of oxides was another major toughening mechanism. Besides, due to the pinning effect of TiC_0.3N_0.7, sliding-induced microcracks were completely suppressed, and the composite exhibited excellent friction and wear performances. In this case, the composite is expected to be fabricated into ceramic parts for service in high temperature environment.