Oxidation behavior and kinetics of in situ (TiB2+TiC)/Ti3SiC2 composites in air

Abstract The isothermal oxidation behavior of in situ (TiB 2 + TiC)/Ti 3 SiC 2 composite ceramics with different TiB 2 content has been investigated at 900–1200 °C in air for exposure times up to 20 h by means of X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive spectroscopy. The oxidation of (TiB 2 + TiC)/Ti 3 SiC 2 composites follows a parabolic rate law. With the increase in TiB 2 content, the oxidation weight gain, thickness of the oxidation scale, and parabolic rate constant decrease dramatically, which suggests that the incorporation of TiB 2 greatly improves the oxidation resistance of the composites. With the increase in oxidation temperature, the enhancement effect becomes more pronounced. Due to the incorporation of TiB 2 , the oxidation scale of (TiB 2 + TiC)/Ti 3 SiC 2 composites is generally composed of an outer layer of coarse-grained TiO 2 and an inner layer of amorphous boron silicate and fine-grained TiO 2 . Only the dense inner layer formed on the surface acts as a diffusion barrier, retarding the inward diffusion of O, and consequently contributing to the improved oxidation resistance of the (TiB 2 + TiC)/Ti 3 SiC 2 composites.