Microstructural evolution and oxidation behavior of TiB₂–SiC–B₄C composite fabricated by reactive spark plasma sintering

Microstructural evolution and oxidation behavior of TiB₂–SiC–B₄C composite fabricated from Ti–SiC–B₄C system with different weight ratios via reactive SPS were investigated in detail. Based on the characterizations of SEM, XRD, TEM and HRTEM, it was found that the solid diffusion induces reactions between Ti and B₄C to form TiB₂(TiB), C and Ti(B,C,Si). Afterwards, the results of oxidation tests at 800 °C, 900 °C and 1000 °C demonstrated that the sample with highest TiB₂ contents performed the best oxidation resistance due to the lowest porosity. Furthermore, the smoothly glassy oxidation layer above substrate composed of TiO₂ and B₂O₃ became thicker with temperature increasing, meanwhile, the vaporized B₂O₃ recrystallized into plate-like, rose-like even large-monolithic grains.