Formation and oxidation behavior of Mo-Si-B composite coatings with B-rich interlayer prepared by slurry sintering method

The Mo-Si-B composite coatings with a B-rich interlayer were prepared on Nb-Si based ultrahigh temperature alloys by slurry sintering method, which exhibited a three-layer structure. The effect of B content (0, 5, 10 and 15 at%) on the microstructure and oxidation resistance of the coatings was investigated. The 10B coating had the lowest mass gain (5.9 mg/cm²) after oxidation at 1250 °C for 100 h. Its good oxidation resistance is attributed to the formation of oxide scales with crack-less, high fluidity and low oxygen permeability, which effectively prevents the inward diffusion of oxygen and prompts the transition from internal oxidation to external oxidation.