Microstructural evolution and oxidation behaviour of Mo-Si-B coatings on an Nb-16Si-22Ti-7Cr-2Al-2Hf alloy at 1250 degrees C prepared by spark plasma sintering

摘要

Mo-Si-(5, 10, 15)B ternary coatings were firstly coated on an Nb-Si based alloy using the spark plasma sintering technique. The Mo-Si-B coatings consisted of an outer MoSi2/MoB/SiO2/Mo2B5 (Mo5Si3) layer and an interdiffusion zone, while SiO2 was formed during SPS. The oxidation kinetics curves exhibited parabolic time dependence and 5B coating had the lowest mass gain of approximately 0.41 mg/cm(2) after oxidation at 1250 degrees C for 100 h. The good oxidation resistance results from a dense and protective borosilicate layer formed on coatings and the low growth rate of the inter-diffusion zone beneath the Mo-Si-B coatings.