Development and oxidation resistance of air plasma sprayed Mo–Si–Al coating on an Nbss/Nb5Si3 in situ composite

A Mo–Si–Al coating, which is mainly composed of Mo(Si,Al)2 and Mo5(Si,Al)3, was developed to protect a Nbss/Nb5Si3 in situ composite by air plasma spraying. After oxidation at 1250 °C, the oxidation curve followed parabolic law and even after oxidation for 100 h, the weight gain of Mo–Si–Al coating was 8.24 mg/cm2. The surface of the oxidized samples became flatter and smoother as time increased due to the formation of SiO2 glass. Moreover, the microstructure of Mo–Si–Al coating changed and a layer structured interdiffusion zone was formed at the substrate-coating interface after oxidation.