Excellent oxidation resistance: A dense and well-bonded MoSi₂/(Nb,X)Si₂ composite coating on Nb-Si based alloy

A dense and well-bonded MoSi₂/(Nb,X)Si₂ composite coating was developed on Nb-Si based alloy by the combination of Si pack cementation with pre-oxidation and then Mo-Si slurry sintering. The formation of a SiO₂ scale with proper thickness by pre-oxidation on (Nb,X)Si₂ layer, can significantly improve the interface bonding between MoSi₂ layer and (Nb,X)Si₂ layer, as well as the compactness of MoSi₂ layer. The MoSi₂/(Nb,X)Si₂ composite coating exhibits excellent oxidation resistance at 1250 ℃ and 1350 ℃, which can be attributed to the dense structure of MoSi₂ layer, the sufficient Si source from (Nb,X)Si₂ layer and the good interfacial bonding.