Influence of SiO2 glass phase (SGP) content on the oxidation and diffusion behavior of MoSi2 coatings on Nb-based alloys

MoSi2 coatings with different SiO2 glass phase (SGP) content were prepared on Nb-based alloy by hot press sintering. Then, the effect of SGP content on the growth behavior of the diffusion and oxidation layers was studied. The results showed that the desired coating could withstand 150 h of static oxidation at 1550 ℃ without failure. The coating with lower SGP content possessed thinner diffusion and oxidation layers after oxidation, resulting in better oxidation resistance. This improvement was due to low SGP content, which reduced the MoSi2/SGP or SiO2/oxide interfaces and restrained the diffusion of silicon and oxygen. •MoSi2 coatings with different SGP content were prepared by HPS.•The desired coating can well protect the Nb-based alloy at 1550 ℃ for more than 150 h.•Low SGP content leads to less MoSi2/SGP or SiO2/oxide interfaces, which suspends the diffusion of silicon or oxygen.•The estimation formulas of the diffusion and oxidation layers thickness were obtained.