Influence of Cr content on microstructure and oxidation behavior of modified Mo-Si-B composite coatings

Cr-modified Mo-Si-B composite coatings were prepared on Nb-Si based alloy by slurry sintering. The effects of Cr contents (0, 5, 10 and 15 wt%) on the microstructure and oxidation behavior of Mo-Si-B coatings were revealed. The addition of high Cr content improved compactness, and the coating evolved from a bilayer to a trilayer. The 10Cr coating exhibited the best oxidation resistance for oxidation at 1380 ℃ for 100 h, which was mainly because the formed oxide scale embedded with CrNbO₄ and TiNbO₄ had lower stresses, lower oxygen permeability and better integrity, thus effectively inhibiting the inward diffusion of oxygen.