Microstructure and oxidation resistance of Mo–Si–B coating on Nb based in situ composites

• Mo–Si–B coating was applied to Nb based in situ composites by a two-step process.
• The obtained coating exhibits the good high temperature oxidation resistance.
• The good oxidation resistance is due to the formation of a protective glass oxide.

The development of robust high temperature oxidation resistant coatings for Nb–Si based alloy was evaluated for a Mo–Si–B coating system that was applied by a two step process. It is observed that the coating is composed of an outer layer of MoSi2 containing boride dispersoids and an inner layer of unreacted Mo. The mass gain of substrate and Mo–Si–B coating is 190.08 and 1.28 mg cm−2 after oxidation at 1250 °C in dry air for 100 h, respectively. The good oxidation resistance of the coating is attributed to the formation of a continuous borosilicate glass coverage.

According to the figure, it shows that a uniform and protective oxide scale (approximately 5–10 μm) formed on the surface of Mo–Si–B coating.Figure optionsDownload as PowerPoint slide