Deposition of a B-modified silicide coating for Nb-Si based alloy oxidation protection

• A B-modified silicide coating was prepared on the Nb-Si based alloy.
• Formation mechanism for the microstructure of the coating has been revealed.
• The B-modified silicide coating exhibits good oxidation resistance.
• Oxidation-resistant mechanism of the coating has been proposed.

A B-modified silicide coating was prepared on the Nb-Si based alloy by Si-TiB2 co-deposition at 1300 °C for 10 h. The results show that the two-layer coating is composed of a (Nb, X)Si2 (X represents Al, Cr, Ti and Hf) + NbTiB4 outer layer and a (Nb, X)Si2 + Cr2Nb inner layer. Static oxidation tests indicate that the mass gain of B-modified silicide coating was 2.39 mg/cm2 after oxidation at 1250 °C for 100 h. The good oxidation resistance is attributed to the formation of a continuous and dense scale mainly consisting of glassy borosilicate.

After oxidation, dense borosilicate scale forms on the B-modified silicide coating. The mass gain of the coating is 2.39 mg/cm2 which exhibits good oxidation resistance of the coating.Figure optionsDownload as PowerPoint slide