Formation and oxidation resistance of germanium modified silicide coating on Nb based in situ composites

• Ge modified silicide coating on Nb based in situ composites was prepared.
• The coating is composed of an outer layer and a transitional layer.
• The coating has good oxidation resistance due to the formation of GeO2 and SiO2.

Ge-modified silicide coating was prepared on the Nb–Si based alloy by Si–Ge co-deposition at 1300 °C for 10 h. The pack powder for co-deposition consisted of 16Si–8Ge–5NaF–71Al2O3 (wt.%). It is observed that the coating is composed of an outer layer and a transitional layer. The mass gain of substrate and Ge-modified silicide coating are 190.08 and 5.42 mg cm−2 after oxidation at 1250 °C for 100 h, respectively. The coating can prevent substrate from oxidizing efficiently. The good oxidation resistance is attributed to the formation of glassy GeO2 and SiO2.

A continuous and compact film is formed on the surface of sample, the dense scale mainly consisted of SiO2 and GeO2 can prevent efficiently substrate from oxidizing.Figure optionsDownload as PowerPoint slide