To protect Nb substrate from oxidation at elevated temperatures and make better use of the industrial solid wastes, spent MoSi₂ heating elements, ZrSi₂ and SiC were applied as raw materials to prepare MoSi₂ and MoSi₂–ZrSi₂–SiC coatings by Spark Plasma Sintering (SPS). After high-temperature sintering, cracks were found in a single MoSi₂ coating while MoSi₂–ZrSi₂–SiC coating was crack-free without any defects by the CTE mismatch reduction. Diffusion layers formed on the substrate and it strengthened the bonding in the coating system with good metallurgical combination. The oxide scale of the composite coatings possessed compact and crack-free morphologies with fractional consumption after oxidation at 1500 °C. Circular Mo₅Si₃ phases that possessed pores and cracks generated in the silica layer of MoSi₂ coating at 1700 °C while MoSi₂–ZrSi₂–SiC composite coating still kept crack-free oxide scale, thus showing excellent 1700 °C anti-oxidation properties.

廢棄物,硅鉬棒,高溫抗氧化,涂層