High-Temperature Cyclic Oxidation Behavior of Ti3SiC2/MoSi2 Composite Coatings on Nb-Si-Based Alloys

The long-term cyclic oxidation behavior of a single MoSi2 coating, 10%, and 50% Ti3SiC2/MoSi2 composite coatings on Nb-Si-based alloys is systematically investigated. The thermal gravimetric analysis reveal that the single MoSi2 coating initially exhibits a stable mass change (-3.7 mg cm(-2)) for approximate to 37 cycles, followed by a rapid increase in mass gain (2.2 mg cm(-2) after 100 cycles). The 50% Ti3SiC2/MoSi2 composite coating demonstrated linear oxidation kinetics with a mass gain of 3.5 mg cm(-2) after 100 cycles. Notably, the 10% Ti3SiC2/MoSi2 composite coating showed superior stability, with minimal mass gain (-2.7 mg cm(-2)) over 100 cycles. The scale formed on the 10% coatings is characterized as compact, dense, and firmly adhered to the substrate, primarily consisting of an amorphous SiO2 matrix interspersed with fine TiO2 grains. After 100 cycles of cyclic oxidation, both the single MoSi2 coating and the 50% composite coating exhibited significant degradation and damage at the edges.