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

The long‐term cyclic oxidation behavior of a single MoSi 2 coating, 10%, and 50% Ti 3 SiC 2 /MoSi 2 composite coatings on Nb–Si‐based alloys is systematically investigated. The thermal gravimetric analysis reveal that the single MoSi 2 coating initially exhibits a stable mass change (–3.7 mg cm −2 ) for ≈37 cycles, followed by a rapid increase in mass gain (2.2 mg cm −2 after 100 cycles). The 50% Ti 3 SiC 2 /MoSi 2 composite coating demonstrated linear oxidation kinetics with a mass gain of 3.5 mg cm −2 after 100 cycles. Notably, the 10% Ti 3 SiC 2 /MoSi 2 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 SiO 2 matrix interspersed with fine TiO 2 grains. After 100 cycles of cyclic oxidation, both the single MoSi 2 coating and the 50% composite coating exhibited significant degradation and damage at the edges.