Coatings for accident tolerant fuel claddings are considered an effective route to improving the safety margin of Zr alloys under high-temperature steam conditions. Cr coatings have attracted particular attention because of their good oxidation resistance; however, pronounced Cr–Zr interdiffusion at elevated temperatures can induce interfacial reactions and microstructural degradation. In this work, Si-containing Cr-based coatings with different architectures were prepared on Zr alloys, and their steam oxidation behavior, interfacial evolution, and elemental diffusion were investigated. After steam oxidation at 1200 °C, the TiSi/Cr nanomultilayer system exhibited less Cr–Zr interdiffusion than the TiSi single-layer system. Its oxidation weight gain was approximately 52% lower than that of the monolithic Cr coating, while good coating integrity was retained. Microstructural analyses further revealed distinct Si distributions and interfacial reaction behaviors in the two architectures. The formation of a Zr–Si diffusion barrier effectively suppressed further Cr–Zr interdiffusion and contributed to improved structural stability under high-temperature steam conditions. These results highlight the role of coating architecture in controlling high-temperature interfacial stability in Cr-coated Zr systems.

Accident tolerant fuel,Zr alloy cladding,Cr-based coating,High-temperature steam oxidation,Diffusion barrier