Hydrothermal corrosion of Cr[sbnd]C and Ti-Al-C carbide ceramic coatings on Zircaloy: Corrosion behavior, mechanism and influence of water exposure on pressurized steam oxidation resistance

The corrosion behavior of Cr[sbnd]C and Ti-Al-C coatings in lithiated/borated water was studied, and the influence of hydrothermal corrosion on coating chemical stability in pressurized steam was investigated. In lithiated/borated water, Cr[sbnd]C coating formed a protective Cr₂O₃ layer, and the Ni[sbnd]Al intermediate layer remained unoxidized. The diffusion degree of O²⁻ differed in the depth direction of the Ti-Al-C coating. O²⁻ penetrated into the Ni[sbnd]Al intermediate layer, facilitating oxidation and cracking. Cr[sbnd]C coating was found to be more resistant to steam oxidation than Ti-Al-C coating. Oxidation stress led to partial delamination of the oxide scale on Cr[sbnd]C coating, while Ti-Al-C coating suffered intergranular oxidation and exhibited microscale facets under the selective attack of steam.