Oxidation behavior, thermal stability, and the coating/substrate interface evolution of CrN-coated Zircaloy under high-temperature steam

Highlights: • A dense CrN layer with excellent oxidation resistance was deposited on Zircaloy. • The steam oxidation mechanism of CrN coating at 1000 ℃ and 1200 ℃ was discussed. • The internal oxidation of Zr inside the nitride coating was observed. • The nitrogen diffusion behaviors in CrN coating at high temperature were studied. • A ZrN nano-twins layer formed at the coating/substrate interface after oxidation. CrN-coated Zircaloy samples were prepared by cathodic arc ion plating, and the microstructure, stability, and oxidation behaviors of the CrN coatings in high-temperature steams were comprehensively investigated. The CrN coating significantly increased the oxidation resistance of Zircaloy exposed to steam through the formation of a dense Cr₂O₃ oxide layer without cracking or spallation. Two different multi-layered coatings were produced after the steam exposures. The nitrogen diffusion properties of the CrN coatings during oxidation were examined. The internal oxidation of Zr particles inside the nitride coating was observed. A ZrN nano-twinned layer formed at the coating/substrate interface.