Oxidation behavior and Cr-Zr diffusion of Cr coatings prepared by atmospheric plasma spraying on zircaloy-4 cladding in steam at 1300 °C

To improve the high-temperature steam oxidation resistance of zircaloy-4 substrate, thick Cr coatings were successfully prepared on zircaloy-4 via atmospheric plasma spraying. The microstructure and oxidation behavior of Cr coatings on the zircaloy-4 in steam at 1300 °C were studied systematically. The Cr coatings showed improved steam oxidation over zircaloy up to 1300 °C. The microstructure evolution, Cr-Zr diffusion, and bubble formation were analyzed and discussed. Leaf-like Cr2O3 whiskers were formed on the surfaces of the Cr coatings. Zr-rich channels in the Cr coatings near the Cr-Zr interface can provide a diffusion path for oxygen to reach the zircaloy. •Thick Cr coatings were prepared on the zircaloy by atmospheric plasma spraying.•The Cr coatings showed improved steam oxidation over zircaloy up to 1300 °C.•Zr-rich channels can provide a diffusion path for oxygen to reach the zircaloy.