High temperature steam-oxidation behavior of arc ion plated Cr coatings for accident tolerant fuel claddings

Ever since the Fukushima accident, accident tolerant fuel (ATF) has been widely studied, and a coating technology for a fuel cladding surface has been considered to decrease the high-temperature oxidation rate of zirconium-based alloy. In this study, arc ion plating technology was applied to coat a Cr layer on Zircaloy-4 as the oxidation-resistant coating layer for ATF cladding. A pure Cr phase was confirmed through an XRD analysis, and Cr film was also found to be homogeneous, dense, and uniform in the cross-sectional observation by SEM. Cr-coated Zircaloy-4 was tested in a high-temperature steam environment at 1473 K for 2000 s. The high-temperature oxidation tests showed that the Cr layer protected Zircaloy-4 from high-temperature oxidation in the steam. The stability of the Cr-coated layer deposited was maintained without peeling after a high-temperature oxidation test, and a Cr2O3 thin oxide layer was observed on the Cr coating layer. Furthermore, the TEM results showed that a Cr-Zr mixed layer was formed during the high-temperature oxidation tests. Based on the results obtained, the Cr film on Zircaloy-4 successfully acted as a corrosion protective layer, and arc ion plating was shown to be a corrosion protective coating system for ATF claddings.