Investigation of the oxidation mechanisms of superlattice Cr-CrN/TiSiN-Cr multilayer coatings on Zircaloy substrates under high-temperature steam atmospheres

Abstract Cr-CrN/TiSiN-Cr multilayer coatings were deposited on Zircaloy substrates by multi-arc ion plating, and the microstructure and oxidation behavior of the as-deposited coatings, specifically the middle CrN/TiSiN layer, were investigated. The CrN/TiSiN layer exhibited a superlattice structure. The multilayer coatings effectively protected the Zircaloy substrates from oxidation. (Cr1-xTix)2O3 and Cr2TiO5 phases were produced in the coating after oxidation at 1200 °C for 1500 s. With oxidation time increases, most of the Cr atoms in these two phases were replaced by Ti atoms. Oxidation mechanisms of the as-deposited coatings are discussed and a decomposition model of the superlattice CrN/TiSiN layer is proposed.