Long-term oxidation resistance and deterioration mechanism of magnetron sputtered Cr-Al-Si-N coatings on zirconium alloys in 1200 °C steam atmosphere

•Long-term oxidation resistance of Cr-Al-Si-N coated Zr-alloy coupons in 1200 °C steam.•To show structural and compositional evolution of coated coupons during oxidation.•To reveal deterioration mechanisms of the oxidation resistance.•To discuss the main factors that determine the oxidation resistance.