Corrosion and fretting wear behavior of Cr-based composite coatings on zirconium alloy

The accident tolerant fuel (ATF) was developed to improve nuclear safety and economic benefits of nuclear power after the Fukushima nuclear accident. The coatings prepared on zirconium (Zr) alloy fuel cladding is one of the primary research directions for ATF. In this research, Cr, CrN, Cr/CrN/CrAlN (Multi-1), and Cr/CrN/ CrAlN/CrAlSiN (Multi-2) coatings were prepared on Zr alloy using magnetron sputtering technology. The characteristics, corrosion, and fretting wear behavior of different coatings were investigated. The results show that different coatings can improve the corrosion resistance of Zr alloy, and Cr coating has the best corrosion resistance in high-temperature pressurized steam condition because a very thin Cr2O3 layer is formed on the surface after corrosion, effectively preventing the penetration of oxygen ions. Zr alloy exhibits the significant wear damage, primarily including adhesive wear, abrasive wear, and oxidative wear. The CrN coating presents the best wear resistance compared with other coatings. The wear depth, wear area, and wear rate of CrN coating are 1/4, 1/3, and 1/8 of Zr alloy, respectively. The wear mechanisms of different coatings predominantly involve abrasive wear and oxidative wear. Based on the above results, CrN coating has both the best wear resistance and good corrosion resistance.