Abstract:After the Fukushima nuclear accident in Japan, accident tolerant fuel (ATF) cladding technology has attracted widespread attention in the industry. The cladding of Cr coatings on zirconium (Zr) alloys for nuclear fuel cladding in nuclear reactor cores is considered to be the most likely technology to be commercially available in the near future. At present, most of the preparation methods for Cr coatings have the disadvantages of expensive equipment, low deposition rate and weak shape adaptability. And the molten salt electrodeposition technology has the advantages of high cathodic current efficiency, fast electrodeposition speed, and strong adaptability of substrate shape, which is expected to solve the problem of efficient and low-cost preparation of high-quality Cr coatings on the surface of cladding Zr alloys. In order to realize the preparation of Cr coating on the surface of Zr alloy by molten salt electrodeposition, this paper adopted aqueous solution electrodeposition and molten salt electrodeposition methods to prepare Ni transition layer and Cr coating on the surface of Zr alloy substrate sequentially, and carried out the characterization of the organization structure, the bonding force and nano-hardness test as well as the study of the high-temperature oxidation behavior of the Zr/Ni/Cr specimens obtained from the preparation. The results showed that the Ni/Cr coating on the surface of Zr alloy was uniform and dense, and the bonding force between the coating and the substrate was about 151N. The hardness and modulus of elasticity of Zr/Ni/Cr increased gradually from inner to outer layers with a quasi-gradient transition. The surface roughness of the Cr coating was about 2 μm, and the hardness and modulus of elasticity were 2.86 GPa and 172.86 GPa, respectively. The Zr/Ni/Cr specimens showed nearly parabolic and nearly linear patterns during steam oxidation at high temperatures of 1000°C and 1200°C, respectively, indicating that the Ni/Cr coatings were able to provide good protection to the Zr alloy matrix at 1000℃. The high-temperature oxidation failure mechanism of Ni/Cr coatings on Zr alloy surfaces was closely related to the rapid diffusion of the Ni transition layer, the oxidation and diffusion depletion of the Cr layer, and the weakening of the Cr layer due to the rapid diffusion of Zr along the Cr grain boundaries.