Abstract: A series of Ni60/La₂O₃ directional structural composite coatings with different contents of La₂O₃ were prepared by a combination of thermal spraying, remelting, and cooling techniques, with Ni60 as the base material and La₂O₃ as the additive. The electrochemical corrosion characteristics and immersion corrosion performance of the composite coating in 3.5 wt.% NaCl solution were studied. The corrosion behavior of the coating in 3.5 wt.% NaCl solution was discussed. The results showed that the corrosion of coatings in 3.5 wt.% NaCl solution is an activation-passivation-hyperpassivation process. With the change of La₂O₃ content, both the charge transfer resistance and corrosion current density decrease first and then increase. Notably, the coating containing 1% La₂O₃ demonstrated the most favorable corrosion resistance, with a corrosion potential of －0.543 V, a maximum charge transfer resistance of 11 791.2 Ω·cm², and a minimum corrosion current density is 3.775 × 10^－6 A/cm². EDS analysis showed that the surface of Ni60/1%La₂O₃ coating forms a dense uniform passivation film composed of NiO,Cr₂O₃, and La₂O₃, which effectively prevents the further penetration of NaCl solution. This passivation layer significantly enhanced the corrosion resistance of the coating in 3.5 wt.% NaCl solution.

Key words: Ni60/La₂O₃ structural structural coating, corrosion, 3.5 wt.% NaCl solution