Effect of La2O3 content on the microstructures and corrosion behavior of Ni60 directionally structure coatings

With the development of science and technology, the traditional single nickel-based coatings cannot meet the service needs of industrial parts. In this paper, the directional structure of Ni-based alloy coatings with La2O3 were prepared in order to further improve the corrosion resistance of nickel-based coatings, and the effect of La2O3 on microstructures and corrosion behavior of the directional structure Ni-based coatings were investigated. The results showed that with increase of La2O3 content, the corrosion resistance of the composite coating shows the tendency of first increasing and then decreasing, and the optimum amount of La2O3 is about 1 %. The corrosion potential of Ni60/1%La2O3 composite coating is −0.697 V, which increase 0.057 V compared to −0.754 V of Ni60 coating, and the self-corrosion current density is reduced to 2.776 × 10−6 A/cm2 that is 0.053 times of 5.235 × 10−5 A/cm2 of Ni60 coating, which shows that the addition of 1 %La2O3 effectively improves the corrosion resistance of the coating. •The directional structure coatings of Ni60 and Ni60/La2O3 were prepared, respectively.•La2O3 resulted in the microstructural evolution of directional structure Ni60 coating.•Moderate amount of La2O3 can promote the growth of uniform and dense passivation film.•The corrosion resistance of coatings can be improved by controlling the addition of La2O3.