Effect of V doping on phase composition and corrosion resistance of laser cladding Ni60AA coatings

Abstract

In this study, the Ni60AA-V composite coating was successfully fabricated by laser cladding technology. The effects of vanadium (V) doping on the phase composition and corrosion behavior of the Ni60AA coating were systematically analyzed. The results show that V is multifunctional in enhancing the coating. Firstly, V can modulate the phase composition of Ni60AA, promoting the generation of the in situ VB phase and inhibiting the formation of other phases. At the same time, the VB phase can and does act as a heterogeneous nucleation site to refine the grains and promote the uniform distribution of Cr elements. Secondly, V can significantly improve the corrosion resistance of Ni60AA. In electrochemical testing, Ni60AA-V coatings exhibit higher self-corrosion potential, smaller self-corrosion current density, and higher electrical resistance. Thirdly, V can enhance the protective properties of the oxide film of the Ni60AA coating. According to potentiostatic polarization curves and Mott-Schottky and XPS analyses, V can increase the growth rate and stability of the oxide film, reduce the oxide film defects, and at the same time send the formation of more oxidation products and less Ni(OH)₂ in the Ni60AA coating. In summary, it is shown that the V element can enhance the corrosion resistance of Ni60AA coatings and provide a more novel approach for designing Ni60AA materials with superior corrosion resistance.