Improvement of Corrosion and Wear Resistance of Ni-W Coatings by Embedding Graphene Oxide Modified by Nano-Al2O3.

Graphene oxide (GO) easily aggregates due to the cross-linking between divalent cations in the plating baths, and the presence of reduced GO in metal coatings promotes corrosion. This paper aims to improve the corrosion and wear resistance of Ni-W coatings by embedding graphene oxide modified with nano-Al₂O₃ nanoparticles (Al₂O₃@GO). Carboxylic acid groups were removed to eliminate cross-linking with divalent cations. Moreover, the increased number of hydroxyl groups ensured that Al₂O₃@GO was highly dispersed in the plating bath. Then, Ni-W-Al₂O₃@GO coatings were fabricated by pulse electrodeposition with different Al₂O₃@GO concentrations in the plating solution. The grain refinement, low number of defects, and low conductivity (1.31 Sm⁻¹) of the reduced Al₂O₃@GO in the coating gave it anti-corrosion properties. The coating with 1 g L⁻¹ of GO addition (Icorr = 0.195 μA) displayed better corrosion and wear resistance properties than Ni-W coating (Icorr = 6.66 μA), Ni-W-GO coating (Icorr = 0.706 μA), and other Ni-W-Al₂O₃@GO coatings. The uniform distribution of Al₂O₃@GO in the coatings allowed it to serve as a physical barrier which eliminated electron pathways and prevented the infiltration of corrosive media. Moreover, the self-lubrication and similar "rolling" of Al₂O₃@GO increased the wear resistance of the coatings. [ABSTRACT FROM AUTHOR]