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-Al 2 O 3 nanoparticles (Al 2 O 3 @GO). Carboxylic acid groups were removed to eliminate cross-linking with divalent cations. Moreover, the increased number of hydroxyl groups ensured that Al 2 O 3 @GO was highly dispersed in the plating bath. Then, Ni-W-Al 2 O 3 @GO coatings were fabricated by pulse electrodeposition with different Al 2 O 3 @GO concentrations in the plating solution. The grain refinement, low number of defects, and low conductivity (1.31 Sm −1 ) of the reduced Al 2 O 3 @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-Al 2 O 3 @GO coatings. The uniform distribution of Al 2 O 3 @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 Al 2 O 3 @GO increased the wear resistance of the coatings.