Electrodeposition and wear behavior of NiCoW ternary alloy coatings reinforced by Al2O3 nanoparticles: Influence of current density and electrolyte composition

Al2O3 nanoparticles incorporated NiCoW ternary alloy coatings were synthesized by direct current electrode-position from sulphate-citrate electrolyte. The influence of applied current density and electrolyte composition on the evolution of surface morphology, element composition, microstructure, microhardness and sliding wear behavior of the as-deposited coatings was investigated. The as-deposited coatings exhibit colony surface morphology and the inter-colony boundaries lead a leaf vein-like cross-sectional structure. The composition of the as-deposited coatings is controlled by the induced co-deposition mechanism and the competition among the reductions of Ni, Co, Ni-W and Co-W. The as-deposited coatings change from crystalline to amorphous structure with the decrease of Ni content in coatings and the critical Ni content for the transformation is about 40 at.%. The incorporation of Al2O3 nanoparticles leads to a little increase of microhardness, degrades adhesive wear and oxidation wear, then significantly improve wear resistance. Variations in electrodeposition conditions lead the as-deposited coatings with different wear behavior, including abrasive wear, adhesive wear and oxidation wear, accompanying with plastic deformation. An attempt is made to establish the relationship between the electro-deposition conditions and wear behavior.