Corrosive Wear and Mechanical Properties of Ni/Al2O3 Micro- and Nanoparticulates-Reinforced Coatings on Ti-6Al-4V Alloy

Abstract

Nanocomposite coatings can endow a plated surface with various properties such as wear resistance, high-temperature corrosion protection, oxidation resistance, and self-lubrication. This work studies the corrosion and corrosive wear resistance of electroplated nickel nanocomposite coatings on Ti-6Al-4V alloy in a Hank's solution, adding various concentrations of an Al2O3 powder in plating solution, with particle diameters of 20–30 nm and 1 μm for comparisons. The experimental results showed that the content of Al2O3 incorporated into the electroplated nickel composite coating increased with the concentration of Al2O3 powder in the electroplating solution, and increasing the surface hardness, corrosion, and corrosive wear resistance of electroplated nickel micro- and nanocomposite coatings caused smearing of the nodule boundary and elimination of voids in the deposits. The Al2O3 nanoparticulates were embedded and distributed more uniformly than the Al2O3 microparticulates in the nickel matrix after a heat treatment of 400°C, producing a more continuous and dense coated composite layer on the Ti-6Al-4V substrate. This phenomenon is responsible for the Ni/Al2O3 composite coating with superior surface hardness, providing high corrosion resistance and corrosive wear protection to the Ti-6Al-4V alloy substrate in Hank's solution.