Wear-Corrosion Properties of Ni/Al2O3 Nano-composite Coatings Electrodeposited on Ti-6Al-4V Alloy

摘要

Nano-composite coatings can give various properties such as wear resistance, hightemperature corrosion protection, oxidation resistance and self-lubrication, to a plated surface. The purpose of this study is to investigate the corrosion and wear-corrosion resistance of electrodeposited nickel nano-composite coatings on Ti-6Al-4V alloy containing Al2O3 powder additive of diameter 20～30nm and diameter 1μm for comparison, and using various concentrations of Al2O3. Surface morphologies, element compositions and surface hardness of the composite coatings are analyzed by scanning electron microscopy (SEM), X-ray energy dispersive analyzer (EDS) and nano-indentation testing system. Electrochemical polarization measurements are performed for analyzing corrosion characteristics, using the block-on-ring surface friction manner to evaluate the wear-corrosion resistance of the composite coatings in a Hank's solution of simulated human body. The experimental results indicated that the content of Al2O3 incorporation in electroplating nickel composite coating increases with increasing concentration of Al2O3 powder in the electroplating solution, and increasing the hardness, corrosion and wear-corrosion resistance of electroplating nickel micro- and nano-composite coatings in accordance with resulting in a smearing of nodule boundary and void elimination in the deposits. While increasing to the concentration of 20g/L Al2O3 the electrodeposited nickel nanocomposite coating exhibits a highest hardness of 6.719 Gpa and a lowest corrosion current density of 9.71×10-8 A/cm2 and does not show any significant wear-corrosion failure phenomena.