Hard and corrosion resistant nanocomposite coating for Al alloy

Ni-TiO2 nanocomposite coatings were prepared by codeposition of Ni and nanoparticles of TiO2 powder onto surface of Al alloy. The influences of the TiO2 nano-particulates concentration and current density on the composition of nanocomposite coatings were investigated. The chemical composition and phase structure of coatings were studied by X-ray diffractometer (XRD) and energy dispersive X-ray system (EDX). The microhardness and erosive wear measurements (in 40 wt.% sand slurry) for pure Ni and Ni-TiO2 composite coatings were evaluated. The corrosion behavior of Ni and Ni-TiO2 nanocomposite coatings was studied by the anodic polarization curves in 3.5% NaCl solution at room temperature. Ni-TiO2 composite coatings exhibited higher corrosion resistances in comparison with pure Ni coating. The morphologies of the coated, eroded and corroded surfaces of pure Ni and Ni-TiO2 Composite coatings were observed using SEM. The results reveal TiO2 nanparticles were uniformly distributed into Ni matrix and significantly improve the microhardness and erosion wear properties of the Ni coating. (C) 2007 Elsevier B.V. All rights reserved.