Study on the Microstructure, Phase Composition, Corrosion Resistance and Mechanical Properties of Selective Plated Nanocomposite Nickel Coatings with Embedded TiO2

Abstract

Nickel and Ni-TiO₂ nanocomposite coatings were deposited on nickel-aluminium bronze by selective electrochemical deposition. TiO₂ nanoparticles below 100 nm were added to a commercial nickel electrolyte to obtain a Ni-TiO₂ composite coating, which was compared with a pure Ni coating. The morphology, phase composition, surface roughness, Vickers microhardness and corrosion behaviour of the coatings were investigated. The Ni-TiO₂ coating showed a compact morphology without defects visible at the optical-microscopy scale. The incorporation of TiO₂ reduced the surface roughness and increased the microhardness from 196 to 215 HV0.2. X-ray diffraction confirmed an fcc Ni matrix and low-intensity reflections attributed to TiO2. Potentiodynamic polarization in 3.5 wt.% NaCl solution showed a more noble corrosion potential, lower corrosion current density and lower corrosion rate for the Ni-TiO₂ coating. The results indicate that selective plating can produce compact Ni-TiO₂ nanocomposite coatings with improved surface, mechanical and corrosion properties for potential marine applications.