Electrodeposition and Investigation of Corrosion Resistance of Ni-W-P/SiO2 Nanocomposite Coatings

In this study, the nanocomposite coatings of Ni-W-P/SiO2 were produced by electrochemical co-deposition of SiO2 nanoparticles with Ni-W-P alloy in solutions with different amounts of these nanoparticles on the copper surface. The composition and structure of the coatings were studied with Field Emission Scanning Electron Microscopy (FE-SEM) and Energy Dispersive Spectroscopy (EDS). The results showed that the incorporation of SiO2 particles in the Ni-W-P/SiO2 composite coatings increases the surface uniformity and smoothness of the coating. The open circuit potential (OCP), electrochemical Impedance (EIS) and potentiodynamic polarization (Tafel) techniques were used to evaluate the corrosion resistance of the coatings in 3.5% NaCl solution. The corrosion results showed that the Ni-W-P/SiO2 nanocomposite coatings were much higher corrosion resistance than pure Ni-W-P coating. By adding SiO2 nanoparticles to the solution, first the corrosion resistance increases and then decreases due to the agglomeration of the nanoparticles. The highest corrosion resistance was obtained for the synthesized composite coating from a solution containing 9 g/L SiO2 nanoparticles. The main reasons for the high corrosion resistance of this coating are the maximum amount of SiO2 reinforcing particles in metal matrix, nanometer structure without surface defects and micro-cracks.