Improvement of nickel nanocomposite coatings by combining zinc-doped TiO2 nanoparticles

Pure nickel and compound of nickel coatings (Ni-TiO2 and Ni-Zn/TiO2) were coated on the steel material using Watts bath with the electrodeposition conditions. Effect of the nanoparticle type and current density on the coating structure, surface morphology of the coating, hardness of the coating, and the corrosion properties of the coatings are presented. Phase and elemental analysis of the coatings were carried out by XRD and EDS techniques, respectively. SEM was used to investigate the surface morphology of the coatings, and Vickers microhardness values were measured to determine the hardness variation of the coatings. NaCl solution (3.5 wt%) was used to evaluate the corrosion properties of the coatings by the potentiodynamic polarization tests. Corrosion current density of 2.890 mu A/cm(2) for pure nickel coating was improved to 0.379 mu A/cm(2) by the coating of Zn-doped TiO2 nanoparticles at the 7A/dm(2) current density. Microhardness of the Zn-doped TiO2 coating was improved compared to the pure Ni coating.