Corrosion, oxidation and wear study of electro-co-deposited ZrO2-TiO2 reinforced Ni-W coatings

Abstract

The pulsed electro-co-deposition process was used on mild steel substrate to develop Ni-W based composite coating which comprises of ZrO2 and TiO2 oxide nanoparticles. In the deposition bath, plating parameters and ZrO2 content were maintained constant, whereas, TiO2 content was varied. Phase constitution, morphology, and chemistry of the coatings were examined by X-ray diffraction, field emission scanning electron microscopy and energy dispersive spectroscopy respectively. Surface-mechanical properties were evaluated by wear and microhardness test. Potentiodynamic polarization technique and electrochemical impedance spectroscopy were employed to determine the corrosion resistance of the coatings in a 3.5% NaCl solution. In addition, the isothermal oxidation test was conducted on the coatings at different temperatures (600, 700 and 800 °C) to evaluate the oxidation properties. From the experimental results, it got evidenced that microstructure, microhardness, wear, oxidation and corrosion properties of coatings significantly affected by the incorporation of ZrO2 and TiO2 nanoparticles. Under constant ZrO2 content, microhardness, corrosion and wear resistance of the coatings were significantly improved with increasing TiO2 content (0–15 g/L bath). Coatings with TiO2 addition were more beneficial as compared to the Ni-W and Ni-W-ZrO2 coatings. The oxidation resistance of Ni-W coating was improved after the dispersion of ultrafine ZrO2 and TiO2 particles in the matrix. Optimum values of hardness (963 HV0.05), corrosion resistance (Rct: 6082 ± 33 Ω·cm2) and wear resistance were achieved in the case of Ni-W-5 g/L ZrO2-15 g/L TiO2 composite coating.