Co-ZrO2 electrodeposited composite coatings exhibiting improved micro hardness and corrosion behavior in simulating body fluid solution

The aim of this work was the deposition of zirconium oxide bioceramic particles in cobalt matrix within the research work aimed at obtaining metal matrix composite coatings (MMC) under direct current and the evaluation of their protective properties. The cobalt/zirconia micro structured composite coating containing bioceramic of ZrO2 dispersed phase was prepared using direct current (DC) electrodeposition method. The surface morphology, cross section and anti-corrosion property in SBF solution of the obtained Co/ZrO2 composite films, are characterized using optical microscopy, scanning electron microscopy (SEM) together with energy dispersive spectroscopy (EDS) system, atomic force microscopy (AFM), ultrahigh-micro-topography, linear polarization and electrochemical impedance spectroscopy (EIS) techniques. The results indicate that, ZrO2 particles are uniformly dispersed into Co matrix and influence the surface microtopography, microhardness and corrosion behavior of composite coatings obtained. Coating thickness increases with increased current density as well as the surface roughness and microhardness. At the same time, the results obtained by polarization curves and EIS methods show that, when compared with the traditional polycrystalline Co film, the obtained Co/ZrO2 composite film exhibits the enhanced corrosion resistance in SBF solution.

Research highlights
► Electrolytic deposition of Co–ZrO2 composite coatings on steel support.
► Improving microhardness and corrosion resistance of Co-ZrO2 composite coatings in SBF solution.
► Correlation of coating thickness with applied current density.
► Uniform distribution of ZrO2 oxide in Co matrix and well bonded composite layer to substrate.
► Comparative surface microtopography and microhardness of Co/ZrO2 and pure Co layers.