The morphology and corrosion resistance of electrodeposited Co-TiO2 nanocomposite coatings

Co-TiO2 nanocomposite coatings with various contents of TiO2 nanoparticles were prepared by electrodeposition in Co sulfate plating bath containing TiO2 nanoparticles. The influence of the TiO2 nanoparticles concentration in the bath, of the current density and of sodium dodecyle sulfate (SDS) as anionic surfactant on the morphology, composition, texture, roughness, and microhardness of the coatings was investigated. The morphology and composition of coatings were studied by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The phase structure of coatings was analyzed by X-ray diffraction (XRD). The results showed that the maximum codeposition of TiO2 nanoparticles in Co matrix was around 4.5?vol% obtained in 60?g/L TiO2 in the bath, 30?mA/cm2 and 0.15?g/L SDS. The microhardness of coatings was increased up to 504 Hv by increasing TiO2 concentration in the bath to 60?g/L TiO2. The electrochemistry tests including potentiodynamic polarization and impedance spectroscopy revealed that by addition of TiO2 into Co matrix, the corrosion current density, polarization resistance, and charge transfer resistance of Co-TiO2 coating were increased compared with Co coating.