Corrosion resistance of nano TiO2/La2O3 composite coatings with high toughness

• A gas-automizing and thermal spraying technology was adopted to get nano TiO 2 /La 2 O 3 coatings. • The corrosion rate is obviously decreased in artificial seawater and sulfate-reducing bacteria solution. • The composite coatings had long-period stability in the marine environment. The thermal spraying nano TiO 2 /La 2 O 3 composite coatings with high corrosion resistance and toughness were obtained in the present study. Compared with micro-size TiO 2 ceramic coatings, the properties of the nano composite coatings were improved observably. An 83.75 % and a 69.57 % decrease in the corrosion rate in artificial seawater and Sulfate-Reducing Bacteria (SRB) solution were gained, respectively. Meanwhile, the corrosion process was investigated by Electrochemical Impedance Spectroscopy (EIS) for 31 d. The corrosion morphologies and corrosion products were tested by Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). The results indicated that the nano coatings were stable in both seawater and SRB solution, and no significant changes were observed on the surface of the coatings after immersion. Meanwhile, the biofilms formed on the surface of the composite coating in the SRB solution resulted in a further improvement in corrosion resistance.