Multi-functional AlZr-TiO2 Bilayer Coatings Combining Anticorrosion and Antifouling Properties
International Conference on Metallurgical Coatings and Thin Films, San Diego-USA, May 19-24
Fouling in marine environment is a costly problem and can be described by the development of biofilms containing various types of micro and macro organisms, which can enhance the processes and rates of steel corrosion in saline seawater. TiO2 coating shows photocatalytic activity and hydrophilic behavior which can promote antifouling properties in order to minimize the biofouling process in the marine structures. Photocatalytic oxidation is a non-toxicity low cost promising technology to control fouling in submerged surfaces by generation of reactive oxygen species . In this work we present a multi-functional coating made by an anticorrosion Al-Zr interlayer covered by an antibiofouling TiO2 top layer. Al-Zr film is proposed as a potential candidate for affording sacrificial corrosion resistance of steels since it presents a good compromise between the mechanical reinforcement and the electrochemical properties. Steel substrates were initially coated by magnetron sputtering with Al-Zr alloy (3 μm thick films) containing 5 at.% Zr. TiO2 films were deposited on the top of the Al-Zr layer by atmospheric pressure Aerosol-Chemical Vapor Deposition (AACVD). The structure and morphology of the multi-functional coatings were analyzed by XRD and SEM. Photocatalytic activity using Orange G under UV light and electrochemical tests in saline solution were performed. The biofouling behavior and performance in natural seawater were also tested by in situ immersion tests.