Aqueous sol–gel synthesis and film deposition methods for the large-scale manufacture of coated steel with self-cleaning properties

A process has been developed to enable the large-scale production of pure TiO2 films deposited on 316L stainless steel in order to get an easy-to-clean surface. This large-scale process requires an easy aqueous sol–gel procedure for the synthesis of the TiO2 sol. This synthesis has been simplified to facilitate the extrapolation toward an industrial scale. Results of TEM, photocatalytic properties, film hydrophilicity and texture obtained with the simplified aqueous sol–gel synthesis (IsoP–TiO2 synthesis) show similar properties to those obtained with the standard aqueous sol–gel synthesis of TiO2 (HAc–TiO2 synthesis) developed previously. Only, X-ray diffraction patterns showed differences, with the presence of anatase-brookite phases in IsoP–TiO2 synthesis while anatase phase only was observed in HAc–TiO2 synthesis. Both the aqueous sol–gel synthesis of pure TiO2 and the film deposition on steel by roll-coating have been successfully extrapolated to a larger scale. The photocatalytic activity and the hydrophilicity of the film were found to be unchanged when compared to films produced at a laboratory scale, thus validating the production of an efficient easy-to-clean material. Although some problems are still to be solved, this study is a hopeful first step in the development of a large-scale process for self-cleaning steel production.