Influence of steel composition and pre-treatment conditions on morphology and microstructure of TiO2 mesoporous layers produced by dip coating on steel substrates

Mesoporous titania films were prepared by template-assisted dip coating on AISI 430, 304 and 316Ti steel substrates that underwent different pre-treatment, namely grinding, grinding–calcination and grinding–etching. The influence of steel grade and pre-treatment conditions on the film morphology and microstructure was studied, and reasons for film degradation were elucidated. Among tested steels, 430 interfered with the coating process the most yielding films of poor integrity and with a strongly distorted pore structure. Steels 304 and 316Ti showed better resistance to the precursor solution, resulting in less fractured films and defined pore morphology. Grinding and subsequent calcination proved to be the best choice among tested pre-treatment methods which reflected in improved film quality. The results show that only a proper combination of steel grade and substrate pre-treatment affords high-quality titania coatings with defined porosity.