Investigation of the photo-catalytic coating on AZ91 alloy

A TiO2 thin film was deposited on AZ91 alloy to enhance the corrosion–resistance and photo-catalytic properties. Experimental results showed that the TiO2-coated AZ91 exhibited hydrophilicity. The corrosion potential of TiO2-deposited AZ91 was higher than that of the uncoated AZ91, suggesting an increase in the intrinsic corrosion resistance. Compared with the uncoated samples, the corrosion resistance of TiO2-deposited samples, on the other hand, deteriorated. FE-SEM observation showed polycrystalline characteristics as well as the presence of pinholes on the film. EDS analysis revealed the pinholes to be locales of incomplete deposition, where accelerated corrosion occurred.