An electrochemical and SEM study of the mechanism of formation, morphology, and composition of titanium or zirconium fluoride-based coatings

Electrochemical rest potential and cyclic voltametry were used to investigate the behaviour of the 6% Al magnesium alloy AM60 in various zirconium or titanium fluoride aqueous acid solutions. These solutions have a wide range of aggressiveness with respect to AM60 due largely to fluoride concentration and in some cases to their highly acidic nature. The morphology and composition of the resulting film have been determined by Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray spectroscopy (EDX). The film nucleation is promoted by a pH increase due to water reduction and is thus more likely to occur on the cathodic parts of the surface. Correlatively, film formation on the anodic primary solid solution occurred in only one solution.