Anodic Behavior of Ti in KOH Solutions Ellipsometric and Micro-Raman Spectroscopy Studies

Over the last three decades, there has been a growing interest for the use of titanium and its alloys in various branches of chemical industry, specifically in transport and stocking of aggressive fluids, electrosynthesis, photoelectrochemical activity, and solar energy conversion. The use of Ti in such wide range of applications arises due to its excellent corrosion resistance. Ti instantaneously forms a surface oxide film when exposed to the atmosphere. The excellent corrosion resistance of Ti is attributed to this spontaneous natural surface oxide film. While the film is highly resistive and is extremely stable to a wide range of contaminants, it has been shown that the natural oxide film dissolves slowly in dilute acid and alkaline solutions. The decrease in corrosion resistivity after exposure to dilute acid solutions has been attributed to the uniform dissolution of the surface oxide. 1 However, the stability of the metal in such environments can be easily restored by anodic oxidation. This attribute of Ti favors it as the material of choice for use in highly corrosive environments. Through anodic oxidation and formation of passive films, it is easily possible to prevent rapid dissolution of the underlying metal and continuously replenish the surface oxide. Further, this method is highly attractive since Ti possesses a wide potential window during which the metal remains in the passive range. Also, the large range of the passivation potentials are observed in most environments. Anodic oxidation is a well-established procedure in the case of