Alternating current anodizing of titanium in halogen acids combined with Anodic Spark Deposition: Morphological and structural variations

The identification of anodic processes able to generate high surface area TiO2 layers is a key requirement, whenever applications focused on its photoactivity or the integration between titanium implants and human body are considered. To achieve this goal, this research proposes an innovative two-step anodizing procedure. The first step consists of supplying alternating current to titanium in halogen acid electrolyte which quickly modifies its morphology. HCl and HBr were found to roughen effectively the metal surface, thus increasing its surface area. The successive step, an Anodic Spark Deposition treatment, generates a thick, semicrystalline oxide, containing both anatase and rutile crystals.