Total Specific Energy as a New Figure of Merit for the Design of Porous TiO2 Surfaces Synthesized via Plasma Electrolytic Oxidation

The plasma electrolytic oxidation (PEO) is a variation of the anodic oxidation technique, one of the simplest and most economical methods to obtain crystalline and porous TiO2 coatings. Beyond the conventional approach of establishing a relationship between the variables of synthesis and the character-istics of the TiO2 coatings, a new figure of merit was defined in the present work for the synthesis of TiO2 coatings by PEO: the total energy per unit of surface (TSE). A strong relationship was found between TSE and the TiO2 anatase fraction. The application of TSE, together with the known influence of the variables of synthesis on the coating characteristics, allows a prediction, previously to the anodization and with reasonable precision, of the anatase fraction and the pore diameter of the coating. Applying the TSE new concept, three coatings were successfully designed. This is the first step toward a surface design using the PEO technique.