Formation and surface characterization of nanostructured Al₂O₃-TiO₂ coatings

Abstract

One pot synthesis of Al₂O₃-TiO₂ nanoceramic coatings from environment-friendly potassium titanium oxalate (PTO) electrolyte using facile electrochemical anodization has been reported for the first time. Systematic analysis of the anodization parameters such as applied current density and concentration of the PTO electrolyte influence on the morphology of the ceramic coatings was done. The textural properties of the coatings (thickness, growth rate, coating ratio) showed a linear regime with current density and electrolyte concentration decreases up to a certain level and then decreases. The growth process, distribution of chemical elements, phase constitutions and corrosion resistance of the coatings were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Tafel polarization technique and electrochemical impedance spectroscopy (EIS). The relation between the corrosion resistivity of the anodic coating and the aforementioned anodization parameters is investigated. The mechanisms that are involved in the formation of the ceramic coatings are also discussed. The coatings formed from 30 g/L concentration of PTO and 0.02 A/cm² current density show good morphology, textural properties and optimum corrosion resistance.