A Study of Dark TiO2 Coating on Pure Titanium By Micro Arc Oxidation

Abstract

Dark TiO2 coatings on Titanium have attracted scientific interest due to their extensive applications such as decorative architectures and optical equipment for solar collectors. Several methods have been reported to prepare successfully the dark TiO2 coatings, such as conventional anodizing, cathodic polarizing, and micro arc oxidation (MAO). It is well known that MAO is a new technique for generating surface oxide coatings on valve metals and alloys, including Titanium, Aluminum and Magnesium. Actually, MAO technique has several advantages for surface coating, such as strong adhesion, high hardness, superior wear and corrosion resistance. However, the dark TiO2 coatings on Titanium prepared by MAO are still seldom reported. The present study investigated the dark TiO2 coating on pure Titanium by MAO technique. For the MAO process, a bipolar pulsed power supply with appropriate electrical parameters, and a phosphate-based electrolyte with vanadium compound as colorant were used. Experimental results indicated the MAO coatings on pure Titanium are mainly composed of TiO2. These MAO coatings exhibit homogeneous dark color and good surface protection, including the corrosion and wear resistance. In this study, the effects of electrical parameters and various electrolytes on the dark TiO2 coatings will also be systematically discussed, including the surface morphology, microstructure and property of wear and corrosion resistance.