Photocatalystic Cathodic Protection of TiO₂ Coating on AZ31 Magnesium Alloy

Abstract

Nano TiO2and S, N co-doped TiO2composite coatings with WO3transitional layer were deposited on AZ31 magnesium alloy by sol-gel method. The morphologies, structure, mechanical properties, compositional depth profiles and anti-corrosion performance of the as prepared coatings were characterized by scanning electron microscope, X-ray diffraction, nanoscratch test, glowing discharge optical emission spectrometry and electrochemical method, respectively. The results show that the nano TiO2coatings are continuous, uniform and dense with thickness ca.3-5μm, elements in the interface diffuse mutually during heat treatment; S-N co-doped TiO2enhances the interface adhesion, WO3transitional layer increases the total coating thickness and strengthens the adhesion to substrate with respect to unitary TiO2coating; S, N co-doped TiO2acts as visible light photocatalyst that can provide permanent cathodic protection for AZ31 magnesium using WO3as electron restoring material.