Corrosion behavior amelioration of Ti-based alloys by the hybrid plasma electrolytic oxidation (PEO)/polymer coatings: A review

Abstract

Ti and Ti-based alloys are increasingly employed as components for various industrial applications, both structural and functional. Forming coatings is one of the potentially highly effective methods to shield products from adverse environmental effects. Among the numerous techniques for forming coatings on Ti and Ti-based alloys, plasma electrolytic oxidation (PEO) stands out. Coatings produced through PEO exhibit high resistance to corrosion, substantial resistance to wear, and strong adhesion to the substrate, which is attributed to the formation of chemical bonds between the underlying material and the coating. Conversely, PEO coatings may not provide sufficient protection for titanium alloys due to the presence of porosity and fine cracks. Establishing an organic film on the PEO coating surface is a potent strategy to seal the defects, thereby inhibiting the intrusion of corrosive elements into the substrate. Applying a polymer layer to the PEO coating could be an effective approach to manage the extent of damage and enhance the resistance to corrosion. This article reviews the latest developments in PEO/polymer composite coatings and investigates the corrosion characteristics of these coatings.

Keywords

• Titanium and its alloy
• Corrosion behavior
• PEO process
• Polymer coating