Effect of sodium lignosulfonate as an additive in enhancing the corrosion and tribocorrosion behavior of micro-arc oxidation coatings on titanium alloy

A corrosion and wear resistant coating was developed on the surface of titanium alloy using micro-arc oxidation (MAO) technology with addition of lignin sulfonate (SLS) as an additive in electrolytes containing 15 g/L of Na 2 SiO 3 ·9H 2 O and 10 g/L of Na 3 PO 4 ·12H 2 O. The effects of concentration of SLS on the surface morphology, microstructure, and corrosion-wear performance of the MAO coatings were systematically investigated. Wetting properties and mechanical characteristics of MAO coatings were determined by contact angle measurements, microhardness testing, and bonding strength assessments. The corrosion resistance of the MAO coating in artificial saliva media was assessed through electrochemical testing, while its tribological and corrosion-wear performance was evaluated via dry friction tests and corrosion-wear tests, respectively. Experimental results indicate that the incorporation of lignin sulfonate as the electrolyte additive enhances pore filling within the coating matrix while improving both mechanical properties and corrosion resistance. Notably, MAO coatings with a concentration of 1 g/L exhibited superior mechanical properties; furthermore, their corrosion current density decreased by one to three orders of magnitude compared to that of the TC4 substrate.