Enhancing cathodic protection and barrier properties of zinc-rich epoxy coatings with mesoporous Ti₄O₇ additive

Searching for an optimal material additive that can enhance both the cathodic protection and barrier properties of zinc-rich epoxy coatings (ZRE) simultaneously remains a significant challenge nowadays. In this study, mesoporous Ti4O7 particles with high conductivity and chemical inertness were synthesised via the thermal reduction method and added to ZRE coating. The impact of different Ti4O7 filler contents on the corrosion resistance of ZRE coating containing 70 wt% zinc was assessed by electrochemical analysis, water uptake measurements, salt spray test and material characterisation techniques. The results demonstrated that the incorporation of mesoporous Ti4O7 significantly enhances the initial cathodic protection and long-term barrier properties of ZRE. The primary mechanism involves the conductive Ti4O7 ameliorating the Zn isolation caused by non-conductive Zn corrosion products and fostering a more efficient network for conductive penetration between zinc particles to improve cathodic protection efficacy. Moreover, mesoporous Ti4O7 promotes the uniform deposition and growth of ZnO/Zn(OH)(2) by adsorption and anchoring of Zn(OH)(4)(2-) and changes the shape of the corrosion product (columnar), thus improving the barrier performance of ZRE coating.