Preparation of Amination g‐ C 3 N 4 and Enhanced Mechanism on UV Aging Resistance of WEP Coatings

ABSTRACT Waterborne epoxy resin (WEP) coatings are widely used for metal protection, but the microcracks and micropores lead to corrosive media penetration. This study prepared aminated g‐C 3 N 4 (ACN) via ultrasonic dispersion‐assisted ammonia treatment. The prepared samples were characterized by XRD, FTIR, SEM, tensile testing, UV aging tests, and electrochemical measurements. Results showed that amino groups were successfully introduced into g‐C 3 N 4 and ACN formed stable chemical bonds with WEP, reducing the microcracks and micropores in WEP coatings. The 2‐ACN/WEP (2% ACN in composite emulsions) exhibited excellent performance on tensile strength (14.8 MPa), which enhanced 131.2% compared with that of pure WEP (6.4 MPa). After 30 min UV aging, the elongation at break only decreased about 24.8% and no obvious corrosion spots in the 720 h neutral salt spray test. The corrosion current density of 2‐ACN/WEP was 5.37 × 10 −11 A·cm −2 and low‐frequency impedance modulus was 9.530 × 10 9 Ω·cm 2 , which was increased about 3 orders than that of WEP. This study provides a reliable approach to improve anti‐corrosion and anti‐UV aging properties of WEP coatings, supporting the development of high‐performance green anti‐corrosive coatings.