A novel superior corrosion resistance polyimide–MXene (PI/Ti3C2Tx) composite coating for low alloy mild steel

Abstract

Two-dimensional (2D) nanomaterials such as graphene, boron nitride/white graphene, molybdenum disulfide, and MXene-based composite coatings are known to have anti-corrosion properties. However, interactions with saline environments can significantly influence the corrosion resistance behavior of the above coatings. Here, we reported MXene-polyimide based superior corrosion resistance coating on low alloy mild steel. MXene-polymer interactions serve as an efficient electron donor for the corrosion pathway, where these electrons modify oxygen-containing functional groups on MXene surfaces to generate reactive hydroxides. Therefore, the cathodic electrochemical reaction due to oxygen reduction is significantly controlled by MXene, as confirmed by the reduced cathodic slope in the Tafel polarization measurements. There is an increase in corrosion resistance of MXene-polyimide composite coating (2.58 × 10¹² Ω·cm²) compared to the pristine polyimide (1.77 × 10⁶ Ω·cm²), studied by electrochemical impedance spectroscopy using 3.5 % NaCl solution. As per the salt spray test, there is a significant enhancement in corrosion resistance of MXene-polyimide composite coating (>500 h, 5 % red rust) compared to the pure polyimide coating (240 h, 5 % red rust). The addition of MXene to the polyimide matrix improves its adhesion strength (1.63 MPa to 2.3 MPa) with steel and electrical conductivity (7.5 × 10⁻⁶ S·cm⁻¹ to 1.0 × 10⁻² S·cm⁻¹) of the composite coating.