DL@Ti3C2Tx enhanced waterborne epoxy coating with superior active/passive anti-corrosion properties under 30 MPa hydrostatic pressure

Abstract

It is challenging for organic coatings with solely physical barrier property to achieve long-term corrosion protection on metal equipment, especially in harsh deep sea environments. Here, we utilized DL-phenylalanine to modify Ti₃C₂T_x nanosheets via noncovalent interaction to obtain DL@Ti₃C₂T_x hybrid additives, which significantly improved the corrosion protection ability of epoxy coating (EP). The impedance modulus of DL@Ti₃C₂T_x/EP composite coating with a thickness of 50 μm was two orders of magnitude higher than that of pure EP after 240 h immersion under 30 MPa hydrostatic pressure. The adhesion strength of DL@Ti₃C₂T_x/EP composite coating remained at a favorable value of 1.84 MPa after long-term immersion in a harsh environment, which was twice as high as that of pure EP coating. In addition, the active corrosion resistance property of DL@Ti₃C₂T_x/EP coating was investigated via the local electrochemical impedance spectroscopy (LEIS) measurement. The improved protection ability of DL@Ti₃C₂T_x/EP was benefited from the synergistic effects of the superior physical barrier property of Ti₃C₂T_x nanosheets and the self-healing feature provided by DL molecules. The corrosion protection and failure mechanisms of composite coating were discussed in detail, supplying broader platforms for constructing active/passive integrated anti-corrosion coatings in harsh deep sea environments.