Achieving dual functional corrosion resistance for epoxy coatings under alternating hydrostatic pressure via constructing P-phenylenediamine/Ti3C2Tx hybrids

Abstract

In the deep-sea environment, it is difficult to enhance the anti-corrosion properties of a metal substrate of epoxy coating (EP) on Ti3C2Tx nanosheets by a single physical barrier mechanism. Thus, to reduce the corrosion on the metal surface, Ti3C2Tx-embodying epoxy coatings with superior barrier performance along with self-healing function can be quite desirable. In this study, p-phenylenediamine (PPD) functionalized Ti3C2Tx was synthesized, and then PPD-Ti3C2Tx nanohybrids used as filler to engraft the epoxy coating using superior physical barrier along with self-healing ability. This anti-corrosion property of PPD-Ti3C2Tx/EP coating was investigated by the electrochemistry test in the saline solution (NaCl, 3.5 wt %). The cross-sectional structure of the compound coating confirmed that 0.5PPD-Ti3C2Tx significantly enhanced the tightness of EP coating, and the adhesion intensity of the 0.5PPD-Ti3C2Tx/EP coating was four times than that of the blank epoxy coating after immersing for 10 days by alternating hydrostatic pressure (AHP). The impedance modulus of 0.5PPD-Ti3C2Tx was four orders of magnitude higher than that of absolute epoxy coating after 10 days of immersing in AHP, which was attributed to the effective shielding performances of well-dispersed PPD-Ti3C2Tx and self-healing ability of PPD inhibitor. The analysis of corrosion products clarified that PPD could facilitate formation of passive film consisting of Fe2O3 along with Fe3O4, indicating superior self-healing capacity.