Polyurea/hydrogen-bonded reduced graphene oxide composite coating with self-repairing functions for applications of anti-cavitation and anti-corrosion

Cavitation and corrosion critically influence the behavior of offshore engineering equipment's dynamic components. To solve this problem, a polyurea coating (H-DAPU) with cavitation resistance, corrosion protection, and self-repairing capabilities based on DA bonds was successfully prepared. The coating has the triple effects of anti-cavitation, anti-corrosion, and self-repairing by adding 4-trifluoromethoxyphenyl isocyanate-functionalized reduced graphene oxide (HRGO) to the polyurea coating (soft segment molecular weight is 650 g/mol, and the content of the hard segment is 40 wt%) with the optimal mechanical properties. The excellent compatibility between HRGO and the polyurea coating increases H-DAPU's stress resistance by 8 MPa compared to the prototype. The coating's superior mechanical properties significantly enhance its anti-cavitation property. After 48 h of continuous cavitation, the mass loss of H-DAP is 6.3 mg, 37.6 % higher than that of the prototype. Additionally, the barrier effect of HRGO enables H-DAPU to have excellent corrosion protection. After 10 days of exposure to 3.5 wt% NaCl solution, the low-frequency modal value of H-DAPU is still 3.2 × 10 7  Ω·cm 2 . Finally, H-DAPU exhibited excellent photothermal healing ability, achieving 92.2 % self-repair efficiency under NIR exposure for 60 s. This research provides a new method for enhancing long-lasting corrosion protection in offshore engineering equipment's power components.