High-temperature corrosion in marine environments demands advanced protective coatings. Inspired by spider silks and mussels, a mechanically tough, high adhesion and healable polyurethane composite coating (PU-FM) was developed. Specifically, a chain extender (FA-FGE diol) rich in multiple Diels-Alder (DA) furan rings was developed to determine the optimal PU matrix, combined with 1 wt% dopamine-modified multi-walled carbon nanotubes. The abundant DA bonds not only provide thermal stability and compactness of the polymer chain for high-temperature anti-corrosion, but also support the compatibility of self-healing properties. PU-FM exhibited outstanding mechanical properties, with a high toughness of 356MJ·m −3 , strength of 72 MPa, and adhesion of 16.2 MPa. After 60 h of cavitation, average corrosion depths of PU-FM were only 3.4 nm (20℃) and 8.4n m (80℃). The |Z| 0.01Hz values of PU-FM maintained 1.111 × 10 9 Ω·cm 2 (20℃) and 7.361 × 10 7 Ω·cm 2 (80℃) after exposed to 3.5 wt% NaCl solutions for 30 d. Moreover, PU-FM also demonstrated 93 % self-healing efficiency under near-infrared light for 90 s, retaining 81 % after three cycles. This approach, combining DA bond-rich chain extenders with nanofiller reinforcement, offers a novel solution for high-temperature anti-corrosion and self-healing coatings, addressing critical challenges in marine and industrial applications.
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.
In order to study whether silica will become a weak point of cavitation of silicone coating and which of the surface roughness , elongation, elastic modulus and hardness has a greater impact on cavitation, composite coatings composed of silicate, polyurethane and silicone coating with different surface roughness, elongation, elastic modulus and hardness containing silica were prepared. The morphology, composition and performance of the composite coatings before and after cavitation were characterized by confocal laser scanning microscope (CLSM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and weight loss. The results showed that cavitation damage mainly occurs in the silicone polymer matrix rather than the silica reinforced powder. Enlarging the elongation, elastic modulus and hardness of polyurethane coating can improve the cavitation resistance of the composite coatings. The cavitation resistance of composite coatings is closely related to their surface roughness.
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