Effect of heating self-healing and construction of composite structure on corrosion resistance of superhydrophobic phosphate ceramic coating in long-term water environment

Despite superhydrophobic ceramic coatings have been successfully prepared, there lacks an improvement in their corrosion resistance in long-term saltwater environments due to the porous properties. In this paper, two coatings were prepared again by heat repair treatment and construction of double-layer composite structure, and the surface characteristics of the coatings were determined by scanning electron microscope, infrared spectrometer and contact angle measuring instrument, and the electrochemical performance and corrosion resistance of the coatings were evaluated by electrochemical test and immersion test. The results showed that the original porous ceramic coating had superhydrophobic property, and the water contact angle (CA) and sliding angle (SA) were 150.4 degrees and 8.7 degrees, respectively. Through knife scratching, sandpaper abrasion and tape peeling tests, the coating had good bond strength and mechanical durability. Compared with the original coating, the corrosion resistance of heat repair coating and composite coating had better corrosion resistance and a protective effect on the substrate. This protective mechanism can be attributed to the repair effect of heat treatment on the hydrophobicity of the coating, and the composite structure resists the penetration of external liquids. Based on these results, heat repair and double-layer composite structures can improve the defects of long-term insufficient durability of superhydrophobic ceramic coatings, which have potential marine application prospects.