Repellent and self-healing modified siliceous hybrid material as conversion layers for protection application of steel

A novel coating system of epoxy matrix containing aniline trimer modified silica conversion layer was prepared on Q235 steel surface. The conversion layer was obtained by electrodeposition on the basis of precursor solution, which contained ethyl silicate and modificatory aniline trimer (MAT). Hydrophobicity, electroactivity and corrosion resistance of as-prepared coating systems were detected. Result showed that the as-prepared MAT-including silica conversion layer (M-SiO2) presented a super-hydrophobicity and excellent electroactivity. Meanwhile, the novel coating system displayed a stronger adhesion force compared with single epoxy coating and silica/epoxy coating system. By electrochemical impedance spectrum and salt spray test, the protective capability of epoxy matrix was largely improved by the coverage of electroactive M-SiO2 conversion layer. This was attributed to the forceful hydrophobicity and self-healing ability of conversion layer. The synergistic effect of above-mention two functions promoted the perfection of corrosion performance for as-prepared novel coating system.