The Influence Of The Modified Interface Between SiO₂ And Epoxy On The Corrosion Resistance Of Coating In NaC1 Solution Environment

The research focuses on the effect of different interfaces, include physical bongding and chemical bonding, between SiO2 and epoxy in the process of coating failure under marine environment. Three research systems have been chosen:varnish, SiO2 epoxy and modified SiO2 epoxy polyamide coating. According to the actual marine environment, two research pressure environment have been studied; atmospheric pressure and high hydrostatic pressure. The failure processes of the three coatings have been studied by electrochemical impedance spectroscopy (EIS), quality test, coating adhesion test and the mechanical properity of coating itself. The effect and mechanism of different interface between the SiO2/epoxy on failure process has been discussed in the paper.In surface seawater enviroment, the chemical modified interface mainly improve the defect and chemical matching of the SiO2/epoxy to increase the compactability of coatings, as well as inhibit the aqueous solution from accumulating in the SiO2/epoxy interface and improve the blocking ability of coatings. Meanwhile, the improvement of blocking properity relieves the corrosion process of metal matrix, and then increasees the adhesion of the coating. Both the increase of blocking and improvement of adhesion properity delay the coating failure process and enhance the protective ability of coatings.In deep-sea enviroment, the coating failure process is accelerated under hydrostatic pressure, and the stronge effect under hydrostatic pressure is more materialized in the transmission process. Hydrostatic pressure didn't change the diffusion of aqueous solution in the coatings and the diffusion is still in accordance with the Fick diffusion. However, diffusion rate of the aqueous solution in the coatings is accelerated under hydrostatic pressure. Meanwhile the corrosion reaction rate of metal matrix is increased under hydrostatic pressure. The lose rate of wet adhesion of the coating is faster under hydrostatic pressure than normal pressure. The coating failure process is accelerated due to the acceleration of the diffusion process of the aqueous solution and exacerbation of the reaction between the coating/metal interface.In deep-sea enviroment, the traditional physical bonding interface between SiO2/epoxy increases the defects among coating. It Makes the diffusion rate of aqueous solution accelerate significantly. The decrease of coating blocking ability effect the protective ability of coating. However, the chemical modified interface can effectively improve interfacial properties, such as physical defects and chemical properties. Thus, the enhancement of coating blocking ability improve the protective ability of coating.