AC Impedance Evaluation Of Protective Effects Of Several Organic Coating Systems In Simulated Marine Environment

Organic coating is one of the most economical means of metal corrosion prevention.How to quickly and effectively evaluate the protective properties of organic coatings is the basis for the screening,development and application of coating systems.This work mainly use EIS to study the degradation process of different coating systems on the surface of 2A12 aluminum alloy and 304L stainless steel in the accelerated cycle of ultraviolet condensation-salt spray-low temperature exposure and the protection of ZS-922 and B72 for the surface protection of copper cultural relics The protective effect of the coating and its surface corrosion treatment and the effect of the type of copper substrate on it,Combined with equivalent circuit fitting,loss of light rate and color difference test and other means to compare and analyze the changing characteristics of the electrochemical parameters of different coating systems,The results show that the electrochemical method is a powerful tool for rapid evaluation of coating performance in the laboratory,The main conclusions are as follows:(1)Four composite coating samples for 2A12 aluminum alloy in marine atmospheric environment,After 6(42 d)cycle acceleration experiments(UV condensation-salt spray-low temperature exposure),The coatings not occurred obvious damage,Showing a good protection for the substrate.However,the low-frequency impedance values of the coated samples all decreased with the extension of the experimental time.Although all four coating systems show good protection,However,the slightly higher resistance value of the coating system is epoxy graphene heavy anti-corrosion primer as the bottom layer,The shielding performance is slightly better,This may because the coatings.have the graphene.(2)The effect of graphene heavy anticorrosion/epoxy cloud iron/fluorocarbon composite coating for aluminum alloy protection is better than graphene heavy anticorrosion/epoxy cloud iron/aspartic polyurea composite coating,This maybe due to the better aging resistance of the fluorocarbon topcoat,The performance of these two composite coatings is better than epoxy iron red/epoxy graphene/polyurethane and epoxy iron red/epoxy graphene/fluorocarbon composite coatings.This maybe related to the heavy anti-corrosion primer of graphene.(3)The four composite coatings on 304L stainless steel substrate(epoxy graphene-zinc/epoxy graphene/polyurethane,epoxy graphene-zinc/epoxy graphene/fluorocarbon,graphene heavy corrosion/(Epoxy cloud iron/fluorocarbon,graphene heavy anti-corrosion/epoxy cloud iron/aspart polyurea)are no obvious difference on this substrate.All have better shielding properties.(3)The test results on the 304L stainless steel substrate show that the four composite coatings have no obvious difference on the substrate,all data are in a relatively high order,and all samples are tested after 6 cycles No corrosion is found,and the low-frequency impedance values are also in higher values,and all have better shielding properties.(4)The protective effect of ZS-922 coating on copper materials is better than that of B72 coating,the different thicknesses Coatings,The protection performance deterioration law is basically the same,But the thicker of the coatings,have the better protective effect.The protective properties effect of BTA pretreatment on the bronze matrix on the coating is not the same,It can improve the long-term protection effect of ZS-922 coating,However,the long-term protection effect of the B72 sealing material is not obvious.(5)The material of the base material affects the Corrosion protection of ZS-922.After the substrate is treated with BTA,The long-term protection effect of ZS-922 on brass substrate is obviously worse than that of bronze and cupronickel.The substrate is not pre-treated with BTA,The protective effect of ZS-922 on bronze is obviously better than that of brass and copper.