Corrosion Failure Of Organic Coating Protective Systems In Simulated Plateau Atmosphere Environment

Organic coating protection systems,which are the most convenient,most economical and most practical way than others,are widely used to protect metallic materials from corrosion in industrial fields.In the atmospheric environment,organic coatings are often subjected to the interaction among multiple environmental factors and are degraded.In order to research the effects of main environment corrosion factors on organic coating protection systems,an accelerated test was used to study the corrosion failure process and mechanism of an organic coating protection system.This has great significance to develop corrosion-resistant coating and to predict the service life of the organic coating protection systems.In this paper,the failure process of 50 kinds of organic coating protection system in simulated plateau environment was studied,which is equivalent to 8 years of natural exposure.The effects of surface treatment process and different organic coatings on the failure process of coated aluminum alloy,coated titanium alloy and coated alloy steel were first investigated.And then,the weight coefficient of each failure mode was determined by comprehensive integration weighting method.The comprehensive evaluation model of organic coating protection system was established by linearly weighted method and verified by electrochemical impedance spectroscopy fitting on EIS.Finally,the synergistic mechanism between UV radiation and wet-dry corrosion was studied based on EIS,SEM,and FITR.The results show that the surface treatment has an obvious effect on coated aluminum alloy protection system.the surface treatment method(Y2)is better than(Y1),the performance of organic coating(H2)is better than organic coating(Hl)and(H3),organic coating(H1)performed same as organic coating(H3).Similarly,coated titanium alloy protection system,the surface treatment method(Y3)is better than(D3).For coated,the performance of organic coating(H2)is better than organic coating(HI),and organic coating(H1)is better than(H3).Coated steel alloy protection system,the performance of organic coating(H2)and(H3)are better than organic coating(H1).In a word,organic coating(H2)is the best on among thee organic coating.Based on the failure modes of the organic coating protection system in simulated atmospheric environment,these failure modes in accordance with the impact degree of each failure mode was established to calculate the weight coefficient.For each failure mode,the comprehensive evaluation model for organic coating protection system of corrosion level was established by linear weighting method and was verified by electrochemical impedance spectroscopy fitting on EIS.At the same time,50 kinds of organic coating systems were evaluated by the comprehensive evaluation model after accelerated test.T1D3H1 coating system remained well after it was subject to wet-dry exposure test.Under the UV radiation condition,the surface of the T1D3H1 coating system showed slight blister.However,under the interaction of UV radiation/wet-dry condition,the surface of T1D3H1 coating system began to appear in the hole,it is indicated that the synergistic effect between UV radiation and wet-dry accelerate the failure of the organic coating protection system.Besides,the FITR analysis and corrosion morphology showed that C=O bonds was easily broken down under UV radiation condition.