5083铝合金环氧涂层盐水浸泡失效研究

发布时间：2018-03-28 08:44

本文选题：环氧涂层　切入点：铝合金　出处：《表面技术》2015年07期

【摘要】：目的研究铝合金基体上环氧涂层在盐水浸泡环境中的电化学阻抗谱变化规律,揭示涂层失效的原因和机制。方法采用电化学阻抗谱技术、红外测试、扫描电镜及能谱分析等方法,研究涂覆在5083铝合金基体上的环氧涂层在盐水浸泡过程中的裂化过程和失效机制。结果在3.5%(质量分数)Na Cl溶液的连续浸泡下,涂层电阻明显下降、电容明显增大,相应的涂层孔隙率和吸水体积百分数均逐渐增加;长期浸泡后,涂层孔隙率和吸水体积百分数均趋于稳定。随着浸泡时间的增加,涂层表面孔洞等缺陷增多,保护作用减弱;涂层内氧元素含量逐渐增加,碳元素含量逐渐减小;涂层内有羟基生成和C—O键的断裂发生。结论环氧涂层中环氧官能基团在电解质溶液中发生水解,水解形成羟基和氨基等亲水基团以及涂层中存在的孔洞等缺陷,进一步促进电解液的渗透,加速涂层的劣化。金属基体表面腐蚀反应会促进涂层与基体的剥离,腐蚀产物在涂层内的累积,也会导致涂层内孔隙和缺陷增多,促进涂层劣化。
[Abstract]:Objective to study the change of electrochemical impedance spectrum of epoxy coating on aluminum alloy substrate in salt water immersion environment, and to reveal the reason and mechanism of coating failure. Methods Electrochemical impedance spectroscopy (EIS) technique and infrared spectroscopy (IR) were used to test the effect of epoxy coating on aluminum alloy. The cracking process and failure mechanism of epoxy coating coated on 5083 aluminum alloy substrate during brine immersion were studied by means of SEM and EDS. Results the resistance of the coating decreased obviously under the continuous immersion of 3.5% NaCl solution. With the increase of the capacitance, the porosity and the percentage of water absorption volume of the coating increased gradually, and the porosity and the percentage of water absorption volume of the coating tended to be stable after a long period of immersion. With the increase of soaking time, the defects such as pores in the coating surface increased. The protective effect is weakened, the content of oxygen in the coating increases gradually, the content of carbon element decreases gradually, the formation of hydroxyl and the fracture of C-O bond occur in the coating. Conclusion the epoxide functional group in the epoxy coating is hydrolyzed in electrolyte solution. Hydrophilic groups such as hydrophilic groups such as hydroxyl group and amino group were formed by hydrolysis, as well as defects such as holes in the coating, which further promoted the permeation of electrolyte and accelerated the deterioration of the coating. The corrosion reaction on the surface of metal substrate would promote the exfoliation of the coating from the substrate. The accumulation of corrosion products in the coating will also lead to the increase of pores and defects in the coating and promote the coating deterioration.
【作者单位】：海军装备研究院;北京化工大学电化学过程与技术北京市重点实验室;中国石油呼和浩特石化公司;
【基金】：教育部科学技术研究重点资助项目(108129)~~
【分类号】：TG174.3

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