摘要
为了探究铝合金表面磷化预处理对其水性环氧清漆涂层防护性能的影响,通过化学转化的方法在2024铝合金表面首先制备磷化膜进行磷化预处理,然后在未经和经过磷化预处理的铝合金表面涂装水性环氧清漆,待清漆完全固化成涂层后,采用电化学阻抗谱(EIS)评价了水性环氧涂层对未经和经过磷化预处理铝合金的保护作用,进而揭示磷化预处理对水性环氧清漆涂层防护性能的影响以及机制。结果表明:铝合金表面磷化膜呈均匀致密的柱状晶体结构,主要由Zn_(3)(PO_(4))_(2)·4H_(2)O组成;在质量分数为3.5%的NaCl溶液中,随着浸泡时间的延长,“环氧层/铝合金(E/A)”体系(未经磷化预处理)和“环氧层/磷化膜/铝合金(E/P/A)”体系(经过磷化预处理)的防护层电阻值(R_(c))和低频阻抗值(|Z|_(0.01))均逐渐减小,但是E/P/A体系的R_(c)和|Z|_(0.01)始终大于E/A体系的;磷化预处理使得水性环氧涂层在铝合金表面的平均附着力由10.47 MPa提高到15.58 MPa。与在铝合金表面直接涂装水性环氧清漆相比,先进行磷化预处理再进行水性环氧清漆的涂装,直观上看使铝合金表面整个防护层由单一的环氧层变成复合的环氧层/磷化膜,导致R_(c)和|Z|_(0.01)的显著增加;但是更为重要的是,磷化膜的存在提高了水性环氧涂层在铝合金表面的附着力,甚至使整个防护层的断裂形式也发生了根本的变化。上述两方面的综合作用改善了水性环氧清漆涂层对铝合金基体的保护作用,通过研究还揭示了磷化预处理提高水性环氧清漆涂层防护性能的机制。
The purpose of this work was to reveal the effect of phosphating pre-treatment on the protective performance of water-based epoxy varnish coating on surface of aluminum alloy(AA).A phosphating film was firstly prepared on the surface of 2024 aluminum alloy by chemical conversion method for phosphating pre-treatment,and then the surface of aluminum alloy without and after phosphating pre-treatment was coated with water-based epoxy varnish.After the varnish was completely cured into a coating,the protective effect of water-based epoxy coating on aluminum alloy without and after phosphating pre-treatment was evaluated by electrochemical impedance spectroscopy(EIS).Finally,the effect of phosphating pre-treatment on the protective performance of water-based epoxy varnish coating and its mechanism were revealed.Results showed that the phosphating coating on surface of aluminum alloy had a uniform and dense columnar crystal structure,which was mainly composed of Zn_(3)(PO_(4))_(2)·4 H_(2)O.In 3.5%(mass fraction)NaCl solution,both the protective layer resistance(R_(c))and the impedance module at low frequency(|Z|_(0.01))of the epoxy/AA(E/A)system and the epoxy/phosphating coating/AA(E/P/A)system decreased gradually with the extension of immersion time;however,both R_(c) and|Z|_(0.01) of the E/P/A system were always greater than those of the E/A system.On the other hand,due to the phosphating pre-treatment,the average adhesive force(Fa)of water-based epoxy coating on the surfaceof AA increased from 10.47 MPa to 15.58 MPa.Compared with the direct coating of water-based epoxy varnish without phosphating pretreat-ment on the surface of AA,the coating with phosphating pre-treatment before water-based epoxy varnish treatment changed the whole protectivelayer on the surface of AA from a single epoxy layer to a composite epoxy layer/phosphating coating,resulting in a significant increase inRcand|Z|_(0.01).More importantly,the existence of phosphating film improved the adhesion of water-based epoxy coating on the surface of AA,a
作者
徐爱民
何卫
马恒
陈胜男
李周选
王利民
刘东
周勇
XU Ai-min;HE Wei;MA Heng;CHEN Sheng-nan;LI Zhou-xuan;WANG LI-min;LIU Dong;ZHOU Yong(Engineering and Technology Department,Zhejiang Huadian Equipment Testing Institute Co.,Ltd.,Hangzhou 310015,China;Engineering and Technology Department,Wuhan NARI Electric Power Engineering Technology&Equipment Co.,Ltd.,Wuhan 430415,China;Key Laboratory for Green Chemical Process of Ministry of Education,Wuhan Institute of Technology,Wuhan 430205,China)
出处
《材料保护》
CAS
CSCD
2022年第2期42-47,共6页
Materials Protection
基金
浙江华电器材检测研究所有限公司科技项目(5211HD190001)资助。
关键词
铝合金
磷化预处理
水性环氧清漆涂层
耐蚀性
EIS
附着力
aluminum alloy
phosphating pre-treatment
water-based epoxy varnish coating
corrosion resistance
EIS
adhesive force
