电化学沉积方法对聚苯胺涂层抗腐蚀性能及电化学性能的影响

Effect of Electrodeposited Methods on Corrosion Resistance and Electrochemical Behavior of Polyaniline Coatings

聚苯胺涂层的电化学特性及耐蚀性与其合成方法及工艺有着密切的关系。在以硫酸为掺杂剂的合成溶液中采用循环伏安和恒电流方法在304不锈钢表面沉积出了聚苯胺涂层。用扫描电镜和电化学方法研究了聚苯胺涂层的表面形貌、抗腐蚀性能和电化学性能。结果表明:聚苯胺涂层表面为多孔结构;开路电位-时间曲线表明,在腐蚀介质中,2种聚苯胺涂层均提高了304不锈钢的腐蚀电位,电化学阻抗谱结果表明,2种聚苯胺涂层在腐蚀初期反应均受扩散步骤控制,对腐蚀介质有一定的阻挡作用,但恒电流方法制备的聚苯胺在浸泡24h后,表现为基体金属的阻抗谱特征。因此,相对于恒电流方法,循环伏安方法制备的聚苯胺对304不锈钢的钝化能力更强,可为基体提供更好的保护。

Polyaniline coatings were electrodeposited on 304 stainless steel via cyclic voltammmetric and constant-current routes in synthe-sized solution containing H2SO4.The morphologies of the coat-ings were observed by using a scanning electron microscope.The corrosion resistance and electrochemical behavior of the coatings were examined by using electrochemical methods.Results indi-cate that the polyaniline coatings have porous structure,and can increase the corrosion potential of the stainless steel in the corro-sive medium.At the initial stage,the corrosion process of the coatings was controlled by diffusion,and the coatings acted as barriers against the corrosive medium.After being immersed for 24 h,the coating deposited by constant-current method had simi-lar electrochemical impedance spectra as the substrate steel.The coating obtained via cyclic voltammmetric route was more effective in passivating and protecting the stainless steel substrate than the one prepared by constant-current method.