海洋工程热喷铝涂层的腐蚀电化学行为  

Corrosion Behaviours of Thermal Spraying Aluminium Coaling for Offshore Engineering

作　　者：刘存[1] 赵卫民[2] 陈虹宇 

机构地区：[1]海洋石油工程(青岛)有限公司,山东青岛266520 [2]中国石油大学(华东),山东青岛266500 [3]中油抚顺石化设备检测监理研究中心,辽宁抚顺113000

出　　处：《材料保护》2016年第10期5-8,共4页Materials Protection

摘　　要：交流阻抗谱可用于电极界面电化学特性、腐蚀机理的研究,但目前有关其用于金属阳极涂层的报道相对较少。基于热喷铝涂层在海洋钢结构中的应用情况,利用热喷涂方法在Q235钢表面制备铝涂层,采用电子探针(EPMA)分析涂层在3.5%NaCl溶液中浸泡30 d后横截面Al、O、Cl、Fe元素分布特征。用动电位极化曲线法测试、拟合喷态涂层和腐蚀挂片试验后涂层的自腐蚀电流密度。用交流阻抗谱法(EIS)研究涂层的电化学腐蚀失效过程。EPMA分析结果表明腐蚀介质主要沿涂层孔隙和夹杂物向涂层内部渗入。原始涂层动电位极化测试显示铝涂层具有明显的钝化现象,这与腐蚀产物Al(OH)3的附着力较强以及存在Al2O3覆膜有关。试验期间铝涂层交流阻抗谱变化分为孔蚀萌生、孔内酸化析氢、涂层作为牺牲阳极、孔蚀群快速发展4个阶段,采用Zsimp Win软件拟合出了对应阶段的阻抗等效电路模型。Aluminum coating was deposited on Q235 steel substrate by using thermal spraying,based on the application of thermal spraying aluminum coating(TSA) on the offshore steel structures.Electron probe micro-analysis(EPMA)was used to analyze the element distribution features of Al,O,Cl and Fe of the coating cross-section after immersed in 3.5%NaCl aqueous solution for 30 d.The potentiodynamie polarization curve was used to test and fit the corrosion current density of coating before and after hanging strip corrosion test.Moreover,the coating electrochemical corrosion failure process was studied by electrochemical impedance spectroscopy(EIS).Results showed that corrosion medium could penetrate into the inner coatings along the pores or inclusions,observed by EPMA.The original coating potentiodynamie polarization proved obvious passivation phenomenon of Al coating,which was related to the strong adhesion of corrosion products Al(OH)_3,and the existence of A1_2O_3 film.During the test process,the EIS of Al coating presented four stages of pitting initiation,acidified hydrogen in pits,coating becoming sacrificial anode and rapid development of pits cluster,and the equivalent circuit models of impedance corresponding to each stage were fitted by ZsimpWin software.

关 键 词：热喷铝涂层 腐蚀电化学 海洋工程 钢结构 交流阻抗谱 

分 类 号：TG174.442[金属学及工艺—金属表面处理]