An electrochemical impedance spectroscopy study of the corrosion behaviour of PVD coated steels in 0.5 N NaCl aqueous solution: Part II. EIS interpretation of corrosion behaviour
An electrochemical impedance spectroscopy study of the corrosion behaviour of PVD coated steels in 0.5 N NaCl aqueous solution: Part II. EIS interpretation of corrosion behaviour
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DOI：
10.1016/s0010-938x(02)00214-7
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发表时间：
2003-06-01
影响因子：
8.3
通讯作者：
Matthews, A
中科院分区：
文献类型：
--
作者：
Liu, C;Bi, Q;Matthews, A
在第一部分，这项工作的电化学阻抗谱（EIS）模拟PVD涂层钢在0.5 NaCl溶液中的等效电路建立。在本文中，第二部分，这种涂层系统的EIS谱建模使用的等效电路。得到的电路参数与钢和PVD硬质涂层的介电特性、显微组织有关。涂层孔隙率和局部腐蚀与暴露时间也已确定使用低碳钢和PVD涂层之间的腐蚀电位差（Δ E（corr））和极化电阻R-p，这是通过EIS建模使用等效电路。此外，扩散速率的反应物（如氧气）通过“可渗透”的缺陷（如孔隙）进行了研究，通过在EIS建模中引入扩散阻抗W和O。研究发现，阻抗W和O的使用与PVD涂层的微晶特征密切相关。瓦尔堡阻抗（W）最适合于柱状晶，而余切双曲扩散阻抗（O）最适合于等轴晶结构。最后，采用目测、扫描电镜和扫描参比电极技术观察了PVD涂层钢在不同浸泡时间下的腐蚀过程，以验证EIS的解释。(C)2002爱思唯尔科技有限公司版权所有。
In Part I, of this work the equivalent circuits for electrochemical impedance spectroscopy (EIS) modelling of PVD coated steels in 0.5 NACl solution were established. In this paper, Part II, the EIS spectra of such coated systems are modelled using the equivalent circuits. The circuit parameters obtained are correlated with the dielectric characteristics, and microstructure of steels and PVD hard coatings. Coating porosity and localised corrosion with exposure time have also been determined using the corrosion potential difference (DeltaE(corr)) between mild steel and PVD coatings and polarisation resistance R-p, which was obtained through EIS modelling using equivalent circuits. In addition, diffusion rates of the reactants (e.g. oxygen) through 'permeable' defects (e.g. pores) are studied by introducing the diffusion impedances W and O in EIS modelling. It has been found that the usage of impedances W and O is closely related to the crystallite features of PVD coatings. Warburg impedance (W) is most suitable for columnar crystallites, while the co-tangent-hyperbolic diffusion impedance (O) is best for the equiaxed crystallite structure. Finally, visual inspection, SEM examination, and the scanning reference electrode technique were employed to observe the corrosion progress of PVD coated steels with immersion time, in order to validate the EIS interpretation. (C) 2002 Elsevier Science Ltd. All rights reserved.