用电化学阻抗技术研究阴极保护

介绍电化学阻抗谱（ＥＩＳ）在研究阴极保护方面的应用，根据受有极保护金属的阻抗特征，可以确定实际保护率达到极大的最佳阴极保护保护电位，ＥＩＳ可以用于监测土壤和混凝土钢结构受阴极保护时的腐蚀情况，海水中阴极保护时形成的钙质沉积层的保护性能可由ＥＩＳ的参数来反映。ＥＩＳ变化趋势可还以反映Ａｌ－Ｚｎ－Ｉｎ合金牺牲阳极沿晶界的择优溶解。     

工业纯铝在3.5%NaCl溶液中的电化学阻抗谱分析

通过电化学阻抗谱（ＥＩＳ）测定，分析和工业纯铝在３．５％ＮａＣｌ中的电化学行为和腐蚀特征，研究结果表明，工业纯铝在３．５％ＮａＣｌ溶液中阳极极化电位较低时钝化膜完整，阻抗呈现单窝抗弧特征，Ｅ〉０．８Ｖ。钝化膜开始局部破坏，ＥＩＳ图出现感抗弧。分析阳极极化过程阻抗的变化规律可以研究耐蚀性能和腐蚀机理。     

电化学控制条件下不可逆电极过程交流阻抗的统一换算电路和电化学参数解析

在曹楚南交流阻抗频谱（ＥＩＳ）分析理论的基础上，导出了电化学控制条件下电化学交流胆抗的普遍表达式和统一换算电路，从而简化了ＥＩＳ等效电路解析方法，为曹楚南交流阻抗频谱理论中的电化学参数的解析提供了方便的换算电路途径．     

AI—Mg合金在不同pH值的NaCI溶液中的腐蚀行为

用电化学阻抗谱（ＥＩＳ）技术研究了ＬＦ３Ｍ和ＬＦ１１Ｍ两种Ａ１－Ｍｇ合金在不同ｐＨ值的２．７％ＮａＣＩ溶液中的腐蚀行为。结果表明，Ａ１－Ｍｇ合金在不同ｐＨ值的ＮａＣＩ溶液中不同极化电位下处于不同的腐蚀状态，阻抗谱呈现不同的特征，分析了Ａ１－Ｍｇ合金在厦门海域显示较强的局部腐蚀敏感性的原因。     

铝—丙烯衍生物电聚合涂层的缓蚀性能的形貌机理研究

对比研究了丙烯酸（ＡＡ）,丙烯腈（ＡＮ）和丙烯酰胺（ＡＭ）三种水溶性丙烯衍生物在铝电极上电化学聚合形成涂层,测试了涂层的缓蚀性能,用ＳＥＭ,ＸＰＳ和ＦＴＩＲ技术确认了涂层的形貌结构,推测了其电化学聚合机理,结果表明,涂层在０．５ｍｏｌ／Ｌ盐酸中的缓蚀性能较差,涂层形貌结构分析表明,丙烯衍生物在铝表面的原位电聚合皆为阴极还原机理。     

富锌涂层的电化学阻抗谱特性

根据在不同浸泡时间测得的富锌涂层的电化学阻抗谱特征，提出了两种等效电路作为其物理模型。讨论了阻抗谱特征变化与富涂层结构及变化的关系，并根据阻抗谱的解析结果为两种富锌涂层的防护性能进行了评价。     

Al6061/SiCp复合材料表面Ce转化膜腐蚀行为的研究

利用金相和 Ｘ射线能谱分析了 Ａ１６０６１／ＳｉＣｐ复合材料表面 Ｃｅ转化膜的腐蚀行为实验表明： Ｃｅ转化膜在 ＮａＣｌ溶液中的腐蚀以点蚀开始,点蚀处基体为 ＳｉＣ颗粒的富集区根据 Ｍａｎｓｆｅｌｄ点腐蚀模型等效电路,通过电化学阻抗谱（ＥＩＳ）研究了 Ｃｅ转化膜在 ＮａＣｌ溶液中的腐蚀程度;转化膜在 ＮａＣＩ溶液中浸泡时间较短的情况下,等效电路中的 Ｗａｒｂｅｒｇ阻抗可忽略,可以对等效电路简化处理研究转化膜点蚀程度     

纳米SiO2改性环氧涂层电化学阻抗谱研究

通过共混法用纳米SiO2对环氧涂层进行改性,采用电化学阻抗谱(EIS)研究浸泡于3.5 mass% NaCl溶液中的涂层/金属电极体系电化学行为;建立了四种等效电路阻抗模型对EIS数据进行拟合,通过分析电化学参数的变化规律表征了体系的腐蚀行为;从Bode图选取了能直观反映涂层保护性能且误差小的高频区参数,研究了涂层防腐...     

Zn粉含量及表面沾污对环氧富Zn漆电化学行为的影响

采用腐蚀电位、电化学阻抗谱(EIS)评价了Zn粉含量以及涂层／基体界面污染程度对环氧富Zn涂层的防腐蚀性能的影响并探索了富Zn涂层的失效机制。实验结果表明，当涂层中Zn含量较少时，Zn粉没有有效的阻挡作用。通过对可能的阻抗模型的分析，认为富Zn涂层的电化学阻抗谱的低频段是由Zn^2 从金属表面穿过腐蚀产物的扩散控制。涂层／基体界面污染不仅影响了环氧富Zn涂层的防腐蚀性能的发挥，也加速了钢铁基体的腐蚀。     

YKI—5海水介质缓蚀剂对907A钢的缓蚀行为及其机理研究

ＹＫＩ－５海水介质缓蚀剂主要成分为多元醇磷酸酯、多元醇聚磷酸酯、聚磷酸盐、正磷酸盐等。本工作运用失重法、极化曲线法和电化学阻抗谱（ＥＩＳ）研究了ＹＫＩ－５对９０７Ａ钢在海水介质中有缓蚀行为,结果表明ＹＫＩ－５在该体系中为混合型缓蚀剂,在不同浓度下体现出不同的缓慢效应;在Ｅｃｏｒｒ下测得ＥＩＳ与空白试验不一样,它由两个容抗弧组成,呈现两个时间常数特征。     

评价有机涂层防护性能的EIS数据处理

根据在有机涂层性能评价的EIS测量中得到的各种谱图,结合涂层体系的实际情况,提出了6种等效电路作为EIS数据处理的物理模型.发展了EIS非线性最小二乘法拟合的计算机软件,讨论了数据处理的原理与方法     

有机涂层防护性能的电化学研究进展

曝晒、盐雾、浸泡、干湿循环、老化等传统的有机涂层防护性能研究方法,因测试周期长,测试结果多为定性分析,不能使涂层材料进行快速检验而投入评估使用.正是由于传统测试方法存在许多局限性,故综述了稳态电化学测试方法和暂态电化学测试方法这两种新技术在有机涂层防护性能中的应用与进展.介绍了动电位极化曲线法、极化电阻法等稳态电化学测试方法,这类方法主要反映涂层的极化电阻和腐蚀速度,并且方法简单,可直接分析实验数据,被广泛应用于有机涂层的失效分析中.而暂态电化学测试方法主要包括电化学阻抗法(EIS)、局部阻抗法(LEIS)、扫描Kelvin探针法(SKP)及电化学噪声(EN)等,主要用于研究涂层防护机制和局部缺陷.目前,在有机涂层防护性能和机理研究中,应用最多的是电化学交流阻抗法.丝束电极法(WBE)、扫描电化学显微镜(SECM)以及原子力显微镜(AFM)用于研究金属/涂层界面物理化学变化规律.阐述了上述方法在涂层防护研究中的应用成果及其优势和不足,指出对于深层次的涂层防护研究,需要应用多种测试手段,从不同的角度和方面综合分析,全面评估涂层的使用寿命.     

Lifetime prediction and failure analysis of organic coatings by EIS

Organic coatings are widely used to control the corrosion of steel structure. The anticorrosive property of these coatings depends on their barrier properties, making a separation between the corrosive medium and the substrate. But unavoidable completely small pores, cracks and other defects in organic coatings may cause ions, water, gases, and other corrosive species penetrate and distribute in the coatings, causing accumulation and swelling of coatings, so leading to the degradation of coatings. In addition, water affects the permeation of oxygen and other corrosive medium, consequently the presence of such substances at coating-metal interface promotes corrosion of metal substrate. So the absorbability of the coatings to water may be one of the most important factors in undercoating corrosion. In recent years, electrochemical impedance spectroscopy (EIS) has been established and frequently used as a non-destructive testing method for assessing the performance of organic coatings, especially for the determination of the water content in organic coatings, since the capacitance of the coatings is sensitive to the penetration of water. So from EIS it can extract a wealth of information on the electrochemical corrosion of coated steels, especially, it can be utilized to assess organic coatings used under particular surroundings. The principle, methods and application of EIS on evaluating life-span and analyzing failure mechanism of organic coatings are also introduced briefly. Combining other analysis techniques such as XRD, SEM and FTIR with electrochemical technique, it will blaze a way in studying degradation mechanism of organic coatings and estimating their lifetime.     

Influence of SiC + WC addition to Cr(VI) bath on corrosion behaviour of coatings in sulphate solution

Abstract

Cr–WC–SiC coatings were deposited from Cr(VI) baths containing a mixture of both WC and SiC particles in the ratio of 1 : 1. X-ray photoelectron spectroscopy data indicated relatively low percentages of both WC (about 2˙68–2˙85 at.-% of W4f) and SiC (0˙16–0˙45 at.-% of Si2p) particles in the top layers of the Cr–WC–SiC coatings. However, these particles have some effect on the morphology and corrosion properties of the Cr coating. Protective properties of the coatings obtained were studied at different exposure times of samples in sulphate solution (pH=2˙8), using the electrochemical impedance spectroscopy method (EIS). Equivalent circuits, based on the electrophysical model describing the electrochemical corrosion at the coated surface, were proposed. The simulation of EIS data with the proposed equivalent circuit models made it possible to reveal the details of the corrosion processes occurring at coated systems (steel/Cr–WC–SiC coatings) immersed in the sulphate solution. Based on EIS data, diffusion in the coating was found to be a significantly controlling factor in the corrosion process for the system under investigation. The electrochemical impedance spectroscopy tests indicated a better corrosion resistance of Cr–WC–SiC coating than that of Cr. Analysis of the EIS data suggests that the enhanced corrosion resistance of Cr–WC–SiC coating was due to the microstructural features of these coatings, presumably containing smaller pores than Cr coating.     

AF1410钢环氧有机涂层电化学研究

利用电化学阻抗谱(EIS)方法研究了AF1410钢试样表面在只涂有1层H06-076环氧底漆状态下的腐蚀情况。试验过程采用了加速环境谱。结果表明:AF1410材料在只涂1层H06-076环氧底漆的情况下其抗腐蚀性能较差,尤其在拐角处封漆不好,介质容易从拐角处进入漆层与基体交界面,引起基体材料腐蚀。EIS方法可提前表征有机涂层涂覆下的金属腐蚀行为并评估有机涂层的防护性能。EIS中0.1 Hz处的阻抗模值与10 Hz处的相位角变化规律一致。     

不同体系中缺陷大小对有机涂层失效形貌的影响

分别在刷涂于铁基体、Al电弧喷涂层和Zn-Al-Mg-RE电弧喷涂层表面的有机涂层中制备了大小不同的人工缺陷,观察了各体系进行电化学交流阻抗(EIS)测试后有机涂层的失效形貌及缺陷处腐蚀产物的微观结构,并分析了各体系的失效机制.结果表明,对于在铁基体和Al电弧喷涂层表面刷涂有机涂层体系,缺陷尺寸越小,有机涂层失效越严重,主要是因为缺陷大小影响腐蚀产物向腐蚀介质中的扩散造成的;对于在Zn-Al-Mg-RE电弧喷涂层表面刷涂有机涂层的体系,缺陷尺寸大小对有机涂层失效形貌的影响不大,主要是因为在人工孔隙中生成了微观结构致密的腐蚀产物造成的.     

Mechanistic changes in cut-edge corrosion induced by variation of organic coating porosity

The scanning vibrating electrode technique (SVET) has been used to investigate the mechanism of corrosion occurring at exposed metallic cut edges of galvanised steel materials coated with identical thickness organic polymeric layers. Organically coated galvanised steel samples have been prepared by application of a 30 μm polyester coating to both sides of a pre-treated hot dip zinc (99.85%) aluminium (0.15%) galvanised steel substrate. In separate samples the coatings were applied to both sides simultaneously and then cured or applied sequentially to each side curing after each application. Electrical impedance spectroscopy (EIS) was used to probe the porosity of the resulting organic coatings. This revealed that simultaneous coating application and curing resulted in both polymer layers showing EIS pore resistance of 0.6 MΩ whereas sequential coating resulted in one side showing a pore resistance of 0.6 MΩ and the other showing a capacitive EIS response with no measurable porosity. When the metallic cut edges of organically coated steel materials, coated with symmetric thicknesses of organic layers of identical pore resistance, are exposed to 5% NaCl the SVET iso-current contour maps show that both zinc layers behaving as local anodes. In addition, there is significant sample passivation in the 24 h exposure period. In the samples coated with materials of identical thicknesses but different porosity, the SVET iso-current contour maps show anodic activity focussed beneath the organic coating with the capacitive EIS signature. The greater porosity of the coating on the opposite side of the exposed cut edge enables oxygen transport to the delaminating surface and this forces anodic activity onto the other zinc layer.     

评价有机涂层耐蚀性能的两种方法初探

通过测试涂层渗水率以及涂层交流阻抗图谱，评价涂层的耐腐蚀性能，并就其机理进行了初步探讨。实验得出的结论为实验室评价涂层耐腐蚀性能提供了很好的指导作用。     

Infrared emissivity and corrosion-resistant property of maleic anhydride grafted ethylene-propylene-diene terpolymer (EPDM-g-MAH)/Cu coatings

Maleic anhydride grafted ethylene-propylene-diene terpolymer (EPDM-g-MAH) was prepared by grafting copolymerization method. Composite coatings with varied infrared emissivity were obtained by using copper (Cu) powder as inorganic pigments, either EPDM or EPDM-g-MAH as organic adhesive. The influences of the content of Cu powder and adhesive kinds on the infrared emissivity of the composite coatings were investigated. The as-prepared coatings were characterized by FTIR spectroscopy, infrared emissometer and SEM. The corrosion-resistant property of the coatings in aqueous 3.5 wt.% NaCl was assessed by the potentiodynamic polarization technique and electrochemical impedance spectroscopy (EIS). The results have shown that the interfacial interaction between EPDM and Cu is improved due to the MAH grafting on EPDM, benefiting from the compatibility of EPDM with Cu and the low porosity of EPDM/Cu coatings, which leads to the lower infrared emissivity and better corrosion-resistant property of the coatings.     

Influence of the Pigment Shape on the Electrochemical Behaviors of Zinc—Rich Paint Coatings in 3.5% NaCl Solution

针对粘合剂种类、Zn粒形状和涂层厚度的协同作用，采用电化学阻抗谱(EIS)研究了富Zn涂层在3．5％NaCl溶液中的电化学行为．富Zn涂层的EIS谱有两个时间常数，其中，锌的电子转移反应发生在低频段，而高频段则体现聚合物和Zn表面氧化层的介电性质．根据等效电路及其元件参数解释了钢铁／富Zn涂层／盐水体系的EIS测量结果．实验结果表明，鳞片锌消耗速度太快以至于鳞片富Zn涂层在相对较短的时间内就失去了阴极保护作用，随后形成了稍微致密的屏蔽阻挡层。