聚苯胺及其衍生物在防腐领域中的应用进展

概述了聚苯胺的结构、性质及其防腐机理。聚苯胺主要通过其屏蔽作用在金属表面促进形成钝化层和提高金属氧化电位,降低金属材料的腐蚀速度。因此,聚苯胺经常被用做缓蚀剂、聚苯胺防腐涂层和防腐涂层的添加剂。相较于缓蚀剂与聚苯胺涂层,聚苯胺复合涂层具有优异的防腐性能。综述了近年来聚苯胺及其衍生物在防腐领域的进展,提出了聚苯胺在防腐应用中需进一步解决的问题。     

聚苯胺膜对X70钢防腐性能的研究

采用电化学极化曲线和交流阻抗方法,研究了聚苯胺膜分别在酸性(质量分数为5%的HNO3)、弱碱性(饱和Na2CO3)、碱性(质量分数为5%的KOH)溶液中对X70钢的防腐性能。结果表明:聚苯胺膜在3种溶液中对X70钢都有防腐作用,但短时间内以酸性溶液中的防腐性能为最适宜。同时以饱和Na2CO3溶液模拟常规的弱碱性土壤环境,考察了此环境中聚苯胺膜对X70钢电极防腐作用的持久性。结果表明聚苯胺膜在弱碱性环境中对X70钢具有长效防腐性能,并初步证实其防腐机理为聚苯胺的屏蔽作用和阳极保护作用(钝化作用)。     

聚苯胺防腐性能及应用研究

在诸多导电聚合物中,聚苯胺因其广泛的应用特别是在金属防腐方面的使用引起广大学者的特别关注。主要针对聚苯胺涂层的相关制备方法、防腐机理及应用进行论述,并根据目前的研究现状,提出今后聚苯胺的主要研究方向。     

聚苯胺乳液在水性带锈涂料中的防腐性能研究

以聚苯胺乳液为防腐添加剂,制备了水性聚苯胺带锈涂料,研究了聚苯胺乳液在带锈涂料中的防腐性能及其对涂料性能的影响,并探讨了聚苯胺与转化剂及铁锈的反应机理。结果表明:聚苯胺具有增强涂料转化效果、提高涂层耐水和耐盐雾性能、赋予涂料自恢复性和抗锈能力等特性;聚苯胺可与转化剂及铁锈反应,生成大分子物质,该物质紧密附着在基材表面,加上聚苯胺的防腐性能,可以实现钢铁的长效防腐。     

电化学聚合导电聚苯胺膜的研究

分析了恒电位法在酸性和碱性溶液中于不锈钢基体上电聚合聚苯胺的过程及其影响因素,测定了聚苯胺膜与基体的附着力、膜的导电性和防腐性.结果表明:该膜在空气中呈绿色,稳定、完整致密,导电性好,与基体的结合情况较好.阳极极化曲线测定表明,在碱性溶液中预镀后酸性溶液中聚合聚苯胺膜,其点蚀电位比酸性溶液中聚合聚苯胺膜升高1 V左右,表明前者的导电聚苯胺膜可显著提高不锈钢的抗点蚀性能,具有良好的点腐蚀防护效果.     

聚苯胺的腐蚀防护机理及其在金属防腐中的应用之我见

聚苯胺是一种新型的化学防护材料,能够起到防治金属被腐蚀的作用,因其良好的防护性能,近年来被广大材料工作者广泛研究,也取得了一定的成果。本文简单介绍聚苯胺对金属腐蚀的防护机理,并据此谈一点关于其在金属防腐工作中的应用,供广大同仁参考。     

聚苯胺让人惊讶的高性能防腐材料

钢铁的腐蚀无处不在,是造成多类设施、装备自然损耗的最主要因素,往往造成巨大的经济损失和社会危害。导电高分子材料聚苯胺具有金属的导电性,又具有有机高分子的低密度和可加工性,被誉为合成金属材料,是有机高分子与金属的桥梁。采用导电聚苯胺作为防腐添加剂加入防腐涂料中,能大大提高防腐涂料的防腐性能。重庆金固特化工新材料技术有限公司是国内较早生产聚苯胺及聚苯胺类防腐涂料产品的厂家,本刊记者就所关心的问题对该公司总经理苑建涛先生进行了专访。     

聚苯胺防腐涂料的研究现状

聚苯胺(PANI)是一种新型的金属防腐保护材料,与常规缓蚀剂相比没有任何的环境副作用,是一种符合时代和科技发展的绿色缓蚀剂,成为当前研究最多的导电高分子材料。本文概述了国内外聚苯胺防腐蚀涂料的研究情况,具体涉及聚苯胺的结构、性能和聚苯胺防腐蚀涂层的制备方法。指出了聚苯胺研究中存在的问题,应用现状和对其发展前景的展望。     

聚苯胺在防腐涂层中应用研究进展

聚苯胺被认为是最有应用前景的导电聚合物,目前被广泛应用在涂料、传感器、电极及电磁屏蔽等领域,而其在防腐涂层中的应用是目前研究的热点。综述了聚苯胺纳米结构的制备及其在防腐涂层中的应用,并归类总结了目前对聚苯胺防腐机理的推测与研究进展。     

聚苯胺/环氧复合阴极电泳涂料防腐蚀性能的研究

运用插层聚合的方法制备了蒙脱土／聚苯胺复合材料，并进行了表征。将该复合材料通过共混的方式加入聚酰胺／环氧阴极电泳（CED）涂料中配制成聚苯胺／环氧复合阴极电泳涂料，并利用电化学阻抗谱方法对各电泳涂层的防腐性能进行了分析。研究发现：在3．5％NaCl溶液中浸泡10d后，腐蚀介质不能到达涂层／基底金属界面，金属表面没有发生腐蚀反应。随着聚苯胺含量的增加，复合电泳涂膜的阻抗值增加，具有较好的防腐性能。当聚苯胺含量相同时，与掺杂态聚苯胺复合电泳涂膜相比，本征态聚苯胺复合电泳涂膜具有很高的阻抗值，表现出更好的防腐性能。     

Undoped polyaniline–surfactant complex for corrosion prevention

Due to the strict regulations on the usage of heavy metals as the additives in the coating industries, the search for effective organic corrosion inhibitors in replacement of metal additives has become essential. Electrically conducting polymers have been shown to be effective for corrosion prevention, but the poor solubility of these intractable polymers has been a problem. We have explored a polyaniline–4-dodecylphenol complex (PANi–DDPh) to improve the dissolution, and it has been shown to be an effective organic corrosion inhibitor. With the surfactant, DDPh, PANi could be diluted into the coatings, and the properties of the coatings were affected. An emeraldine base (EB) form of PANi was also found to be oxidized by the hardener. The oxidized form of polyaniline provides improved corrosion protection of metals than that of emeraldine base since the value of the standard electrode potential for the oxidized form of PANi is higher than that of EB. Additionally, the surfactant improves the wet adhesion property between the coating and the metal surface. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2849–2856, 1999     

Preparation and electrochemical properties of polyaniline doped with benzenesulfonic functionalized multi-walled carbon nanotubes

Nanocomposite of benzenesulfonic functionalized multi-walled carbon nanotubes doped polyaniline (PANi/f-MWCNTs) was synthesized via a low-temperature in situ polymerization method. The PANi/f-MWCNTs composite has a thin film of PANi coating uniformly on the surface of the f-MWCNTs. The electrochemical results show that PANi/f-MWCNTs nanocomposite possesses good rate response, which could ascribe to the uniform structure and the better conductivity of composite as well as the in situ doping/de-doping process between the benzenesulfonic acid groups of f-MWCNTs and PANi chain. In addition, the composite also has better capacity and cyclability than PANi/p-MWCNTs composite. It could attribute to the presence of f-MWCNTs, which makes more electrolyte contact with PANi to participate in faradaic redox reactions and dopes with the PANi polymer chain through the benzenesulfonic acid groups to form stable polyemeraldine salts.     

Electrochemical synthesis: a novel technique for processing multi-functional coatings

Electrochemical synthesis is a powerful tool for surface modification, substrate cleaning and formulation of thin films and bulk materials. It is especially suited for surface modification of fibers, metals and films. In the past decade electrochemical method has become the preferred technique for in situ passivation, and coating of commodity metals such as aluminum, zinc, copper and steel.

We have successfully synthesized different kinds of conducting polymers, including polypyrrole (PPy)–polyaniline (PANi) composites. The processability and corrosion performance of PPy/PANi, composite coatings are significantly better than those for either PPy or PANi, coatings.

In this paper, we will discuss the use of electrochemical technique in the synthesis and characterization of multi-functional corrosion resistant conducting polymer coatings for aerospace and automotive applications.     

Electrochemical behaviour of PANi/polyurethane antifouling coating in salt water studied by electrochemical impedance spectroscopy

Electrochemical behaviour of polyaniline–polyurethane (PANi–PU) antifouling coating in 3.5 wt% NaCl is studied by electrochemical impedance spectroscopy (EIS). A thick coating (∼1 mm) of 10, 15 and 20% PANi in marine grade PU, is cast over corrosion resistant aluminium alloy 2024 and its impedance characteristics are measured by EIS and compared with neat PU. On addition of 10% PANi, the impedance of the coating drastically comes down from 10⁹ to 10⁷ Ω. 20% is the maximum processable amount of PANi for the selected PU system. The coatings are exposed to 3.5 wt% NaCl and its impedance characteristics are monitored as a function of time. Changes in the impedance characteristics of the systems were found to occur as a function of the exposure time in all cases, though their evolution with time showed marked differences with PANi content. Water sorption and break down frequency are derived from the experimental results and analysed.     

Polyaniline Coating on Iron–Synthesis and Characterization

Protective coating has been used widely for metal corrosion control. Polyaniline (PANi) films can be electrosynthesized by oxidation of aniline on a metal surface from an aqueous acid medium. In this study, an iron surface was coated by polyaniline thin film. While iron easily oxidizes in acid solutions, the electropolymerization reactions were carried out in dilute acidic media. Rust, fats, etc. on the surface of iron were removed by alkali-ethanol solution, dichloroethylene, and, finally, hydrochloride (HCl) solution (10%), respectively. Coating was carried out in different potential (1.0, 1.5, and 2.5 V). To observe the effect of elemental contents of iron samples, spectral analysis also was taken before electropolymerization. Especially, effects of chromium and nickel elements were investigated. Physical resistance of the coating was examined by “band test.” Dissolving and defective coatings were also tested in acidic solutions and common organic solvents. In addition, to observe the morphology of coating, photos of samples were taken by scanning electron microscope (SEM) and metal microscope (MM).     

Application of polyaniline/nylon composites coating for corrosion protection of steel

In this research, we investigated the corrosion inhibition properties of polished steel plates (low carbon) coated with a polyaniline (emeraldine base form) blend with nylon 66 (termed PANi/Ny) via cast method with formic acid as the solvent. Polyaniline (PANi) was prepared chemically from aqueous solution using aniline (0.2 M) as a monomer and ammonium persulfate (0.2 M) as an oxidant. The polymer powder produced was changed into emeraldine base (EB) form after treatment with dilute ammonia solution (0.5 M) in order to do further processing. The corrosion experiments were performed in the open circuit, exposing samples to different aggressive and corrosive conditions (e.g., NaCl, HCl). To produce a good comparison, the corrosion study was performed on both polymer-coated and bare-steel samples. Corrosion monitoring was performed by simple immersion tests and determination of the concentration of iron ions and metal weight loss in test solutions. It was found that PANi/Ny coatings can provide an anodic protection against corrosive environments in which the metals are exposed. The corrosion rate for the polymer coated steel was significantly lower than the bare steel (~10–15 times).     

Effect of composite coating with poly-dopamine/PCL on the corrosion resistance of magnesium

We report the use of poly(ε-caprolactone) (PCL) and poly-dopamine (PD) as a protective coating that inhibits corrosion of the underlying magnesium metal. The PD coating layer also improved the adhesion of the PCL layer, which has been found to have a significant effect on corrosion behavior. In this study, electrochemical methods were employed to investigate the corrosion behavior of Mg after applying PCL composite coatings. Potentiodynamic polarization measurements determined that the PCL coating pretreated with PD effectively inhibited metal corrosion. In addition, the coating layer with improved adhesion has shown the possibility of inhibiting metal corrosion.     

Real time mapping of corrosion activity under coatings

Current accelerated testing of aircraft coating systems for corrosion protection relies heavily on salt spray methods. Electrochemical techniques such as electrochemical impedance spectroscopy (EIS) and electrochemical noise methods (ENM) provide insight into the global properties of a coating system, and both techniques are being used on a limited basis. However, there is a need to investigate corrosion events with greater spatial resolution under coatings at the metal/coating interface. Such corrosion activity may be related to coating defects and variations in the surface chemistry of the underlying metal.

The scanning vibrating electrode technique (SVET) has been developed to allow high spatial resolution investigation of localized corrosion activity that may be associated with coating defects or galvanic coupled regions of the metal surface. The SVET offers high resolution in current measurements of the order of 0.5 μA/cm² and is able to detect in-situ initiation and progress of corrosion activity under a protective coating. Using the SVET, minute variations in d.c. current associated with localized corrosion activity are detected and used to map both anodic and cathodic corrosion activities in a localized area. The difference in initial corrosion activity under various coatings can be correlated to the performance life of the coatings. The application of SVET to aircraft coatings and corrosion is reported to demonstrate the utility of this important new electrochemical tool.

In the current study, the SVET was used to discriminate the corrosion protection performance of selected sol–gel based coating systems. Sol–gel based surface treatments are being developed as part of an environmentally compliant coating system alternative to the currently used chromate-based systems. The SVET results are compared with data obtained from chromium inhibition coating systems. The SVET analyses are compared with electrochemical impedance measurements. The comparison of such data will provide the basis to adopt SVET measurements as an early performance discriminator for newly developed coating systems.     

金属件涂装前纳米级转化膜处理工艺技术

根据涂装金属的腐蚀行为分析,涂层的防腐蚀性能主要取决于涂层与基体表面的附着力。本文结合传统的磷化处理技术特征,提出了节能环保型的涂装前纳米级转化膜处理技术,分别阐述了纳米陶瓷锆盐、硅烷处理金属时在其表面形成的纳米级转化膜的处理工艺技术,研究试验结果表明,纳米级转化膜均可显著提高涂层与金属基体的附着力,其相应的耐腐蚀性能亦接近或达到了磷化处理技术要求。金属件涂装前纳米级转化膜处理技术可广泛地应用于家电、汽车、五金等领域的油漆、粉末及电泳等涂装前处理生产中。     

In situ investigation of corrosion localised at the buried interface between metal and conducting polymer based composite coatings

Conducting polymers are controversially discussed for application in corrosion protection. In our earlier work we presented a hypothesis for explaining why sometimes very good performance is observed and sometimes fast and disastrous coating break-down, especially in the presence of defects in the coating. By avoiding continuous macroscopic networks of conducting polymer in composite coatings the latter can be prevented, opening up the application of conducting polymers for secure performance in intelligent corrosion protection. In this paper we add further proof. However, at the interface between coating and metal, corrosion induced by galvanic coupling between conducting polymer and the metal still remains a problem, even in the absence of defects in the coating. Now we found that for some metals this corrosion at the buried interface can be studied in situ by Scanning Kelvin Probe microscopy, providing the means to better develop strategies for counter acting this problem.