Study of impedance model and water transport behavior of modified solvent-free epoxy anticorrosion coating by EIS

This paper studies the evolution of impedance model of 30 μm solvent-free epoxy coating on Q235 steel surface in 3.5% NaCl solution using electrochemical impedance spectroscopy. The electrochemical process of the system was divided into five stages. Water absorption occurred at the coating mainly during the early stage of immersion. In the meantime, coating resistance became smaller and coating impedance deviated from purely capacitive characteristics. After water permeated into the metal/coating interface, corrosion reaction began. During the middle stage of immersion, due to the barrier effect of the coating, the electrochemical reaction at the coating/metal interface was controlled by diffusion of corrosion products. Since the coating prepared was relatively thin, transport distance was short for water, which could easily reach the coating/metal interface. During the middle-late stage of immersion, coating peeled off from the metal surface, diffusion of water molecules gradually turned to a macroscopic infiltration process, and the coating lost its protective effect. A logarithm of coating capacitance and the square root of time showed a linear relationship in the early immersion stage, which was a typical characteristic of Fick’s diffusion. Water diffusion coefficient in the coating was calculated to be 8.23 × 10^?11 cm²/s, while volume fraction and total water absorption at saturation of coating were 3.5% and 105 μg/cm², respectively, indicating good water resistance and protective properties of the coating. By solving the Fick’s diffusion equation, the kinetic equation which described the diffusion of water in the coating and included time and location variables were obtained.     

环氧改性有机硅耐高温防腐涂料的研制

以环氧改性有机硅树脂作为漆基,制备了磷酸锌底漆、云母氧化铁中间漆以及不同颜色的面漆,研究了不同漆膜的耐热性以及以磷酸锌底漆加云母氧化铁中间漆复配不同颜色面漆所得复合涂层的耐热性和耐蚀性。结果表明,以磷酸锌底漆、云母氧化铁中间漆和氧化铬绿面漆复配所得的涂层具有较好的耐高温防腐蚀性能,该复合涂层在350°C烘烤3h后,耐冲击强度≥40kg·cm,附着力≤2级,柔韧性≤2mm。     

聚氨酯改性环氧富锌防腐涂料的制备

通过正交实验法,以涂膜的吸水率为依据,确定了制备聚氨酯改性环氧共聚物时,聚氨酯的最佳用量,适当的反应时间和反应温度,固化剂的最佳添加量;并通过浸泡腐蚀失重法,确定了锌粉的最佳含量。对涂膜进行了红外光谱、极化曲线和扫描电镜分析,对比检测了未改性环氧富锌防腐涂料、聚氨酯改性环氧富锌防腐涂料的各方面性能。结果表明,聚氨酯改性环氧富锌防腐涂料具有较高的机械强度、低吸水率、良好的附着力和耐化学腐蚀性能。     

防腐环氧树脂粘接涂层的研究进展

简要介绍了粘接涂层防腐的几种机制。从填料的发展、缓蚀剂的发展、EP(环氧树脂)基体的发展和导电EP粘接涂层的发展等方面,介绍了国内外防腐EP粘接涂层的研究进展。最后基于环保性趋势对防腐EP粘接涂层的发展方向作了展望。     

无溶剂环氧导静电涂料的研制

研制了一种无溶剂环氧导静电涂料,给出了该涂料的配方并测试了涂层性能.讨论了活性稀释剂、导电填料、颜料及浸泡介质对涂层导电率的影响.结果表明,该涂料安全环保,性能符合国标要求.     

Study on corrosion electrochemical behavior of several different coating systems by EIS

Corrosion electrochemical behavior of chlorinated rubber top coating (single-layer), inorganic zinc-rich primer/chlorinated rubber top coating (double-layers) and inorganic zinc-rich primer/epoxy middle paste/chlorinated rubber top coating (tri-layers) in 3.5 wt% NaCl solution was studied by electrochemical impedance spectroscopy (EIS). A series of impedance spectra of the three coating systems during immersion were measured; and their protective properties were compared according to the spectra. The experimental results showed that, the protective properties of the double-layers coating system were even worse than that of the single-layer coating system; and the tri-layers coating system had the best protective properties in the three coating systems; epoxy middle paste had played a very important role for protective properties of the composite coating system.     

EIS法研究3种配套涂层体系的腐蚀电化学行为

采用电化学阻抗谱(EIS)研究了由水性无机富锌底漆、环氧中间漆和氯化橡胶面漆3种涂料配套而成的3种不同涂层体系在3.5%NaCl溶液中的电化学腐蚀行为,考察了氯化橡胶面漆、水性无机富锌底漆／氯化橡胶面漆、水性无机富锌底漆／环氧中间漆／氯化橡胶面漆这3种涂层体系的阻抗谱在浸泡过程中的演化并据此比较了3种涂层体系的防护性能。结果表明,两涂层体系的防护性能比单涂层的还要差,三复合涂层体系的防护性能最好。根据涂层腐蚀电化学阻抗谱特征推测,中间漆在三复合涂层体系中起到了使底漆和面漆结合更加紧密的桥梁作用。     

环氧改性聚氨酯光固化涂料研究

采用甲苯二异氰酸酯(TDI)、聚乙二醇(PEG)、二羟甲基丙酸(DMPA)和环氧树脂合成了环氧改性水性聚氨酯乳液。该乳液由于含有不饱和双键而具有感光性能,故可用作水性紫外光固化涂料或胶粘剂的预聚物。探讨了环氧丙烯酸酯(EB)和亲水扩链剂(DMPA)的添加量对涂料和涂膜性能的影响以及光引发剂用量、中和度对光固化涂料转化率的影响。结果表明,随着EB用量的增大,涂膜的硬度、耐水性、耐溶剂性及力学性能增强,但乳液外观和稳定性变差,故适宜的环氧树脂添加量为10%;随着DMPA用量的增加,涂膜硬度、强度提高,而断裂伸长率降低,耐水性变差,故DMPA用量在6%～8%范围为宜;光固化转化率随着中和度的提高而加快,适宜的引发剂用量为3%。本品的缺点是耐汽油性不够理想。     

Protective performance of epoxy resin modified with coal tar coating studied by electrochemical impedance spectroscopy

The effect of different amounts of titanium powder, used as additive, on the protective performance in aqueous 3.5 wt.% sodium chloride solution of coal tar epoxy resin cured with polyamine has been studied by electrochemical impedance spectroscopy (EIS). In this paper, the electrochemical impedance spectra and breakpoint frequency (f_b) of the coating as a function of titanium content and immersion time, and the electrical resistance of the coating by calculating permittivity of the coating were analyzed and discussed. It is shown that EIS performance of the coating can be explained by change of the permittivity of the coating with time, and the protective performance (the protective life) is determined by the breakpoint frequency of the coating in given system.     

Evaluating water transport through high solid polyurethane coating using the EIS method

Buried pipelines are commonly coated with high solid polyurethane to prevent corrosion. The diffusion of water through the coating plays an essential role in the performance and endurance of the coating. This study focuses on the evaluation of water diffusion through polyurethane coatings. The effects of thickness and ambient temperature on water diffusion through polyurethane, which is coated on mild steel and immersed in 3.5% (weight fraction) NaCl solution, are evaluated using electrochemical impedance spectroscopy (EIS). Experimental observations clearly indicate that the water diffusion coefficient strongly depends on service temperature and the thickness of coating. Higher temperature (lower than T _g) increases water uptake of the polymer but no measurable changes were observed for the temperature change studied. EIS results show that the mechanism of corrosion does not change in the range of thicknesses and temperature investigated in this study.     

红外光谱法研究环氧类涂料对水汽的吸附

用红外光谱法研究了湿度对环氧类涂料表面吸附水汽的影响,并讨论了不同湿度对环氧类涂料和粘合剂之间的附着力的影响,为涂料的施工提供了快速质量监控的方法。     

Monitoring the degradation of a high solids epoxy coating by means of EIS and EN

This paper reports a study of the degradation processes suffered by steel samples painted with a high solid content epoxy coating. Because this coating shows a high resistance when exposed to NaCl solutions, HCl solutions were employed to accelerate the corrosion processes. Macroscopic images were used to observe the coating degradation. Then electrochemical techniques, electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) were employed to monitor the corrosion behaviour of the system studied. A close correlation was found between EIS and EN data. Several parameters were estimated using these techniques: R_po, R_ct, C_c, C_dl and Z_0.1 Hz using EIS, and R_n using EN. In addition, a new parameter estimated by means of EN was employed, Z_0.1 Hz(EN). The evolution of all these parameters with time enabled the effective monitoring of the degradation stage of the coating.     

超支化聚酯改性无溶剂环氧涂料的研制与应用

以超支化聚酯CYH-277制备了一种改性无溶剂环氧涂料.经检测,其黏度低,涂层性能良好.用它及现有的环氧清漆、水性环氧地坪底漆、硅烷分别对混凝土试块进行维修涂饰,对比了渗透深度、吸水量比、抗Cl?渗透、抗压强度等性能.结果表明,超支化聚酯改性环氧涂层渗透性好,抗吸水、抗Cl?渗透的能力突出,对混凝土基体有良好的保护作用.由于该双组分涂料活性高,适用期只有8～10 min,因此必须快混快用,优先采用枪外混合喷涂作业模式.     

Studies of the impedance models and water transport behaviors of cathodically polarized coating

Cathodic protection (CP) is usually combined with organic coatings to protect metallic structures exposed to seawater. However, the application of CP would enhance coating failure, such as cathodic delamination. To date, there has been few works characterizing the impedance models and water transport behaviors of cathodically polarized coating. In the present article, the analyses of impedance models and water uptake processes of chlorinated rubber coating subjected to various levels of cathodic protection were studied during coatings aging process by electrochemical impedance spectroscopy (EIS).Four distinguished electrical equivalent circuits (EEC) were used to fit the EIS plots of coatings without CP, while only two were employed for samples with CP. Since no corrosion was expected to take place at the metal/coating interface for sample which was polarized cathodically. Coating capacitance was used to investigate the sorption characteristic of water in coating since the increase of C_c was associated with water penetration into the coating. Compared with the sample without CP, those coating systems under CP have a smaller water diffusion coefficient and a further water uptake process after the saturation period.     

无溶剂聚氨酯改性环氧树脂隔热涂料的研制

介绍了无溶剂聚氨酯改性环氧树脂及无溶剂隔热涂料的制备方法。对树脂、涂料的热性能进行了评价。结果显示,无溶剂聚氨酯改性环氧树脂隔热涂料的拉伸强度大于10MPa,断裂伸长率大于3%,附着力大于10MPa,室温下比热容1.26kJ/(kg·K),隔热参数为0.07kg2/(m4·s),隔热效率0.175W/(m2·K),综合性能优良。     

导静电涂层的腐蚀行为探讨及对策

以电渗透现象分析导静电涂层在酸性介质中的腐蚀行为。并指出在底漆中加入锌粉，有助于改变涂层电位分布，增进涂层防腐蚀能力。     

一种水性环氧钢结构防腐涂料的制备及其性能研究

在三乙烯四胺和丁基缩水甘油醚(BGE)的反应产物中加入E-51及聚乙二醇(PEG-2000)与E-51的嵌段聚合物反应制得W220、W250、W1503种水性环氧固化剂(PEG质量分数分别为0、14%、25%)。研究了不同固化剂体系和胺氢/环氧基团比对清漆性能的影响,并设计了一种水性环氧防腐涂料配方,考察了防锈颜料配比及颜基比对涂料防腐性能的影响。结果表明:选用固化剂W250,胺氢/环氧基团物质的量比为1.1:1,涂料颜基比为1.1:1,氧化铁红与三聚磷酸铝质量比为1:1.5时,涂料的防腐性能最佳,可耐盐雾400h。     

聚天门冬氨酸酯聚脲涂层湿热失效行为的电化学

采用电化学阻抗谱研究了聚天门冬氨酸酯聚脲涂层在湿热环境作用下的失效行为,采用SEM研究了聚天门冬氨酸酯聚脲涂层失效前后表面形貌的变化。电化学研究结果表明:涂层湿热失效过程分为3个主要阶段:前期电解质在涂层中的渗透、中期基体金属腐蚀发生起始的过渡、后期基体金属的腐蚀扩展并导致涂层的失效。湿热试验中,涂层孔隙率和涂层吸水率均呈3个阶段变化,即快速增长阶段、缓慢增长阶段和稳定阶段,很好地验证了PAEP涂层湿热失效的3个过程。表面形貌研究发现,湿热试验4572 h后,涂层表面粗糙度增加,出现了裂缝等缺陷,表明涂层已经失去防护作用。     

氟硅改性无溶剂环氧涂料的制备与性能

采用甲基丙烯酸十三氟辛酯（TFM）改性氨基硅油（AS）制备氟化氨基硅油（FAS）,并用其改性环氧树脂（EP）探究氨基硅油及氟化氨基硅油添加量对环氧涂层性能的影响。本文通过红外光谱对改性结果进行表征,通过柔韧性测试、画圈附着力测试、铅笔硬度测试、耐冲击测试、热失重测试、接触角测试、紫外加速老化实验和Tafel极化曲线测试,分别评价涂层的柔韧性、附着力、硬度、耐冲击性、耐热性、疏水性、耐候性和防腐性能,通过扫描电镜对涂层断面进行分析,并通过EDS对涂层进行表面元素分析。结果表明,氟添加量为15%制备氟化氨基硅油改性环氧树脂时,氟硅改性EP涂层相对于未改性EP涂层,硬度由2H提升至3H,附着力由2级提升至1级,柔韧性由1mm提升至0.5mm,耐冲击由45cm提升至50cm,热稳定性增强,接触角由70.5°提升至123°,耐紫外老化（432h）由3级提升至1级,E_corr由-0.6187V正移至-0.1720V,I_corr由1.9858×10^-8A/cm²减小至3.7125×10^-10A/cm²。适量氟化氨基硅油的引入,显著提升了环氧涂层的机械性能、耐候性能和防腐性能。     

带环氧基丙烯酸树脂改性环氧树脂防腐涂料的性能

利用自由基聚合法合成了带环氧基丙烯酸树脂,并对其结构进行了表征,研究了引发剂和链转移剂用量对带环氧基丙烯酸树脂黏度的影响。将带环氧基丙烯酸树脂与环氧树脂按1∶9的质量比混合,复配防腐颜料及填料制备改性环氧树脂防腐涂料,并测定了其层间附着力和防腐蚀性能。结果表明:单体发生完全聚合,且聚合物带环氧基;随着引发剂和链转移剂用量的增加,带环氧基丙烯酸树脂的黏度下降;与纯环氧树脂防腐涂料相比,改性环氧树脂防腐涂料的层间附着力更高,n(MMA)∶n(BA)∶n(GMA)为6.00∶3.00∶0.475和6.00∶3.00∶1.000的涂料配方耐盐雾性和电化学阻抗更优。