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1.
利用10 kHz下的相位角、10 kHz下的相对介电常数和对应于45°相位角的特征频率这3种EIS高频区的参数对两种环氧涂层体系在盐水浸泡+紫外照射的腐蚀条件下的失效过程进行了表征,并与涂层阻抗值进行了对比。测量结果表明,上述3种高频区参数的结果一致,都能够反映涂层性能的变化及相对优劣。当频率10 kHz处的相位角下降到40°,相对介电常数增大到40,或特征频率接近10 kHz时,所研究的两种环氧涂层体系的阻抗值都对应降低到106 Ω8226;cm2左右,涂层保护性能接近失效。由于这几种EIS高频区参数能够很快测得,因此可以利用这些参数快速评价该涂层的保护性能与失效程度。 相似文献
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Electrochemical impedance spectroscopy (EIS) and Electrochemical noise measurements (ENM) were used to evaluate protective properties of three different organic coating systems. The coatings under investigation were two-component aerospace coatings, applied on aluminum substrate. They were immersed in a 0.5 mol l−1 sodium chloride (NaCl) solution, within a controlled flow cell and were tested for 1 year.
The impedance modulus in the low frequency domain and the noise resistance were calculated and compared. From EIS data, coating capacitances and coating resistances of coating performance were estimated. The electrochemical results are in good agreement with final visual observations. The results of this study yield a performance ranking of the three different coatings. 相似文献
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采用电化学阻抗谱(EIS)研究了不同孔径环氧导静电涂层的电化学特性,获得了储油罐内防护涂层逐渐遭受破坏的电化学阻抗变化规律.结果表明,EIS谱图中10mHz频率处103~104 Ω的总阻抗值是判定环氧导静电涂层防护性能失效的依据. 相似文献
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Characterization of active pigments in damage of organic coatings on steel by means of electrochemical impedance spectroscopy 总被引:2,自引:0,他引:2
Active anticorrosive pigments are solid additives for primers which can give further protection for areas with coating damage in addition to their barrier effect. These pigments are expected to prevent corrosion of metal substrate in coating damage by build-up of permanently passive conditions at the metal surface (electrochemical protection) and/or by build-up of solid compounds which plug the coating damage (chemical protection). Electrochemical Impedance Spectroscopy (EIS) was applied to characterize the corrosion protection behaviour of alkyd primers containing different pigments. Impedance spectra were recorded in the frequency range 50 mHz f 50 kHz at the open-circuit potential as a function of the type of pigment and the exposure time in different corrosive media. In general, two different parts can be distinguished in the impedance diagrams. The higher frequency part is related to the insulating properties of the primer and the lower frequency part can be attributed to electrochemical processes taking place within the coating defects. The parameters derived from EIS results show that the low frequency data can be used for characterization of the protective properties of anticorrosive pigments in the presence of defects in organic coatings. 相似文献
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EIS法研究3种配套涂层体系的腐蚀电化学行为 总被引:3,自引:0,他引:3
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。 相似文献
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High corrosion protection of a polyaniline/organophilic montmorillonite coating for magnesium alloys
Epoxy coatings containing polyaniline (PANI) and polyaniline/organophilic montmorillonite (PANI/OMMT) powders were prepared on the surface of AZ91D magnesium alloy. The corrosion performance of the coatings was evaluated by electrochemical impedance spectroscopy (EIS) and open-circuit potential analysis in 3.5% NaCl. The results indicate that the PANI/OMMT coating retained its high corrosion protection for AZ91D magnesium alloy after 6000 h of immersion. The protective mechanism conferred by the PANI/OMMT coating was also discussed. The effects of oxygen on the protective mechanism of PANI were evaluated by EIS measurements in a 3.5% deaerated NaCl solution. 相似文献
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Study on corrosion electrochemical behavior of several different coating systems by EIS 总被引:5,自引:0,他引:5
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. 相似文献
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为了检测饮料金属包装实罐产品的腐蚀情况,研制了适用于罐体产品腐蚀监测的电化学传感器,并研究了传感器在某功能饮料中的有效测试面积。应用所研制的传感器对服役期分别为1个月、3个月,27个月,43个月(编号分别为s1,s2,s3,s4) 的四个功能饮料实罐产品进行了电化学阻抗谱(EIS)测试和电化学噪声(EN)测试。EIS结果表明,实罐s1的EIS尚未发展成为两个容抗弧的特征,涂层电阻值大于108Ω?cm2,表明涂层防护性能良好;实罐s2,s3和s4的EIS均呈现双容抗弧特征,涂层电阻值均小于108Ω?cm2,表明该有机涂层失去了防护性能。EN结果表明:s3和s4电流噪声的暂态峰的数量相比s1和s2多,幅值增大,表明局部腐蚀敏感性增加。电化学测试结果表明4个实罐的性能不同,且与服役期有关,因此所研制的传感器可以进行实罐性能检测,并为评估金属包装产品的货架寿命提供科学依据。 相似文献
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采用电化学阻抗谱(EIS)技术与局部交流阻抗技术(LEIS)研究了深海环境用重防腐环氧涂层H44-61在深海模拟环境(青岛海水,常压以及6 MPa交变压力)下的腐蚀电化学行为,探讨了交变压力对深海用涂层防护性能的影响。结果表明,涂层在6 MPa交变压力下的涂层电容较常压下高且涂层电阻较低,涂层的防护性能下降,但低频阻抗膜值均在107 Ω·cm2以上,说明涂层仍有较好的防护性能;LEIS的研究表明交变压力下人造缺陷区域的阻抗值较小,缺陷周围涂层的剥离面积较大,说明压力交变能加快电解质溶液向涂层金属界面扩散,加速涂层下金属的腐蚀过程,降低涂层的防护性能。 相似文献
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D.P. Schmidt B.A. Shaw E. Sikora W.W. Shaw L.H. Laliberte 《Progress in Organic Coatings》2006,57(4):352-364
The present investigation assessed the corrosion protection performance of 17 different Zn and Al sacrificial coating system configurations during marine atmospheric exposure at Kure Beach, NC. The coating systems incorporated several conversion coating layers, primers and organic topcoats. Visual observations and electrochemical measurements (including electrochemical impedance spectroscopy, EIS) were made on six different occasions throughout the 20-month exposure time. Milled scribes on each of the coating specimens allowed for defect protection as well as barrier protection to be investigated. A novel corrosion analysis technique utilizing a specialized conducting agar (SCAR) cell enabled impedance measurements to be made on both intact and defect areas. Visual observations, Eoc's, and EIS as a function of atmospheric exposure time provided complementary results. Impedance results were found to be useful in determining a coating's barrier protection and scribe damage analysis accurately represented defect protection. 相似文献
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The use of electrochemically synthesized polyindole (PIN) film was investigated for protective coating on 304-stainless steel (SS). Polyindole was deposited via anodic oxidation of the corresponding monomer, indole in acetonitrile (ACN) solution containing LiClO4. It provided an adherent and stable coating on SS. The corrosion performance of coated and uncoated SS was investigated in 3.5% NaCl solution using electrochemical impedance spectroscopy (EIS), anodic polarization curves and open-circuit potential–time (Eocp–t) diagrams. These tests demonstrated that PIN coating provided important barrier effect to SS for important immersion times in aggressive medium. 相似文献
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《Journal of Adhesion Science and Technology》2013,27(3):379-391
One of the most modern methods of characterizing the electrical properties of coatings is by electrochemical impedance spectroscopy (EIS). EIS can provide useful information about the transport of water and corrosive species through a coating. In this study, impedance measurements were performed in different frequency ranges at open circuit potential for an alkyd coating with TiO2 as a mineral pigment in 3% NaCl. The most probable impedance equivalent circuit method (MPI) was considered for data analysis. The interpretation of the impedance spectra permitted the determination of water permeation, the formation of blisters, swelling of the coating, and the loss of adhesion. 相似文献
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The effect of titanium oxide as an additive on the performance of a polyurethane/polysiloxane hybrid coating was characterized by an electrochemical approach. The performance evolution was quantified by exposing the hybrid coating on an aluminum substrate to NaCl solution at pH 5 over time. Real-time measurements were performed to quantify and correlate the mechanisms that occur at the coating/substrate interface. Electrochemical impedance spectroscopy (EIS) quantified the hybrid coating/substrate interface performance over the course of the 263 days of exposure, and electrically passive elements described and characterized the degradation/performance stages upon exposure to the acidic NaCl solution.The addition of TiO2 produced hydrophobicity functionality, and TiO2 acted as a physical barrier layer that influenced the initial damage stage. Different exposure times were associated the different stages of damage evolution for the hybrid coating and coating/substrate interfaces. Electrochemical testing with high-resolution techniques such as AFM (atomic force microscope) and IFM (infinite focus microscope) characterized the coating surface and the interface performance and resolved the surface and defect formation observed with different levels of TiO2 content. Of the systems tested, the system with 10 wt% TiO2 provided the best corrosion inhibition. 相似文献
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The electrochemical impedance spectroscopy (EIS) of epoxy-coated aluminum alloy LY12 has been investigated during exposure to 3.5% NaCl solution. Using the continuous simulation of EIS by expanded general electrical model, the time-dependent impedance model of the alloy/coating/solution system was deduced. The results shown that the composite electrode displayed a barrier behavior before water and oxygen penetrated to alloy base. After water and oxygen reached the base, the impedance associated with corrosion of alloy base changed with the immersion time as following: (i) active corrosion period at the beginning (double-layer capacitance, Cdl, in parallel to the charge transfer resistance of electrochemical corrosion Rct), (ii) impeding of the diffusion of corrosion production at the intermediate period as a result of the presence of coated film (a constant phase element Zdiff was additionally in series with Rct), and (iii) appearance of the characteristic impedance related to Cl− ion-participating reaction with alloy base at the later stage. From the linear part of ln Cc–t0.5 curve in the early immersion stage, the apparent diffusion coefficient of water was obtained. The diffusion coefficient of water and Cl− ion through the coating was also calculated by the required time for diffusion of permeation species through the coating to the metal interface obtained from the simulation of EIS data by which the occurrence of characteristic impedance element(s) corresponding to special species arrival can be determined. 相似文献
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Sudeshna Chaudhari 《Electrochimica acta》2007,53(2):927-933
Poly(o-ethoxyaniline) (POEA) coatings were synthesized on copper (Cu) by electrochemical polymerization of o-ethoxyaniline in aqueous salicylate solution by using cyclic voltammetry. These coatings were characterized by cyclic voltammetry, UV-vis absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The performance of POEA as protective coating against corrosion of Cu in aqueous 3% NaCl was assessed by the potentiodynamic polarization technique and electrochemical impedance spectroscopy (EIS). The results of the potentiodynamic polarization and EIS studies demonstrate that the POEA coating has ability to protect the Cu against corrosion. The corrosion potential was about 0.330 V versus SCE more positive in aqueous 3% NaCl for the POEA coated Cu than that of uncoated Cu and reduces the corrosion rate of Cu almost by a factor of 140. 相似文献
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Companies producing organic coatings for the automotive industry often need to test newly formulated products, which may have used different production or application parameters, to determine their actual behaviour before large-scale production and use of the coating. Proper choice of the test for this characterisation and the method of evaluation are critical. The results must be obtained in relatively short times so it is impracticable for manufacturers to wait for the completion of outdoor exposure tests. To reduce lead times in the development process, the use of an accelerated aging test (such as salt spray resistance) to predict durability of the coating is essential. Yet, the time needed to perform such tests is usually at least 500 h. This article proposes the use of electrochemical impedance spectroscopy (EIS) and an electrochemical test, AC/DC/AC, which consists in a combination of impedance results and cathodic polarisations, in order to optimise in a very short time the cataphoretic process parameters (mean applied voltage) and the curing temperature needed for a primer in order to obtain the maximum anticorrosion performance. Results show very good degree of concordance between the two electrochemical tests although the AC/DC/AC method is much faster. The accelerated electrochemical test lasted 24 h to differentiate anticorrosive coatings performance, while same conclusions were obtained after more than 100 days by electrolyte immersion and evaluated by EIS. 相似文献