Polyaniline for corrosion prevention of mild steel coupled with copper

Polyaniline emeraldine base/epoxy resin (EB/ER) coating was investigated for corrosion protection of mild steel coupled with copper in 3.5% NaCl solution. EB/ER coating with 5-10 wt% EB had long-term corrosion resistance on both uncoupled steel and copper due to the passivation effect of EB on the metal surfaces. During the 150 immersion days, the impedance at 0.1 Hz for the coating increased in the first 1-40 days and subsequently remained constant above 10⁹ Ω cm², whereas that for pure ER coating fell below 10⁶ Ω cm² after only 30 or 40 days. Immersion tests on coated steel-copper galvanic couple showed that EB/ER coating offered 100 times more protection than ER coating against steel dissolution and coating delamination on copper, which was mainly attributed to the passive metal oxide films formed by EB blocking both the anodic and cathodic reactions. Salt spray tests showed that 100 μm EB/ER coating protected steel-copper couple for at least 2000 h.     

Enhanced corrosion prevention effect of polysulfone–clay nanocomposite materials prepared by solution dispersion

A series of polymer–clay nanocomposite (PCN) materials containing polysulfone (PSF) and layered MMT clay were successfully prepared by effectively dispersing inorganic nanolayers of MMT clay in an organic PSF matrix via a solution dispersion technique. The synthesized PCN materials were subsequently investigated with a series of characterization techniques, including Fourier transform infrared (FTIR) spectroscopy, wide‐angle powder X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The prepared PCN coatings with low clay loading (1 wt %) on cold‐rolled steel (CRS) were found to be superior in corrosion prevention to those of bulk PSF, based on a series of electrochemical measurements of corrosion potential, polarization resistance, corrosion current and electrochemical impedance spectroscopy (EIS) in a 5 wt % aqueous NaCl electrolyte. The effects of material composition on the molecular barrier, mechanical strength and optical clarity of PSF and PCN materials, in the form of membranes, was also studied by molecular permeability analysis (GPA), dynamic mechanical analysis (DMA) and UV‐Visible transmission spectra, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 631–637, 2004     

Polyaniline as corrosion inhibitor for iron in acid solutions

In recent years, polymer amines have been studied as an efficient corrosion inhibitor for iron in acid media. In this article, the performance of water soluble polyaniline as corrosion inhibitor for iron in 0.5M H₂SO₄ has been evaluated by potentiodynamic polarization, linear polarization, and electrochemical impedance spectroscopy and compared with the performance of the aniline monomer. It has been found that polyaniline is an efficient inhibitor, since the maximum efficiency of 84% has been observed at a concentration of 100 ppm, whereas the monomer has accelerated the corrosion. FTIR studies have shown that the polyaniline is strongly adsorbed on the iron surface and inhibits the corrosion effectively. However, aniline has been found to improve the passivation tendency of iron at higher concentrations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2144–2153, 2006     

Zinc-rich powder coatings characterisation in artificial sea water: EIS analysis of the galvanic action

Two zinc-rich powder coatings are applied onto phosphatised steel substrate and are studied using electrochemical impedance spectroscopy (EIS). Measurements are performed before (dry experiment) and during immersion in artificial sea water. Before immersion, EIS spectra show that percolation threshold is not attained for coating A, while coating B presents an effective percolation. In this latter case, and in order to account for the distribution of the zinc particles within the coating described as isolated, semi-isolated and percolant grains, a distributed transmission line model is proposed. When panels are immersed, the model is modified due to the electrolyte penetration through the coating, in particular with the introduction of an ionic resistance. However, it is shown that EIS spectra are not significantly modified when this ionic resistance is changed.     

基于细胞阻抗传感器的腹泻性毒素检测系统设计与实现

针对海洋水产品腹泻性毒素检测问题,设计了一种新型的基于细胞阻抗传感器(ECIS)的毒素快速检测分析系统。相对于传统的毒素检测方法,该系统具有操作简便,高一致性和高通量等特点。介绍了系统的硬件设计和软件设计,通过对系统整体性能测试以及使用神经母细胞瘤细胞(Neuro-2a)对腹泻性贝毒(DSP)大田软海绵酸(OA)进行毒性检测实验,用以验证系统平台的可行性。实验结果表明,基于细胞传感器的海洋水产品腹泻性毒性检测系统具备快速,长期,无损和高通量测量的特点,为腹泻性毒素检测提供了新的平台。     

氧化亚铜纳米线的制备及其光电性能

摘要：通过电沉积法在阳极氧化铝模板中制备了Cu2O纳米线，利用X射线衍射(XRD)、扫描电子显微镜(SEM)对Cu2O纳米线的组成和形貌进行了表征，并测试了Cu2O/AAO阵列体系的光电压、交流阻抗性能。测试结果表明，制备的Cu2O纳米线的直径约120nm，长约2μm；Cu2O/AAO阵列体系在紫外灯(365nm)照射下，光电压约25mV, 阻抗值大大减小。     

An electrochemical impedance spectroscopy and scanning electron microscopy study of the influence of positive plate compression on the electrochemical behaviour of lead-acid batteries

This study has developed an electrochemical impedance spectroscopy (EIS) method for the in situ investigation of the influence of positive plate compression on the electrochemical behaviour of lead-acid batteries during charge/discharge cycling. The EIS data for a fully charged and fully discharged battery are internally consistent with the expected kinetics of a battery in the opposite states of charge, and demonstrate that EIS measurements may be recorded with a high level of reproducibility. Furthermore, this study has necessitated the development of a special cell incorporating horizontally orientated battery plates that can be subjected to elevated pressure through the stacking of lead bricks on top of the cell, as well as a physically robust reference electrode system that can withstand the application of pressure. For this purpose, a platinum-wire pseudo-reference electrode has been developed, and has been shown to exhibit sufficient electrode stability over the period of an EIS recording, enabling the measurement of reproducible and meaningful EIS data. Additionally, the influence of positive plate compression on the behaviour of the lead-acid battery has been investigated by using scanning electron microscopy (SEM). Clearly, the experimental data show that plate compression enhances significantly the kinetics and concomitant performance of the lead-acid battery, and this is related to the enhanced reactivity of the active material, as rationalized by using the agglomeration-of-spheres (AOS) model.     

Characterization of boron-doped diamond electrodes by electrochemical impedance spectroscopy

Charge transfer on boron doped diamond (BDD) electrodes was studied by cyclic voltammetry and electrochemical impedance spectroscopy. The diamond films of 5 μm thickness and boron content between 200 ppm and 3000 ppm were prepared by the hot filament CVD technique on niobium substrate and mounted in a Teflon holder as rotating disk electrodes. The electrochemical measurements were carried out in aqueous electrolyte solutions of 0.5 M Na₂ SO ₄ + 5 mM K₃[Fe(CN)₆]/K₄[Fe(CN)₆]. Significant deviation in the redox behaviour of BDD and active Pt electrodes was indicated by a shift of the peak potentials in the cyclic voltammograms with increasing sweep rate and lower limiting diffusion current densities under rotating disk conditions. In the impedance spectra an additional capacitive element appeared at high frequencies. The potential and rotation dependence of the impedance spectra can be described quantitatively in terms of a model based on diffusion controlled charge transfer on partially blocked electrode surfaces. Direct evidence for the non-homogeneous current distribution on the diamond surface was obtained by SECM measurements.     

直接和间接电合成制备出的高铁酸钾的物理和电化学性能

K2FeO4 powders were synthesized by the ex-situ and in-situ electrochemical methods, respectively, and characterized by infrared spectrum （IR）, scanning electron microscopy （SEM）, X-ray powder diffraction （XRD） and BET. Their electrochemical performances were investigated by means of galvanostatic discharge and electrochemical impedance spectroscopy （EIS）. The results of physical characterization showed that the two samples have simi- lar structural features, but their surface morphologies and oriented growth of the crystals are different, which results in smaller specific surface area and lower solubility of the ex-situ electrosynthesized K2FeO4 sample. The results of discharge experiments indicated that the ex-situ electrosythesized K2FeO4 electrode has much larger discharge capacity and lower electrode polarization than the in-situ electrosynthesized K2FeO4 electrode. It was found from the results of EIS that lower electrochemical polarization might be responsible for the improvement on the discharge performance of the ex-situ electrosynthesized K2FeO4 electrode.     

化学镀Ni-P-Cr2O3和Ni-P-SiO2复合镀层的研究

本文对化学镀镍及化学镀镍磷基质中SiO2与Cr2O3的共沉积进行了研究.微粒在不断生长的膜层中共沉积引起了新的化学复合镀层的出现,这些复合镀层许多都具有优异的耐磨及耐蚀性能.通过选取镀层合金/复合微粒/金属基体的组分可改进镀层,获得所需的性能,以满足特别的需求.在对这些复合镀层的应用需求正在迫近与增长的同时,其市场正在迅速扩张.本文开发出了一种合适的复合化学镀镍液,并通过维氏硬度法对化学复合镀镍层进行了表征.采用动电位极化及交流阻抗法测定了镀层的Taber耐磨性能及耐蚀性能.采用SEM及XRD对复合镀层的表面形貌进行了分析.