Effect of water-soluble chitosan on the electrochemical corrosion behaviour of mild steel

This article outlines the role of chitosan as a potent inhibitor on mild steel in 3.65% NaCl. The protective ability of chitosan was evaluated by potentiodynamic polarization (PP) mea- surements in 36.5% sodium chloride medium. The outcome of the experiment shows that mild steel in sodium chloride solution containing chitosan nanoparticles exhibit better cor- rosion protection than mild steel in NaCl solution alone because the anodic and cathodic site of the steel were blocked by chitosan nanoparticles, thereby minimising the incursion of the salt solution by forming a thin film on the mild steel surface. The inhibitive effi- ciency of chitosan nanoparticles was also studied using weight loss. The weight loss by mild steel in NaCl solution was found to be higher than those immersed in NaCl-chitosan nanoparticulate solutions. The loss in weight reduces as the concentration of chitosan nanoparticles increases, indicating the fortifying ability of chitosan nanoparticles. Results obtained show that chitosan could offer inhibition efficiency above 90%. The mixed inhibi- tion characteristic of chitosan was demonstrated by the Tafel curve. The Langmuir isotherm possesses an R 2 value of 0.9957 indicating the effectiveness of chitosan as an inhibito

Corrosion Protection Effect of Chitosan on the Performance Characteristics of A6063 Alloy

This article outlines the behaviour of water-soluble chitosan as an effective inhibitor on aluminium alloy in 3.65% NaCl at room temperature. The inhibitive ability of water-soluble chitosan was examined using electrochemical potentiodynamic polarization techniques, mass loss measurements and computational studies. The outcome of the experiment reveals that chitosan inhibited aluminium alloy in sodium chloride solution exhibits better corrosion protection than the uninhibited because chitosan nanoparticles minimize the ingression of chloride ion into the active sites of aluminium alloy by forming thin film on its surface. The losses in mass by the inhibited aluminium alloy were found to reduce as the concentration of chitosan increases. Results obtained showed that chitosan could offer inhibition efficiency above 70%. Polarization curve demonstrated that chitosan in 3.65% NaCl at room temperature acted as a mixed-type inhibitor. Adsorption of chitosan nanoparticles on the aluminium alloy was found to follow Langmuir adsorption isotherm with correlation regression coefficient (R2 ) value of 0.9961

Improved corrosion resistance of permanganate-phosphate conversion coat on steel surface by surfactants

Abstract In the present work, we studied the effect of the presence of different concentrations of each of Triton-X-100 and Tween-80 surfactants in the bath of permanganate-phosphate conversion coating (PPC) on the corrosion resistance and the microstructure of the prepared coats. The coats were investigated using a scanning electron microscope (SEM), an energy dispersive X-ray spectrometer (EDX), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization techniques. The SEM results show that, on addition of the surfactants to the PPC bath, the porosity of the coat decreases and the coating layer becomes more compact. EIS results indicated that the presence of 0.01 M Triton-X-100 or 0.01 M Tween-80 in the coating solution caused an increase in the protection efficiency of the coat up to 93.7% and 84.1%, respectively. The potentiodynamic polarization results indicated that the two surfactants mainly act as anodic inhibitors due to the adsorption of their molecules at the anodic sites of the surface of steel and retard its oxidation reaction. The EDX and XPS results confirmed the results of the other techniques. A mechanism for the role of the surfactants in the coating process was proposed using the results of XPS and the other techniques

Kinetics of oxidation of metals in the air at room temperature using EDX

The kinetics of oxidation of Zn, Cu, Ni and C. steel were studied using the surface techniques, SEM, EDX and XRD, and electrochemical impedance spectroscopy (EIS) technique. EDX results showed that the variation of weight percent oxygen (Wt% O) on the surface of the four metals with the exposure time gave the same behavior, there is an increase of Wt% O with increasing the exposure time until about 2 h followed by a plateau, then the Wt% O increases again with increasing the time of exposure than 4 h. Fitting the experimental data of the four metals to the kinetic laws of oxidation indicated that the logarithmic law was fitted in short exposure (0.5 – 4 h), however, the parabolic law was fitted in long exposure (6 – 10 h). The values of each logarithmic rate constant (kl) and parabolic rate constant (kp)for the four metals were calculated. The kinetic of oxidation of the metals under study with exposure time is confirmed utilizing XRD technique. The protective action of the air-formed oxide films was investigated by EIS technique. The electrochemical impedance spectroscopy results confirmed the EDX results

An Electrochemical Investigation in the Anticorrosive Properties of Silver Nanoparticles for the Acidic Corrosion of Aluminium#br#

采用材料失重、动电位极化和电化学交流阻抗技术，分别测试了温度为30 ℃，浓度为1.0 mol·L-1盐酸溶液中不添加和添加银纳米颗粒时铝的腐蚀速率. 结果表明，当银纳米颗粒的浓度为0.014 g·L-1时，其防护效率达96.4%. 随着银纳米颗粒的浓度增大，铝/溶液界面的双电层电容值减小，说明铝的表面发生了银纳米颗粒的吸附. 朗缪尔吸附等温方程和动力学-热力学模型均可以较好地拟合所得到的实验数据. 为了确认铝金属表面与银纳米颗粒的相互作用类型，得到了铝的零电荷电位值. 研究发现，通过扫描电子显微镜和能量散射X-射线能谱分析，并结合电化学实验后铝电极表面的外观观察，可以很好地解释材料失重和电化学测试得到的数据.The mass loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were used for the determinations of the corrosion rates for aluminium in 1.0 mol·L-1 hydrochloric acid (HCl) solutions both in the absence and presence of silver nanoparticles (SNPs) at 30 ℃. The protection efficiency was evaluated to be 96.4% for 0.014 g·L-1 of the SNPs. It has been found that the capacity of the electrical double layer at the aluminium/solution interface was decreased with increasing the concentration of the SNPs, indicating that the SNPs were adsorbed at the aluminium surface. The Langmuir adsorption isotherm and the kinetic-thermodynamic model were fitted to the experimental data. The potential of zero charge (PZC) for aluminium was determined in order to clarify the type of interaction between the metal surface and the SNPs. The experimental data obtained by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy, together with the visual inspections at the surfaces of the aluminium electrodes after the electrochemical tests, all gave very good support to those obtained by the mass loss and electrochemical measurements.This work was supported by Faculty of Science, Alexandria UniversityThis work was supported by Faculty of Science, Alexandria University作者联系地址：1. 埃及亚历山大大学理学院化学系， 易卜拉欣， 亚历山大 21321， 埃及； 2. 埃及亚历山大大学理学院生物系， 易卜拉欣， 亚历山大 21321， 埃及Author's Address: 1. Department of Chemistry, Faculty of Science, Alexandria University, Ibrahimia, P.O. Box 426, Alexandria 21321, EGYPT; 2. Department of Botany, Faculty of Science, Alexandria University, Ibrahimia, P.O. Box 426, Alexandria 21321, EGYPT通讯作者E-mail：howida_fetouh @yahoo.co