吸氧腐蚀的实验创新设计

使用被氯化钠溶液浸湿的2片滤纸包住锌片和铜片,连接好电流表构成原电池,使学生能够直观地看到吸氧腐蚀的现象,推测出原电池正负极的电极反应原理,从而进一步理解课本中的铁的吸氧腐蚀是由于铁钉中含有碳等杂质与铁形成的微电池的电化学腐蚀原理。     

基于原理解读的铁吸氧腐蚀实验再设计

由教材中吸氧腐蚀原理的解读引发思考, 对相关铁吸氧腐蚀实验再研究, 从溶液中的氧气参与吸氧腐蚀反应的角度设计吸氧腐蚀实验器, 用数字化实验技术中的溶解氧传感器进行实验, 能直观形象地看到溶解氧参与反应, 且有电流产生, 还探究了氯化钠溶液进行实验时的最佳浓度。     

基于传感器探究酸性条件下铁的吸氧腐蚀

人教版《化学反应原理》中介绍了金属的电化学腐蚀，主要是钢铁的吸氧腐蚀和析氢腐蚀。结合教材分析铁的腐蚀原理，得出铁的析氢腐蚀会导致体系压强增大，吸氧腐蚀会导致体系溶解氧减小。据此利用压强传感器和溶解氧传感器探究酸性条件下铁的吸氧腐蚀，并设计正交实验寻找发生吸氧腐蚀的最佳条件，帮助学生进一步理解铁的吸氧腐蚀。     

铁钉锈蚀实验的新观察

常规的铁钉锈蚀反应在溶液中进行,由于扩散效应,氧化产物和还原产物很快混合,不容易观察反应过程的细节。将该反应转到含有指示剂的琼脂凝胶中进行,可以清晰地观察到金属腐蚀过程自发形成的阳极区和阴极区,结合数码设备拍摄铁钉以及铁钉与其他金属连接体的反应,能够很好地展示金属的吸氧腐蚀过程以及与之相伴的原电池结构。     

利用数字化实验系统探究铁的吸氧腐蚀实验

分析教材中铁的吸氧腐蚀实验的影响因素,围绕学生学习过程中的困惑,通过改进传统的实验方法,结合先进的数字化实验系统,运用正交试验法进行定量研究,对铁的吸氧腐蚀实验提供探究建议,从而更有效地用实验解释吸氧腐蚀的原理。     

铁的析氢腐蚀实验探究

针对析氢腐蚀实验中出现的异常现象,依据金属电化学腐蚀原理,通过实验探究确定影响析氢腐蚀实验的主要因素——氧气。在此基础之上,设计出演示吸氧腐蚀、析氢腐蚀的套管实验以及析氢腐蚀的微型化实验方案。     

数码技术在金属电化学腐蚀教学中的应用*

数码显微、延时摄影等数码技术可以应用于铁的吸氧腐蚀实验,帮助学生观察细节现象及变化过程。在“探究海洋工程中钢管桩腐蚀速率曲线的奥秘”的教学中,数码技术支持下的吸氧腐蚀实验,能促进学生构建供氧均匀和供氧不均匀2种吸氧腐蚀认知模型,达成教学目标。     

基于三重表征的实验教学——以铁的吸氧腐蚀为例

传统的铁吸氧腐蚀实验耗时长,现象不明显,课堂演示效果差。利用U型管及灵敏电流表等装置对教材中铁的吸氧腐蚀实验进行改进,并且结合原理分析完整地呈现了铁的吸氧腐蚀的宏观现象、微观本质和符号表征,丰富了学生对该部分知识的认知。研究结果表明基于三重表征的实验教学能够促进学生成绩的提高。     

铁吸氧腐蚀的实验创新

铁的吸氧腐蚀一直是化学教学中的一个难点,对正极氧气参与的电极反应学生难以理解和接受。按照人教版《化学反应原理》中铁的吸氧腐蚀实验的方案进行实验[1],5~8分钟才有明显现象;其次该实验说服力也不够强,导管中液面上升不能证明     

对铁棒腐蚀问题的探究

通过实验探究了铁棒在电解质溶液界面和液面下的腐蚀情况,结合实验现象从理论上对铁棒在电解质溶液中发生的腐蚀反应进行了阐述分析,澄清了人们对所述铁棒腐蚀现象的错误看法,对两道高考试题中的电化学腐蚀问题进行了重新认识。     

Influence of inhibitor structure and metal/solution interface on the corrosion resistance of the protected metal

Seven systems of more than 60 compounds with possible inhibiting properties are investigated. Several methods are used: electrochemical, gravimetric, XPS, and SEM analyses. The inhibition efficiency Z is related to the chemical structure of inhibitors (sequences of compounds with regard to Z are found), their electronic structure, the surface area of the inhibiting molecule, and the structure and composition of the metal/solution interface (impedance, adsorption equilibrium parameters, etc.). The most efficient of the investigated inhibitors have Z = 94–99%. Conclusions are drawn which allow identification of compounds with prognosticated inhibiting action. Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 11, pp. 1352–1364. Based on the report delivered at the 8th International Frumkin Symposium “Kinetics of the Electrode Processes,” October 18–22, 2005, Moscow. The text was submitted by the authors in English.     

Corrosion fatigue on 2024T3 and 6056T4 aluminum alloys

Fatigue corrosion phenomenon is a form of degradation that is because of the combined occurrence of a mechanical cyclical stress and a corrosive environment. Fatigue corrosion can be an issue in commercial and military aircraft, and has the potential to affect the structural integrity and the useful life of an aerostructure. Although the distinct consequences of both fatigue and corrosion have been extensively documented for aluminum alloys, their synergistic action is not completely understood and continues to be an area of considerable scientific and industrial interest. In this paper, a novel approach is proposed and applied for monitoring the electrochemical behavior of different types of aluminum alloy samples while they are subjected to fatigue loading. Cyclic load experiments were conducted on bare 2024T3 and 6056T4 aluminum alloy samples in the presence of an aggressive aerated solution of 3.5% NaCl over a range of frequencies. The R‐ratio was 0. Two different aluminum alloys have been tested in both high‐ and low‐cycle fatigue. In the former case, the maximum stress experienced by the specimen is lower than the material yield strength, which means that the average expected number of cycles to failure is high; in the latter case, the maximum stress experienced by the specimen during the test is higher than the material yield strength, which means that the average expected number of cycles to failure is low. The open circuit potential(OCP) was monitored versus time during the tests described above. The observed OCP variations are interpreted as the occurrence of corrosion during crack initiation and propagation at the air formed oxide/solution interface film. As expected, there is a more pronounced influence of corrosion at lower fatigue frequencies. Crack propagation allows bulk material to be progressively more exposed to the aggressive environment, which stimulates accelerated crack propagation, resulting in a lower fatigue resistance. Copyright © 2010 John Wiley & Sons, Ltd.     

Pitting on the 20Kh13 steel in chloride solutions

The dependences of the pitting potential, determined by potentiodynamic method, on the NaCl solution concentration, pH, and temperature are found. The repassivation potential and the induction time for the pitting under different conditions are determined. The corrosion potential and kinetic parameters of the steel dissolution in pits are measured. The corrosion current is evaluated, leading to the determination of the steel dissolution rate in pits at the corrosion potential.     

化学/电化学腐蚀法快速制备超疏水金属铝

提出一种金属铝超疏水表面的快速制作方法. 先以化学腐蚀在铝表面形成微米级粗糙结构, 再通过电化学腐蚀构筑纳米结构, 在20 min内完成了超疏水表面所需粗糙结构的制备. 这种化学腐蚀/电化学腐蚀两步法比单独化学或电化学腐蚀方法在时间上缩短了1~2个数量级, 且不受铝材晶形限制, 同时电化学腐蚀所用电流密度也降低了1个数量级, 降低了对电源设备的要求, 可望大规模应用于工业生产和其它金属的超疏水表面制备.     

利用手持技术探究铁的电化学腐蚀实验*

借助手持技术,利用电压传感器和pH传感器测定不同酸碱性环境下金属铁发生电化学腐蚀的模拟原电池电压变化情况,探究金属铁发生析氢腐蚀和吸氧腐蚀对应的pH范围,帮助学生深入理解铁的电化学腐蚀原理,感受化学定量实验的魅力。     

Sources of electrochemical noise in corroding systems

The electrochemical noise method is reasonably well established as a technique that can estimate corrosion rate through the electrochemical noise resistance or impedance. A more interesting potential application is the identification of the nature of the corrosion process. In this paper, a number of corrosion types are examined, and it is concluded that the majority constitute a form of shot noise, possibly with a superimposed baseline current. Methods by which parameters describing the shot noise process can be estimated from the measured data are presented. It appears to be feasible to extract the charge in the shot noise events, and their frequency, providing all of the anodic or cathodic current, is associated with these events. However, the analysis requires a number of assumptions that are not always valid, and these are discussed. Finally, some alternative methods that have been used to identify the type of corrosion are briefly discussed. Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 5, pp. 557–566. The text was submitted by the author in English.     

Characteristics of CO2 corrosion scale formed on P110 steel in simulant solution with saturated CO2

The SEM, X‐ray diffraction (XRD), and XPS were employed to systematically characterize the component and microstructure of the corrosion scale formed on P110 steel exposed to carbon dioxide (CO₂) environment. A loose and porous microstructure in corrosion scale was observed under turbulent flow condition for 120 h at 100 °C with a carbon dioxide partial pressure of 4 MPa in which the principal component was iron carbonate (FeCO₃), whereas at 160 °C the corrosion scale was composed mainly of FeCO₃ and a little amount of FeO(OH). In addition, complex carbonate (Mg,Fe)CO₃ was produced because some Fe positions in FeCO₃ lattice were substituted by Mg. It showed that a double‐layer structure of corrosion scale was observed at 160 °C compared with the result at 100 °C. Copyright © 2008 John Wiley & Sons, Ltd.     

A Brief Review on Fruit and Vegetable Extracts as Corrosion Inhibitors in Acidic Environments

The corrosion of metals, i.e., the initiation and acceleration of the surface deterioration of metals through an electrochemical reaction with the surrounding intrusive environment, is a global concern because of the economic and environmental impacts. Corrosion inhibitors are considered the most practical choice among the available corrosion protection techniques due to their effectiveness in terms of functionality and cost. The use of traditional and toxic corrosion inhibitors has led to environmental issues, arousing the need for green counterparts that are environmentally friendly, easily accessible, biodegradable, and cost-effective. In this review, the utilization of green corrosion inhibitors purely acquired from renewable sources is explored, with an in-depth focus on the recent advancements in the use of fruit and vegetable extracts as green corrosion inhibitors. In particular, fruits and vegetables are natural sources of various phytochemicals that exhibit key potential in corrosion inhibition. To shed light on the true potential of such extracts in the protection of steel in acidic environments, the experimental techniques involved in corrosion inhibition and the mechanism of corrosion inhibition are discussed in detail. The study highlights the potential of fruit and vegetable extracts as non-toxic, economical, and effective corrosion inhibitors in the pursuit of green chemistry. In addition to discussing and outlining the current status and opportunities for employing fruit and vegetable extracts as corrosion inhibitors, the current review outlines the challenges involved in the utilization of such extracts in corrosion inhibition.     

Analysis of pitting corrosion rate

A method for estimating pitting corrosion rate is proposed. The method is based on the analysis of anodic and cathodic voltammograms that were measured on the specimens of two types: on the test specimen coated with an oxide film, which formed under the open-circuit conditions, and on the specimen, whose surface was totally activated with aggressive ions. The use of Tafel portions of these voltammograms in various combinations enables us to estimate the corrosion potential and corrosion current for general corrosion proceeding in the induction period, for pitting corrosion at the initial stage of its development, for a highly developed pitting corrosion, when the major area of specimen surface is occupied with pits, and also in the intermediate case.     

Effect of temperature on CO2 corrosion of carbon steel

This work investigates the effect of temperature on the corrosion product layer of carbon steel exposed to a CO₂‐containing solution. The measurement techniques, such as scanning electron microscopy with energy dispersive spectrometry, X‐ray diffraction, and X‐ray photoelectron spectroscopy, were used to systematically characterize the morphology and composition of the corrosion product layer. The corrosion rates were calculated by weight loss method. The corrosion mechanisms as a function of temperature are studied and discussed. The results showed that temperature is an important factor in the corrosion rate of carbon steel. Copyright © 2009 John Wiley & Sons, Ltd.