A more general method for ranking the enrichment of alloying elements in passivation films

The corrosion of alloys is often characterized by an enrichment of one or other of the alloying elements within the surface oxide or even within the underlying metallic phase. For some three decades the measurement of such surface enrichment has been one of the most important contributions made by XPS to corrosion science. X‐ray photoelectron spectroscopy permits the composition of the oxide film to be distinguished from that of the metallic surface underlying the oxide so that both can be determined independently. In the mid‐1970s these measurements were crucial in showing that the selective enrichment of chromium in the electrochemical passivation of stainless steel occurred by selective dissolution of iron, and not by selective oxidation of chromium. Measurements of this type are important also in active corrosion, where there is no stable oxide film, as in studies of dealloying phenomena. The literature now contains numerous cases, many published by one of us (K.A.) based on studies of novel alloys produced in the Institute for Materials Research at Sendai. Typically, measurements are made for a series of binary compositions A_xB_y ranging from A‐rich to B‐rich alloys, in media that reflect the intended use of the alloy. The results are normally produced in the form of plots of cation composition Aⁿ⁺/(Aⁿ⁺ + B^m+) against bulk composition A/(A + B) or, in the case of dealloying, as A_surface/(A_surface + B_surface) against the bulk composition. Although graphical representation is useful in giving the full picture of the alloy's behaviour, it is not so useful in cataloguing or indexing performance. In this paper we suggest a means to give a rank or performance index as a single number that will characterize the behaviour of the alloy over a wide range of composition for a given medium or exposure condition. The rank number does not imply that any particular mechanism of enrichment is in operation; in various cases of corrosion it might occur by selective precipitation (FeOOH on steels, CuO on cupronickels), by selective dissolution (dezincification of brass) or by preferential incorporation of ions in a passivating oxide or oxyhydroxide (Cr³⁺ on stainless steels). Although the rank has no mechanistic implications, it is useful within a known class of mechanistic behaviour for indicating the magnitude of the effect and thus for enabling an XPS measurement to be indicative of wanted, or unwanted, behaviour. For example, the rank number could be useful in indicating, perhaps from a single alloy composition, whether a degree of passivation is likely to be achieved for that mix of metallic elements. Copyright © 2004 John Wiley & Sons, Ltd.     

Adsorption of organic anions on iron in aqueous solutions: An ellipsometric study

Adsorption of anions of higher aromatic amino acids on the surface of iron from aqueous solutions is studied by an ellipsometric method concurrently with electrochemical measurements. It is demonstrated that ellipsometry is an effective method for studying in situ regularities governing the adsorption of anions of organic acids on the surface of metallic electrodes. Variations of ellipsometric parameters with the adsorbate concentration make it possible to obtain adsorption isotherms and determine adsorption characteristics.     

Dynamics of lithium electrode passivation in aprotic organic electrolytes,studied by electrochemical noise method

Lithium electrode passivation is studied in different organic electrolytes, namely, 1 M LiClO₄ in 1,3-dioxolane, 1 M LiN(CF₃SO₂)₂ in 1,3-dioxolane, 1 M LiPF₆ in an ethylene carbonate-diethyl carbonate mixture, 1 M LiPF₆ in an ethylene carbonate-dimethyl carbonate mixture, using the electrochemical noise method. The dynamics of passive film formation on the lithium surface in the mentioned electrolytes that differ in their corrosivity towards lithium is followed.     

The mechanism of pulse anodic activation of iron dissolution in acid solutions

Basing on the model of spatial separation of the dissolution and passivation of hydrophilic metals, formation of stationary surface morphology during pulse anodic activation of iron dissolution in sulfuric acid solutions is analyzed.     

多功能氨基酸衍生物钝化的高性能钙钛矿太阳能电池

采用含有羧基、氨基和苯基等多官能团的氨基酸衍生物分子(Fmoc-L-异亮氨酸,Fmoc-Ile-OH)钝化钙钛矿薄膜表面缺陷。首先,该氨基酸衍生物可降低钙钛矿薄膜中PbI₂杂质含量,并提高钙钛矿薄膜的颗粒尺寸。其次,氨基酸衍生物的引入可有效改善钙钛矿薄膜的光学特性和钙钛矿/电荷传输层界面载流子输运性能。另外,经钝化处理的钙钛矿太阳能电池表现出更优的器件二极管理想因子、更低的陷阱填充极限电压和更高的载流子复合电阻,这些结果证实了Fmoc-Ile-OH可有效钝化钙钛矿薄膜表面缺陷。最后,通过工艺条件优化,制得了转化效率为21.09%的高效钙钛矿太阳能电池器件,其性能远优于对照组器件的效率(18.00%)。     

Mild steel corrosion inhibition by acid extract of leaves of Hibiscus sabdariffa as a green corrosion inhibitor and sorption behavior

A new corrosion inhibitor, namely acid extract of leaves of Hibiscus sabdariffa, has been synthesized, and its inhibiting action on the corrosion of mild steel in acidic bath (1.2 N HCl and 1.2 N H₂SO₄) has been investigated by corrosion-monitoring techniques. The results of the present study show that this compound has decent inhibiting property for mild steel corrosion in 1.2 N H₂SO₄ than 1.2 N HCl. Four sorption isotherms are tested for the data, namely Langmuir, Frumkin, Florry–Huggins, and Langmuir–Freundlich isotherms; of these the Langmuir isotherm fits the data well having correlation coefficient over 0.99 in both the acid environments.     

Electrochemical polarization and passivation of iron in acid solutions

Summary The potentiodynamic polarization of the iron electrode in sulphuric acid solutions was studied. The formation of a passivating film on the electrode upon anodic oxidation in sulphuric acid solution depends on the concentration of the acid. Addition of Cl^– ions to sulphuric acid solutions raises the current densities along both the active and passive regions. The difference between the dissolution current in halogen-containing media and solutions devoid of these ions, i. e., the enhancing effect of Cl^– ions, i, varies with the aggressive ions concentration according to log i=a ₅+b ₅ logC _agg. Organic carboxylates enhance the active dissolution of iron through their participation in the dissolution mechanism, while they inhibit pitting corrosion through competitive adsorption with Cl^– ions for adsorption sites on the metal surface.

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Elektrochemische Polarisation und Passivierung von Eisen in sauren Lösungen

Zusammenfassung Es wurde die potentiodynamische Polarisierung der Eisenelektrode in schwefelsauren Lösungen untersucht. Die Ausbildung eines passivierenden Films auf der Eisenelektrode nach der anodischen Oxidation hängt von der Säurekonzentration ab. Zugabe von Cl^–-Ionen zur Schwefelsäurelösung erhöht die Stromdichten sowohl in den aktiven als auch den passiven Bereichen. Der entsprechende Lösungsstrom mit bzw. ohne diese Ionen, also der verstärkende Effekt der Cl^–-Ionen variiert mit der Konzentration der aggressiven Ionen: log i=a ₅+b ₅ logc _agg. Organische Carboxylate verstärken die aktive Lösung von Eisen durch ihre Teilnahme am Lösungsmechanismus, andererseits inhibieren sie Narben-Korrosion, da sie mit den Cl^–-Ionen bezüglich möglicher Adsorptionsstellen an der Metalloberfläche konkurrieren.

     

Study of electropolishing inhibition of steel using natural products as a green inhibitor in ortho-phosphoric acid

ABSTRACT

Anodic inhibition of steel in 8?mol?L^?1 H₃PO₄ was investigated in the absence and presence of different concentrations of extracts of Lawsonia inermis. An experimental measurement, including galvanostatic polarization studies, was done. The anodic corrosion rate and the inhibition efficiencies of the extract were calculated. The results obtained show that the inhibition was found to increase with increasing concentration of Lawsonia inermis extract. The inhibition actions of extracts are discussed on the basis of adsorption of Lawsonia inermis at the steel surface. Theoretical fitting of different isotherms were tested to clarify the nature of adsorption. Polarization curves revealed that Lawsonia inermis inhibitor acts as a corrosion inhibitor. The activation energy (E_a) as well as other thermodynamic parameters (ΔH*, ΔS*, ΔG*) for the inhibition process were calculated. These thermodynamic parameters show strong interaction between the inhibitor and the steel surface. The scanning electron microscope analysis study confirmed the adsorption of inhibitor molecules on the steel surface. The social organization and morphology of the extract were characterized by Fourier transform infrared spectroscopy.     

药物莫西沙星对Q235钢在盐酸溶液中的缓蚀作用

为了探寻新的环境友好型缓蚀剂,采用电化学方法、失重法和量子化学计算研究了莫西沙星在1 mol/L HCl溶液中对Q235钢的缓蚀性能和缓蚀机理。结果表明,莫西沙星对Q235钢在盐酸溶液中是一种良好的以抑制阴极为主的混合抑制型缓蚀剂,缓蚀效率随其浓度的增加而增大,但随温度增加而减小,35℃下,在其浓度为200 mg/L时,缓蚀效率达90%;莫西沙星在Q235钢表面的吸附为自发过程,且符合Langmuir和El-Awady等温方程,同时,计算和讨论了相关的热力学和动力学参数。此外,采用量子化学计算对莫西沙星的缓蚀机理进行了进一步的分析,结果发现,莫西沙星的缓蚀作用由物理吸附和化学吸附共同产生。     

双溶剂法制备CuCl@MIL-101(Cr)配位型吸附剂及其脱硫性能

分别以CuCl2和维生素C为Cu(Ⅱ)源和绿色还原剂,MIL-101(Cr)为多孔载体,采用双溶剂法直接将CuCl2引入MIL-101(Cr)孔道内并全部还原成CuCl,成功实现了在金属有机骨架材料上构筑Cu(Ⅰ)活性位.结果表明,双溶剂法不会影响载体MIL-101(Cr)的结构,引入的铜物种全部被选择性地还原成CuC...     

金属络阴离子在笼形聚氨肟树脂上的吸附行为

研究了Ce（NO3）_6~3-、VO_3~-、Cr2O_7~2-、CrO_4~2-、MoO_4~2-、WO_4~2-、MnO_4~-、Fe（CN）_6~2-、Fe（CN）_6~3-、和PtCl_6~2-等金属络阴离子在笼形聚氨肟树脂（CAO）上的吸附行为。发现Ce（NO3）-6~2-离子在强酸性介质中不被CAO树脂吸附但被还原为Ce3+。其它金属络阴离子被酸处理笼形聚氨肟树脂（ACAO）所吸附，吸附容量顺序是：MnO_4~-＞Fe（CN）_6~2-＞Cr2O_7~2-＞MoO_4~2-＞PtCl_6~2-＞CrO_4~2-＞VO_3~-＞Fe（CN）_6~3-＞WO_4~2-减处理笼形聚氨肟树脂（BCAO）不吸附CrO_4~2-离子，但可吸附Cr2O_7~2-、MnO_4~2-和PtCl_6~-等离子。吸附容量顺序：MnO_4~-＞Cr2O_7~2-＞PtCl_6~2-根据吸附动力学研究结果，认为ACAO树脂通过离聚体的离子场对外来给阴离子进行多层吸附，但金属络阴离子在BCAO树脂大分子场力作用下在树脂表面形成单吸附层。     

Potential decay behavior of iron in dilute nitric acid

Potential-time decay curves were used to investigate the passivation of iron in dilute nitric acid solutions of different concentrations. The effect of sulfate ions on the decay curves was also examined. It was observed that the decay curves formed an almost flat potential segment ending after reaching the Flade potential (the potential at the end of the plateau). The duration of the plateau was a function of both the initial holding potential and the acid concentration. The addition of sulfate ions affected the decay duration without interfering with the Flade potential. This is worth noting in view of the well-known dependence of the open-circuit potential decay on both pH and on the constituents of the solution. Received: 26 February 1997 / Accepted: 14 May 1997     

Mono-Substitution of iron pentacarbonyl catalyzed by polynuclear iron carbonyl anions

The specific formation of LFe(CO)₄ (L = PPh₃, P(OPh)₃, P(OMe)₃ can be achieved by the reaction of Fe(CO)₅ with L in the presence of a catalytic amount of iron carbonyl anion. A convenient synthetic procedure was developed in which the iron carbonyl anion catalyst is generated in situ. It is shown that the mechanism does not proceed by the simple cleavage of the Fe₂(CO)₈^2? or Fe₃(CO)₁₁^2? anions, because triphenylphosphine reacts with these anions in the absence of Fe(CO)₅ to produce (PPh₃)₂Fe(CO)₃.     

微分吸附计时电位法测定痛力克

非成瘾性高效镇痛新药痛力克在硫酸底液中产生一灵敏的微分吸附计时电位溶出峰，峰电位在－１．０Ｖ。利用该峰测定痛力克的线性范围为０．０２－２．０ｍｇ／Ｌ，检测限为０．００４ｍｇ／Ｌ。用线性扫描，循环伏安等方法研究了该体系的电化学行为和电极反应机理，认为所研究体系属于有吸附性的不可逆还原过程，电极反应的电子转移数为２，参与电极反应的质子数为２。用该方法测定了片剂中痛力克的含量，结果满意。     

笼形聚偕氨肟树脂的研究──HA/ACAO对金属络阴离子的交换吸附

研究了Ce（Ⅳ）、Ⅴ（Ⅴ）、Cr（Ⅵ）、Mo（Ⅵ）、W（Ⅵ）、Mn（Ⅶ）、Fe（Ⅱ）、Fe（Ⅲ）、Pd（Ⅲ）、Pt（Ⅳ）、Ir（Ⅳ）和An（Ⅲ）等络阴离子在酸处理笼形聚偕氨后树脂（HA／ACAO）上的交换吸附行为。在酸性溶液中，Ce（Ⅳ）与HA／ACAO上的偕氨厉基及可能存在的羟肪酸基进行氧化还原反应。HA／ACAO对上述络阴离子除进行交换吸附外，也发生物理吸附。     

Ultrathin organic layers for corrosion protection

The adsorption and self-organisation process of alkyl-phosphonic acids and phosphoric acid monoalkyl esters on technical aluminium surfaces have been investigated by different surface sensible techniques: Grazing angle FT-IR- spectroscopy, angle dependent XPS and Auger- spectroscopy. The aim of these studies was to replace the present technical procedure for pretreatment of aluminum surfaces with Chromate acid in order to improve the corrosion inhibition and the coating adhesion. The ability for self-assembly is given by substances which have a surface reactive group and a long-aliphatic or aromatic spacer and a supramolecular order is built-up between these spacers. The results show that these molecules are able to adsorb spontaneously onto the aluminum surface and subsequently a structured molecular order is formed. These effects were confirmed by industrial linked adhesion and corrosion tests.     

金属有机骨架材料MOF-5上噻吩硫化物的吸附分离

将金属有机骨架材料应用于燃油深度脱硫研究。采用水热法合成了金属有机骨架材料MOF-5,利用XRD、N2吸附和SEM等技术对其结构进行了表征。通过测定固定床吸附穿透曲线,考察了模型燃油类型对MOF-5吸附分离噻吩效果的影响。结果表明,MOF-5对硫化物的吸附容量超过了文献报道;在脂肪油中其穿透容量和饱和容量质量分数分别为0.90%和1.92%,在芳香模型物质中其穿透容量和饱和容量质量分数分别为0.64%和1.72%。通过采用与活性炭分层填装吸附柱技术,解决了溶解水对脱硫的影响,为吸附脱硫技术提供了新思路。     

Infrared analysis of thin inorganic and organic films on metals

Infrared spectroscopy is shown to be an adequate method for qualitative and quantitative characterization of technical surface layers for corrosion protection. The measuring conditions for each type of sample have to be selected carefully. For the sake of reliability a certain redundancy in the evaluated data might be useful. It is the aim of this work to gather experience for routine quality control of steel and aluminium surfaces.Duridine, Granodine and Alodine used in this work are registered trademarks of Collardin GmbH     

Efficient polymer passivation of ligand‐stripped nanocrystal surfaces

Water‐dispersible, polymer‐wrapped nanocrystals are highly sought after for use in biology and chemistry, from nanomedicine to catalysis. The hydrophobicity of their native ligand shell, however, is a significant barrier to their aqueous transfer as single particles. Ligand exchange with hydrophilic small molecules or, alternatively, wrapping over native ligands with amphiphilic polymers is widely employed for aqueous transfer; however, purification can be quite cumbersome. We report here a general two‐step method whereby reactive stripping of native ligands is first carried out using trialkyloxonium salts to reveal a bare nanocrystal surface. This is followed by chemically directed immobilization of a hydrophilic polymer coating. Polyacrylic acids, with side‐chain grafts or functional end groups, were found to be extremely versatile in this regard. The resulting polymer‐wrapped nanocrystal dispersions retained much of the compact size of their bare nanocrystal precursors, highlighting the unique role of monomer side‐chain functionality to serve as effective, conformal ligation motifs. As such, they are well poised for applications where tailored chemical functionality at the nanocrystal's periphery or improved access to their surfaces is desirable. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

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.