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141.
Electrochemical and Photoelectrochemical Study of Self‐assembled Monolayer of Phytic Acid on Brass 总被引:1,自引:0,他引:1
XU Qun-Jie WAN Zong-Yue ZHOU Guo-Ding YIN Ren-He CAO Wei-Min LIN Chang-Jian 《中国化学》2008,26(9):1579-1584
Phytic acid is an environment-friendly reagent for processing metals. The anticorrosion and inhibiting mechanism for phytic acid monolayers self-assembled on a brass (HSn70-1) electrode has been investigated by using electrochemical and photocurrent response methods. The electrochemical measurements indicate that phytic acid is liable to form surface complexes on the brass electrode, and the self-assembled monolayers (SAM) change the structure of the electric double-layer and shift the potential of zero charge positively. The photochemical measurement indicates that the brass electrode shows a p-type photoresponse owing to the formation of a Cu2O layer on its surface, and the presence of SAM weakens significantly the photoresponse, suggesting an excellent effect on anticorrosion, which is consistent with the EIS and polarization curve measurements. Adsorption of phytic acid was found to be typical of chemisorption, which can be reasonably described on the basis of the Langmuir isotherm. 相似文献
142.
Eckhard K Erichsen T Stratmann M Schuhmann W 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(13):3968-3976
For a better understanding of the initiation of localised corrosion, there is a need for analytical tools that are capable of imaging corrosion pits and precursor sites with high spatial resolution and sensitivity. The lateral electrochemical contrast in alternating-current scanning electrochemical microscopy (AC-SECM) has been found to be highly dependent on the frequency of the applied alternating voltage. In order to be able to obtain data with optimum contrast and high resolution, the AC frequency is swept in a full spectrum at each point in space instead of performing spatially resolved measurements at one fixed perturbation frequency. In doing so, four-dimensional data sets are acquired (4D AC-SECM). Here, we describe the instrument set-up and modus operandi, along with the first results from the imaging of corroding surfaces. Corrosion precursor sites and local defects in protective organic coatings, as well as an actively corroding pit on 304 stainless steel, have been successfully visualised. Since the lateral electrochemical contrast in these images varies with the perturbation frequency, the proposed approach constitutes an indispensable tool for obtaining optimum electrochemical contrast. 相似文献
143.
对X60管线钢在硫酸盐还原菌(SRB)和CO2共存环境中进行浸泡实验, 对浸泡不同时间后的腐蚀形态及膜层的组成进行观察和分析, 并对膜层覆盖的X60钢的腐蚀电化学参数特征进行分析. 结果表明, SRB吸附形成的微生物膜覆盖程度加大导致X60钢电位正移, 腐蚀产物FeS和FeCO3含量增加导致X60钢电位负移. X60钢表面膜层中腐蚀产物含量较低时, 仅有一个与电极电位有关的时间常数, 当膜层中腐蚀产物的含量高时, 增加了与腐蚀产物膜有关的时间常数. 在浸泡初期, 随微生物膜覆盖程度增加, X60钢的电荷传递电阻增大; 随腐蚀产物含量增加, 电荷传递电阻先下降后增大. 随浸泡时间的延长, X60钢双电层电容和膜层电容均增大. 相似文献
144.
145.
《Arabian Journal of Chemistry》2023,16(2):104515
In this work, the development of the eco-friendly comprehensive scale and corrosion inhibitor based on green polyaspartic acid (PASP) was presented. In this view, PASPG was prepared by a ring-opening graft modification reaction of polysuccinimide (PSI) with glycidyl. In addition, the molecular structure and the thermal stability of PASPG were characterized by using three different methods (FTIR, 1H NMR, and TGA). PASPG’s scale inhibition efficiency and corrosion inhibition efficiency were also evaluated, respectively. More concretely, the scale inhibition efficiency of PASPG achieved 94.6 % and 95.1 % for CaCO3 and CaSO4, respectively. With the aid of the FTIR and SEM measurement techniques, it was found that PASPG could induce the irregular growth of the CaCO3 and CaSO4 morphology and destroy the formation of crystals. On the other hand, the higher corrosion efficiency of 85.17 % was achieved by PASPG in comparison with PASP (72.53 %). PASPG is a mixed inhibitor and the adsorption of PASPG on the Q235 steel surface followed the Langmuir mono-layer adsorption isotherm. The formation of a protective film on the surface of carbon steel was proved by PASPG’s adsorption, which increased the resistance to be eroded. Thus, the surface of carbon steel can be effectively protected. The present work provides a simple and effective pathway for the synthesis of high-efficiency green scale and corrosion inhibitor, by introducing a functional group into the PASP chains. The implementation of such type of chemical modification method may also be an effective strategy for improving the efficiency of other polymers green scale and corrosion inhibitors. 相似文献
146.
Corrosion resistances of passive films on low‐Cr steel and carbon steel in simulated concrete pore solution 下载免费PDF全文
Ming Liu Xuequn Cheng Gucheng Zhao Xiaogang Li Yue Pan 《Surface and interface analysis : SIA》2016,48(9):981-989
The passive ranges of carbon steel rebar and 3Cr steel rebar in saturated Ca(OH)2‐simulated concrete pore solution with pH 12.6 were determined by means of cyclic voltammetry and potentiodynamic polarization curves. Chronopotentiometry was used to obtain steady‐state conditions for the formation of passive films on rebar samples at different anodic potentials. Electrochemical impedance spectroscopy, Mott–Schottky and X‐ray photoelectron spectrometer curves were employed to compare the formed passive films at different potentials. Additionally, cyclic polarization curves were used to compare the corrosion resistances of formed passive films on the two rebars in saturated Ca(OH)2‐simulated concrete pore solution with different concentration of Cl?. The results show that the passive ranges of the two rebars are all between ?0.15 and +0.6 V, and more stable passive films can be formed on both rebars at the anodic potential of +0.3 V. In the absence of Cl?, the stability and corrosion resistance of the passive film formed on the 3Cr rebar are better than those of CS rebar. The passive film of 3Cr steel has the relatively better pitting corrosion resistance than carbon steel in saturated Ca(OH)2‐simulated concrete pore solution that contains different concentration of Cl?. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
147.
Effect of formulation of silica‐based solution on corrosion resistance of silicate coating on hot‐dip galvanized steel 下载免费PDF全文
Shuang‐hong Zhang Gang Kong Zi‐wen Sun Chun‐shan Che Jin‐tang Lu 《Surface and interface analysis : SIA》2016,48(3):132-138
Several silica‐based solutions with 50 g/l of SiO2 were prepared from sodium silicate solutions and silica sol; the silicate conversion coatings were obtained by immersing hot‐dip galvanized steel sheets in these solutions. These solutions were characterized using high‐resolution transmission electron microscopy and 29Si nuclear magnetic resonance; the morphology of the coatings was observed by SEM and atomic force microscopy while the corrosion resistance was evaluated by electrochemical measurements as well as neutral salt spray tests. The results show that the coatings obtained from the single silica sol solution had poor adhesion and the coating obtained from the sodium silicate solution with low SiO2/Na2O molar ratio was uneven. By adding the silica sol to the silicate solution with low molar ratio, uniform coatings with better protection property were obtained. According to the results of 29Si nuclear magnetic resonance spectra, the effects of the distribution of silicate anions with various polymerization degrees in the silica‐based solutions on the microstructure and corrosion resistance of the silicate coatings are discussed. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
148.
Understanding Complex Electrochemical Impedance Spectroscopy in Corrosion Systems Using in‐situ Synchrotron Radiation Grazing Incidence X‐ray Diffraction 下载免费PDF全文
Muhammad Tanzirul Alam Emilyn Wai Lyn Chan Roland De Marco Yanliang Huang Stuart Bailey 《Electroanalysis》2016,28(9):2166-2170
The difficulty in interpreting electrochemical impedance spectroscopy (EIS) data has limited the potential of the method despite its utility as an electrochemical method for studies of electrode reactions and interfacial structures. Taking the test case of the carbon dioxide corrosion of carbon steel, in‐situ synchrotron radiation grazing incidence X‐ray diffraction (SR‐GIXRD) has been demonstrated to be a powerful technique for validating and understanding the interfacial structures associated with complex EIS data. Carbon dioxide corrosion was found to occur in several steps, which may only be surmised by EIS, but the use of SR‐GIXRD in conjunction with EIS has enabled the establishment of a link between EIS time constants and structural changes associated with the evolution of corrosion products with time. By comparison to previous studies by the authors and others in this field, this communication provides the first direct experimental evidence linking SR‐GIXRD surface compositional data to otherwise indistinctive EIS time constants. 相似文献
149.
Johannes Wandt Peter Jakes Josef Granwehr Hubert A. Gasteiger Rüdiger‐A. Eichel 《Angewandte Chemie (International ed. in English)》2016,55(24):6892-6895
Aprotic lithium–oxygen (Li–O2) batteries have attracted considerable attention in recent years owing to their outstanding theoretical energy density. A major challenge is their poor reversibility caused by degradation reactions, which mainly occur during battery charge and are still poorly understood. Herein, we show that singlet oxygen (1Δg) is formed upon Li2O2 oxidation at potentials above 3.5 V. Singlet oxygen was detected through a reaction with a spin trap to form a stable radical that was observed by time‐ and voltage‐resolved in operando EPR spectroscopy in a purpose‐built spectroelectrochemical cell. According to our estimate, a lower limit of approximately 0.5 % of the evolved oxygen is singlet oxygen. The occurrence of highly reactive singlet oxygen might be the long‐overlooked missing link in the understanding of the electrolyte degradation and carbon corrosion reactions that occur during the charging of Li–O2 cells. 相似文献
150.
Quantitative,In Situ Visualization of Metal‐Ion Dissolution and Transport Using 1H Magnetic Resonance Imaging 下载免费PDF全文
Dr. Joshua M. Bray Prof. Alison J. Davenport Prof. Karl S. Ryder Dr. Melanie M. Britton 《Angewandte Chemie (International ed. in English)》2016,55(32):9394-9397
Quantitative mapping of metal ions freely diffusing in solution is important across a diverse range of disciplines and is particularly significant for dissolution processes in batteries, metal corrosion, and electroplating/polishing of manufactured components. However, most current techniques are invasive, requiring sample extraction, insertion of an electrode, application of an electric potential or the inclusion of a molecular sensor. Thus, there is a need for techniques to visualize the distribution of metal ions non‐invasively, in situ, quantitatively, in three dimensions (3D) and in real time. Here we have used 1H magnetic resonance imaging (MRI) to make quantitative 3D maps showing evolution of the distribution of Cu2+ ions, not directly visible by MRI, during the electrodissolution of copper, with high sensitivity and spatial resolution. The images are sensitive to the speciation of copper, the depletion of dissolved O2 in the electrolyte and show the dissolution of Cu2+ ions is not uniform across the anode. 相似文献