Protection of Copper Surface Against Corrosion by Cationic Surfactant in Seawater

The protection power of the cationic surfactant decylammonium acetate (DAA) in seawater has been studied to define the perfect conditions have to be found for using it as a corrosion inhibitor for copper surface. The adsorption isotherm of this surfactant on copper surface has been determined at different interval times at 30°C. The given isotherms have, in general, similar shapes exhibiting a Languimirian L-shape. The corrosion measurement has been determined according to weight loss method. The study declines that cationic DAA, in seawater, protects well the copper surface against corrosion when added with low concentrations, while high concentrations show bad inhibition efficiency. ICP spectroscopic analysis assures this result where high Cu% has been obtained in the presence of high DAA concentration.     

氯离子对铜或黄铜表面膜半导体性质的影响

Di Quarto等对Cu在弱酸性溶液中氧化膜层的光电化学进行了较为广泛的研究.关于Cl~-离子的影响,他们认为,在低浓度下([Cl~-]≤5×10~(-2)mol·L~(-1),即质量比0.0029),仅增加Cu 电极的腐蚀速度,而不影响Cu 电极表而氧化层Cu_2O 的半导体特性.但尚未见细致的工作报导:Cl~-离子浓度究竟达到多大时能对Cu 电极氧化膜层的半导体特性产生影响?我们在弱碱性溶液中逐步添加Cl~-,通过在周期性光照(14Hz)下,用锁定放大器测得的光电流i_(ph)对E 的关系,来研究Cl~-对铜或黄铜表面膜层半导体性质的影响.     

Copper corrosion in buffered and non-buffered synthetic seawater: a comparative study

The electrochemical behaviour of copper in neutral buffered and non-buffered synthetic seawater and in pure chloride solutions has been studied by cyclic voltammetry, weight loss measurements, open circuit potential and scanning electron microscopy (SEM). Values of the repassivation potentials of Cu in non-buffered and buffered synthetic seawater, at 50 mV s^–1, were 0.12 and 0.46 V vs. SCE, respectively. The sharpness, heights and location of the different peaks as well as their charges were shown to be influenced by the composition of the solution, buffering conditions, deoxygenation, polarization potential and time. High chloride concentrations lead to higher oxidation charges. The anodic and the cathodic charges were shown to increase as the chloride concentration increases. The open circuit potential transients of copper in non-deoxygenated, non-buffered synthetic seawater indicate pitting from the beginning of the exposure, while in buffered solutions the pitting appeared only after a quite long exposure period, i.e. after 40 days. Corrosion rates of Cu samples after 3 months of immersion were higher in solutions of pure chloride (0.5 M) than in synthetic seawater. After six months the differences were even more noticeable. SEM images have showed a somewhat higher density of pits on copper samples immersed in the chloride solution (0.5 M), in comparison with those in synthetic seawater.     

天然海水中聚吡咯膜的防微生物附着及防腐蚀性能

采用恒电流法在316 L不锈钢电极表面合成聚吡咯(PPy), 通过开路电位、 生物显微镜(BM)、 Tafel极化曲线及电化学交流阻抗(EIS)研究了聚吡咯防止微生物附着及防腐蚀特性. 研究表明, 沉积聚吡咯的316 L不锈钢电极浸泡在天然海水中(0~20 d), 开路电位基本保持不变, 表明电化学合成的聚吡咯膜有良好的防止微生物附着能力, 并通过生物显微镜进行了验证, 且在浸泡的过程中其腐蚀电流密度维持在10^-7 mA/cm², 表现出良好的防腐蚀特性; 浸泡50 d后, 其防腐蚀效率仍高达97.45%. 因此, 电化学合成的聚吡咯具有优异的防止微生物附着和防腐蚀特性.     

Effect of biofilm on naval steel corrosion in natural seawater

The behaviour of steel in natural environments is not only dependent on material properties and environmental aggressiveness, but also on micro-organisms which can exist within it. The electrochemical evolution of the interface formed on BV-grade A naval steel exposed to natural seawater in the presence and absence of marine micro-organisms has been studied over 30?days. The results obtained by electrochemical techniques including linear polarisation and electrochemical impedance spectroscopy revealed that a heterogeneous layer formed by a mixture of corrosion products and biofilm grew on the material surface in natural seawater, producing an increase of the corrosion rate and then a decrease in the corrosion resistance under diffusion process. In this case, the protective layer formed by the corrosion products can be subject to the localised breakdown. In sterile seawater, the formation of two layers at the metal surface generated by organic and/or inorganic compounds deposits (outer layer) and corrosion products (inner layer) is concluded. Using our experimental data, electrical models are proposed. They describe the impedance distribution for carbon steel exposed to both environments. Scanning electron microscopy, energy dispersive X-ray spectrometry analysis and optic microscope reproductions were obtained. They allowed an interpretation of the effect of the marine biofilm on the behaviour of the carbon steel in seawater.     

硝基酚类化合物在海水中的光化学氧化研究

酚类化合物尤其是硝基苯酚属于国家严格控制排放的有毒物质 .由于工业排污等原因 ,在近岸水体中能检测到许多酚类化合物 .我国胶州湾和杭州湾表层海水中酚的含量分别高达 3和 9mg/L[1] .酚的毒性会影响海水生物的生长和繁殖 ,危及人类健康 .由于硝基苯酚难于生化降解 ,因此研究其在水体中的光降解十分重要 [2～ 6 ] .文献中关于有机污染物的光化学研究大多侧重于废水处理 ,且降解方法也多采用 Ti O2 催化降解 [7,8] .对于硝基苯酚在天然水体中的光降解则知之甚少 .本文通过模拟海水条件下硝基苯酚的光化学反应及其影响因素 ,更加深入地了…     

Characterization of the patina formed on a low tin bronze exposed to aqueous hydrogen sulfide

The dark gray corrosion layer (patina) formed on the surface of a polished low tin bronze alloy following exposure to a deoxygenated and saturated aqueous solutions of H₂S has been characterized by X‐ray photoelectron spectroscopy, scanning electron microscopy‐energy dispersive spectroscopy and X‐ray diffraction. The system represents a model for bronze corrosion in reducing conditions where sulfate‐reducing bacteria in soils or deoxygenated seawater may generate H₂S during respiration. The initial surface was dominated by metallic copper together with Sn, Pb and Zn oxides and hydroxides. Surface enrichment of Pb and Zn was noted because of a smearing effect during polishing. At least some of the lead was crystalline. In contrast, the corrosion layer formed by H₂S(aq) exposure was dominated by polycrystalline Cu₂S (low and high chalcocite) and smaller concentrations of CuSO₄ · nH₂O. This surface was enriched with Zn as Zn(OH)₂. Lead was present as redeposited PbS (galena) crystallites in at least two different morphologies. Unlike bronzes exposed to oxidizing conditions, which develop protective SnO₂ layers, the H₂S(aq)‐exposed surface was considerably depleted in Sn. Copyright © 2014 John Wiley & Sons, Ltd.     

Investigation effect of benzotriazole on the corrosion of brass-MM55 alloy in artificial seawater by dynamic EIS

The electrochemical behavior of brass-MM55 alloy was studied in artificial seawater with benzotriazole by using a novel method called dynamic electrochemical impedance spectroscopy (DEIS). This method gives possibility to investigate the protection of metals in corrosive medium by using inhibitors in galvanostatic conditions for a long time. Instantaneous impedance spectra for brass-MM55 were recorded for 10 h in artificial seawater for different concentration of benzotriazole. It was found that a few hours were not enough for the accurate calculation of corrosion inhibition. Also with this method it is possible to figure out how the charge transfer resistance (R _ct) changes by the time. Usefulness of the DEIS technique in the investigation of non-stationary phenomena has been proved in the field of inhibitor research. All studies clearly show that benzotriazole inhibits the corrosion of brass-MM55 alloy in artificial seawater solution and the value of inhibition efficiency increases with increasing concentration of benzotriazole.     

金属缓蚀剂Gemini型咪唑啉双季铵盐的合成及其性能的研究

合成了系列新型咪唑啉双季铵盐阳离子缓蚀剂（S-HSJ）,研究并讨论了其在5%盐酸介质中对铜、铝等金属的缓蚀性能及缓蚀剂结构中亲油基部分碳链长度、缓蚀时间、缓蚀剂浓度等对缓蚀效果的影响。研究表明：S-HSJ系列咪唑啉双季铵盐对红铜、黄铜、铝及马口铁四种金属均表现出较传统单季铵盐与苯并三氮唑缓蚀剂好的缓蚀性能,S-HSJ-16双季铵盐添加量0.1%时缓蚀效率可达94~99%,S-HSJ与阴离子表面活性剂复配对铜腐蚀表现出明显协同效应。     

Evaluation of passive film behaviour of super austenitic stainless steels at different potential regions using dynamic electrochemical impedance spectroscopy

Potentiodynamic anodic polarisation and dynamic electrochemical impedance spectroscopic (DEIS) measurements were carried out on 316L stainless steel and alloys 926 and 31 in natural seawater in order to assess the crevice corrosion resistance. DEIS measurements were performed over a wide range of potentials covering the corrosion potential, passive region, breakdown region and dissolution region. The impedance measurements in potentiodynamic conditions clearly reveal the changes that occur in the passive layer with change in potential. The impedance spectra at different potential regions were also discussed elaborately. The surface morphology of the alloy after crevice corrosion was studied using optical microscope and atomic force microscopy.     

The biocompatibility of metal-organic framework coatings: an investigation on the stability of SURMOFs with regard to water and selected cell culture media

Highly porous thin films based on a [Cu(bdc)(2)](n) (bdc = benzene-1,4-dicarboxylic acid) metal-organic framework, MOF, grown using liquid-phase epitaxy (LPE) show remarkable stability in pure water as well as in artificial seawater. This opens the possibility to use these highly porous coatings for environmental and life science applications. Here we characterize in detail the stability of these SURMOF 2 thin films under aqueous and cell culture conditions. We find that the material degrades only very slowly in water and artificial seawater (ASW) whereas in typical cell culture media (PBS and DMEM) a rapid dissolution is observed. The release of Cu(2+) ions resulting from the dissolution of the SURMOF 2 in the liquids exhibits no adverse effect on the adhesion of fibroblasts, prototype eukaryotic cells, to the substrate and their subsequent proliferation, thus demonstrating the biocompatibility of SURMOF 2 surface coatings. Thus, the results are an important step toward application of these porous materials as a slow release matrix, for example, for pharmaceuticals and growth factors.     

Synthesis and study of polyol borates as corrosion inhibitors for steel and nonferrous metals

Interaction of sodium tetraborate with polyols, D-sorbitol and D-mannitol, in aqueous solutions was studied using the method of isomolar solutions, combined with polarimetry and conductometry. The possibility of synthesizing sodium sorbitol borate and mannitol borate with a 1: 1 component ratio was examined. The compounds obtained were tested as corrosion inhibitors for steel, copper, aluminum, and brass in an aqueous medium.     

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.     

海水超级电容溶解氧电池

以氧化处理的碳纤维刷（Carbon fibre brush,CFB）作阴极材料,提出海水超级电容溶解氧电池（Seawater battery with electrochemical capacitance, SWB-EC）概念,并制造了3台联用实海测试样机. 分别由循环伏安和稳态恒流放电方法研究了氧化处理前后的CFB和镁合金牺牲阳极的放电性能. 结果表明：氧化处理的CFB具有准电容特性,在动态海水中其氧阴极还原反应（Oxygen reduction reaction, ORR）活性比未处理的CFB有大幅度提高;镁合金牺牲阳极的开路电位为-1.74 V,工作电位高,溶解较均匀. 用以上阴、阳极材料制成3台联用样机作连续实海放电测试,经运行2个月,相关实验数据分析表明：与商品化海水电池SWB1200初步相比,该海水超级电容溶解氧电池具有更高的体积比功率密度.     

Simultaneous Determination of Pyridine-Triphenylborane Anti-Fouling Agent and Its Degradation Products in Artificial Seawater by CZE

We developed a CZE method for simultaneous determination of pyridine-triphenylborane (PTPB) anti-fouling agent and its degradation products such as diphenylborinic acid (DPB), phenylboronic acid (MPB), and phenol in artificial seawater (ASW) with no extraction procedure. The ASW samples, in which 20 % (v/v) acetonitrile was added, were injected directly into the capillary using vacuum injection. As the background electrolyte, 60 mM sodium tetraborate adjusted to pH 9.8 was used. The LODs (S/N = 3) for PTPB, DPB, MPB, and phenol were, respectively, 55, 78, 126, and 30 μg L⁻¹. The RSDs (n = 4) for analytes listed above were in the respective ranges of 2.7–5.7, 0.68–6.1, and 0.69–1.1 % for the peak area, peak height, and migration time. Simple degradation experiments were conducted to verify the usefulness of the proposed method. The PTPB samples dissolved in ASW were put in the open air, and rooms with and without light. The sample solutions were analyzed over time. We inferred that PTPB in ASW was more degraded by photolysis than by hydrolysis. The proposed CZE method has been demonstrated as a useful tool to elucidate the PTPB degradation process and its degradation products in ASW.

     

Simultaneous Determination of Pyridine-Triphenylborane Anti-Fouling Agent and Its Degradation Products in Artificial Seawater by CZE

We developed a CZE method for simultaneous determination of pyridine-triphenylborane (PTPB) anti-fouling agent and its degradation products such as diphenylborinic acid (DPB), phenylboronic acid (MPB), and phenol in artificial seawater (ASW) with no extraction procedure. The ASW samples, in which 20 % (v/v) acetonitrile was added, were injected directly into the capillary using vacuum injection. As the background electrolyte, 60 mM sodium tetraborate adjusted to pH 9.8 was used. The LODs (S/N = 3) for PTPB, DPB, MPB, and phenol were, respectively, 55, 78, 126, and 30 μg L^?1. The RSDs (n = 4) for analytes listed above were in the respective ranges of 2.7–5.7, 0.68–6.1, and 0.69–1.1 % for the peak area, peak height, and migration time. Simple degradation experiments were conducted to verify the usefulness of the proposed method. The PTPB samples dissolved in ASW were put in the open air, and rooms with and without light. The sample solutions were analyzed over time. We inferred that PTPB in ASW was more degraded by photolysis than by hydrolysis. The proposed CZE method has been demonstrated as a useful tool to elucidate the PTPB degradation process and its degradation products in ASW.     

Sliding friction and wear behaviors of plasma sprayed aluminum–bronze coating in artificial seawater

The friction and wear behaviors of plasma sprayed aluminum–bronze (CuAl) coating sliding against silicon nitride (Si₃N₄) in artificial seawater were investigated and compared with those in pure water and dry sliding. The morphologies of the worn surfaces were analyzed by three‐dimensional non‐contact surface mapping and scanning electron microscopy. Moreover, chemical states of the tribochemical products of CuAl/Si₃N₄ in seawater were characterized by X‐ray photoelectron spectroscopy. Results show that the plasma sprayed CuAl coating possessed a specific wear rate (in order of 10^?7 mm³/Nm) in seawater more than 600 times smaller than that in dry sliding due to the great alleviation in abrasion wear and splats delamination. Besides, the CuAl/Si₃N₄ had a friction coefficient of 0.06 in seawater, significantly lower and more stable than those in pure water and dry sliding. The tribochemical products of CuAl/Si₃N₄ in seawater, which were proved to be silica, alumina, and their hydrates, transformed into a loosened wear‐debris layer under the coagulation effect of the seawater and dominated the excellent lubrication state in artificial seawater. Copyright © 2014 John Wiley & Sons, Ltd.     

Layer-by-layer identification of copper alteration products in metallic works of art using the voltammetry of microparticles

An in situ technique for layer-by-layer electrochemical analysis of solid surfaces using the voltammetry of microparticles is presented. The method is based on the determination of several shape-dependent parameters for voltammetric curves recorded at a graphite pencil working electrode in contact with the sample, all immersed into aqueous electrolytes. Repetitive square wave voltammetry and sequential application of constant potential reductive steps and voltammetric scans yield discernible responses for the corrosion products distributed in stratified layers on metal-based surfaces. This methodology is applied to identify alteration products of copper and copper alloys distributed in different layers in copper coupons submitted to different corrosive treatments and a contemporary brass sculpture.     

Determination of the Speciation of Cadmium, Lead, and Copper in Seawater and the Complexing Ability of Seawater Components with Respect to Cd, Pb, and Cu

The concentrations of cadmium, lead, and copper in the water of Amur Bay were determined by anodic stripping voltammetry, and the speciation of these elements in the seawater was calculated. The predominant complexes of cadmium, lead, and copper were determined in the seawater by ion exchange under dynamic conditions. The concentrations of anionic, cationic, and neutral complexes of cadmium, lead, and copper in the seawater were calculated. The ability of seawater components to form complexes with these trace elements was assessed.     

The New-generation of Green Surfactant （Alkylpolyglucoside） as an Inhibitor to the Corrosion of 907 Steel in Seawater

Weight-loss trials and potentiodynamic polarization curves have been used to study the inhibitive properties of alkylpolyglucoside (APG) towards the 907 steel in seawater. The inhibition was different, if the length of alkyl chain APG was different. As the result, calcium gluconate, zinc sulfate and APG can protect 907 steel from being corrupted in static seawater. The compound corrosion inhibitor was found to control both the anodic process and the cathodic process.