锈层对海水淡化一级反渗透产水中碳钢腐蚀行为的影响

采用扫描电镜(SEM)、红外光谱(IR)、X射线衍射(XRD)及电化学方法研究了碳钢在海水及海水淡化一级反渗透(RO)产水中锈层形态及其电化学特性.结果表明,碳钢在两种水体中形成的锈层在结构、成分及功能上具有显著差异,导致其腐蚀情况截然不同.海水淡化一级RO产水中,腐蚀产物γ-FeOOH的还原电位高于碳钢自腐蚀电位,易被还原成Fe3O4,使锈层形成Fe3O4内层及γ-FeOOH外层的双层结构.外锈层很薄,无阻碍氧扩散作用,且因γ-FeOOH的还原加快了腐蚀反应.Fe3O4内层具有良好导电性及Fe2+传递性,使氧还原反应从金属表面转移至内锈层表面进行;同时因其大阴极作用,显著促进了氧还原过程.由于锈层的上述作用,碳钢在一级RO产水中的腐蚀得到了极大加速,其腐蚀速率最终由溶液至内锈层之间的氧极限扩散电流密度决定.防腐方法应能抑制腐蚀产物γ-FeOOH的还原.     

锈层下碳钢和耐候钢的微区和宏观腐蚀电化学行为

采用扫描电化学显微镜(SECM), 辅以极化曲线和电化学阻抗谱(EIS), 并结合SEM和XRD研究了耐候钢和碳钢在干湿交替环境下的腐蚀行为, 包括微区阳极溶解过程和阴极还原行为、 宏观腐蚀过程和微观结构及组成等. SECM测试结果表明, 锈层下碳钢和耐候钢的腐蚀过程都受阳极控制, 锈层的存在促进氧的还原. 宏观和微区电化学测试结果均表明, 在实验周期内, 初期形成的锈层降低了Fe阳极溶解速率, 从而提高碳钢和耐候钢的耐蚀性能, 后期形成的锈层由于其组成和结构特征的变化, 2种钢的腐蚀速率增加; 同时耐候钢的腐蚀速率较碳钢大, 且氧还原也较碳钢强, 有利于锈层的形成, 从而有利于长期的防护, 但是耐候钢的锈层在短期内并没有很好的保护性. 锈层不够致密, 呈疏松多孔状, 其组成主要有晶态的γ-FeOOH, Fe₃O₄和γ-Fe₂O₃等, 相同的干湿循环条件制备的耐候钢锈层较碳钢厚.     

锈层下碳钢的腐蚀电化学行为特征

采用极化曲线、线性极化电阻(LPR)和电化学阻抗(EIS)研究了海水中带锈碳钢的电化学行为,结果发现:长期浸泡的内锈层对电极过程有较大影响;短期浸泡,LPR和EIS测定的极化电阻(Rp)逐渐增大;而长期浸泡,Rp却逐渐减小;随着浸泡时间的延长,Rp出现了先增大后减小的变化趋势.将锈层逐层剥离后研究了碳钢的电化学行为,并结合傅里叶变换红外(FTIR)光谱和横截面结构分析表明,这主要是因为长期浸泡后,内锈层中出现了具有较高电化学活性的β-FeOOH,并且其含量随着浸泡时间的延长而逐渐增加.当进行电化学测试时,在对体系进行一定程度极化的过程中,β-FeOOH参与了阴极还原反应,使电极过程不再是简单的阳极金属溶解和阴极氧还原,加快了阴极反应速度,从而导致Rp逐渐减小.     

钙处理对桥梁钢耐大气腐蚀性能的影响

以NaCl+NaHSO₃溶液为腐蚀介质,采用干/湿周浸加速腐蚀实验、失重分析、XRD、SEM和电化学方法,研究了钙(Ca)处理对桥梁钢在湿热工业-海洋大气中腐蚀行为的影响. 结果表明：Ca处理前后,实验钢的腐蚀深度随时间变化曲线总体符合幂函数W=Atn分布规律,锈层主要由非晶物质和少量晶体α-FeOOH、β-FeOOH、γ-FeOOH、Fe₃O₄组成. 微量Ca能促进铁素体生成、强化钢表面保护膜,以阻止裸钢的快速腐蚀;还能细化钢组织晶粒、抑制腐蚀产物的晶体转变,以细化锈层颗粒、减少锈层缺陷产生,进而改善锈层的致密性.     

用丝束电极研究模拟碳化混凝土孔隙液中缓蚀剂对碳钢局部腐蚀的抑制行为

应用丝束电极(WBE)的电位/电流扫描技术, 研究了含Cl-的模拟碳化混凝土孔隙液中, Q345B碳钢局部腐蚀在空间和时间上的发生和发展特征, 同时比较了四乙烯五胺(TEPA)和亚硝酸钠缓蚀剂对局部腐蚀抑制能力的差异. 结果表明NO-2离子能快速渗透腐蚀产物层, 并抑制锈层下的碳钢活性溶解, 而乙烯胺由于在锈蚀层内的扩散速率低, 初期反而会促进锈层下的局部腐蚀, 随着烯胺分子扩散并吸附于锈蚀层/金属界面处, 碳钢活性溶解才受到抑制. 电化学阻抗谱(EIS)可反映局部腐蚀的萌发, 但难以表征缓蚀剂在碳钢表面的不均匀吸附特征. 基于丝束电极表面电位/电流分布所提出的局部腐蚀因子(LF), 可定量表征腐蚀的不均匀特征以及缓蚀剂对局部腐蚀的修复能力.     

镀锡薄钢板在功能饮料中的腐蚀行为

应用电化学阻抗谱(EIS)技术,结合扫描电镜(SEM)、能量散射X射线谱(EDS)、X射线光电子能谱(XPS)、扫描探针显微镜(SPM)等表面分析技术,研究了镀锡薄钢板在功能饮料中的腐蚀过程并探讨了腐蚀机制.结果表明:浸泡前期,EIS低频阻抗模值的增加与前31 h镀锡薄钢板表面形成的腐蚀产物膜有关;随着浸泡时间的增加,EIS低频阻抗模值有所下降,这与腐蚀产物膜的部分脱落以及暴露的基底金属碳钢的腐蚀有关.镀锡薄钢板在功能饮料中浸泡24天后其表面的腐蚀产物膜由外层的富锡层和内层的富铁层组成,XPS结果表明其成分主要是Sn(Ⅱ)/Sn(Ⅳ)与柠檬酸阴离子及Fe(Ⅲ)与柠檬酸阴离子组成的化合物,其腐蚀类型主要是功能饮料中的有机酸对镀锡薄钢板的腐蚀.     

3.5% NaCl饱和Ca(OH)2溶液中醇胺缩聚物对碳钢腐蚀的抑制

利用动电位极化, 电化学阻抗谱(EIS)和表面形貌观察方法, 并结合量子化学计算, 在3.5% NaCl饱和Ca(OH)₂ 溶液中研究探讨了山梨醇与二乙烯三胺缩聚物(SDC)对碳钢腐蚀的抑制行为. 结果表明: SDC的加入可有效降低碳钢的腐蚀电流密度, 提高碳钢的点蚀电位, 表明阻绣剂对Cl^-诱导的局部腐蚀具有良好的抑制作用, 为混合型阻锈剂; 且在所研究浓度范围内, 随添加浓度增加, 缓蚀效率提高. 化合物对碳钢腐蚀的抑制主要源自阻锈剂分子在碳钢表面的静电吸附, 且吸附遵循Langmuir等温吸附规律.     

蛋氨酸衍生物缓蚀剂的合成与性能研究

以蛋氨酸为基础通过酰胺化反应合成一种新型的蛋氨酸衍生物缓蚀剂,应用极化曲线、电化学阻抗谱图研究蛋氨酸及其衍生物在3(wt)%Na Cl溶液中对N80碳钢的缓蚀作用,利用SEM观察添加缓蚀剂过后钢片表面的腐蚀形貌,并从分子结构上探讨了缓蚀剂在碳钢表面的作用机理。结果表明,蛋氨酸及其衍生物都属于阳极型缓蚀剂,且缓蚀率随着添加浓度增加而增加,添加250mg/L蛋氨酸衍生物在3(wt)%Na Cl溶液中对N80碳钢的缓蚀率达到86.94%。相同浓度条件下蛋氨酸衍生物的缓蚀率要高于蛋氨酸,其原因是蛋氨酸衍生物分子结构中增加了吸附位点和疏水长链。     

含O2高温高压CO2环境中3Cr钢腐蚀产物膜特征

采用高温高压反应釜分别开展3Cr钢在CO2和O2共存、单独CO2和单独O2三种气体条件下的腐蚀实验,利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能量色散X射线能谱(EDS)和电化学方法研究了3Cr钢在高温高压含有O2的CO2环境中的腐蚀产物膜特征.结果表明,在含有O2的CO2的条件下,3Cr钢表面腐蚀产物膜疏松多孔,主要成分为FeCO3、Fe3O4和Fe2O3,腐蚀产物中未见明显Cr元素富集,3Cr钢表现出点蚀的腐蚀形态.3Cr钢在高温高压含O2的CO2腐蚀条件下内外膜层电阻(Rf1、Rf2)和电荷传递电阻Rt均比仅含有CO2腐蚀环境的低,双电层电容(Cdl)和内外膜层电容(Cf1、Cf2)均比仅含有CO2腐蚀环境的高.含有O2的CO2条件下,其保护性显著低于单一CO2条件下形成的腐蚀产物膜.提出了在含O2的CO2气体条件下,3Cr钢表面存在由多种物质组成的腐蚀产物,这导致腐蚀产物疏松多孔,不会形成单一CO2条件下存在的显著提高腐蚀产物膜保护性的Cr(OH)3层,从而促进了3Cr钢的析氢腐蚀和酸性介质中的吸氧腐蚀的机理.     

稀土含量对1OPCuRE耐候钢耐蚀性能的影响

通过浸渍干湿循环加速腐蚀试验,采用失重法测量年蚀率,电化学方法测试极化电阻和阳极极化曲线.研究了不同稀土含量的10PCuRE耐候钢与A3钢的耐候性能,并加以分析.结果表明:10PCuRE耐候钢性能明显优于A3钢.耐候钢和A3钢经室内加速腐蚀后表面呈不同状态.耐候钢表面生成均匀美观的黄褐色锈层,显微镜下可观察到细小的球状氧化物颗粒均匀分布,而A3钢表面锈层粗糙有瘤状氧化物突起,锈层呈黑色与黄褐色不规则分布.比较样品的腐蚀率等参数可知,在较纯净的钢中含有一定量的稀土即可大大提高耐候钢的耐蚀性能.     

镀锌扁钢电力接地材料在NaCl介质中的腐蚀特性

应用极化曲线、电化学阻抗谱和中性盐雾腐蚀试验法,研究电力接地材料镀锌扁钢在5%NaCl溶液中的腐蚀行为,扫描电子显微镜（SEM）、X射线衍射仪（XRD）观察与表征镀锌扁钢样品腐蚀的表面形貌及其产物性质.结果表明,在20～60℃温度范围内,镀锌扁钢腐蚀电流随温度升高而增大,60℃时腐蚀速率达到0.8408mA.cm-2（...     

Surface Modification by Compositionally Modulated Multilayered Zn‐Fe Alloy Coatings

Compositionally modulated multilayered alloy (CMMA) coatings of Zn-Fe were developed from acid chloride baths by single bath technique. The production and properties of CMMA Zn-Fe coatings were tailored as a function of switching cathode current densities (SCCD’s) and thickness of individual layers. Corrosion rates (CR) were measured by electrochemical methods. Corrosion resistances were found to vary with SCCD’s and the number of sub layers in the deposit. SCCD’s were optimized for production of Zn-Fe CMMA electroplates showing peak performance against corrosion. The formation of discrete Zn-Fe alloy layers having different compositions in the deposits were demonstrated by scanning electron microscopy (SEM). Improvements in the corrosion resistance of multilayered alloys are due to the inherent barrier properties of CMMA coatings as evidenced by electrochemical impedance spectroscopy (EIS). Corrosion resistance afforded by Zn-Fe CMMA coatings are explained in terms of the n-type semiconductor films at the interface, supported by Mott-Schottky’s plot. It was observed that the alloy with high w(Fe) on the top showed better corrosion resistance compared to that with the less w(Fe) on top. At optimum SCCD’s of 3.0—5.5 A•dm－2, a Zn-Fe CMMA coatings with 600 sub layers showed ca. 45 times better corrosion resistance than conventional Zn-Fe alloy of the same thickness. The deposit showed no red rust even up to 1130 h in salt spray test.     

缓蚀剂对船用钢在潮湿大气中的防蚀研究

模拟 90 7A钢在海水的潮湿大气环境和表面覆有薄层缓蚀剂液膜状态下其腐蚀受抑制的情况 ,利用恒电量仪连接ACM控头 ,监测其腐蚀状态 ,结合电化学阻抗谱 (EIS)的测量 ,探讨 90 7A钢在薄层缓蚀剂液膜下的腐蚀受到抑制机理 .结果表明 :此时大气腐蚀反应已转变为阳极过程控制占优势 ,在浸润后期的EIS呈现出由腐蚀介质扩散和电化学放电混合控制特征 ,如果利用恒电量激励下的等效电路模型解析 ,则可以更清楚地获知薄层缓蚀剂液膜下金属表面膜层的信息     

EIS evaluation of protective performance and surface characterization of epoxy coating with aluminum nanoparticles after wet and dry corrosion test

The effect of addition of aluminum (Al) nanoparticles to epoxy coating on the ability to protect the carbon steel was studied by electrochemical impedance spectroscopy and focused ion beam-transmission electron microscopy. The EIS was conducted in 0.1?M NaCl solution after wet/dry cyclic corrosion test. The addition of Al nanoparticles increased the film resistance (R _f) and the charge transfer resistance (R _ct) of epoxy-coated steel. The surface analysis showed that uniform and fine Al–Fe complex oxide layers were formed acting as barrier layers that enhanced the corrosion protection of the epoxy-coated steel. It has been concluded that the Al nanoparticles had a beneficial role in improving the corrosion resistance of the epoxy-coated steel.     

Heterometallic CeIII-FeIII-salicylate networks: models for corrosion mitigation of steel surfaces by the 'green' inhibitor,Ce(salicylate)3

The syntheses and structures of the novel Ce-Fe bimetallic complexes [[Fe(sal)2(bpy)]2Ce(NO3)(H2O)3].EtOH and [[Fe(sal)2(bpy)]4Ce2(H2O)11][salH]2.EtOH.3H2O (salH2 = salicylic acid) suggest Fe(3+)-sal2- units and Ce-OC(R)O-Fe bridging contribute to the formation of corrosion inhibitive layers on steel surfaces exposed to [Ce(salH)3(H2O)].     

Mössbauer spectroscopy of corrosion products of mild steel due to microbiologically influenced corrosion

Corrosion products of mild steel exposed to four different cultures of sulfur reducing bacteria (SRB) grown in a synthetic medium have been studied by transmission Mössbauer spectroscopy (TMS). Cultures of SRB studied are two hydrogenase positive strains,Desulfovibrio desulfuricans (DD) andDesulfovibrio vulgaris (DV) and two hydrogenase negative strainsDesulfotomaculum orientis orientis (DO) andDesulfotomaculum nigrificans (DN). The corrosion products generated on the coupons as well as in the broth were studied. In all the cases, the corrosion products removed from coupons showed the presence of green rust 2 (GR2), ferrous sulfides, γ-FeOOH and superparamagnetic (SPM) α-FeOOH in different proportions. The corrosion products from the broth showed a symmetrical central doublet, which indicates the presence of γ-FeOOH and SPM α-FeOOH along with ferrous sulfides. The corrosion products from coupons suspended in sewage water also showed the presence of GR 2 and ferrous sulfides together with oxyhydroxides. FTIR spectrum supports the presence of these phases in corrosion products. The formation of GR 2 on coupons seems to be the first step for the SRB induced corrosion. The corrosion rate has been found in the order of DO>DN>DV>DD.