阳极氧化AZ91D镁合金在氯化钠稀溶液中的腐蚀行为

利用盐雾实验、极化曲线扫描、电化学阻抗谱和电化学噪声技术等电化学研究方法结合扫描电镜表面观测技术对AZ91D镁合金氧化膜在1%(w)氯化钠溶液中的耐蚀性能进行了评价. 结果表明, 氧化前后的镁合金腐蚀行为发生明显改变, 如未封孔的阳极氧化膜耐中性5%氯化钠盐雾试验时间超过200 h; 氧化后的镁合金自腐蚀电位明显正移, 点蚀诱导期延长; 阳极氧化膜的高频阻抗约为裸露镁合金的数千倍, 这些变化证明阳极氧化处理使镁合金获取了十分优异的耐蚀性能. 首次利用分形维数Df的变化规律初步描述氧化后AZ91D镁合金的腐蚀过程. 可以发现随着浸泡时间的延长, Df呈现出初期快速增长, 随后出现波动, 最后稍有降低的变化过程. 这种现象对应于氧化后AZ91D 镁合金在1%氯化钠溶液中腐蚀的三个阶段.     

铈、锂盐对铝阳极氧化膜的协同封闭作用

研究了铈、锂盐在铝阳极氧化膜封闭处理中的协同作用.场发射扫描电镜和X射线衍射谱对铈、锂盐协同封闭前后铝阳极氧化膜形貌和结构的研究结果表明，封闭后膜表面的孔洞消失，封闭产物分布均匀，封闭后膜仍然以非晶态形式存在.根据X射线光电子能谱的结果，封闭后的膜主要由含结晶水的Al2O3及铈、锂的混合氢氧化物组成，同时膜中还含有及封闭溶液组分中的一些阴离子.电化学阻抗谱的研究结果表明铈、锂盐协同封闭能够显著提高膜的耐蚀性能.在实验结果基础上，初步认为铈、锂盐封闭是通过生成结构紧密的封闭产物填充、覆盖膜孔，从而显著提高铝阳极氧化膜的耐蚀性能.     

Co-W合金镀层表面氧化膜在碱性体系中的电化学研究

采用电化学手段以及Mott-Schottky理论, 并结合氧化膜点缺陷模型(PDM)分析研究了Co-W合金镀层在1 mol• L^－1 NaOH溶液中表面氧化膜的半导体性质, 并分别计算出了不同W含量的Co-W合金镀层在－0.15, －0.25和－0.35 V三个不同电位下阳极氧化后氧化膜的供体密度、平带电位及氧空穴扩散系数. 结果表明, Co-W合金镀层在1 mol•L^－1 NaOH溶液中表面氧化膜的Mott-Schottky曲线线性区斜率为正, 表现出N型半导体性质|随着阳极氧化电位的升高或合金镀层W含量的降低, 氧化膜供体密度N_D逐渐增大, 导致氧化膜被破坏或发生点蚀的几率升高|随着阳极氧化电位的降低或合金镀层W含量的降低, 氧化膜平带电位呈降低趋势, 说明其耐蚀性升高|不同W含量的Co-W合金镀层在三个不同电位下阳极氧化后的氧化膜的氧空穴扩散系数为(1.543～8.533)×10^－14 cm²•s^－1.     

基于电化学噪声研究模拟海洋大气环境下304不锈钢的点蚀行为

基于电化学噪声技术建立了不锈钢海洋大气点蚀监测系统,利用该系统对处于干湿循环环境下不锈钢的点蚀行为进行监测. 使用时域谱图、时域统计、频域谱图和散粒噪声理论等分析方法对采集到的电化学噪声数据进行处理分析,并结合动电位极化法,形貌分析法共同研究不锈钢的点蚀行为. 研究结果表明,304不锈钢在模拟海洋大气环境下的点蚀行为分为钝化、亚稳态点蚀和稳态点蚀三个阶段. 在钝化阶段,电位电流噪声信号出现少量的同步异向波动,腐蚀事件发生频率高,平均电量低;在亚稳态点蚀阶段,电位电流噪声信号出现大量的同步同向波动,腐蚀事件发生频率降低,平均电量上升,通过扫描电镜观察蚀点;在稳态点蚀阶段,电位电流噪声信号不仅存在大量的同步同向波动,还出现了同步异向波动,腐蚀事件发生频率较低,平均电量大幅度上升,通过扫描电镜观察到电极表面出现小而浅的蚀点. 而动电位极化法可以证实304不锈钢点蚀的发生. 两种分析方法所得结果具有较好的一致性,证明该监测系统很好地实现了对模拟海洋大气环境下304不锈钢点蚀行为的连续监测,并能判断点蚀的发生.     

碳钢在NaNO_2-NaCl溶液中的电流波动

用动电位和恒电位极化法研究了A3碳钢在NaNO2＿NaCl溶液体系中的电流波动特征.A3钢在不含Cl-的0.1mol/LNaNO2溶液中能保持良好的钝态,当加入一定浓度的Cl-后,电流出现了明显的快速上升,再缓慢下降的波动特征,表明此时碳钢表面生成了溶解较快而再钝化相对较慢的亚稳态孔蚀.实验中可观察到因电流波动而产生的累积腐蚀损伤的蚀孔.实验表明,随着Cl-浓度的增加,出现亚稳态孔蚀的初始电位Em降低,相应的电流波动峰值增大,峰频增加;而升高电位,则电流波动的峰值和峰频也都增加,况且再钝化时间延长,由此可见电位的升高促进了亚稳态孔的溶解,并能激活更多的活性点使孔诱发速率增大.     

烯胺阻锈剂对钢筋在模拟碳化混凝土孔隙液中的点蚀抑制

通过电化学噪声(ECN)、电化学阻抗(EIS)及极化曲线研究了四乙烯五胺(TEPA)在碳化模拟混凝土孔隙液中对Q345B碳钢点蚀的抑制机理. 结果表明: 通过吸附成膜和隔离Cl^-离子对钝化膜的侵蚀, TEPA浓度升高导致碳钢点蚀电位正移. 低浓度的TEPA会造成亚稳态蚀点形核速率略微增加, 但会降低其寿命. 随着TEPA浓度增加, 噪声电阻上升, 而亚稳态蚀点寿命和平均点蚀电量则迅速下降, 表明其明显加速了亚稳态蚀点修复, 当TEPA浓度达0.10 mol·L^-1时, 噪声峰消失, 基底电流趋于零, 蚀点全面钝化. TEPA不仅能抑制Cl^-离子引起的亚稳态和稳态蚀点生长, 还可吸附于钝化膜表面, 抑制膜的均匀溶解. 形貌观察表明, 亚稳态蚀点主要在稳态蚀点周围形核和生长, 并不断为稳态蚀点所吞并, 造成碳钢表面蚀坑一般沿平面而不是垂直方式扩展.     

几种稀土盐封闭的铝阳极氧化试样的腐蚀行为

为提高铝硫酸阳极氧化膜的抗污染和防腐蚀性能，分别采用环境友好的铈盐、钇盐和镧盐溶液对阳极氧化膜进行了封闭处理。采用动电位极化法比较了不同稀土盐封闭的铝阳极氧化试样在弱酸性NaCl腐蚀介质中的电化学行为，采用扫描电子显微镜（SEM）和能量色散谱（EDS）对封闭试样腐蚀前后的表面形貌、组成进行了表征。结果表明：在腐蚀介质的侵蚀及强电化学极化条件下，铈盐和镧盐封闭的阳极氧化膜对铝基体具有较好的保护作用，而钇盐封闭膜的保护作用则较差。这种差别的主要原因是不同稀土盐封闭过程中封闭产物的析出倾向及速率不同。     

铅锑合金在硫酸溶液中的阳极膜II.电位对阳极膜生长的影响

本文使用线性电位扫描法还原预恒电位法氧化形成的阳极膜,研究电位对Pb-7Sb,Pb-7Sb-0.3Ag和Pb-5Sb-0.2As三种合金在30℃,4.5MH2SO4溶液中的阳极膜的生长速度的影响,在铅锑合金中添加银可降低合金阳极膜的生长速度,但在高电位1.4V(vs.Hg2SO4电极时,Pb-7Sb-0.3Ag合金上的PbO2膜的生长速度在上述三合金中居首,这可能是由于在银上的氧析出超电势较低的缘故,本文讨论了这种阳极膜的生长机理。     

碳钢在N-甲基二乙醇胺介质中的电化学阻抗谱研究

应用电化学阻抗谱(EIS)研究碳钢在N-甲基二乙醇胺(MDEA)介质中的腐蚀行为.实验表明,未经预阴极活化处理的碳钢表面存在氧化膜,溶解氧促使它腐蚀速率增大,经活化处理去除氧化膜后则相反.在不含热稳定性盐(HSS)的MDEA溶液中,碳钢的腐蚀性随MDEA浓度的增加呈先上升后下降趋势;而在HSS高含量的溶液中,其腐蚀性则随MDEA浓度的增加而单调下降.在含有HSS模拟溶液中,碳钢的阳极极化EIS随极化电位由低到高分别出现感抗、负阻抗以及Warburg阻抗响应等特征,对应于孔蚀、活化状态向钝化状态过渡以及进入钝化的趋势,腐蚀反应的阴极过程表现为电化学反应和扩散传质混合控制,阳极过程为电化学反应控制.     

环氧树脂涂覆LY12铝合金在NaCl溶液中的阻抗模型

分别研究了裸LY12铝合金及涂覆环氧树脂涂层后合金在3.5％NaCl溶液中的电化学阻抗谱（EIS）.结果表明,LY12铝合金在点蚀电位以下阻抗谱上出现两个容抗弧,高频段对应Cl－参与的成膜阻抗,低频段对应铝阳极溶解的电化学反应阻抗.合金发生点蚀后出现低频感抗弧.合金/电极在NaCl溶液中先发生涂层吸水,当水及O2抵达基体后建立起电化学反应界面,合金遭受腐蚀；受涂层阻挡的影响,腐蚀产物的扩散逐渐成为控制步骤；当扩散速度较慢的Cl－抵达涂层/金属界面后,与界面处聚集的腐蚀产物间发生化学反应,完成成膜过程,阻抗谱上出现盐膜的阻抗,而扩散阻抗消失.提出了不同浸泡失效阶段涂层电极体系的阻抗模型.     

Formation of artificial micro‐pits on Al alloy with the photon rupture method and the localized corrosion behavior of the formed pits

An in situ artificial micro‐pit fabrication method with an area selective electrochemical measurement technique was applied to investigate the effect of the geometry of artificially formed pits on their localized corrosion behavior in anodized 1000 series aluminum. This technique enables the fabrication of artificial micro‐pits with different aspect ratios (pit depth/pit diameter) in solutions. The aspect ratios of the fabricated artificial micro‐pits in this experiment could be varied from 0.13 to 1.83 by controlling the irradiation time of the focused pulsed YAG laser beam. By applying a constant potential to the final laser‐beam‐irradiated spot in chloride environments, localized dissolution occurred only at the laser beam irradiated area, because the anodic oxide film acted as an insulator. The corrosion current and charge increase with increasing aspect ratio at any applied potential. Copyright © 2010 John Wiley & Sons, Ltd.     

铝合金表面改性对有机涂层附着力的影响及腐蚀防护性能研究

利用电化学阻抗（EIS）、扫描微参比技术（SRET）、接触角、粗糙度、附着力、盐雾等测试方法,研究了铝合金阳极氧化与贻贝黏附蛋白（MAP）/CeO₂/硅烷γ-APS（MCA）表面复合修饰的腐蚀防护性能以及对改性聚氨酯涂层附着力和耐蚀性的影响。结果表明,MCA复合膜可抑制铝合金的腐蚀,并具有一定的自修复功能;阳极氧化和MCA表面复合修饰可为铝合金提供有效的早期腐蚀防护作用,且能提高铝合金表面粗糙度和润湿性,显著提升改性聚氨酯涂层在铝合金表面的附着力和耐蚀性,因而结合改性聚氨酯涂层和表面复合修饰可实现对铝合金长期有效的腐蚀防护。     

Effect of Aluminum Alloy Surface Modification on Adhesion of the Modified Polyurethane Coating and Its Corrosion Protective Performance北大核心CSCD

The ordinary organic coatings on aluminum alloy usually encounter a problem of low adhesion to the substrate, which results in destruction and failure of the long-term protective performance of the anticorrosion systems. The surface modification of aluminum alloy is able to enhance the adhesion of organic coating on aluminum alloys, and to improve their protective performance. In this work, a combined surface modification of anodic oxidation and mussel adhesion protein/CeO2/3-aminopropyltriethoxysilane composite film (MCA) was developed on the aluminum alloy. The adhesion of modified polyurethane coated on the treated aluminum alloy and its corrosion protective performance were evaluated comprehensively by using contact angle, adhesion strength, electrochemical impedance spectroscopy (EIS), and scanning reference electrode technique (SRET). The measurements of EIS and SRET demonstrated that the MCA composite film on anodic oxidized Al possessed self-healing function and provided effective protection against early corrosion of aluminum alloy. The pull-off test showed that both anodic oxidation treatment and MCA composite film modification were able to increase the adhesion of modified polyurethane coating on aluminum alloy, and their combined action were supposed to remarkably enhance the adhesion strength up to 17.1 MPa. The reason for the improvement of adhesion was that the anodic oxidation treatment and MCA composite film modification could improve the surface roughness of aluminum alloy, and enhance the surface wettability and surface polarity, which is beneficent to enhance the bonding of the modified polyurethane coating to aluminum alloy surface. The EIS results showed that no any corrosion occurred for the modified polyurethane coating on the treated aluminum alloy during 65 d immersion in 3.5wt.% NaCl solution. The impedance value in low frequency range of the modified polyurethane coating always maintained at a high order of magnitude on the aluminum alloy treated by anodic oxidation and MCA composite film modification, showing an excellent protective performance of the coating system. The evaluation of Neutral Salt Spray (NSS) indicated that the modified polyurethane coating on the treated aluminum alloy owned superior corrosion protection performance, and the adhesion strength remained 13.1 MPa and no any corrosion was found at the scratch locations even after 1200 h of salt spray testing. It was concluded that combination of anodic oxidation and MCA composite film were capable of significantly improving the adhesion of modified polyurethane coating on aluminum alloy and providing long-term effective corrosion protection for aluminum alloy. © 2021 Authors. All rights reserved.     

高温高浓度溴化锂溶液对低合金钢的电化学行为作用

通过电化学测式技术和化学浸泡方法 ,在高温 55%LiBr +0 .0 7mol/LLiOH溶液中研究了MoO4 2 - 对低合金钢的电化学行为作用 .结果表明 ,MoO4 2 - 作为阳极型缓蚀剂能促进钝化 ,阻滞了阳极和阴极反应 .Na2 MoO4 浓度达到 2 0 0mg/L时 ,可有效地抑制低合金钢的活性溶解 .低合金钢中添加Cr和Ni元素可改善耐蚀性能 ,而AI元素则使耐蚀性能变劣 .Mo元素参与成膜过程 ,Cr和Mo元素的协调作用 ,使A钢能在较低Na2 MoO4 浓度下进入钝态     

纯铝在一种新型碱性电解液中的腐蚀和阳极行为

通过集气、动电位极化曲线、恒流放电、扫描电镜和X射线能谱等方法研究了纯铝在含有锡酸钠的4 mol·L-1氢氧化钾的甲醇-水(甲醇和水的体积比为4:1, 下同)混合溶液中的腐蚀和阳极溶解行为. 实验结果表明, 锡酸钠的添加通过具有较高析氢过电位的金属锡在电极表面的沉积, 极大地抑制了铝在4 mol·L-1氢氧化钾的甲醇鄄水溶液中的腐蚀;而由于在锡沉积层中裂纹的出现, 导致较大浓度锡酸钠的缓蚀作用有所降低. 恒流放电结果表明, 铝在含有锡酸钠的4 mol·L-1氢氧化钾的甲醇鄄水溶液中的恒流放电性能明显改进, 而且铝阳极的放电性能随着锡酸钠含量的增大而逐渐提高. 在20 mA·cm-2的放电电流密度下, 铝阳极在含有10.0 mmol·L-1锡酸钠的电解液中显示了电位相对较低且较平坦的放电平台.     

Effect of AlSiFe on the anodizing process of 6063 aluminum

AlSiFe phase can form microscopic galvanic couples that decrease corrosion resistance of 6063 aluminum which may influence the anodizing process. Two samples of 6063 aluminum were prepared. One sample was cut along the extrusion direction of the billet, and the other was cut perpendicular to the extrusion direction. Both samples exhibited the same characteristics, except for the distribution of the second phase AlSiFe. Both samples were subjected to anodizing treatments. Comparison between anodic oxide films was performed. The microstructure of Al substrates and anodic oxide films were examined using a scanning electron microscope, an optical microscope, and a glow discharge optical emission spectrometer. Results indicated that the thicknesses and elemental distributions of the anodic oxide films were almost the same. Moreover, the second phase AlSiFe influenced the anodic oxidation process, resulting in cavities in the anodic oxide film that affected its brightness. Copyright © 2016 John Wiley & Sons, Ltd.     

Corrosion-Electrochemical Behavior of Special-Purity Aluminum and Its AK1 Alloy Alloyed with Scandium

The anodic behavior of aluminum of varied purity, the effect of scandium on the corrosion resistance of AK1 alloy based on special-purity aluminum in NaCl electrolyte solutions was studied.     

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 halides on the electrochemiluminescence of heavy metals at an aluminum electrode

The effect of halides on cathodic electrochemiluminescence spectra of mercury-like ions at an aluminum electrode is studied. A method of changing the solution in concordance with the potential change is proposed to inhibit pitting corrosion arising in the anodic oxidation of aluminum in chloride-containing solutions. This method allows tin, lead, thallium, and mercury to be rapidly determined in model solutions and seawater.