恒电位组装的硫醇单层膜的电化学性质

采用恒电位组装的方法在金基底上制备了十二硫醇单层膜,用反射傅立叶红外光谱、循环伏安法和电化学阻抗谱对得到的硫醇膜进行了表征.结果表明,恒电位组装1 min即可在金基底上形成没有针孔缺陷的硫醇单层膜.随着恒电位组装时间的增加,硫醇膜上的凹陷点缺陷逐渐减少,致密程度逐渐增加.当恒电位组装时间达到5 min时,得到的硫醇膜与自组装24 h的硫醇膜具有相当的致密度和更少的凹陷点缺陷.     

水性环氧铝粉涂层/碳钢体系的腐蚀电化学行为

应用电化学阻抗谱(EIS)和扫描振动电极技术(SVET)研究了碳钢基体上含人造缺陷的水性环氧铝粉涂层浸泡在3.5%NaCl溶液中的腐蚀电化学行为.结果表明,浸泡初期,涂层缺陷处为阳极活性区,涂层阻抗随时间延长逐渐降低,活性区逐渐扩展;之后,由于腐蚀产物的自修复作用使整个涂层/金属界面电化学反应活性降低,导致涂层阻抗快速增加.浸泡后期,由于腐蚀介质渗入到涂层/基体界面,出现了更多的阳极活性区,涂层产生破坏剥离.     

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.     

阻抗谱定量分析金属/有机涂层界面粘接力

采用传输线类型的CR电路解析阻抗谱得到离散的电容参数,它们随离散特征频率变化的线性区间斜率与有机涂层/金属界面的瞬时脱层速率有关,不受缺陷位置腐蚀产物的影响,重现性好.建立了阻抗谱与粘结力的定量关系和数据处理方法,并进行了验证,说明了精度较高的原因.用硅烷直接预处理,或者磷化、热浸锌后再处理,会明显影响A3钢与环氧粉末涂层之间的粘结力.     

模拟深海压力环境下有机涂料/基底金属腐蚀电化学行为研究Ⅰ.海水压力对水在涂层中传输行为和涂层防护性能的影响

于实验室模拟深海压力环境,应用电化学阻抗谱(EIS)研究了有机涂料/基底金属的腐蚀电化学行为.分析海水压力对水在涂层中传输行为和涂层防护性能的影响.结果表明,与常压海水相比,在高压海水(3.5MPa)条件下,该涂层具有不同的电化学阻抗特征,主要表现在高压海水加快了涂层的吸水过程,增大了涂层的吸水率,从而加速了涂层的腐蚀失效过程,致使防护性能变差.     

自组装金团簇电极库仑台阶现象和电化学阻抗谱研究

采用示差脉冲伏安法研究了自组装单层保护金纳米团簇(C8AuMPC)在常温下二氯甲烷溶液中的量子化电容充电效应. 研究结果表明, 该团簇在-0.8~0.8 V 电位范围内有4 对明显的量子化电容充电峰. 同时采用电化学阻抗谱对C8AuMPC修饰金电极体系的界面结构进行了表征, 研究结果表明, MPC自组装层存在两个界面, 即金电极-MPC层界面和MPC层-溶液界面; 这两个界面的界面电容在MPC的零电荷电位(ca.-0.2 V)附近均基本保持不变, 随着电位正移或负移到一定程度, 界面电容发生变化. 进一步利用双隧道结金属岛库仑阻塞效应理论讨论了已有报道中对MPC量子化电容充电的理论分析结果, 并证明电化学阻抗谱也是研究MPC量子化电容充电效应的有效方法. 另外, 用示差脉冲伏安法及循环伏安法研究了电活性物种二茂铁对C8AuMPC量子化电容充电的影响, 发现溶液中的电活性物种对MPC层-溶液界面的电子传递的贡献可以忽略, 表明该界面的电子传递主要发生在纳米粒子之间.     

基底电位对硫醇自组装膜形成的影响

应用电位阶跃法,在不同组装电位下制备金/正十二硫醇自组装单分子膜.交流阻抗谱表征该硫醇膜的电化学性质,发现金基底的电位对硫醇自组装膜的形成有重要影响.在-0.8~-0.4 V的电位区间内,随着组装电位的增加,该自组装膜的致密性、有序性增加,缺陷减少,并于0.4 V时达到最佳.组装电位高于0.4 V,膜的致密性、有序性降低,缺陷增多.本文为硫醇及其衍生物的电位调控组装提供了重要依据.     

铁表面自组装缓蚀功能膜的电化学阻抗谱研究

在铁表面自组装十四烷基胺膜.研究该膜在0.5 mol/LH2SO4溶液中对铁的缓蚀性能.电化学阻抗谱测试表明,随着组装时间的延长,缓蚀性能也随之增强,最大缓蚀效率为68.7%.而以十二烷基硫醇和十四烷基胺修饰的混合膜则更为致密、稳定,对铁的缓蚀能力也明显优于仅以十二烷基硫醇或十四烷基胺修饰的单一膜,其缓蚀效率可提高至78.2%.     

不锈钢表面Schiff碱自组装分子膜的制备及性能

以乙二胺和乙酰丙酮为原料,在盐酸催化下合成了新的Schiff 碱化合物,其收率为73.2%。 采用红外光谱和核磁共振谱对化合物的结构进行了表征。 并将其自组装在不锈钢基体表面,利用极化曲线、电化学阻抗谱和自腐蚀电位 时间曲线进行电化学分析。 结果表明,在1 mol/L HCl中,不锈钢表面自组装分子膜能快速有效的抑制异相电子的转移,促进不锈钢表面发生钝化,减少了不锈钢基体的腐蚀。 总结了Schiff碱自组装分子膜对金属防护的效用和价值。     

WBE联合EIS技术研究缺陷涂层下金属腐蚀

用电化学阻抗谱(EIS)结合丝束电极(WBE)技术研究了缺陷涂层浸泡在3.5%(质量分数)NaCl溶液中的劣化过程.从浸泡开始到完好涂层鼓泡失效,缺陷涂层丝束电极阻抗响应一直是缺陷区电极腐蚀反应过程特征,而完好涂层的劣化过程和涂层下的腐蚀反应过程特征被"平均掉".根据电极表面的电流分布,结合阻抗谱技术实现了对表面任意局部阴极和阳极区阻抗测试.研究发现,浸泡开始时,缺陷涂层阴极电流和阳极电流均出现在缺陷区,随着腐蚀过程的发展,阳极电流仍然保持在缺陷区,但阴极电流逐渐向完好涂层下扩展.根据实验结果,对缺陷处和涂层下金属腐蚀反应发生发展的机理进行了深入讨论.     

铜电极表面硅烷膜的自组装及其性能研究

应用自组装技术在铜电极表面上制备3巯基丙基三甲氧基硅烷自组装膜.红外光谱研究该自组装膜结构,电化学方法考察3-巯基丙基三甲氧基硅烷膜在5%NaCl溶液中对铜电极的缓蚀性能.结果表明,于不同浓度的3-巯基丙基三甲氧基硅烷乙醇溶液中自组装的硅烷膜表现出较好的抗腐蚀性.     

Enhanced corrosion protection performance with MWCNT dispersed epoxy coating prepared under supercritical CO2 assistance

The corrosion protection performance of epoxy coatings could be enhanced by incorporation of nanofillers such as MWCNT. However, a homogeneous dispersion of MWCNT in epoxy polymer is still a teasing challenge. Herein, we report an environmentally benign single‐step supercritical CO₂ processing method to improve the dispersion of MWCNT in epoxy matrix in order to achieve an effective anticorrosive coating. The executed approach provides a cluster‐free uniform distribution of MWCNT in epoxy matrix as characterized with UV‐visible spectroscopy, Fourier transforms infrared spectroscopy, X‐ray diffraction, and surface analysis. The anticorrosive characteristics of MWCNT/epoxy coating were studied in NaCl as well as in photodegraded dye medium through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. We observed the remarkable corrosion of model metal substrate in photodegraded dye medium besides NaCl medium. In both mediums, the protection efficacy of MWCNT/epoxy coating was deduced from the stable impedance arcs in Nyquist plot and increased impedance modulus. The electrochemical impedance spectra were best fitted with equivalent circuits showing the higher values of pore resistance. Also, the MWCNT/epoxy coating exhibited a positive shift of corrosion potential and possessed a lower corrosion rate as compared with neat epoxy coating. More direct evidence of the excellent barrier properties for MWCNT/epoxy coating was visualized in SEM images. The obtained results implied that the superior dispersion of MWCNT into epoxy matrix significantly reduces the porosity of coating and inhibits the permeability of corrosive ions. We expect supercritical CO₂ assisted dispersion method can offer an efficient, cost‐effective, and industrially viable route to develop high performance protective coatings for varied commercialized applications.     

自组装膜修饰悬汞电极的制备及电化学特性

电子跨膜传递一直是生物能学的中心问题 ,长期以来生物学家和化学家一直为能在分子水平上研究生物膜上电子传递过程的模型体系而不懈努力．提出的模型体系有平板双分子层膜（ｐｌａｎｎｅｒｂｉｌａｙｅｒｌｉｐｉｄｍｅｍｂｒａｎｅ,ＢＬＭ）［１］、泡囊［２］、和固体支撑双分子层膜（ｓｏｌｉｄｓｕｐｐｏｒｔｅｄｂｉｌａｙｅｒｌｉｐｉｄｍｅｍｂｒａｎｅ ,Ｓ ＢＬＭ）［３］等 ,ＢＬＭ膜与实际生物膜最为相似 ,但极不稳定 ;Ｓ ＢＬＭ膜稳定性好 ,但基底不平 ,缺陷大 ,研究电子跨膜传递困难．而８０年代初 ,自组装(Ｓｅｌｆ Ａｓｓｅ…     

Preparation,Characterization, and Evaluation of the Anticorrosion Performance of Submicron/Nanocarbon from Jute Sticks

Jute stick, one of the most commonly and abundantly available agricultural waste product, was converted to a value-added submicron/nano jute carbon by using pyrolysis and high-energy ball milling techniques. The submicron/nano jute carbon was characterized using FE-SEM, TEM, EDS, XRD, XPS and Raman spectroscopy. The anticorrosive performance of the submicron/nano jute carbon was investigated through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) and salt spray techniques, on mild steel plates coated with a mixture of epoxy resin and the submicron/nano jute carbon. The electrochemical impedance of the steel coated with the composite coating was two orders of magnitudes higher than that of the specimen coated with neat epoxy. Consequently, the corrosion rate of specimens coated with composite coating was 13–20 times higher than that of steel coated with neat epoxy coating. The salt spray results also indicate an improvement in the corrosion resistance performance of the composite coating compared to the neat epoxy. The uniform distribution of the submicron/nano jute carbon particles in the epoxy resin improved the denseness of the composite coating by acting as a barrier against the diffusion of chloride, moisture, and oxygen, thus, improving the corrosion resistance of the developed coating.     

Application of Polytyramine Nanoparticles to the Corrosion Protection of Copper

Electrochemical polymerization of tyramine was achieved on copper electrode surface from tyramine in 0.3 M oxalic acid (pH=1.2) solution by using cyclic voltammetry technique. The formation of polytyramine nanoparicles (PTN) were characterized by cyclic voltammetry (CV), fourier transform infrared‐attenuated total reflectance (FTIR‐ATR) spectroscopy and scanning electron microscopy (SEM). The corrosion behavior of PTN coated copper was investigated by means of the change of open circuit potential with exposure time (E_ocp t), electrochemical impedance spectroscopy (EIS) and anodic polarization curves in 3.5 % NaCl solutions at room temperature. The obtained results showed the shift of corrosion potential toward positive values for electropolymerized copper and a significant decrease in corrosion current and corrosion rate in comparison with bare copper, so that the PTNs coating could be used as an important protection against corrosion of copper.     

Comparison between CH3(CH2)15SH and CF3(CF2)3(CH2)11SH monolayers on electrodeposited silver

In this paper, two monolayers self-assembled on a silver substrate are compared: a monolayer of n-hexadecanethiol and a monolayer of n-11-perfluorobutylundecanethiol. The protecting properties of both monolayers have been extensively studied by X-ray photoelectron spectroscopy, contact angle, polarization modulation infrared reflection absorption spectroscopy, conventional electrochemical techniques (polarization curves and electrochemical impedance spectroscopy), and scanning vibrating electrode technique. Both monolayers were successfully self-assembled but organization is slightly different, the fluorinated segment introduces small disorganization. Nevertheless, good homogeneous corrosion protection is observed for each monolayer.     

自由体积与亲水性对环氧涂层防护性能的影响

报道了涂层聚合物自由体积和亲水性对涂层腐蚀防护性能影响的初步研究结果.实验表明,相对于自由体积,树脂的亲水性是决定树脂吸水率的更主要因素.低亲水性涂层腐蚀防护性能的提高主要源自到达涂层/金属界面的水量的显著降低.但由于采用活性酯固化的环氧树脂涂层中水通道的尺寸相对较大,水合离子扩散较容易,因此该类涂层覆盖下的金属基体被润湿部分的腐蚀趋势反而较一般涂层为大.     

烯丙基硫脲和十二烷基硫醇对铜的缓蚀作用

用自组装技术在铜电极表面上制备了纯烯丙基硫服自组装膜，并以十二烷基硫 醇进一步修饰得到混合自组装膜。最后，将混合膜覆盖的铜电极浸入NaCl溶液中， 进行交流电处理，电化学交流阻抗谱和极化曲线测定表明，经过交流电处理后，在 0．5mol·dm^-3 NaCl溶液中，电荷传递电阻增大，腐蚀电流密度下降，膜的最大 覆盖度为98．6％，对金属铜腐蚀的续蚀效率为98．5％。而且，不论交流电处理与 否，混合自组装膜在较宽的电极电位范围内均表现出很强的稳定性。     

Alkanethiol-oxidized copper interface: the critical influence of concentration

In this contribution, self-assembled monolayers of n-dodecanethiol (C(12)H(25)SH) at different concentrations on polycrystalline copper have been elaborated. Using XPS, PM-IRRAS, and electrochemical methods (cyclic voltammetry curves and cathodic desorption), the effect of the C(12)H(25)SH concentration on the reduction of the oxide layer has been studied. In all cases, a monolayer of good quality has been obtained. Results provide proof that while the concentration is increased, the thickness of the oxide layer is decreased, to a point that leads to metallic copper for the higher concentration. The results presented in this publication indicate the importance of controlling the interface when forming SAMs of organothiols on oxidizable metals.     

Designing an epoxy composite coating having dual-barrier-active self-healing anti-corrosion functions using a multi-functional GO/PDA/MO nano-hybrid

The graphene oxide, functionalized with polydopamine (PDA) bio-polymers and molybdate (MO) ions, was incorporated into the epoxy coating. The FT-IR, Raman, UV-visible, XRD, and FE-SEM/EDS analyses were utilized for the GO/PDA/MO nanoparticle characterization. The sequence of inhibitors' release from the nano-hybrid and their effect on the electrochemical behavior of the steel sample was explored by the OCP, polarization, and, EIS analyses in the aquatic saline media. EIS analyses revealed inhibition efficiency of 88% for the sample immersed in the GO/PDA/MO-contained solution after 48 h immersion. The polarization results showed a 91% corrosion mitigation index for the sample submerged in the GO/PDA/MO extract-containing solution after 48 h immersion. An increase of the scratched coating Nyquist diameter, the lower corrosion product, and coating blister formation after exposure to the salt spray chamber, as well as the lower adhesion loss in the pull-off test (26%), revealed that the epoxy coating reinforced with GO/PDA/MO nano-hybrids could mitigate the mild steel corrosion by improving the barrier performance and active corrosion protection (self-healing mechanism) behavior.