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混合控制下腐蚀过程的电化学动力学参数测定 总被引:1,自引:0,他引:1
通过恒电量脉冲技术测定Q235碳钢在天然海水中腐蚀过程的电化学动力学参数. 分别利用不同极化幅度的恒电量瞬态响应分析获得极化电阻和Tafel斜率, 进而计算腐蚀电流icorr. 并对比了恒电量方法和考虑扩散影响的稳态极化曲线方法的测量结果. 结果表明, 采用恒电量强极化积分算法(CPSI)获得的Tafel斜率与极化曲线方法有很好的相关性. 同时, CPSI测定的阴极Tafel斜率符合氧还原反应的理论Tafel斜率值. 因此, 采用恒电量瞬态响应测量大大减小了浓差极化的影响, 有利于快速测定电荷传递和扩散传质混合控制下腐蚀过程的电化学动力学参数. 相似文献
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缓蚀剂对船用钢在潮湿大气中的防蚀研究 总被引:3,自引:1,他引:2
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 相似文献
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采用恒电流法电化学除氯处理受氯离子污染的钢筋混凝土试样,并用pH/Cl-复合探针原位检测电化学除氯过程钢筋混凝土不同位置孔隙液的氯离子含量与pH值分布,同时用线性极化曲线和交流阻抗谱图等电化学技术考察钢筋的腐蚀性能,探讨电化学除氯过程的混凝土微环境和钢筋腐蚀速率. 研究结果表明:在电化学除氯过程,混凝土孔隙液的氯离子浓度逐降,而pH值在初期略有升高,随之其pH值略降;电化学除氯施加的阴极电流,使钢筋处于阴极极化状态而得到保护;除氯停止(即退极化)后钢筋的腐蚀电位明显正移,腐蚀电流降低,极化电阻升高,表明电化学除氯能改善钢筋的腐蚀环境,降低钢筋的腐蚀速率. 相似文献
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应用电化学阻抗谱(EIS)研究环境介质中氯离子对混凝土中钢筋腐蚀行为的影响.结果表明,在测量的频率范围内,钢筋混凝土体系的阻抗谱图包含两个时间常数,分别对应于界面的双电层和钢筋表面的混凝土保护层.其低频段的半圆有些压扁,表明界面双电层的充放电行为偏离理想电容器,可归因于钢筋表面的不均一性.在浸泡后期,低频段出现拖尾,同时电荷转移电阻Rct减小了近两个数量级,这是由于钢筋表面的钝化膜已经破裂,发生活性腐蚀,况且氯离子浓度的增大加速了腐蚀发展过程.讨论了混凝土中在钢筋腐蚀发生,发展的过程中,其腐蚀电位Ecorr以及等效电路中的Rct和Warburg阻抗等元件的变化特征. 相似文献
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模拟混凝土孔隙液中D-葡萄糖酸钠复合缓蚀剂对钢筋的阻锈作用 总被引:1,自引:0,他引:1
应用电化学技术, 结合扫描电子显微镜(SEM)观测, 研究D-葡萄糖酸钠、钼酸钠和硫脲三组分复合缓蚀剂对模拟混凝土孔隙液中钢筋腐蚀行为的影响及其阻锈作用. 结果表明: 在含3.5% (w) NaCl的模拟混凝土孔隙液中, 复合缓蚀剂具有协同效应, 对钢筋有良好的阻锈作用. 当D-葡萄糖酸钠、钼酸钠和硫脲浓度分别为750、250和500 mg·L-1时, 对钢筋的缓蚀效率可达到94.5%. 应用软硬酸碱(HSAB)理论分析缓蚀机理, 可认为三组分复合缓蚀剂在钢筋表面共同形成保护膜而阻止钢筋的腐蚀. 相似文献
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应用电化学噪声技术,结合电化学阻抗谱研究了干湿循环条件下3种不同pH值的3.5%NaCl溶液中混凝土钢筋的腐蚀过程.结果表明,钢筋的腐蚀分为3个阶段:钝化膜的溶解期、腐蚀活化期和腐蚀产物的累积期.在pH1的溶液中经过30个干湿循环后主要以均匀腐蚀为主,而对pH3和pH7溶液,则主要以点蚀为主,散粒噪声分析证实了混凝土中钢筋在强酸性溶液中更容易发生腐蚀.电化学阻抗谱分析也进一步说明了混凝土中钢筋的腐蚀经历了3个阶段:第1阶段Nyquist谱图中出现两个时间常数,高频区为混凝土层的容抗性质,低频区为钢筋与混凝土界面的电荷转移电阻;第2阶段,中频区增加一个时间常数,这与腐蚀产物的累积有关;第3阶段,随着腐蚀产物向混凝土中的扩散,中频区容抗弧有所减小,特别是pH1体系,中频弧几乎消失.SEM形貌表征观察到随着溶液酸度的增加钢筋表面的锈层明显增多. 相似文献
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多个时间常数线性体系恒电量响应的频谱分析 总被引:1,自引:0,他引:1
从线性条件出发,利用拉普拉斯变换及其逆运算推导多个时间常数体系在恒电量激励条件下线性响应暂态方程,并推导出恒电量激励下Rs(C1(R1(C2(R2(C3R3)))))电路模型的极化电位响应式. 通过线性响应方程的理论验证以及与实际腐蚀体系的EIS进行对比,结果表明:对恒电量瞬态响应进行频谱分析,可以促进恒电量测量结果与EIS进行更加细致的对比验证. 对含有多时间常数的电极过程,利用阻抗拟合软件进行局部拟合,可以确定初始值的设置,以避免时域的曲线拟合时出现多种结果的局面,大大地提高了恒电量瞬态响应数据解析的准确性. 相似文献
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Corrosion of steel reinforcement is the most serious threat to the service life of modem reinforced concrete structure and the corrosion behavior of the steel reinforcement has a close dependence on the chemical environment at the steel/concrete interface. Among all the species which can affect the corrosion rate, H+ is of the greatest influence on the stability of the steel bars. However, the in-situ measurement of pH value at steel/concrete interface is still underway. In this paper fabrication of Ir oxide electrode which serves as the pH probe working at the steel/concrete interface was explored. 相似文献
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V. N. Nekrasov N. N. Batalov A. A. Lystsov M. A. Konopel’ko 《Russian Journal of Electrochemistry》2007,43(8):936-947
An extended analysis of the kinetic behavior exhibited by the hydrogen electrode in a molten carbonate electrolyte is performed by a method of mathematical modeling of relaxation processes as applied to chronoamperometric and coulostatic experiments. A set of differential equations with corresponding initial and boundary conditions, which fixes the balance of charge and substance at the electrode/electrolyte interface, is presented for several particular versions of reaction schemes and the method used for bringing the system out of equilibrium. Numerical calculations are performed and their results are compared with the experimental time dependences of the current and overvoltage obtained in chronoamperometric and coulostatic conditions, respectively. As a result, possible intervals of variations in the kinetic, adsorption, and transport parameters of the system are evaluated. The deviations of their values when using different investigation procedures and different electrode materials (gold, nickel) are discussed. To differentiate assorted reaction schemes as applied to a real electrode process of the anodic oxidation of hydrogen in a carbonate electrolyte it is necessary to expand the base of experimental material to be analyzed and the circle of procedures to be used for investigation. 相似文献
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Experimental results on the polarization resistance estimation in a three-electrode setup that consists of two carbon steel
electrodes and the silver reference electrode are presented. The corrosion rate varies with the conditions changing inside
the concrete structure due to its irregular wetting in an aqueous solution of NaCl. The change of polarization resistance
of a single steel electrode can be identified by voltage and current electrochemical noise measurements. The observed change
does not exceed the factor of a few times of the originally recognized value. The newly proposed method of electrochemical
noise analysis for monitoring of swift corrosion rate changes is presented in detail.
Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 5, pp. 611–616.
The text was submitted by the authors in English. 相似文献