刘英伟，张 洋
AuthorsHTML:刘英伟，张 洋
AuthorsListE:Liu Yingwei，Zhang Yang
AuthorsHTMLE:Liu Yingwei，Zhang Yang
Unit:哈尔滨工程大学材料科学与化学工程学院，哈尔滨 150001
Unit_EngLish:College of Materials Science and Chemical Engineering，Harbin Engineering University，Harbin 150001，China
Abstract_Chinese:本文提出了一种新的二维浓差腐蚀数学模型．该模型将管道壁面附近的离子导电层作为研究对象，并对其进行离散化处理．根据电学中的基尔霍夫第二定律，导出了关于离子导电层腐蚀电位与离子电流以及极化电流关系的离散方程组．在施加适当的边界条件后，求解该方程组，得到了单元的极化电位、极化电流等关键信息，并根据这些信息计算出了总的腐蚀电流．结果表明：浓差腐蚀引起的极化电流和自腐蚀电流有相同的数量级，它的存在极大地改变了腐蚀电流的分布．一般而言，管道壁面氧浓度高的部位，不考虑浓差腐蚀时，腐蚀电位较高、腐蚀电流较大，而氧浓度较低的部位情况正相反；但当考虑浓差腐蚀时，电位将产生极化，原来腐蚀电位较高的部位将产生阴极极化，同时腐蚀速度亦有所降低；而原来腐蚀电位较低的部位将产生阳极极化，同时腐蚀速度也有所增大，即这种机制有将腐蚀电位均匀化的趋势，这和电化学理论相符合．
Abstract_English:In this paper, a new two-dimensional mathematical model of differential concentration corrosion is pro-posed. The model takes the ionic conductive layer near the pipe wall as the research object and discretizes it. Then, in accordance with Kirchhoff’s second law in electricity, the discrete equations of corrosion potential, ion current, and polarization current of the ionic conducting layer are derived. After the appropriate boundary conditions are applied, the equations are solved, and key information, such as polarization potential and polarization current are obtained. Then, the total corrosion current is calculated based on this information. Results show that the polarization current caused by differential concentration corrosion has the same order of magnitude as the nature corrosion current, and its existence has greatly changed the distribution of corrosion current. Generally, when differential concentration corro-sion is not considered, the parts with high oxygen concentration on the pipe wall will have high corrosion potential and high corrosion current. By contrast, the parts with low oxygen concentration will have the opposite situation. In the other side, when concentration corrosion is considered, the corrosion potential will produce polarization, the parts with high corrosion potential will produce cathodic polarization, and the corrosion rate will also be reduced. Moreover, the parts with low corrosion potential will produce anodic polarization, and the corrosion rate is also increased, Hence, this mechanism tends to homogenize the corrosion potential. This finding is compounded with the theory of electrochemistry.
Keyword_Chinese:腐蚀；浓差腐蚀；极化；浓差宏电池
Keywords_English:corrosion；differential concentration corrosion；polarization；concentration difference macro cell

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