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A new perspective on measuring the corrosion rate of localized corrosion
Materials and Corrosion ( IF 1.6 ) Pub Date : 2020-02-03 , DOI: 10.1002/maco.201911467
Ueli Angst 1 , Markus Büchler 2
Affiliation  

Many corrosion phenomena are nonuniform, which means that anodic and cathodic locations are spatially separated. An example is macrocell corrosion of steel in concrete. Under these conditions, determining the corrosion rate from polarization resistance measurements and using the Stern–Geary equation is fundamentally not possible. We present a novel theoretical approach for the interpretation of galvanostatic pulse measurements, to make them applicable as a method for corrosion rate measurements in situations of localized corrosion. Experiments show that it is important to consider that (a) only a fraction of the applied current flows through the anode of the macrocell, and (b) this current is not constant over time. We propose an approach to quantify and consider these two effects, based on information generally accessible in condition assessment of concrete structures. Our results show that galvanostatic pulse measurements are a robust method to determine the corrosion current. With the traditional empirical approach, the measurement error was generally below factor 3, and occasionally up to factor 10. With the novel approach, this error could be reduced to a factor of maximum 2 in all cases.

中文翻译:

测量局部腐蚀速率的新观点

许多腐蚀现象是不均匀的,这意味着阳极和阴极的位置在空间上是分开的。一个例子是混凝土中钢的宏胞腐蚀。在这种情况下,根本不可能通过极化电阻测量结果确定腐蚀速率并使用Stern-Geary方程。我们提出了一种用于解释恒电流脉冲测量的新颖理论方法,以使其可作为局部腐蚀情况下腐蚀速率测量的方法。实验表明,重要的是要考虑(a)只有一小部分施加的电流流过宏单元的阳极,并且(b)该电流在一段时间内不是恒定的。我们提出了一种量化和考虑这两种影响的方法,基于在混凝土结构状态评估中通常可以获取的信息。我们的结果表明,恒电流脉冲测量是确定腐蚀电流的可靠方法。使用传统的经验方法,测量误差通常低于3倍,有时高达10倍。采用新颖的方法,在所有情况下,该误差都可以减小到最大2倍。
更新日期:2020-02-03
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