In this work the concept of using arrays of bipolar electrodes for a fast and simple way to screen corrosion properties is presented.

When an isolated conducting object is exposed to an external electric field the resulting potential difference across its surface can cause part of the total current to pass through said object. The result of this is that the object will act as an anode and a cathode simultaneously and that there will be a gradient in electrochemical potential ranging between the two end poles. The effect has proved useful in various industries and research fields with applications ranging from large scale chemical reactors to the modification of nano-objects¹.

We have previously demonstrated that bipolar electrochemistry can be used to generate gradients in corrosion damage on steel samples to evaluate their corrosion properties².

When a number of steel samples are placed together in an array configuration and subjected to an external field they all act as individual bipolar electrodes, and in this way many samples can be compared in the same experiment at the same time.  The shape of the gradient that forms on the anodic end of the samples will depend on the steels corrosion resistance.

When all steel samples placed together are of the same type the BPE-induced gradients are all alike. If steels of different corrosion properties are placed together the least resistant steel will pass more of the current and therefore corrode further³. This effect can be used to enhance differences between samples. 

Figure 1: Schematic of the BPE-array setup.

Figure 2: Gradients on the same type of steel from different setups, arrows roughly indicates the length of the gradient.

 References

[1]    G. Loget, D. Zigah, L. Bouffier, N. Sojic, A. Kuhn, Accounts of Chemical Research 2013, 46, 2513-2523.

[2]    S. Munktell, M. Tydén, J. Högström, L. Nyholm, F. Björefors, Electrochemistry Communications 2013, 35, 274-277.

[3]    S. Munktell, L. Nyholm, F. Björefors, Journal of Electroanalytical Chemistry 2015, 747, 77-82.