I did electrochemical corrosion test for stainless steel and for coated stainless steel with Fe-based MG. The curves I get is strange.
Can anyone help me to analyze it, please?
I attached two plots as an example
You may notice that as potential moves towards positive direction, current first decreases and starts increasing. The potential at which this direction reverses is Ecorr.
Icorr is determined from the cross-section point of the two tangents drawn on linear portion of plots on either side of Ecorr. Since, the attached plots show fluctuation in the linear portion, it is difficult to locate linear portion. This fluctuation may be due to breakage of coating. You may repeat the test with utmost precaution.
Thanks for your answers. I tried to repeat my experiment and I got the same results. My issue is how to analyze such a strange plot. I followed all the required procedures for electrochemical corrosion test.
What type of stainless steel is it and in which solution? Makes it sense to measure corrosion currents on passive / coated systems? Maybe you have to deal with localized corrosion?
The anodic spike and cathodic loops formed may be due to formation of passive film and its breakage. In such a situation, it's wise to repeat the experiment using freshly prepared environment and coupon surface. Better still, concentrate on localized corrosion as passive film are easily formed on stainless steel materials due to their high chromium content.
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