Using voltammetry to monitor corrosion



  • how can we do OCP with the cheapstat?
    Can we use LSV to monitor the rate of corrosion?



  • I don't think you can measure the open circuit potential (OCP) directly using the cheapstat. I think this is typically done by measuring the potential between the reference and working electrodes when zero current is being sourced. The cheapstat does in a sense measure the voltage between the reference and working electrodes - it is used in the op amp feedback loop for sourcing current. Unfortunately, this voltage isn't connected to the microcontroller via an analog intput - so you can't measure it directly. That said you might be able to use a multi-meter in conjunction with
    the cheapstat to measure the OCP. Basically when the cheapstat isn't sourcing current (maybe even remove the counter electrode from the test cell) use the multi-meter to measure the potential between the reference and working electrode. For the reference electrode you might look at the output of the follower op amp instead of connecting the multimeter directly to the electrode.

    I'm not very familiar with corrosion measurements - do you have a reference or could you give me a brief description of the sort of measurements you wish to perform?



  • I am measuring LSV and CV using the cheapstat. The system comprise of a Ag/AgCl reference electrode, Platinum counter electrode and a mild steel working electrode using Sulphuric acid as electrolyte. We do the LSV and CV scan and get data but it is not following any known pattern. We the scans with and without inhibitors for corrosion hoping to see a lowering of the corrosion potential. But it is just not clear



  • Hi Joseph,
    Do you have a feeling for whether the problem is with the equipment (the Cheapstat) or the experimental procedure ? We are not really familiar with this method, so I am not sure how to help.

    Can I ask -- have you tried this experiment successfully with other electrochemical equipment ? Do you think that you cannot get it to work with the Cheapstat specifically ?

    Thanks,
    Jo



  • Corrosion monitoring and analysis usually takes a large dynamic range (eg polarization curves etc.) or requires measurements with respect to open circuit (LPR, EIS , OCP-monitoring). These are not well-suited to the current version of cheapstat.


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