Very educational. I am looking to do impressed current cathodic protection on my steel boat (in hard freshwater) and trying to understand what reference electrode I need. I did an easy test and measured the hull potential against a solid copper wire reference in the water and got 0.66V as expected given the hull has magnesium anodes. My question is how much difference does the salt make compared to using just a piece of solid zinc, for example. I don't need more than around 0.1V accuracy, I think. I imagine if permanently submerged, the salt won't last all that long?
From what I read this is an active protection system that uses electrical current to prevent corrosion. This site indicates that it is not suitable for freshwater applications: www.marineinsight.com/tech/hull-corrosion-and-impressed-current-cathodic-protection-iccp-on-ships-construction-and-working/ That makes sense to me, since it is difficult to pass current through freshwater. You should need less protection in freshwater and I would think that a passive sacrificial electrode (the magnesium anodes) is better, perhaps some specialty paint (passive barrier). Please know that I do not have marine experience. My PhD focused on imaging mass spectrometers and I have been teaching chemistry since.
@@Chemistryuniversity Thanks for the reply and apologies that this reply got so long. I don't see why ICCP should be any less effective than passive anodes in freshwater. Since conductivity is less, corrosion will also be less and thus the required current should also be less. My boat already has magnesium anodes and I have since developed a monitoring system that I've run with both copper and zinc reference electrodes - about -0.25V on zinc and +0.79V on copper. Both produce extremely stable readings that over weeks change by only a few tens of mV, probably depending on weather, etc. I am still unsure whether electrolyte is necessary or what exactly produces the small changes I observe. In theory I'd think that as long as you're not drawing much current, the reference electrodes will be able to easily produce the necessary electrons without affecting the potential. But I might be missing something. My ADC has a 17k input resistance and I'm taking a reading only once a second. I am looking for an alternative to having to repaint the hull every 2-3 years as is customary with narrowboats. The bottom base plate customarily doesn't get painted. I've read the article and it really doesn't make sense to me. Clearly a reference cell still detects a potential difference in freshwater and portable ones are used in practice to evaluate efficacy of passive anodes. It also appears to contradict itself by saying in freshwater the rectified voltage is increased to maximum to limit the induced current. Also, as far as I understand over-protection isn't really a thing on steel boats and they likely will just anodize themselves with whatever anode is used. One boater told me that his base plate is actually anodizing itself from just passive anodes in certain spots on the base plate. It all seems a bit like a black art with many opposing opinions. I'd just like to get some hard facts on the topic.
this is like calligraphy asmr meets electrochemistry i love it
Fantastic explanation. Well done👏!
Really good explanation! Thanks
Very educational. I am looking to do impressed current cathodic protection on my steel boat (in hard freshwater) and trying to understand what reference electrode I need. I did an easy test and measured the hull potential against a solid copper wire reference in the water and got 0.66V as expected given the hull has magnesium anodes. My question is how much difference does the salt make compared to using just a piece of solid zinc, for example. I don't need more than around 0.1V accuracy, I think. I imagine if permanently submerged, the salt won't last all that long?
From what I read this is an active protection system that uses electrical current to prevent corrosion. This site indicates that it is not suitable for freshwater applications:
www.marineinsight.com/tech/hull-corrosion-and-impressed-current-cathodic-protection-iccp-on-ships-construction-and-working/
That makes sense to me, since it is difficult to pass current through freshwater. You should need less protection in freshwater and I would think that a passive sacrificial electrode (the magnesium anodes) is better, perhaps some specialty paint (passive barrier).
Please know that I do not have marine experience. My PhD focused on imaging mass spectrometers and I have been teaching chemistry since.
@@Chemistryuniversity Thanks for the reply and apologies that this reply got so long.
I don't see why ICCP should be any less effective than passive anodes in freshwater. Since conductivity is less, corrosion will also be less and thus the required current should also be less. My boat already has magnesium anodes and I have since developed a monitoring system that I've run with both copper and zinc reference electrodes - about -0.25V on zinc and +0.79V on copper. Both produce extremely stable readings that over weeks change by only a few tens of mV, probably depending on weather, etc.
I am still unsure whether electrolyte is necessary or what exactly produces the small changes I observe. In theory I'd think that as long as you're not drawing much current, the reference electrodes will be able to easily produce the necessary electrons without affecting the potential. But I might be missing something. My ADC has a 17k input resistance and I'm taking a reading only once a second.
I am looking for an alternative to having to repaint the hull every 2-3 years as is customary with narrowboats. The bottom base plate customarily doesn't get painted.
I've read the article and it really doesn't make sense to me. Clearly a reference cell still detects a potential difference in freshwater and portable ones are used in practice to evaluate efficacy of passive anodes. It also appears to contradict itself by saying in freshwater the rectified voltage is increased to maximum to limit the induced current. Also, as far as I understand over-protection isn't really a thing on steel boats and they likely will just anodize themselves with whatever anode is used. One boater told me that his base plate is actually anodizing itself from just passive anodes in certain spots on the base plate.
It all seems a bit like a black art with many opposing opinions. I'd just like to get some hard facts on the topic.