4 ms·

Out of curiosity, does electron flow influence oxidation speed at all? Or is its speed purely a consequence of temperature + environmental gases?

by ethbr0 3y ago

scotty79 3y ago
Maybe if it warms up the cable it could speed up oxidation?
- ethbr0 3y ago
  It would. I think that's what most people were figuring. And also, assuming it's wrapped but not encased to cabling standards (e.g. there's oxygen between the insulator and wire, but the insulator itself is contiguous and airtight), oxidation would eventually deplete the available oxygen "inside" the cable, right?
  - ltbarcly3 3y ago
    The plastic on cheap farm cable like this is not going to be air tight, almost certainly isn't water vapor tight, and probably isn't even 'rust tight', in that I've seen rust migrate through plastic coated steel fencing and accumulate on the outside. I wouldn't count on it for anything other than making the rust slightly less obvious.
jugg1es 3y ago
this is an interesting question. Electrical current creates an EM field that could repel water molecules and oxygen ions. Temperature could also slow oxidation down... like I'm trying to imagine a red hot piece of iron rusting. I wouldn't think it would rust as fast as a cold piece of iron.
- ethbr0 3y ago
  High temperature speeds oxidation. Learned as a consequence of blacksmithing. ;) So red hot iron absolutely rusts, you just beat the (brittle) oxidation off as you work the piece.
  - jugg1es 3y ago
    learned something today - thanks!
- zmgsabst 3y ago
  Anodizing (controlled oxidation) is done via water with a current through the piece to anodize. https://www.youtube.com/watch?v=gIwvLuNzliI https://www.youtube.com/watch?v=gIwvLuNzliI I’d think that charge would create a faster rusting.
- HeyLaughingBoy 3y ago
  > Temperature could also slow oxidation down Gonna have to guess that you've never had to replace a car exhaust :-)
  - mauvehaus 3y ago
    Car exhaust is a weird case though. The water vapor in the exhaust condenses on the cold metal. If you drive far enough, you add enough heat to evaporate the water back out. Else, you end up with a bunch of water in the exhaust facilitating the rusting. In general, you have this problem with cold metal when there's enough humidity to cause condensation. Bare cast iron in an unconditioned space under cover will definitely rust from condensation.
deleted 3y ago
[deleted]
pitched 3y ago
I’ve found that having a charged, exposed cable laying around will start to rust within about 6 months. This is from cheap phone cables so it being copper-coated instead of full copper is likely. I’ve also heard of cathodic protection or electronic rust proofing doing the opposite though? Maybe it has to do with moving charges vs static charges? Or ground a cable preventing rust vs charging it accelerates rust?
rsync 3y ago
"Out of curiosity, does electron flow influence oxidation speed at all?" Oxidation (and reduction) are literally electron flows. Oxidation is a loss of electrons and reduction is a gain of electrons. Since the oxidizing material is the anode in this (oxidation "circuit") you can connect a "sacrificial anode" to the material you want to preserve and the electrons will flow from that instead of the (material you want to save). We have sacrificial anodes connected to our underground propane tank: http://www.pettank.com/wp-content/uploads/2016/03/cathode-protection.pdf http://www.pettank.com/wp-content/uploads/2016/03/cathode-pr... ... which means a bag of magnesium does all the rusting instead of the tank they are connected to.
- ethbr0 3y ago
  My understanding was that the speed of the reaction was dependent on temperature (and probably pressure/gas mix), and the electron flow was a byproduct rather than driver of the chemical reaction. But it seems like you can indeed block the reaction from occuring by saturating the surface with enough electrons (i.e. by applying an appropriate amount of current) that it makes oxidation impossible from an electrochemical standpoint. https://www.corrosionpedia.com/definition/1237/impressed-current-cathodic-protection-iccp https://www.corrosionpedia.com/definition/1237/impressed-cur... (In addition to the more common, passive bolt-on-a-sacrifical-cathode method)

Out of curiosity, does electron flow influence oxidation speed at all? Or is its speed purely a consequence of temperature + environmental gases?

by ethbr0 3y ago

Out of curiosity, does electron flow influence oxidation speed at all? Or is its speed purely a consequence of temperature + environmental gases?

scotty79 3y ago

Maybe if it warms up the cable it could speed up oxidation?

ethbr0 3y ago
It would. I think that's what most people were figuring. And also, assuming it's wrapped but not encased to cabling standards (e.g. there's oxygen between the insulator and wire, but the insulator itself is contiguous and airtight), oxidation would eventually deplete the available oxygen "inside" the cable, right?
- ltbarcly3 3y ago
  The plastic on cheap farm cable like this is not going to be air tight, almost certainly isn't water vapor tight, and probably isn't even 'rust tight', in that I've seen rust migrate through plastic coated steel fencing and accumulate on the outside. I wouldn't count on it for anything other than making the rust slightly less obvious.

jugg1es 3y ago

this is an interesting question. Electrical current creates an EM field that could repel water molecules and oxygen ions. Temperature could also slow oxidation down... like I'm trying to imagine a red hot piece of iron rusting. I wouldn't think it would rust as fast as a cold piece of iron.

ethbr0 3y ago
High temperature speeds oxidation. Learned as a consequence of blacksmithing. ;) So red hot iron absolutely rusts, you just beat the (brittle) oxidation off as you work the piece.
- jugg1es 3y ago
  learned something today - thanks!
zmgsabst 3y ago
Anodizing (controlled oxidation) is done via water with a current through the piece to anodize. https://www.youtube.com/watch?v=gIwvLuNzliI https://www.youtube.com/watch?v=gIwvLuNzliI I’d think that charge would create a faster rusting.
HeyLaughingBoy 3y ago
> Temperature could also slow oxidation down Gonna have to guess that you've never had to replace a car exhaust :-)
- mauvehaus 3y ago
  Car exhaust is a weird case though. The water vapor in the exhaust condenses on the cold metal. If you drive far enough, you add enough heat to evaporate the water back out. Else, you end up with a bunch of water in the exhaust facilitating the rusting. In general, you have this problem with cold metal when there's enough humidity to cause condensation. Bare cast iron in an unconditioned space under cover will definitely rust from condensation.

deleted 3y ago

[deleted]

pitched 3y ago

I’ve found that having a charged, exposed cable laying around will start to rust within about 6 months. This is from cheap phone cables so it being copper-coated instead of full copper is likely. I’ve also heard of cathodic protection or electronic rust proofing doing the opposite though? Maybe it has to do with moving charges vs static charges? Or ground a cable preventing rust vs charging it accelerates rust?

rsync 3y ago

"Out of curiosity, does electron flow influence oxidation speed at all?" Oxidation (and reduction) are literally electron flows. Oxidation is a loss of electrons and reduction is a gain of electrons. Since the oxidizing material is the anode in this (oxidation "circuit") you can connect a "sacrificial anode" to the material you want to preserve and the electrons will flow from that instead of the (material you want to save). We have sacrificial anodes connected to our underground propane tank: http://www.pettank.com/wp-content/uploads/2016/03/cathode-protection.pdf http://www.pettank.com/wp-content/uploads/2016/03/cathode-pr... ... which means a bag of magnesium does all the rusting instead of the tank they are connected to.

ethbr0 3y ago
My understanding was that the speed of the reaction was dependent on temperature (and probably pressure/gas mix), and the electron flow was a byproduct rather than driver of the chemical reaction. But it seems like you can indeed block the reaction from occuring by saturating the surface with enough electrons (i.e. by applying an appropriate amount of current) that it makes oxidation impossible from an electrochemical standpoint. https://www.corrosionpedia.com/definition/1237/impressed-current-cathodic-protection-iccp https://www.corrosionpedia.com/definition/1237/impressed-cur... (In addition to the more common, passive bolt-on-a-sacrifical-cathode method)