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Ardent Listener
Administrator
USA
4841 Posts |
 Posted - 10/15/2007 : 19:25:25
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Sacrificial Zinc Anode
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Galvanic corrosion, often misnamed "electrolysis," is one common form of corrosion in marine environments. It occurs when two (or more) dissimilar metals are brought into electrical contact under water. When a galvanic couple forms, one of the metals in the couple becomes the anode and corrodes faster than it would all by itself, while the other becomes the cathode and corrodes slower than it would alone. Either (or both) metals in the couple may or may not corrode by itself (themselves) in seawater. When contact with a dissimilar metal is made, however, the self-corrosion rates will change: corrosion of the anode will accelerate; corrosion of the cathode will decelerate or even stop.
Smart watermen know this fact and employ the use of sacrificial zinc anodes on their zinc-galvanized metal crabpots. With the sacrificial anode attached, the crabpot becomes the cathode. The result is that the anode will corrode (hence "sacrificial") and the crabpot won't. This effectively doubles the life of the crabpot.
Note that zinc anodes are not used with polyvinyl chloride (PVC) coated wire crabpots since vinyl is non-metallic and does not corrode (PVC does, however, become fouled with marine growth rather quickly.)
The light patches are zinc anodes
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Fanaticism is doubling one's efforts, yet forgetting one's purpose.
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horgad
1000+ Penny Miser Member
USA
1641 Posts |
Posted - 10/15/2007 : 20:26:25
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| I've always wondered why they don't do this for cars. How would like to own a car that was guarenteed never to rust as long as you replaced your zincs on a regular schedule? |
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Ardent Listener
Administrator
USA
4841 Posts |
Posted - 10/16/2007 : 09:45:04
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quote:
Originally posted by horgad
I've always wondered why they don't do this for cars. How would like to own a car that was guarenteed never to rust as long as you replaced your zincs on a regular schedule?
The way I understand it is that the process requires salt water such as in the Ocean. But I been thinking of sanding down some zinc pennies and screwing them onto the rust areas of an old car that I'm driving this Winter. The salt spray from the road should be more than enough to make the galvanic corrosion process work.
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Fanaticism is doubling one's efforts, yet forgetting one's purpose.
*********************
Realcent.forumco.com disclosure please read
All posts either by the members, moderators, and the administration of You must be logged in to see this link. are for entertainment purpose only. It is not the intent of realcent.forumco.com to provide investment, medical, legal or tax advice and nothing posted here should be considered to be so. |
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Cerulean
Penny Hoarding Member
USA
993 Posts |
Posted - 10/16/2007 : 13:32:35
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Yes, it requires saltwater to complete the galvanic cell. Zinc anodes aren't nearly as effective in freshwater, but ships in freshwater don't have as much problems with rust. That's why ships on the Great Lakes last much longer than ocean-going "salties".
RUNNING TOTAL
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3501 zincs (1982-2007) 75.4%
1106 coppers (1959-1982) 23.8%
31 wheats (1920-1958)
7 Canadian (1968-1995)
1 dime (2004)
Wanna take money away from the Fed? Spend dollar coins! |
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horgad
1000+ Penny Miser Member
USA
1641 Posts |
Posted - 10/16/2007 : 15:26:23
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I am building a salt water pond to park my car in as we speak:)
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Sacrificial zinc anodes
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