Zinc anode sacrificial plates GQ

[SamIam]

I plan to attach about 15 of these to the old girl; doors, body, chassis etc and was looking for a thread where it had been discussed/done before.

Put likely words in the forum search but came up with nix... Any help from the "old salts" with a thread or two?

[PeeBee]

Do you intend spending a lot of time submerged? Can you explain how these would work on your 4WD?

[Truckus]

Do you intend spending a lot of time submerged? Can you explain how these would work on your 4WD?

Yep, spot on PB, generally this would be the nautical application where by the salt water is the electrolyte for the cathodic action.

You are better off using an impressed current inhibitor instead, but you never know, maybe a lot of water crossings up his way, and mate, what we seeing on the Central coast at the moment withwaether and flooding, perhaps not as controversial an idea s it seems.:smile:

Anyhow check these out fella. https://www.erps.com.au/

[SamIam]

Yeah thanks fellas, prompt and good answers. I will take a look at erps

My thinking is that the old girl has spent most of her life the other side of the range where a corrugated Iron roof lasts 120 years or more and is relatively rust free for her age.

Took her to Fraser a couple of weeks ago and plan to do a good bit of beach driving. While I can and do wash the underside as best as a hose can do I don't believe I get the salt off or out of all the nooks and crannies. It was suggested to me by a truck mechanic out west who has done a lot of work for me on the GQ in the past.

So Trukus; wots the downside of using zinc anode "buttons" at $5 a pop? Yes there is work in it, I have to find or drill a (usually) non visible bolt in every panel/part, rub the spot it goes in back to bare metal and bolt on the button... I have to do this in every panel/part that is (or might be by way of grease or seal) electrically isolated from the rest eg the bonnet. But otherwise there is no adverse reaction or chemical reaction when not submerged in salt water? Yes it is arguably over-engineered but on the other hand it will remove any inhibition to driving lower down the beach where the washouts from creeks are less dangerous...

[PeeBee]

I have the EPRS system installed, early days yet, some polarising opinion on their worth. What i will say is if you have an HF radio, its operations(the radio) will be rendered useless due to the harmonics generated into the steelwork. For use, I need to switch the EPRS system off and let the field decay for 15 minutes to get a signal cleanly reaching the set - took me a while to get onto this little downside.

[MB]

FWIW: I completely gave up on the concept of rust prevention contraptions in my early 20’s whilst island working up north out of my faithful steel FJ55 Landcrab.
Would lazily utilise the wagon to haul my tools across a salt water tidal creek to a building site daily until my nightly sprinkler flush regime & CRC cans got too exhausting & expensive [emoji23]
Magnetic Islanders mostly ran Aluminium Rovers but my steel chassis, same as theirs, was still ready for next adventures beyond the Cape[emoji106][emoji106]
Fish Oil is sticky bullshit IMHO?


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[Truckus]

So Trukus; wots the downside of using zinc anode "buttons" at $5 a pop? Yes there is work in it, I have to find or drill a (usually) non visible bolt in every panel/part, rub the spot it goes in back to bare metal and bolt on the button... I have to do this in every panel/part that is (or might be by way of grease or seal) electrically isolated from the rest eg the bonnet. But otherwise there is no adverse reaction or chemical reaction when not submerged in salt water? Yes it is arguably over-engineered but on the other hand it will remove any inhibition to driving lower down the beach where the washouts from creeks are less dangerous...

Sure mate, rather than typing a huge post check out these links

https://en.wikipedia.org/wiki/Cathodic_protection

https://eoncoat.com/what-is-cathodic-protection-and-how-does-it-work/

In summary, you need a conductor, or conduit or electrolyte to carry the sacrificial electrons (as the anode is ionized) from the anode to the cathode. So you need a constant conductor, that in itself is not prone to becoming ionized (so a chassis or body shell may also become ionized if carrying free electrons from the anode, and thus also corrode) where as if an electrolyte such as Salt water, not an issue,(hence steel hulls on ships and rig platforms and wharves use these) as the anode cops all the corrosion only.

Without the electrolyte the cathode (body/chassis of car) losses its ability to remain as the cathode as it ionizes along the current path, thus promoting electrolysis and corrosion.

You with me there.

[SamIam]

Well I have thought a bit about this and had a look at the base chemistry... As far as your point about electrolyte, well the salt air up here is a partial one, that is why the car is rusting more.... I take these things as not absolute black and white ie Electrolyte/no electrolyte... but a range depending on the air humidity/salt content up to driving on the beach at Bribie/Moreton/Fraser. The fact that corrosion forms on a vehicle means that a reduction/oxidation is happening without the apparent assistance of immersion in an electrolytic liquid such as the sea.

Therefore I am forming the view that the sacrificial zinc anode buttons are a worthy experiment BUT that I should combine this with coating protection if I wanted the max. Remember a button here and there is NOT the same as a full Gal dip/coating, electrical resistance in the body of the car dictates this. I am including an extract below. If you can use it for an above ground tank then you can use it for an above ground vehicle, no the vehicle is not earthed like a tank but a static strap would fix this. I have yet to determine if its an issue. I am going to run an experiment on exposed metal and document here.

Corrosionpedia Explains Sacrificial Anode
The mechanism of the sacrificial anode protection system is very similar to the reaction mechanism of electrochemical cells. In sacrificial anodes the protected metal is placed on the cathode side and then a more reactive metal or alloy (having a larger potential difference than the protected metal) is chosen and connected to the protected metal as an anode. The redox reaction will proceed spontaneously. An oxidation reaction occurs at the anode, which means that the sacrificial metal will be consumed. At the same time, the reduction reaction occurs on the cathodic side, preventing the protected metal from erosion. Thus, corrosion on the protected metal is successfully shifted to the anode, protecting the metal.

Sacrificial anodes are normally supplied with either lead wires or cast-m straps to facilitate their connection to the structure being protected. The lead wires may be attached to the structure by welding or mechanical connections.

sacrificial anode attached to water main pipe
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The materials used for sacrificial anodes are either relatively pure active metals, such as zinc or magnesium, or are magnesium or aluminum alloys that have been specifically developed for use as sacrificial anodes.

Advantages of using sacrificial anodes:

Can be used where there is no power
Lower initial cost
Less supervision required
Comparatively simple installation and additional anodes can easily be added if the initial installation proves to be inadequate
Sacrificial anodes are used to protect:

Hulls of ships
Water heaters
Pipelines
Distribution systems
Above-ground tanks
Underground tanks
Refineries
The anodes in sacrificial anode cathodic protection systems must be periodically inspected and replaced when consumed.

RELATED QUESTION
Why should cathodic protection and a coating be used together to protect against corrosion? (https://www.corrosionpedia.com/7/5352/corrosion-prevention/cathodic-protection/why-should-cathodic-protection-and-a-coating-be-used-together-to-protect-against-corrosion)

[mudnut]

I think the British car builders knew about corrosion and used positive earth systems.

[Clunk]

I think the British car builders knew about corrosion and used positive earth systems.Didn't bloody work though hey..... [emoji1787]

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