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Spaceframe sacrificial Mg anode


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#1 NRoshier

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Posted 23 April 2021 - 10:07

I friend recently removed some 6061 alloy sheeting from a historic racecar spaceframe and found the corrosion was significant at the point where the rivets held the sheet. In discussion I suggested that a sacrificial anode of a less noble material may help - ala marine anodes of Mg. This 3mm x 20mm x 20mm Mg anode would be held in contact with the steel/alloy with a rivet/bolt. Does this sound a reasonable precaution?



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#2 Greg Locock

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Posted 24 April 2021 - 01:09

Sounds sensible. I knew a family who had an Aston Martin DB5, by the time it was 30 years old you could poke holes in the bodywork.



#3 NRoshier

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Posted 24 April 2021 - 11:09

I have heard similar stories of classic cars with Supraleggra construction.



#4 DogEarred

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Posted 24 April 2021 - 11:31

It works on oil rigs.

 

By implication, it would would on Aston Martins   :rotfl:



#5 Kelpiecross

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Posted 24 April 2021 - 13:57

 I zinc it would help. 



#6 NRoshier

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Posted 25 April 2021 - 03:19

 I zinc it would help. 

I saw what you did there --- Mg is light and 'racey'!



#7 desmo

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Posted 25 April 2021 - 14:17

I have heard similar stories of classic cars with Supraleggra construction.

I assume you meant superleggera. It just means "superlight" in Italian. It's not actually a thing.



#8 Magoo

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Posted 25 April 2021 - 21:04

Will the car be operated in seawater for prolonged periods? 



#9 NRoshier

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Posted 26 April 2021 - 01:26

No of course not. The chassis will be operated on the usual roads, but it's much easier replacing an anode in 10 years than chassis sheeting.



#10 gruntguru

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Posted 26 April 2021 - 03:52

Is a return path required for cathodic protection to work?



#11 Greg Locock

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Posted 26 April 2021 - 05:14

Ah, I  think I get it. Unless there is something to complete the circuit between the wet bit of the frame and the anode then you'll only protect the area local to the anode.



#12 kikiturbo2

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Posted 26 April 2021 - 09:18

I assume you meant superleggera. It just means "superlight" in Italian. It's not actually a thing.

it actually is... a method of bodywork construction with small steel tubes covered by alloy sheet

 

https://en.wikipedia...ki/Superleggera



#13 MatsNorway

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Posted 26 April 2021 - 18:09

So is Sink coating not good enough on Alu parts? I completely forgot the name of that list of metals arranged by uh.. purity/corrosion.



#14 NRoshier

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Posted 27 April 2021 - 11:30

so an anode would need to go in each wheelwell?