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Aluminium/Copper Corrosion, does it stop? - Page 2

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Posted by dow on November 4, 2009, 7:45 pm
 

Are you sure you can get real tin? Most of what is called "tin" is
actually steel thinly plated with tin.

Tin will also corrode, by galvanic action, if it is in direct contact
with copper in an environment where moisture might be present at the
junction. The only metals that won't corrode are copper itself, and
ones that are less active, chemically, than copper. These tend to be
expensive, like silver, gold, or platinum!

As others have suggested, you can stop the galvanic action by putting
an electrically-insulating layer between the metals.

                                               dow

Posted by Josepi on November 4, 2009, 8:27 pm
 
You may be able to stop the corrosion by insulating the return path for the
galvanic action from the takeoff piping and not bother with the contact
surfaces.

 It takes a complete path to complete an electrical circuit. Breaking it
anywhere will stop the current.


Are you sure you can get real tin? Most of what is called "tin" is
actually steel thinly plated with tin.

Tin will also corrode, by galvanic action, if it is in direct contact
with copper in an environment where moisture might be present at the
junction. The only metals that won't corrode are copper itself, and
ones that are less active, chemically, than copper. These tend to be
expensive, like silver, gold, or platinum!

As others have suggested, you can stop the galvanic action by putting
an electrically-insulating layer between the metals.

                                               dow



Posted by Solar Mike (NZ) on November 4, 2009, 7:34 pm
 

I have constructed a number of such panels and have had no problems,
painted the copper risers and fins with an etch primer and allowed to
harden before clamping together. The primer provides isolation between
the two metals preventing the galvanic reaction.

Cheers
Mike (NZ)

Posted by Anti-Spam on November 7, 2009, 8:37 am
 On Wed, 4 Nov 2009 11:34:56 -0800 (PST), "Solar Mike (NZ)"


That sounds like a very good idea, I will be making another one soon
for somebody else, so will employ that method, thanks.

In the meantime, all the while my one is relatively efficient (we
don't have to try so hard, down here in sunny spain), I think I will
just leave it to see what happens. Thanks to all responders.

Mark in Spain.

Posted by Jean Marc on November 9, 2009, 7:35 am
 
4acaf55ar9s5vu17kgi7f6l24kd8f1tb9t@4ax.com...

It is not going to stabilize, and will continue 'till no contact occurs. You
may want to spray oil (or grease) at the joint to insulate electricaly and
slow the process.

HIH
JM



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