Letter 16039

Plating aluminium tubing to allow soldering

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Dear sir,

We want to solder aluminium (heat exchangers), but we can't. According to experts, we must electroplate it first with copper. We try to plating it with copper but not success, please explain the process, and also what is the pre treatment for the aluminium (zincate ? = zinc sulphate?).

Hartono Hadiprojo
steel - Cilegon, Babten, Indonesia

Yes, you need to zincate the aluminum before you cyanide copper plate it. In fact, you should "double zincate" it (zincate it, strip the zincate in nitric acid, zincate it again). But zincate is not zinc sulphate, it is zinc dissolved in caustic soda and stabilizers. You should either buy a proprietary zincate or research the subject via a compterized lit search. Good luck.

Ted Mooney, P.E.  finishing.com Brick, NJ

 

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