Electroplating onto aluminum

A. Have you tried chrome plating as last step? Do lab trials and evaluate for corrosion. Also try Duplex Nickel method.

A. Make sure the aluminium substrate is suitable grade for electroplating. You are right to use a double zincate system, or something similar. As suggested above, make sure you use a duplex nickel, but also make sure it is at least 5 microns thick, as this is about the minimum thickness needed to ensure a pore free layer. I like the idea of a chromium layer and wonder whether a hexavalent deposit would be better than trivalent; you can get thicker deposits with hexavalent chromium.

A. Hi Lars. You may be interested in listening to our podcast series "The Lost Art of Tin-Nickel Plating".
Just because you are not currently getting top salt spray results from tin-nickel plating doesn't necessarily mean it's the wrong process :-)

Regards,

A. Dear Friends,

Please pardon my ignorance but isn't anodized aluminum, especially hard anodized, enough for high salt spray test hours?

Just how high is your target corrosion protection? Does anybody have an idea why anodizing isn't ideal in this application?

Thanks,

A. Sounds like it needs a heavy coat of gold plating, carat determined by corrosion resistance and effect of the alloy on the electronic properties.

A. I plate on aluminum by zincate > copper > nickel (duplex or Tri) > coupled with chrome. For a very good finish, polish the copper lightly before nickel. The surface should come out brilliant and the corrosion resistance should be a minimum of about 300- 500 salt spray hours depending on how thick you plate the nickel.

Hi Tan. Thanks for the informative posting which will benefit many readers even though Lars feels he isn't able to use nickel.

Regards,

silly :-)  You could always try a nice thick layer of platinum

A. Hi, Felix. It's not only possible, it's fairly common.

You probably need to mask the side which you don't want plating on. Then you zincate, cyanide copper plate, silver strike, and silver plate. In place of the copper plating step you can alternately electroless nickel plate if you don't need nickel-free. Good luck.

Regards,

A. Without asking more about the details of the application or numerical limits, Radio Frequencies (RF), above a few GHz don't like ferromagnetic conductors (e.g.: Ni). Silver is not all that corrosion resistant in salt, even though it may pass salt spray, if thick enough. Also, it is soft, so it is not usually useful if there is mechanical abrasion.

The tried and true answer here in probably heavy Cadmium. It's also high on the toxicity list, probably undeservedly so, but it is available from specialized (read: expensive) electroplaters.

A. Hi Joe. Anyone can do electroplating for a grammar school science project, it's dead easy, like plinking out "Twinkle Twinkle Little Star" on a piano. But robust industrial quality electroplating that will adhere and provide corrosion protection is more like "Rhapsody in Blue". And robust plating onto aluminum ... well, most professional electroplaters with years of experience have great difficulty with it.

If you want to do it yourself, I'd suggest electroless nickel plating. Go to a hobby plating site and investigate a kit for zincating and electroless nickel plating of aluminum ... and practice, practice, practice on scrap before risking your good parts. Good luck.

Regards,

A. I may have found a solution to electroplating aluminium. It comes from a patent issued in 1899 to Frank S Leod:
https://www.google.com/patents/US630246

In 1895 he speaks of preparing it with hydrofluoric acid but he later patented a mercury step. I'm still looking into it but mercury does react to aluminium.

Hi John. Thanks. But readers should be warned that hydrofluoric acid is about the most dangerous thing an electroplating professional deals with. Zincating seems to be a more practical (and certainly far more widely used) way to pretreat aluminum substrates in preparation for electroplating other metals onto them than mercury pretreatment.

Regards,

Hi Devesh. Anodizing the aluminum or chromate conversion coating it, or partially anodizing and partially chromating it are certainly possible and are appropriate to some needs, in lieu of plating something onto it. Anodizing is insulative, chromating is sort of conductive.

Regards,

A. Hi again, Devesh. Yes, aluminum can be anodized and/or chromate conversion coated. But, sorry, whether that is better than the possible alternatives is hard to say unless we describe the parts and the application. You may be right that it's best for Jon's aluminum "gun parts" but I do not understand his situation clearly enough to say unequivocally. Thanks for participating and for your suggestion.

Regards,

? Hi Bharat. I am not trying to hassle you but, sorry, I have no idea at all what you are talking about. Apologies.

Regards,