Nickel electroplating of aluminum

A. Hi, cousin Wali. Most plating has some ductility, but not infinite ductility, and good adhesion but not perfect adhesion. When the substrate is aluminum, the situation is a bit trickier because there is an immersion zincate step in there (you did zincate and alkaline electroless nickel plate, or zincate and copper cyanide plate the aluminum before the sulfamate nickel plating, I hope). If you didn't zincate the aluminum, that's your answer.

What you might want to say to quantify your problem is something like: my plating is .00x" thick on .0xx" thick aluminum stock and I can bend the strip around a X" dia mandrel without peeling or breaking but I can't bend it around a Y" dia. mandrel without peeling.

Nickel sulfamate is one of the more malleable nickel platings, but some other metals like copper, tin, gold, and cadmium are probably softer.

A. Firstly ensure the aluminum is suitable for electroplating; some alloys really don't take to plating at all well. Secondly, make sure your nickel is chloride free; use either a sulphamate bath or one with nickel bromide or preferably, fluoride. The sulphamate nickel should give you a more ductile (relatively) deposit. I suppose you could use an electroless nickel, but I have no experience of that process. In any case, I would suspect it will not be very ductile.

A. Sorry, I have not heard of doing electrolytic nickel plating directly on zincate. My understanding is that this is because nickel plating is acid, and zincate almost instantly dissolves in acid.

Regards,