I have come across an unusual electrolytic plate application & wondered if anyone here had an answer.
Merlin big end journals have big holes bored in them to make the crank as light as possible. These are closed off by a pair of aluminium plugs, held together by a through bolt. These plugs are nickel plated. Bearing in mind that this was being done at a time when nickel could not readily be obtained, it is just typical of Rolls-Royce. Apparently, it was done to combat corrosion from acids carried in the oil - not that I'd have thought that a Merlin destined for combat would have had tin rot on it's mind!
Anyway. I'm aware that for plating to be successful, the metals should be close together in atomic weight & the farther away they get, the less successful the process. Here's the most common ones :-
24 Cr Chromium 51.9961(6) 26 Fe Iron 55.845(2) 28 Ni Nickel 58.6934(2) 29 Cu Copper 63.546(3)Aluminium is 13th in the table at 26.981538 and nickel far away at 29th, practically twice the weight.
Any suggestions how the esteemed mechanition pulled this one off?
Regards,
Kim Siddorn.