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We burned cadmium parts by accidentally plating at 2-3 times normal amperage

July 24, 2008

What happens if during cadmium plating process to a steel part HT 200 to 300 KSI, the amperage utilized is excessively high (2 or 3 times above necessary or more) for the area and thickness required? It's possible to burn the part and the metal became brittle? Thanks a lot.
Sincerely
Jorge

Jorge M-Fortun
aviation tech - Miami, Florida, USA

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July , 2008

Unfortunately, I think the parts probably must be scrapped. Jorge. When you plate at a higher current density than the solution allows, what that really means is all those extra electrons at the cathode cannot reduce cadmium ions to cadmium metal because there is insufficient cadmium within the boundary layer. Yet the current is flowing, and the explanation is hydrogen ions are being pulled out of the water and converted to atomic hydrogen (hydrogen gas). Operating a plating process at 2 to 3X the recommended amperage produces a huge amount of atomic hydrogen to cause hydrogen embrittlement.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey