Summary for copper under hard chrome Discussion
Copper flashing under hard chrome plating is discussed as a possible way to create a wear indicator on 4130 steel. Amy Harmon Krtanjek asks whether a thin copper layer under hard chrome would affect adhesion and whether it is a sensible way to show when the chrome has worn through. Ted Mooney says he has not heard of the practice but thinks it should reveal wear as intended, and notes that hard chrome can adhere well to copper if the process is done correctly. Chris Snyder adds practical experience from oil tool shafts, saying both electroless nickel and copper were used under hard chrome and held up well in tests, including rough grinding to check whether the intermediate layer would survive. He explains that copper was chosen partly because it was easier to activate than electroless nickel and helped prevent undermining of the hard chrome.
Q. A chrome plating supplier has suggested that a thin copper layer can be plated onto 4130 steel prior to hard chrome plating without any effect on the adhesion of the hard chrome. Does anyone have any experience with this who could support or dispute this claim? Purpose of this experiment is to provide a visual indicator of when the hard chrome is worn through. Any comments on further questions to ask, or conditions to be aware of would also be appreciated.
Thanks!
Amy Harmon Krtanjek
consultant – Seven Valleys, Pennsylvania, USA
2004
A. I haven’t heard of doing this, but I suppose it will reveal when the chrome is worn though, as advertised. Hard chrome can adhere well to copper as long as it’s done right.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
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Need project assistance? $100/hr.
2004
A. If the substrate is hardened and the part is going to be subject to severe friction and sliding wear, the underlying copper lacks enough hardness to provide adequate support to the hard chrome. Scratch resistance will be reduced. For the mentioned purpose, I personally don’t think it’s a good idea. Alternatively, worn through chrome can be detected by swabbing the surface with a weak mixture of copper sulphate
⇦ on
eBay or
Amazon [affil link] and sulfuric acid. Immersion copper deposit will proceed on areas where chrome has gone.
Guillermo Marrufo
Monterrey, NL, Mexico
2004
A. Hello Amy Harmon Krtanjek, we want to point out that we have patented this process of wear indication under hard chrome platings.
Best regards,
Michael Hekli
Switzerland
2004
Hi Michael. Could you please give us the patent number so people can see what is and isn’t covered? Thanks.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
2004
A. In oil tool shafts we used both electroless nickel and copper under hard chrome. Both held good thru tests we rough cut hard chrome with grinding wheel to see if copper would hold up in between to harden surfaces and both held up as good as hard chrome directly 4340 HT. The reason for the test was that we needed a a coating between to stop the undermining of the hard chrome and of course copper was easier to activate than electroless nickel.
Chris Snyder
plater – Charlotte, North Carolina
2004