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Green patches on hard chrome
I have done hard chrome on a stainless cylinder for marine application, now I can see green patches on the chrome after a few days, can any of you tell me why could this happen.
Sandeep RamakrishnanHYTEC INTERNATIONAL LLC - Dubai
2002
I am interested in the discoloring effect you have. Does the defect always occur? Are the spots local to certain geometric features (tight corners?) I am seeking ways to intentionally colorize chromed steel. What materials, process are you using?
Joe Martone- New Britain, Connecticut, USA
2002
Sandeep,
Probably the hard chrome layer has been affected somehow by HCl.
Metalchrom S.A. - Athens, Greece
2002
An interesting problem! Ideally we should know more details such as how thick is the chromium and what is the substrate. It could well be a chromium (III) salt being produced on the part, but it could also be a nickel salt being produced from a sublayer if the chromium coating is too thin and/or porous. I would suggest you get an independent analysis of the parts carried out.
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2003
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