Letter 5044

Hexavalent or Trivalent Chrome ? 

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We are running a plating on plastic line for A.B.S plastic. I am in the process of looking at converting our hexavalent chrome bath to a trivalent bath as I am led to believe the operating parameters are wider, the chrome content is lower hence less dragout and the bath is alround a lot more user and environmently friendly.

I would be interested in hearing some other opinions form anyone who is running a trivalent chrome bath (ideally plating on plastic). Any comments regarding pitfalls and potential problems would be greatly appreciated .

Tim Strickland
- New Zealand

The operating parameters of a Trivalent chromium process are similar to a bright nickel process than hexavalent chromium process. You need to control temperature, pH and chromium metal and trace metals, eg. Cu, Ni,Zn, more closely in the trivalent chromium solution.

You stated the benefits of a trivalent electrolyte like lower metal, lower drag out etc. the other benefit is no white washing from passive nickel like you can see with hexchrome. The one disadvantage of trivalent chromium is the color is slightly darker than the std. hexavalent chromium deposit.

George Shahin Atotech USA Inc. Rock Hill, SC

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