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topic 1844

Cobalt co-deposition in conventional hard chrome baths.


In my experience, typical hard chrome deposits have a very small percentage of Cobalt co-deposited, around .02 to .05 %. Our customer says its possible to regulate the amount of cobalt co-deposition to maintain the cobalt at .01 to .02%. Any input on this?

David B. McKay
Highland Hts, Ohio


Do you also find about the same amounts of iron and nickel in your chromium deposits? I have never heard of this, or of this being a problem. I would not have expected this result since iron and nickel are known to build up in hexchrome baths.

You would expect the chromium deposit to contain higher and higher amounts of cobalt, iron, and nickel, as the bath becomes more and more contaminated. Yet, this is never mentioned as a problem in hard chrome troubleshooting, only that the bath loses efficiency as impurities build.

tom pullizzi animated   tomPullizziSignature
Tom Pullizzi
Falls Township, Pennsylvania


Does anyone know if these impurities make the hard chrome harder? May be these are interstesial and beneficial and so there never was a problem.

Mandar Sunthankar
- Fort Collins, Colorado


I have never heard of or read anything that talked about traces of cobalt or nickel being codeposited.

That is still 99.98 to 99.99% pure. It is hard to visualize that as a problem compared to all of the possible variations in the chrome from plating parameter variation.

A porous pot( Hard Chrome Consultants in Cleaveland is the least expensive one that works that I have found) will remove most other metal ions as well as trivalent chrome from the solution with time. This might allow you to satisfy the customers requirement and it will help your chrome plating in general.

James Watts
- Navarre, Florida

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