Black Chrome Again

Can you give me a procedure for the black chromium plating process?


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Q. I would like to know more about the black chromium plating process. Can you give me a procedure for the process?  T.B.

A. Black chrome has been used for many years, primarily as a decorative finish. Most of the black chromium plating processes are proprietary in nature. The major problem with the process is getting consistent color and deposit characteristics. Sometimes a black chromium deposit is plated over a regular chromium deposit. There are proprietary processes based on both hexavalent and trivalent chromium.

A typical bath formulation is given in the table below:

ComponentConcentration
Chromic acid250g/L
Acetic acid260 g/L
Barium acetate7.6 g/L
Operating ConditionsRange
Temperature100°F
Current density40-90 ASF

 

While the above formulation will give you a decent finish, you will be much better off if you use a proprietary formulation. 

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