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:
|Acetic acid||260 g/L|
|Barium acetate||7.6 g/L|
|Current density||40-90 ASF|
While the above formulation will give you a decent finish, you will be much better off if you use a proprietary formulation.