Q. We have a number of parts that require rework. Can you recommend a method for stripping nickel chrome from steel? We have attempted to use a sodium nitrate solution using six volts, but have not had good results. P.C.
A. You did not mention in your e-mail whether you are just attempting to strip the chrome or strip both the chrome and the underlying bright nickel. Chrome can be stripped in a number of ways, none of which are perfect.
A non-electrical method is to use a hydrochloric acid solution. The recommended concentration is usually 16 fl oz/gal at 110–130°F. another method involves using electrical current and either sodium hydroxide or sodium carbonate. Sodium hydroxide is used at a concentration of 7 oz/gal and sodium carbonate is used at approximately 9 oz/gal. The work is made anodic with 6 V at room temperature. This procedure works reasonably well but does cause smutting of the surface.
If you are trying to strip nickel from steel, sulfuric acid is recommended. A typical concentration is approximately 80 fl oz/gal at 6 V. Lead cathodes are usually used and the work is made anodic. This process must be used with care, since there is a tendency of the steel substrate to pit.
An overview of decorative and hard chromium electroplating processes.
Why is it important for you to know this?
The processes, chemicals and equipment, plus control and troubleshooting.