Coating Nickel Plated Parts

Question:

I am the engineer in charge of the coating line at our plant. We produce copper products here. Some of these products are nickel plated. We apply clear UV-curable and thermoset-acrylate coating to these products. There is no adhesion problem with the copper parts. However, the coatings do not always adhere to the nickel plated parts and this has become a quality control nightmare. V. K.

Answer:

Adhesion to nickel plating can be a problem. As I understand it, and please remember I am an organic chemist not a Plating Wizard, plated nickel deposits in platelets with spaces between them, similar to those between floor tiles. Corrosion occurs in these spaces causing poor adhesion. The longer the period between plating and coating the poorer the adhesion of organic coatings. The best way to solve the problem is to coat as soon as possible after nickel plating. Usually, if you can’t coat immediately after plating, sanding and light abrasive blasting will promote adhesion. This will be a problem in your case. Since you are applying a clear organic coating, the abraded nickel will show through. Therefore, your only choice is to coat the nickel plated parts immediately after plating.