Nickel Sulfamate and Pits
Question: We are having problems with pits in our nickel sulfamate plating line.
Question:
We are having problems with pits in our nickel sulfamate plating line. What suggestions do you have to eliminate this problem? R.M.
Answer:
Your e-mail does not give me much to go on, but here are typical causes of pitting in nickel sulfamate plating baths.
Is there enough boric acid dissolved in the bath? Boric acid is not very soluble in a plating bath. Dropping of the bath temperature will cause boric acid to precipitate. It does not dissolve very readily when the plating tank is brought back up to operating temperature.
Is there enough antipitting agent in the bath? If the bath does not contain enough antipitting agent, bubbles tend to "stick" to the plated surface and pits are formed. You should monitor the level of antipitting agent by measuring the surface tension of the bath on a regular basis. The optimum surface tension for an air-agitated plating bath is 30-35 dynes/cm.
Do you have organic impurities in the bath? These usually can be removed by peroxide treatment followed by activated carbon filtration. Your chemical vendor can supply you with information on the proper procedure.
Related Content
-
Trivalent Chrome Overview
As the finishing industry begins to move away from the use of hexavalent chromium to trivalent chromium, what factors should finishers consider as they make new investments? Mark Schario, chief technology officer for Columbia Chemical offers a helpful overview of this complicated topic.
-
Troubleshooting Alkaline Zinc
One of the most common problems that can arise when plating with alkaline zinc is an imbalance of brightener in the solution. In this helpful Ask the Expert article, Chad Murphy of Columbia Chemical discusses how different zinc metal concentrations and brightener concentrations can impact efficiency.
-
How to Choose Between Sulfate and Chloride-Based Trivalent Chromium
There are several factors to consider when choosing between sulfate and chloride-based baths for trivalent chromium plating. Mark Schario of Columbia Chemical discusses the differences and what platers should keep in mind when evaluating options.
