Slow plating can generally be divided into two types, one is that the coating is bright and slow, and the other is that the coating is not bright in the low current area, or there is a leakage plating appearance. So what are the reasons for the slow electroplating?
1. The current is too small.
Especially for the oversized piece with complex shape, the current is too small, so that the current distribution in the depression is too weak.
2. Lack of brightener.
Add brightener to solve.
3. Poor dispersion ability of plating solution.
The main reason is that the potassium chloride content is low. Supplement after testing.
4. Too much lead impurities.
It is often manifested in gray and dark color in the low current area, and the coating is thin. After treatment with zinc powder (add 1g of zinc powder per liter of plating solution), filter the plating solution as soon as possible, and add 4-5mL/L of cylinder opening agent.
In addition to the above four reasons, one of the reasons is that the temperature of the bath is too high and there are too many differentiated products in the bath. The main reason for this appearance is that the iron content in the bath is too high. Although the electrode potential of iron impurities is more positive than that of zinc, the separation potential of zinc in the potassium chloride zinc plating system is more positive than that of iron. Therefore, iron is mainly distinguished at high currents. When the iron ion content in the plating solution is high, it will be enriched at the corners of the workpiece. The content of iron in the coating is high, the stress is large, and the coating is easy to crack. When iron impurities in the plating solution are long, there is an obvious feature: the plating solution is dirty. Either red and dirty, or white and dirty. The effect of iron can be eliminated by adding hydrogen peroxide.