When using acidic zinc plating additives, sometimes the composition of the plating solution is not well controlled, which can result in a low content of potassium chloride. What are the effects of low potassium chloride content on plating solution?
In zinc plating solution, potassium chloride is the conductive salt of the plating solution. In addition to its conductivity, potassium chloride can also enhance cathodic polarization and dispersion ability of the plating solution. When the potassium chloride content in the plating solution is low, the surface of the coating is prone to black stripes, the brightness range will be reduced, and the conductivity of the plating solution will also deteriorate.
We generally analyze the potassium chloride content in zinc plating solution as follows: first, measure the total chlorine content in the plating solution, subtract the chloride ion content in zinc chloride, and then calculate the potassium chloride content in the plating solution. In fact, when we adjust the pH value and add chloride ions to hydrochloric acid, we also calculate the amount of potassium chloride, so the actual content of potassium chloride in the plating solution will be lower than the calculated value.
There was once a customer who experienced a large amount of hydrogen evolution during the production of acid zinc plating solution after major treatment, resulting in black stripes or blackening of the coating, poor brightness, and poor dispersibility. The calculated content of potassium chloride at that time was also within the specified range, but only at the lower limit. After further addition of potassium chloride, the obtained galvanized layer became shiny and fine, greatly improving production efficiency and eliminating faults.
Therefore, when using acidic zinc plating additives, the content of potassium chloride should be controlled within the specified upper and middle limits to ensure stable production efficiency. If you would like to learn more about acid zinc plating additives, please feel free to call us for consultation. Our engineers at Bigely are always available to answer your questions.
