In the potassium chloride galvanizing process, whether the mass concentration of potassium chloride is high or low, it will cause poor coating quality, so how to judge by the Hull cell test?
Judging by the brightness of the test piece
When the low end brightness of the Hull cell test of potassium chloride galvanized is poor, the mass concentration of potassium chloride may be too low.
Step 1: Adjust the PH value to normal.
Step 2: Using 250 mL Hall tank, static plating 2A × 5min, if the middle and low end of the specimen brightness is poor, we can add potassium chloride (20~40g/L) to the plating solution before beating, in most cases, the specimen brightness should be improved.
How does potassium chloride affect the quality of coating?
This question, in fact, we can split into two levels to answer: the mass concentration is high (or low) and the mass concentration is excessive. If the content of potassium chloride is high or low, it is easy to cause the coating to produce dark streaks; If the potassium chloride content is excessive, then the potassium chloride galvanized brightener may also be oily due to the salting out phenomenon.
I believe you should have this experience, sometimes even after adjusting the plating solution according to the analytical test, the dispersion ability and deep plating ability of the plating solution is still not good, but the analysis of potassium chloride content is not low, why?
This is because when performing a laboratory analysis, you are analyzing the chloride ions in the potassium chloride galvanizing solution, and then converting it to potassium chloride, rather than analyzing the potassium ions. Whether it is to adjust the PH value, or to pickling the workpiece, we are using hydrochloric acid, which will cause the illusion of high potassium chloride content, then the appropriate addition of potassium chloride, in most cases can solve the problem.