Why is it that when using potassium salt galvanizing brightener, the current is often not turned high enough, resulting in defects such as burning and graying of the coating? In electroplating production, 95% of faults are caused by improper human operation, such as unreasonable process parameters like pH value and temperature. In this issue's article, we will analyze how a pH value that is too high causes the above-mentioned fault phenomena.
The PH value is too high
When using potassium salt galvanizing brighteners, the pH value will affect the quality of the coating. The pH value of the plating solution is generally controlled between 4.5 and 5.5. If the pH value is too high, the bright current density range of the plating solution will narrow, the low current density area will become dark, the high current density area will be charred, the coating will have rough crystallization and no luster, and the adhesion of the coating will deteriorate.
If the pH value exceeds 5.5, zinc hydroxide precipitates will form, the plating solution will become turbid, anodic passivation will occur, hydroxides or basic salts will form on the surface, the cell voltage will rise, and in severe cases, black streaks will appear on the coating. When the pH value is less than 4, organic gloss agents will precipitate.
When the pH value is around 3, the cathodic polarization effect, current efficiency, dispersion ability and deep plating ability of the coating will be reduced.
In addition, when using potassium salt galvanizing brightener, under low pH conditions, the iron impurity ions in the plating solution cannot form precipitates, which will lead to the accumulation of iron ions. In severe cases, black stripes will appear on the coating, and this is more obvious during barrel plating.
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Guangdong Bigely Technology Co., Ltd. ,founded in 2003, is a high-tech enterprise integrating R & D，production, sales and service, specializing in the production of electroplating additives. As a famous electroplating additives source manufacturer in China, our products are widely used to meet the plating needs of different industries and exported to many countries from all over the world. They can meet the environmental protection standard after use, mainly used in automobile parts, sanitary ware, electronic products, hardware, furniture, building accessories and other fields.
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