What causes blistering in acid zinc coatings? On one hand, it relates to excessive amounts of acid zinc brighteners; on the other hand, it also has a causal relationship with excessively high cathode current density.
The selection of cathode current density is closely related to factors such as the temperature of the main plating bath, the quality of the acid zinc brightener, the distance between the anode and cathode, and whether a cathode movement device is employed.
High cathode current density offers the following advantages:
①Accelerate the sedimentation rate
② Expand the brightness range of the coating
③ Improve the flowability of the plating solution
If the current density is excessively high, excessive potassium chloride zinc brightener becomes trapped within the coating. Simultaneously, if the pH value in the cathode region rises too rapidly, causing metal hydroxides or basic salts to become entrapped within the coating, this will result in coating brittleness, poor adhesion of the passivation film, and reduced corrosion resistance.
If the current density is too low, the plating layer will form fine crystals but at a slow deposition rate, which will affect the production efficiency of the electroplating plant.
When electroplating plants use Bigely acid zinc brighteners, the cathode current density is typically controlled between 0.5 and 6.0 A/dm². During routine production management, for applications requiring thin plating layers and white passivation, the cathode current density may be appropriately increased. Conversely, for thicker plating layers and colored passivation, the current density should be kept lower to enhance corrosion resistance.
About Bigely Technology
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 chemicals. As a fast growing electroplating chemicals supplier 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.
If you need our high-quality electroplating additives, please contact us. We can provide you samples for test, and also provide a series of services.
