What should be done if the deposition rate of the workpiece is too slow during the electroplating process when using alkaline zincate brighteners?
Based on field experience and product characteristics, Bigely Technology conducted the following analysis:
1.The temperature of the plating solution is low. In this case, appropriately raising the temperature can yield significant improvement.
2. The cathode current density is low. In this case, appropriately increasing the current yields a noticeable improvement.
3. The content of sodium hydroxide or alkaline zincate zinc plating additives in the plating solution is too low. Both of these conditions reduce the upper limit of cathode current density, leading to slower deposition rates. The lower current density in deep recesses of the parts results in incomplete zinc coating. Insufficient sodium hydroxide content in the plating solution can also cause rough deposits, which can be adjusted based on analysis. Low levels of alkaline zincate zinc plating brighteners reduce the upper limit of cathode current density, resulting in poor coating gloss, which can be
adjusted using the Hull cell test.
4. The plating solution is turbid. First, adjust the solution composition based on analysis, then filter the solution to remove solid impurities.
5. The plating solution contains impurities such as lead. The presence of lead impurities in the plating solution can prevent zinc from depositing on the cathode. Even if a coating is formed, when this coating is immersed in 3% nitric acid for brightening, it not only lacks brightness but may also develop black spots. Subsequent passivation will fail to produce a satisfactory passivation film. In such cases, the source of lead impurities (which mostly originate from impure zinc oxide or impure anodes) should be identified, and the plating solution should be treated with zinc
powder to remove lead and other foreign metal impurities.
In summary, if the deposition rate is too slow during the electroplating process, attention should be paid to the following points: low plating solution temperature, low cathode current density, insufficient sodium hydroxide or alkaline zincate brightener content in the solution, turbidity of the solution, or the presence of foreign metal impurities such as lead.
