How to prevent blistering of the coating during zincate zinc plating?

Production practice has proven that zincate zinc plating electrolytes are less reliable than cyanide zinc plating electrolytes when poorly managed.

Coating blistering is related to many factors: First, the quality of additives and brighteners. Improper selection or excessive use of additives, or excessive use of cationic brighteners, can lead to severe inclusions in the coating, increasing coating stress; excessive cathodic polarization can cause excessive initial hydrogen permeation, easily resulting in coating blistering.

In production, all additives should be added frequently in small amounts. For electrolytes that have been in use for a long time, excessive accumulation of additive decomposition products should be periodically or continuously removed by activated carbon adsorption.

Secondly, changes in process specifications affect coating blistering. For example, excessively low working temperatures (<10℃) and high current densities (>15g/L) during electroplating can increase the tendency for blistering in the plating layer. In production, the alkali-zinc ratio should be controlled, generally NaOH/Zn = 11~12. In summer, the Zn2+ concentration can be as high as 12g/L, and the current density can also be increased; in winter, the Zn2+ concentration should be controlled at around 8g/L, and the current density can be reduced. Furthermore, immersing the workpiece in the plating tank while it is still charged or moving the cathode is beneficial for ensuring plating quality. Poor pre-plating treatment, such as incomplete degreasing or rust removal, can also lead to poor adhesion between the substrate and the plating layer, making blistering more likely. Different treatment methods should be used for special steels. Products with low surface roughness are prone to blistering; therefore, anodic electrolytic degreasing and pre-plating activation treatment should be strengthened.