In the production process of using alkaline galvanizing brightener, sometimes the galvanized layer of the workpiece will appear pitted small bubbles, which will seriously affect the appearance of the workpiece and the performance of the coating, and the customer will not accept it.o does this phenomenon mean that the alkaline galvanizing brightener is used too much?
Bigolly Technology made an analysis based on the field experience and the characteristics of the product's BZ-515, Although excessive addition of alkaline galvanizing brightener will reduce the dispersing ability of the plating solution, such pitted small bubbles will appear in severe excess, and the brittleness of the coating is relatively large.But in addition to the factors of excessive brightener, there may be the following three situations:
1. The workpiece is not clean in the pretreatment.The workpiece is not thoroughly degreasing or washed with water in the pretreatment, and the residual oil on the surface will foam when galvanized due to the poor bonding force of the coating.Therefore, the workpiece should ensure that the surface is clean before galvanizing, so as to obtain a galvanized layer with good bonding force.
2. During the galvanizing process, the temperature of the bath is low and the current density is relatively high.In the galvanizing process, the temperature of the bath is low, the conductivity of the bath is poor, and the adsorption capacity of the brightener is relatively poor.If the current density is large, the corners of the workpiece are easy to be scorched, and the coating is easy to be mixed with additives, resulting in increased brittleness and bubbling.Therefore, in the production process, the temperature and current density of the plating solution should be well controlled.
3. There are many organic impurities in the plating solution.When there are many organic impurities in the alkali-zinc plating solution due to the introduction of oil stains or the decomposition of brighteners, the brittleness of the galvanized layer will increase, resulting in streaks, blistering, and blooming.Therefore, the bath should be treated with activated carbon regularly to reduce the influence of organic impurities in the bath.
Therefore, in the production process of using alkaline galvanizing brightener, if there are pitted small bubbles in the coating of the workpiece, it is not necessarily because the alkaline galvanizing brightener is used excessively, but it may also be caused by these three reasons.