Acid Potassium Chloride Zinc Electroplating Softener
Softener Solubilizing main brightener, auxiliary brightening effect, increase the coating thickness in low area, improve the depth capacity of the bath, reduce the surface tension of the bath, on the cathode surface wetting effect. The content in the bath is 25ml/L - 30ml/L The coating brittleness increases and passivation quality is affected by high content. The content is too low, the bright effect is not good, the coating is easy to flower, stay in the air and change color quickly.
Description
The role of various chemical components in the plating solution
Additives
Additives play an important role in plating solution. In general, additives are added according to KA.h consumption. If the proportion is out of proportion, add it according to the bath volume after adjusting by hull bath experiment.
Without additive plating solution, the coating is gray and rough, and the range of cathode current density is very small.
After adding appropriate amount of additives, the coating can be fine and bright, the current density is expanded, the dispersion ability and covering ability are improved, too high additives will cause brittleness of the coating, passivation film fall off and color change.
The general total amount should be controlled within the range of 25-30ml/L.
Brightener
The main brightener can produce remarkable brightening and leveling effect.
If the content is too high, the coating in the low current density area will become thinner, and the bottom will be exposed after passivation, which will easily lead to increased brittleness of the coating and affect the passivation quality.
The content is too low, the coating bright leveling effect is not good. The content in the bath is maintained at 0.8-2ml/L.
Softener
Solubilizing main brightener, auxiliary brightening effect, increase the coating thickness in low area, improve the depth capacity of the bath, reduce the surface tension of the bath, on the cathode surface wetting effect.
The content in the bath is 25ml/L - 30ml/L
The coating brittleness increases and passivation quality is affected by high content.
The content is too low, the bright effect is not good, the coating is easy to flower, stay in the air and change color quickly.
Anode zinc plate
The purity of the anode zinc plate has a great influence on the plating solution in the production. The inferior zinc plate often contains impurities such as iron, copper and lead, resulting in dark coating, slow deposition rate of the coating and mist phenomenon after passivation. It is recommended to use 0# standard zinc plate in potassium chloride galvanizing, and the quality of zinc plate shall not be lower than 1# zinc standard in GB470-64 standard.
Current
Current is too high, coating rough, foaming, peeling, tank temperature rise.
The current is too low, deep plating ability is poor or no coating. Generally, 0.5-3A/dm2 is appropriate.
PH value
When the PH value of the bath is low, the coating is bright but hydrogen precipitates out, the current efficiency is reduced, and the covering ability is decreased. High PH value, coating rough black, local gray black. Usually the PH value will rise slowly in the process of electroplating, then pay attention to adjust the PH value with dilute hydrochloric acid in time. Adjust the PH value to constantly stir, to prevent the local acidity is too high and cause the additive precipitation. General bath PH value should be controlled in the range of 4.5-5.4, with 4.8 as the best.
Temperature
High bath temperature can increase the current density, but high temperature bath dispersion ability and coverage ability decreased, low area coating thinner, parts overall brightness decreased, coating fog. If the bath temperature is high, the additive consumption will increase, and reducing the bath temperature can reduce the consumption of brightener. When the bath temperature is too low, it shows that the additive is too much, especially when the brightener is too much, the plating parts will be burnt in the high area. Especially in winter, the first bath bath, prone to zinc burst layer, so to take a small current to extend the plating time.
Common failures and processing method
|
Problem Description |
Probable cause |
Solutions |
|
Poor brightness |
Lack of brightener Lack of softener Organic impurity pollution
|
Brightener supplement Softener supplement Activated carbon filtration |
|
Poor coverage No coating in hole and concave
|
Lack of brightener Lack of softener Low potassium chloride The bath temperature becomes higher Aluminum impurity pollution |
Brightener supplement Softener supplement Potassium chloride supplement Lowering temperature Treat with zinc powder |
|
The bright range is narrow and the coating is easy to burn
|
The PH value of the bath increases Lack of zinc Lack of boric acid Lack of softener |
Adjust PH value with dilute hydrochloric acid Zinc chloride supplement Boric acid supplement Softener supplement |
|
The coating has white mist
|
Effect of organic impurities Poor cleaning after plating |
Activated carbon filtration Change the cleaning water |
|
The coating blackening after acid dipping |
Iron impurity Copper impurity |
Hydrogen peroxide treatment and filtration Treat with zinc powder |
|
Roller holes appear in the coating
|
Lack of softener Iron impurity Excessive current Lower zinc Over loading of work
|
Softener supplement Hydrogen peroxide treatment and filtration Lower total current Zinc chloride supplement Reduced loading |
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