We use high-sulfur nickel additives to obtain nickel coatings with a sulfur content of 0.12% to 0.25%.It is mainly used for the protection of steel and zinc alloy substrates and the intermediate layer of decorative coatings, which can effectively improve the corrosion resistance of coatings.So when we use high-sulfur nickel additives, how should the bath be maintained?
Bigolly Technology made an analysis based on the field experience and the characteristics of the product's high-sulfur nickel additives Ni-320,there are mainly 5 points:
1. Control the temperature of the plating solution.With the increase of temperature, the cathode current density will increase, and the appearance of the coating will be better.However, if the temperature is too high, the coating will be rough, and the sulfur content of the coating will decrease as the temperature of the bath increases.Therefore, the temperature of the plating solution should be controlled at 40-45 °C.
2. Control of pH value of plating solution.The pH value of the plating solution is controlled at 3.8~4.2.The high pH value of the plating solution is easy to generate Ni(OH)2 and affect the bonding force between the plating layers.The pH value is too high and can be adjusted with dilute sulfuric acid.Note: Adjust pH with dilute hydrochloric acid only if the chloride content of the bath is too low.
3. Supplement of high-sulfur nickel additives.Generally, the consumption of high-sulfur nickel additive Ni-320 is 500-600ml/KAH, and the consumption of saccharin is 20-30g/L.In order to keep the sulfur content in the coating consistent, Ni-320 should be added in a small amount for many times, and the coating is easy to peel off when adding too much.During the production process, the replenishment interval of additives should not exceed 4 hours.
4. Air stop time.After the workpiece is plated with high-sulfur nickel, the air stop time should not be too long, and the coating is easy to passivate after a long time.It makes the bonding force between the high-sulfur nickel layer and the bright nickel layer not good.
5. Control of potential difference.During production, the potential difference of the nickel layer of the workpiece should be measured frequently.If the potential difference exceeds -120~-150mv, activated carbon and sulfuric acid can be used for combined treatment.Since the adsorption capacity of activated carbon cannot reach 100%, it can only adsorb 50% of the additives, so the supplementary additives should be supplemented according to the general amount.
Therefore, in the process of using high-sulfur nickel additives, we maintain the plating solution according to the method provided by Bigolly, which can reduce the occurrence of failures and keep the quality of the plating layer good.
.If you are interested in high-sulfur nickel additives, please contact Bigolly customer service to get free samples and detailed technical information!
If you want to know more about nickel plating, you can check "Electroplating encyclopedia".