Common problem

When using alkaline galvanizing brightener, how does the sodium carbonate in the plating solution come from?

2022-03-16

    In the production process of using alkaline galvanizing brightener, if there is a large amount of sodium carbonate in the plating solution, it will affect the normal use of the plating solution and cause failures.So how does the sodium carbonate in the plating solution come from?

    Since the alkaline zinc plating solution contains a large amount of sodium hydroxide, it will continuously absorb carbon dioxide in the air to generate sodium carbonate during the production process.The sodium hydroxide concentration in the bath will therefore be reduced. At this time, it is necessary to add the amount of sodium hydroxide in time to maintain its concentration, but with the accumulation of time, the sodium carbonate content in the plating solution will gradually increase.

    In addition, the addition of sodium hydroxide will also bring sodium carbonate. According to GB209-63, the mass fraction of sodium carbonate in secondary caustic soda is ≤2.5%. According to the calculation of 2.5%, every time 1000kg of sodium hydroxide is added, 25kg of sodium carbonate will be brought in. With the addition of sodium hydroxide, the sodium carbonate will continue to accumulate.

    Generally, when the sodium carbonate exceeds 80g/L in the alkaline zinc plating solution, the internal resistance of the plating solution will increase, the temperature rise will increase, and the upper limit of the current density will decrease.Some of Bigolly's customers have also experienced such a situation: when the current density is 1-4A/dm2, but in fact it is only about 1.5A/dm2, the current is slightly higher, and the corners of the product will be burnt, the dispersing ability and deep plating ability of the plating solution deteriorate, and the brittleness of the galvanized layer is also large. After analysis, it was determined that the sodium carbonate content in the plating solution was too high.

    Therefore, when we use alkaline galvanizing brightener, we should control the content of sodium carbonate in the plating solution, which can stabilize the quality of the plating solution and effectively reduce the failure rate.If you are interested in alkaline galvanizing brightener, please contact Bigolly customer service, you can get free samples and detailed technical information!   
    If you want to know more about zinc plating, you can check "common  problem".