Zinc Ammonium Chloride is mainly used by the galvanizing industry in order to prepare the flux bath in which the steel parts have to be dipped before going through the galvanizing itself.
In order to be able to prepare this flux bath we have different products depending on the amount of Zinc Chloride and Ammonium Chloride in them. Nevertheless, the most common are:
- Zinc Ammonium Chloride Double Salt
- Zinc Ammonium Chloride Triple Salt
Both products have a white powder appearance and can be shipped in different packaging, according to the general packing specs.
The pretreatment of the surfaces with the use of the flux baths has big importance, and a high impact on the consumption of metallic zinc and the formation of zinc ashes in the galvanizing process. To illustrate that fact we include here a text taken from the magazine: Metall, 52. Jahrgang, Nr. 5/98. W.Katzung, R.Rittig
Zinc ash formation and zinc consumption in dependence on parameters of pretreatment in hot dip galvanizing
Formation of zinc ash and zinc consumption are decisively influenced on kind, concentration, Fe2+ content and pH of flux solution in hot dip galvanizing.
From test results with flux solutions of basis ZnCl2/NH4 and ZnCl2/NH4/Alkalichlorid with different concentration of salt, Fe2+ and pH 1,7 and 4,5 it could be stated:
- Zinc ash formation and zinc consumption are the lowest in flux solutions which are Fe2+ free. This fact is independent of pH.
- Formation of zinc ash is reduced with increased flux concentration; optimal results regarding formation of zinc ash and zinc consumption are received when the salt concentration in the flux is 400 to 500 gr/l.
- Comparable good results regarding the formation of zinc ash are also received in flux solution with salt concentration 300 gr/l and Fe2+ content up to 20 gr/l. However the zinc consumption is about 5% higher
- Flux solutions with high Fe2+ content (60, 100 gr/l) increase ash formation by 1,5 to 2,5 times compared with Fe2+ free flux solutions. Zinc consumption is higher about 10% to 17%.
- The worst results are obtained with "fume poor" solutions. Ash formation in comparison with ZnCl2/NH4 flux solutions increases by 3 to 5 times, the zinc consumption is higher about 12%.
Optimal regarding quality and economic efficiency is the use of ZnCl2/NH4 flux solutions in the range of pH 4. The Fe2+ should be the lowest practically possible, generally lower than 20 gr/l.
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