ZnCl 2 nhci - ZnCI (NH) + NH hci t t + 2
Dissociate the released ammonia and hydrogen chloride gases with the residual oxides on the surface of the workpieceZinc oxide formed on the surface of zinc solution reacts:
FeO + NH + 2 hci - FeCI (NH) + HO
tZnO + NH + 2 HCL - ZnCI (NH) + HO
tZnci.2nhci is stable in a co-plating solution composed of zinc chloride and ammonium chloride.Chemical composition of double salt, easy to crystallize on the surface of steel. The role of NHCI in plating AIDSIt is fundamental, but NHCI is volatile, so the content should not be too high to avoid the workpiece being immersed.Too much smoke is formed in the zinc process. ZnCI ACTS as a coating to reduce workpiece pickling during picklingOxidation after and before zinc immersion. Meanwhile, zncl.2nhci is zinc chloride and ammonium chloride!The co-plating agent of the composite foundation has good automatic drying effect. According to the study, in Europe, the mixing ratio of zinc chloride and ammonium chloride is about 0.8: in the United States and Japan, the solution of trisalt zncl.3nhci or four-salt zncl.4nhci is commonly used, and the ratio of ammonium to zinc is about 1.2-1.6: in ChinaHot galvanizing is usually not baked.The drying or drying effect is not good, and it is recommended to use 1.2-1.6 ammonium, considering the cost of use.Zinc ratio.
In order to keep production running normally, the concentration of ammonium chloride must be kept higher than that of zinc chloride0.05-0.07g/1 has the best effect, and the total value of ammonium chloride and zinc chloride concentration cannot only be specified. Once the concentration of zinc chloride is higher than that of ammonium chloride, pinhole leakage will appear on the workpiece surfacePlating.