In the actual production process, the common factors affecting the speed and quality of galvanizing are as follows:
(1) The pretreatment is not complete. There is oxide film on the surface of the workpiece, which affects the normal deposition of zinc.
(2) Poor conductivity. The current is consumed on the conductor, and the current distributed to the workpiece surface is too small.
(3) The carbon content of workpiece is high. High carbon steel and iron castings will reduce the hydrogen precipitation potential, accelerate the hydrogen evolution on the surface of the workpiece, and reduce the current efficiency.
(4) The binding of workpieces is too tight. When galvanizing, the parts are partially shielded, resulting in too thin coating.
(5) The bath temperature is low. When the temperature of the bath is low, the current density and deposition rate of the coating will decrease correspondingly.
(6) The content of sodium hydroxide in the bath is too high. When the content of sodium hydroxide is high, the current efficiency will decrease correspondingly.
(7) The content of additives in the bath is low. The low content of additives will affect the dispersion ability, and the coating is too thin.
(8) The area estimation of the plated parts is insufficient, and the current density of distribution is too small.
(9) If the suspension method of workpiece is improper and the distance between workpiece and zinc anode is too large, the position shall be adjusted.
(10) The workpiece is corroded. When the potential of hydrogen precipitation is reduced, the current efficiency of accelerating hydrogen evolution on the surface of workpiece is reduced, which affects the deposition rate of zinc. A proper amount of corrosion inhibitor should be added to the pickling solution, and the local oxide skin is too thick, which should be removed by mechanical method first, and more inspection should be carried out during pickling.
(11) Anode passivation. The decrease of effective area affects the normal distribution of current.
(12) The content of sodium hydroxide is low. If the sodium hydroxide content is low, the current density is not high, and the anode is passivated.