What are the factors that affect the quality of the galvanized production process of galvanized sheet?

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What are the factors that affect the quality of the galvanized production process of galvanized sheet?

Mar. 14, 2022

Galvanizing refers to the surface treatment technology that coats a layer of zinc on the surface of metal, alloy or other materials to play the role of beauty and rust prevention. The main method used is hot-dip galvanizing. What factors affect the quality of galvanized sheet galvanized production process?

(1) The pretreatment is not thorough. There is an oxide film on the surface of the workpiece, which affects the normal deposition of zinc.

(2) Poor electrical conductivity. Current is drawn on the wire and too little current is distributed to the workpiece surface.

(3) The workpiece has high carbon content. High carbon steel, cast iron, etc. will reduce the hydrogen precipitation potential, accelerate the hydrogen evolution on the surface of the workpiece, and reduce the current efficiency.

(4) The workpiece is tied too densely. When galvanizing, the workpiece is partially shielded and the coating is too thin.

(5) The temperature of the plating solution is low. When the temperature of the plating solution is low, the current density delivered is correspondingly reduced, and the deposition rate of the coating must also be reduced.

(6) The sodium hydroxide content in the plating solution is high. When the sodium hydroxide content is high, the current efficiency decreases accordingly.

(7) The additive content in the plating solution is low. The low additive content will affect the dispersion ability, and the coating will appear too thin locally.

(8) The estimated area of ​​the plated parts is insufficient, and the current density distributed during plating appears to be too small.

(9) The hanging method of the workpiece is improper, and the distance between the workpiece and the zinc anode is too large, and the position should be adjusted.

(10) The workpiece is too corroded. When the hydrogen evolution potential is reduced, the hydrogen evolution acceleration current efficiency on the surface of the workpiece decreases, thereby affecting the deposition rate of zinc. An appropriate amount of corrosion inhibitor should be added to the pickling solution, and the local oxide scale is too thick to be removed by mechanical methods first, and more inspections should be made during the pickling process.

(11) Anode passivation. The effective area is reduced, which affects the normal distribution of current.

(12) The sodium hydroxide content is low. If the sodium hydroxide content is low, the current density will not increase, and the anode will be passivated.