Views: 4 Author: Site Editor Publish Time: 2021-09-22 Origin: Site
Zinc plating refers to a surface treatment technology that coats a layer of zinc on the surface of metals, alloys or other materials for aesthetics and rust prevention.
In the actual production process, the common factors that affect the galvanizing speed and quality are:
(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 conductivity. The current is consumed on the wire, and the current distributed to the surface of the workpiece is too small.
(3) The workpiece contains high carbon content. High-carbon steel, cast iron, etc. will lower the hydrogen evolution potential, accelerate hydrogen evolution on the surface of the workpiece, and reduce current efficiency.
(4) The workpiece is tied tightly. Part of the workpiece is shielded during galvanizing, which causes the coating to be too thin.
(5) The bath temperature is low. When the temperature of the plating solution is low, the current density delivered will decrease accordingly, and the deposition rate of the coating will inevitably decrease.
(6) The sodium hydroxide content in the plating solution is relatively high. When the sodium hydroxide content is high, the current efficiency decreases accordingly.
(7) The content of additives 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 area of the plated parts is under-estimated, and the current density distributed during plating appears to be too small.
(9) The workpiece suspension method 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 over-corroded. Reduce the hydrogen precipitation potential, and accelerate the current efficiency of hydrogen evolution on the surface of the workpiece, thereby affecting the deposition rate of zinc. Appropriate amount of corrosion inhibitor should be added to the pickling solution. If the local oxide scale is too thick, mechanically remove it first. Do more checks 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.