How does electrogalvanizing deposit zinc on steel strip?

Electrogalvanizing, or electrolytic galvanizing, applies a zinc coating to steel strip through electrolytic deposition rather than by immersion in a molten bath.12

In this process, the steel strip acts as a cathode by connecting to the negative side of a direct current source. The strip is passed through a series of electrolytic cells containing an acidic solution of zinc sulfate or zinc chloride.2

Within these cells, the following occurs:
* Deposition: Positively charged zinc cations in the electrolyte are converted into metallic zinc atoms by the electric current and deposited onto the surface of the steel strip.2
* Zinc Supply: The electrolyte is replenished with zinc cations either by using soluble zinc anodes that dissolve during the process or by continuously adding zinc compounds to the bath, in which case insoluble anodes (such as titanium coated with iridium oxide) are used.2
* Control: Because the amount of zinc deposited is directly related to the electrical current, coating thickness is highly controllable. Parameters such as current density, line speed, and electrolyte composition are adjusted to achieve precise, uniform, or differential coatings.2

This method typically produces thinner, more uniform coatings than hot-dip galvanizing and is often used for specialized applications requiring high surface quality.2