The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Hot Zinc Galvanizing Versus Electroplated Zinc

Dear Sirs:

We would appreciate your advice on the following:

• We want to replace hot zinc galvanized steel rods with electroplated zinc. These rods have a thickness of zinc of 80 microns. They are buried in the ground in the construction of highways. If we replace them with electroplated zinc with a top iridescent yellow chromate, what should be the zinc thickness to obtain the same service life to red corrosion than the hot zinc galvanizing finish with 80 microns ?
• Is there an industry standard for equivalence regarding corrosion for hot zinc galvanizing versus electroplated zinc?
• Where can I obtain literature and technical information regarding hot zinc galvanizing?

Thanks in advance,

Oscar Infante
- Santiago, Chile
2001

---

Corrosion resistance of zinc is directly related to its thickness. Since it will be difficult to reach 80 microns thickness with electroplating, it is not possible to solve your problem. Hot dip zinc plating creates intermetallic compounds between steel and zinc layer. This layer is very brittle and easy to break if you deform the material after plating. That is the reason why electroplating is preferred for deformed steel sheet materials.

Good Luck

Ertan YAZICI
- Turkey
2001

Hot dip, zinc coatings generally provide superior rust protection. Normally, the hot dip process has a thicker coating, than electro. The heavier the coating, the more protection. It may be difficult to electro galvanize 80 microns.

Terry T. Magyar
Berwick Steel Co. - Columbus, Ohio, USA
2001