Electro-galvanized and hot-dip galvanized are two common methods used to coat fasteners such as bolts, screws, and nails to protect them from corrosion. The main difference between the two methods is the way the coating is applied and the thickness of the resulting coating.
Electro-galvanizing is a process of electroplating where a layer of zinc is applied to the surface of the fastener by passing an electric current through a solution containing zinc ions. This results in a very thin and uniform coating of zinc, typically about 5-10 microns thick. Electro-galvanized coatings are suitable for use in mildly corrosive environments and are often used for indoor applications.
Hot-dip galvanizing, on the other hand, is a process where the fastener is dipped into a bath of molten zinc at a temperature of about 450°C. The zinc reacts with the steel to form a thick layer of zinc-iron alloy on the surface of the fastener, providing superior corrosion protection. The resulting coating is typically around 50-100 microns thick and is suitable for use in harsh and corrosive environments, such as outdoor applications.
In summary, while electro-galvanizing is a cheaper and faster process that results in a thinner and less durable coating, hot-dip galvanizing is a more expensive and time-consuming process that produces a much thicker and more durable coating that can withstand harsh environmental conditions. The choice of coating method will depend on the intended use and the level of corrosion resistance required for the application.
