The difference between electro-galvanizing and hot-dip galvanizing

The difference between electro-galvanizing and hot-dip galvanizing

The steel surface usually has a galvanized layer, which can prevent the steel from rusting to a certain extent. The galvanized layer of steel is generally constructed by hot-dip galvanizing or electro-galvanizing. So what are the differences between hot-dip galvanizing and electro-galvanizing?

Electro Galvanizing Process

Electrogalvanizing, also known as cold galvanizing in the industry, is the process of using electrolysis to form a uniform, dense and well-bonded metal or alloy deposition layer on the surface of the workpiece.

Compared with other metals, zinc is a relatively cheap and easily plated metal. It is a low-value anti-corrosion coating and is widely used to protect steel parts, especially against atmospheric corrosion, and for decoration. Plating techniques include tank plating (or rack plating), barrel plating (for small parts), blue plating, automatic plating and continuous plating (for wire, strip).

Features of electro-galvanized

The purpose of electrogalvanizing is to prevent steel objects from being corroded, improve the corrosion resistance and service life of steel, and at the same time increase the decorative appearance of the product. Steel will be weathered, water or soil corrosion over time. The steel that is corroded every year in China accounts for almost one-tenth of the total amount of steel. Therefore, in order to protect the service life of steel or its parts, electro-galvanizing is generally used to process steel.

Since zinc is not easy to change in dry air, and can produce a basic zinc carbonate film in a humid environment, this film can protect internal parts from corrosion damage, even if the zinc layer is damaged by some factor. In some cases, zinc and steel combine over time to form a microbattery, with the steel matrix protected as a cathode. Summary Electrogalvanizing has the following characteristics:

1. Good corrosion resistance, meticulous and uniform combination, not easy to be entered by corrosive gas or liquid.

2. Because the zinc layer is relatively pure, it is not easy to be corroded in acid or alkali environment. Effectively protect the steel body for a long time.

3. After passivation by chromic acid, it can be used in various colors, which can be selected according to customers’ preferences. The galvanizing is elegant and decorative.

4. The zinc coating has good ductility and will not fall off easily during various bending, handling and impact.

What is the difference between hot-dip galvanizing and electro-galvanizing

The principles of the two are different. Electrogalvanizing is to attach a galvanized layer on the surface of the steel by an electrochemical method. Hot-dip galvanizing is to immerse the steel in a zinc solution to make the surface of the steel with a galvanized layer.

There are differences in appearance between the two. If the steel is electro-galvanized, its surface is smoother. If the steel is hot-dip galvanized, its surface is rough. Electro-galvanized coatings are mostly 5 to 30 μm, and hot-dip galvanized coatings are mostly 30 to 60 μm.

The scope of application is different, hot-dip galvanizing is mostly used in outdoor steel such as highway fences, and electro-galvanizing is mostly used in indoor steel such as panels.