Cold galvanized VS hot-dip galvanized of solar street light pole

At present, the material used for solar street light poles is mostly made of high-quality Q235 steel. The solar street light is exposed to the wind, sun and rain outside, so if you want to use it for a longer time, the light pole's corrosion resistance is very important. In order to improve this characteristic, the steel is usually galvanized.

Galvanizing treatment is divided into two types: hot-dip galvanizing and cold galvanizing. It is usually recommended to purchase a hot-dip galvanized type due to better corrosion resistance. So why is the corrosion resistance performance of hot-dip galvanized is better and what is the difference between them?

1. Definition

1) Cold galvanized

It is also called electro-galvanizing. Put the degreasing and pickling steel into the zinc salt solution, connect the negative electrode of the electrolysis equipment, put the zinc plate on the opposite side, and connect the positive electrode of the electrolysis equipment. With directional movement, the surface of the steel pipe will also form a uniform, dense and well-bonded zinc deposit.

2) Hot-dip galvanized

After the steel surface is cleaned and activated, it is immersed in a molten zinc solution, and a layer of metallic zinc is formed on the surface of the steel through the physical and chemical reaction between iron and zinc at the interface. This treatment method forms the bonding strength between the coating and the base layer. The compactness, durability, maintenance-free and economy of the coating are better than those of cold galvanizing.

2. The difference between the two

1) How to work

From the names of the two, we should be able to know the difference. The zinc in cold galvanized steel pipes is obtained at room temperature, while the zinc in hot-dip galvanized steel is obtained at 450℃~480℃.

2) Plating thickness

The thickness of the cold galvanized coating is generally only 3~5μm, which is much easier to process, but the corrosion resistance is not very good; while the hot-dip galvanized coating usually has a thickness of 10 μm and above, and the corrosion resistance is much better, probably dozens of times that of cold galvanized lamp poles.

3) Coating structure

Hot-dip galvanizing has a relatively brittle compound between the coating and the substrate, but this does not have much effect on its corrosion resistance, because its coating is a pure zinc coating, the coating is relatively uniform, there are no pores, and it is not easy to The coating of cold galvanized is composed of some zinc atoms, which belongs to physical adhesion. There are many pores on the surface, which are easily corroded by environmental influences.easily corroded by environmental influences.

4) Price difference

Hot-dip galvanizing is a lot more troublesome in production and has more requirements, so some enterprises with relatively old equipment and relatively small scales generally use the mode of cold galvanizing, which is much lower in price and cost. The manufacturers of hot-dip galvanizing are generally more formal and larger in scale. They can better control the quality, and the cost is higher. 

In addition to producing all kinds of solar lamps, “Litel Solar” also produces all kinds of light poles. If you need to purchase light poles, please contact us freely.