Steel is easy to rust in air, water or soil, or even completely destroy.The steel loss caused by corrosion accounts for about 1/10 of the total steel output every year. On the other hand, in order to make the steel products and parts have some special functions on the surface and give them a decorative appearance on the surface, it is generally treated by electroplating.
: because zinc is not easy to change in dry air, and in humid air, a dense, alkaline zinc carbonate film can be formed on the surface, which can effectively protect the interior from corrosion.And when for some reason the coating breaks down and the steel base is exposed, the zinc and the steel matrix form microcells, which protect the steel substrate from becoming a barrier electrode.
Ii. Performance features:
1. The zinc coating is relatively thick, with fine crystallization, uniform daily pores and good corrosion resistance:
2. The zinc coating obtained by electroplating is relatively pure and corrodes slowly in fog such as acid and alkali, which can effectively protect the steel matrix:
3. After chromic acid passivation, the zinc coating forms white, color, military green, beautiful and generous, with certain decorative properties;
4. Because the zinc coating has good ductility, it can be formed by cold punching, rolling and bending without damaging the coating.
Iii. Application scope:
With the development of science and technology, electroplating industry is involved in more and more fields.At present, the application of electrogalvanization has been throughout the national economy of various production and research departments.For example, machine manufacturing, electronics, precision instruments, chemicals, light industry, transportation, weapons, aerospace, atomic energy and so on are of great significance in the national economy.
Hot dip galvanizing:
Hot dip zinc is an excellent coating method for protecting steel matrix.It is in the state of liquid zinc, after a rather complex physical and chemical action, on the iron and steel not only coated with a thick layer of pure zinc, but also produced a zinc-ferroalloy layer.This plating method not only has the corrosion resistance characteristic of electrogalvanizing, but also has the zinc-ferroalloy layer.It also has strong corrosion resistance which can't be compared with that of electrogalvanizing.Therefore, this plating method is especially suitable for various strong acid, alkali fog and other corrosive environment.
The hot galvanizing layer is formed by zinc in three steps in a high temperature liquid:
1. The surface of iron base is dissolved by zinc solution to form zinc-ferroalloy phase layer;
2. The zinc ion in the alloy layer further diffuses to the matrix to form the zinc-iron intersoluble layer:
3. The surface of the alloy layer is surrounded by the zinc layer.