Cold galvanizing is a method of protecting the surface of steel with zinc, which is usually used for anti-corrosion treatment of steel wire, steel pipe and other products. Cold galvanizing refers to the mixing of zinc powder and additives into a slurry substance, which is coated on the steel surface by spraying, impregnating and other ways to form a zinc layer to protect the steel from oxidation corrosion.
First of all, the surface of the steel needs to be cleaned before cold galvanizing treatment, and it is appropriate to ensure that the surface is free of any impurities by means of oil removal, dust removal, etc., to avoid impurities hindering the immersion and adhesion of the zinc liquid.
Secondly, the cold galvanized coating needs to choose the appropriate combination of zinc liquid, the general zinc powder particles are small and uniform, usually nano-scale zinc powder is used, and the zinc powder is fully mixed with additives, to ensure that the ratio of zinc powder and additives is appropriate, in order to achieve good anti-corrosion effect.
After the mixture is made into a slurry, the steel can be cold galvanized in a variety of ways. The specific choice of method depends on the process and requirements, mainly the following:
1. Spraying method: The zinc slurry is sprayed on the steel surface. Spraying requires uniform and complete coverage of the surface to obtain a better anti-corrosion effect. It can be sprayed with hand-held or mechanical spraying equipment.
2. Dipping method: The steel is immersed in the zinc slurry, so that the zinc liquid penetrates into every corner of the steel. The impregnation time is generally a few minutes to tens of minutes, depending on the coating thickness and process. After dipping, the steel is removed and the coating is evenly dried by vibration or air drying.
3. Alkaline phosphoric acid washing method: The surface of the steel is washed by alkaline phosphoric acid to remove the oxide layer, rust and oil and other impurities on the surface of the steel, and then the steel is soaked in an acidic solution containing zinc ions to form a zinc layer on the surface of the steel through chemical reaction. This method can be used for various complex shapes of steel, but attention should be paid to the disposal of waste liquid.
4. Electrolysis method: By electrochemical action, zinc layer is deposited on the surface of the steel wire. This method has the advantages of low cost and uniform coating thickness, but the operation is relatively complicated and requires high equipment and technical requirements.
When the cold galvanized treatment is completed, it is necessary to ensure that the coating is dried evenly, which can be dried by natural air drying or heating drying. At the same time, it is also necessary to undergo quality inspection to ensure that the uniformity, thickness and adhesion of the coating meet the requirements.
In order to improve the corrosion resistance of cold galvanized coating, other materials, such as flame retardants or corrosion resistant agents, can be added to the surface of the coating, and dried or cured.
Post time: 07-05-24