1. Coating method:
The first step of coating construction is rust removal. A good coating depends on thorough rust removal. Therefore, the coating with high requirements usually uses sand blasting to remove rust, expose the luster of metal, and remove all rust and oil stains. The coating of steel structure company can be removed by hand. The selection of coating should consider the surrounding environment. Different coatings have different resistance to different corrosion conditions. Coatings are generally divided into primer (layer) and topcoat (layer).
The primer contains more powder and less base material. The film is rough, has strong adhesion with steel structure and good adhesion with topcoat. The topcoat has many base materials, glossy film, can protect the primer from atmospheric corrosion, and can resist weathering. The compatibility of different coatings should be paid attention to when selecting different coatings. Proper temperature (5 ~ 38 ℃) and humidity (relative humidity no more than 85%) should be used for coating.
The dust in the coating construction environment should be less, and there should be no condensation on the surface of components. No rain within 4 hours after painting. The coating is generally made 4 ~ 5 times. The total thickness of dry film is 150 μ m for outdoor engineering and 125 μ m for indoor engineering, and the allowable deviation is 25 μ M. The total thickness of dry paint film can be increased to 200 ~ 220 μ m on the sea or in the atmosphere with strong corrosivity.
2. Thermal spraying aluminum (zinc) composite coating:
This is a kind of long-term anti-corrosion method equivalent to hot-dip galvanizing. The specific method is to remove rust on the surface of steel members by sand blasting to make the surface show metallic luster and roughen. Then, the aluminum (zinc) wire is melted by acetylene oxygen flame and blown onto the surface of steel member with compressed air to form honeycomb aluminum (zinc) spray coating (thickness about 80 μ m ~ 100 μ m). Finally, epoxy resin or chloroprene rubber paint was used to fill the pores to form a composite coating.
3. Hot dip galvanizing:
Hot dip galvanizing is to immerse the steel members after rust removal into molten zinc at about 600 ℃ to make the surface of steel members adhere zinc layer. The thickness of zinc layer shall not be less than 65 μ m for thin plates less than 5mm and 86 μ m for thick plates. So as to play the purpose of anti-corrosion. The advantages of this method are long durability, high industrialization and stable quality. Therefore, it is widely used in outdoor steel structures which are seriously corroded by the atmosphere and difficult to maintain.
