Steel grating has the advantages of saving steel, corrosion resistance, fast construction, neat and beautiful, non-slip, ventilation, no dents, no water accumulation, no dust accumulation, no maintenance, and a service life of more than 30 years. It is increasingly being widely used by construction units. The surface of the steel grating is treated, and only after some special treatment can its service life be extended. The use conditions of steel grating in industrial enterprises are mostly open-air or in places with atmospheric and medium corrosion. Therefore, the surface treatment of steel grating is of great significance to the service life of steel grating. The following introduces several common surface treatment methods of steel grating. (1) Hot-dip galvanizing: Hot-dip galvanizing is to immerse the rust-removed steel grating in a high-temperature molten zinc liquid at about 600℃, so that a zinc layer is attached to the surface of the steel grating. The thickness of the zinc layer shall not be less than 65um for thin plates below 5mm, and not less than 86um for thick plates. Thereby achieving the purpose of corrosion prevention. The advantages of this method are long durability, high degree of industrialization of production, and stable quality. Therefore, it is widely used in outdoor steel grating projects that are severely corroded by the atmosphere and difficult to maintain. The first step of hot-dip galvanizing is pickling and rust removal, followed by cleaning. Incompleteness of these two steps will leave hidden dangers for corrosion protection. Therefore, they must be handled thoroughly. (2) Hot-sprayed aluminum (zinc) composite coating: This is a long-term corrosion protection method with the same corrosion protection effect as hot-dip galvanizing. The specific method is to first sandblast the surface of the steel grating to remove rust, so that the surface reveals a metallic luster and roughens. Then use acetylene-oxygen flame to melt the continuously delivered aluminum (zinc) wire, and blow it onto the surface of the steel grating with compressed air to form a honeycomb aluminum (zinc) spray coating (thickness of about 80um~100um). Finally, fill the capillaries with coatings such as cyclopentane resin or urethane rubber paint to form a composite coating. The advantage of this process is that it has strong adaptability to the size of the steel grating, and the shape and size of the steel grating are almost unrestricted. Another advantage is that the thermal impact of this process is local and constrained, so it will not cause thermal deformation. Compared with hot-dip galvanizing of steel grating, this method has a lower degree of industrialization, and the labor intensity of sandblasting and aluminum (zinc) blasting is high. The quality is also easily affected by the mood changes of the operator. (3) Coating method: The corrosion resistance of the coating method is generally not as good as the long-term corrosion resistance method. It has a low one-time cost, but the maintenance cost is high when used outdoors. The first step of the coating method is rust removal. High-quality coatings rely on thorough rust removal. Therefore, high-requirement coatings generally use sandblasting and shot blasting to remove rust, reveal the luster of the metal, and remove all rust and oil stains. The choice of coating should take into account the surrounding environment. Different coatings have different tolerances to different corrosion conditions. Coatings are generally divided into primers (layers) and topcoats (layers). Primers contain more powder and less base material. The film is rough, has strong adhesion to steel, and has good bonding with topcoats. Topcoats have more base materials, have glossy films, can protect primers from atmospheric corrosion, and can resist weathering. There is a problem of compatibility between different coatings. When choosing different coatings before and after, pay attention to their compatibility. The coating construction should have appropriate temperature (between 5~38℃) and humidity (relative humidity not more than 85%). The coating construction environment should be less dusty and there should be no condensation on the surface of the component. It should not be exposed to rain within 4 hours after coating. The coating is generally applied 4~5 times. The total thickness of the dry paint film is 150um for outdoor projects and 125um for indoor projects, with an allowable deviation of 25um.
