1. Hot dip galvanizing. Zinc has good corrosion resistance under atmospheric conditions. Galvanizing is a method of sacrificing an anode to protect the cathode metal. Its corrosion life depends on the thickness of the galvanized layer and the corrosion rate. The thickness of the hot dip galvanized zinc layer is generally above 65 um (455 g/m2). The bonding surface of zinc and iron forms a layer of zinc-iron alloy, which enhances the adhesion of the zinc layer. Atmospheric exposure tests were carried out on hot dip galvanized coatings under various environmental conditions abroad. From the test results, hot dip galvanizing can meet the service life requirements of steel cable trays.
Because hot dip galvanizing has good corrosion resistance and high performance and price ratio, steel hot dip galvanized bridge is widely used at home and abroad.
For members with relatively thin walls and large slenderness ratios, deformation and other problems are likely to occur during hot dip galvanizing, and it is necessary to consider the structure of the cable tray and the galvanizing process.
2. Electroplating zinc. Compared with hot dip galvanizing, electrogalvanizing is simple in process and low in cost. There are no special requirements for the structure of the cable tray. Electroplated zinc can significantly improve its protective properties after passivation. The electro-galvanized layer is generally around 12. Therefore, it is not suitable for occasions where the corrosion life requirement is high.
Electroplating zinc has a ministerial standard. There are clear regulations on the choice of plating type, coating thickness, coating adhesion strength, corrosion resistance test, etc. These standards are selected differently and the content requirements are also different. At present, there are many manufacturers of electrogalvanized bridges in China, which are different when referring to the above relevant technical standards.
In order to improve the corrosion resistance of electrogalvanizing, it is possible to use a zinc-nickel alloy or a high passivation treatment after galvanizing (products such as "galvanized zinc bridge").
3. Electrostatic spraying. The spray material is generally polyvinyl chloride powder, polyester powder or anti-corrosion powder. The coating thickness is around 100. Electrostatic spraying has the characteristics of beautiful appearance and good chemical corrosion resistance. However, compared with the metal plating, the adhesion strength is low, and the erosion resistance and the particle abrasion resistance are poor. There is a problem of deterioration during use, which tends to cause the partial coating to fall off, which causes the steel substrate to rust, resulting in a large area of bubbling and peeling of the coating. In addition, the coating has poor UV resistance and is generally not suitable for outdoor use. The modern bridge factory produces such as: "electrostatic spraying cable tray".
4. Apply anti-rust paint. For components with large structural dimensions, due to the limitations of zinc pots, plating tanks, ovens, etc., they can only be treated by anti-rust paint. Although it has the characteristics of low cost and convenient use, it has poor corrosion resistance. Short service life and large maintenance workload are generally not suitable. (Products such as "rust-proof paint cable tray")
5. The bridge is made of aluminum alloy, which has been applied abroad. Whether it is coastal salty areas or high humidity and contains sulfur dioxide gas. The cable tray made of aluminum alloy material adopts natural exposure. The test results show that it has significantly superior corrosion resistance than the steel cable tray. Especially the aluminum alloy adopts anodizing, and its anticorrosion effect is better. Modern products such as: “aluminum Alloy cable tray".
5. Non-metallic cable tray, referred to as clear frame. This new fiberglass cable tray is made of flame retardant synthetic resin as the binder and glass fiber as the reinforcing material. It has high corrosion resistance, electrical insulation properties, and has excellent properties such as light weight, high strength, good flame retardancy, bright color and beautiful appearance, and reliable use. Suitable for chemical, mine, and salt spray corrosion areas. The use of FRP cable tray not only saves a lot of steel, but also saves a lot of maintenance costs, reduces labor intensity and extends cable life.