First, the application of anti-atmospheric corrosion coating.
Outdoor steel structures such as steel structure workshops, steel box girder bridges, TV towers, building antennas, transmission substations, steel poles, etc. These steel members are exposed to the atmosphere due to long-term exposure to the atmosphere, and are rapidly oxidized by the surface. The formation of a layer of ferric oxide seriously affects the strength and service life of the steel structure. In order to prevent oxidation of the surface of steel structures, paint protection has been generally used in the past. The corrosion protection period is generally 3-5 years, so it is necessary to carry out maintenance and maintenance frequently. The common method is to copy the shovel paint, which consumes a lot of manpower and material resources. Now it is protected by zinc-spraying and aluminum-spraying process on the surface of steel structure. The anti-corrosion period can reach more than 30 years without maintenance. If the paint is closed in addition to the zinc-aluminum coating, the corrosion protection period is longer.
The surface of the steel structure can only be anodicly protected by spraying zinc and spraying aluminum, thus achieving the purpose of long-lasting corrosion protection of the steel structure. Therefore, many major engineering and municipal projects in the country have been designated for this process. Such as: Yangtze River Three Gorges permanent gate, Shanghai Oriental Pearl TV Tower, Yangpu Bridge main guard bar, Guangzhou inner ring elevated steel beam, Shanghai Securities Building steel structure antenna, Pudong Airport Road common ditch gas pipeline, Shanghai South Bridge 500,000 kilowatt substation, etc. Etc. to ensure a hundred years of major engineering.
Second, water resistant corrosion coating.
Steel sluice gates are the main steel structure for controlling hydropower in hydropower stations and reservoirs. Some of them are immersed in water for a long time, and the surface is exposed to microbial attack (such as the adsorption of nails, and the excretion is acidic). The other part is exposed to the atmosphere for a long time, especially the waterline part. It is affected by surfing and floating objects on the water surface. At the same time, it is affected by high tide and low tide. This part of the steel structure is often wet and dry alternately, especially rust. Nowadays, the zinc-spraying and aluminum-spraying process of the wire is used to greatly improve the corrosion resistance of the steel gate, which is 5-6 times higher than the anti-corrosion period of the original paint process.
Third, the zinc spray, aluminum spray process and similar process performance comparison (hot galvanizing process)
1. The hot-dip galvanizing process pretreatment adopts pickling and phosphating process, and there are residues of acid and alkali liquid on the surface of the workpiece, leaving a hidden danger of corrosion, which makes the hot-dip galvanized layer easy to fall off. The zinc-spraying and aluminum-spraying process pretreatment adopts the sandblasting process, so the surface of the workpiece is very clean and rough, and the surface is sprayed with zinc and sprayed without aluminum to cause corrosion from the inside to the outside, so that the zinc layer does not fall off.
2. The hot-dip galvanizing process has a certain temperature, about 440 °C, so the workpiece will be deformed after hot-plating; while the temperature of spraying zinc and aluminum spraying is very low, the surface temperature of the workpiece is <80 °C, so the workpiece is not deformed. .
3. The hot-dip galvanizing process is adopted, and the workpiece is limited by the length, width and height of the plating tank; while the zinc-spraying and aluminum-spraying process is used, the workpiece is not limited.
4, using hot-dip galvanizing process, there are still problems in the field repair. In the process of welding, welding, loading and unloading during transportation, the repair can only be done with paint, thus creating a technological breakthrough. If zinc spraying or aluminum spraying is used, the site can be repaired by spraying zinc and spraying aluminum to avoid the process breakthrough.
5. Since the pretreatment of the hot-dip galvanizing process adopts pickling and phosphating, the surface of the workpiece has no roughness and the coating adhesion is poor. The pretreatment of zinc spraying and aluminum spraying process adopts sand blasting, Sa≥2. 5 grade, so the surface of the workpiece has roughness and the coating bonding force is good. Tensile strength ≥ 0. 6kg / mm2.
6. The hot-dip galvanizing process is very serious for water pollution, and the environmental protection problem is very prominent. Therefore, the hot-spraying zinc and aluminum-spraying processes are becoming more widespread. The wider the application of steel structure surface corrosion protection.
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Label: aluminum coating zinc layer spray aluminum dry and wet alternate anti-corrosion coating
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