ã€China Aluminum Network】 1. Principles of Spraying Aluminum Spraying and Zinc Preservation in Steel Structures Aluminum arc spraying and zinc anticorrosion technologies for steel structures are particularly popular for arc spraying applications, and their application prospects are more extensive. The principle of arc spray anti-corrosion is to use arc spraying equipment to heat, melt, atomize and spray two charged metal wires (such as zinc, aluminum, etc.) to form an anti-corrosion coating and a long-term anti-corrosion composite coating with an organic sealing coating. The salient features of this coating are:
Longer corrosion life The corrosion life can be up to 50 years and the anticorrosive coating does not need any other anticorrosive maintenance during the 30-year service period; after 30 years of maintenance, only the arc spray coating should be used to seal the coating; Re-spray to achieve a corrosion, the coating is effective for a long time.
The arc sprayed layer and the metal substrate have excellent coating adhesion (up to 10 Mp or more). The metal sprayed layer is mechanically inlaid and combined with the micro metallurgy and the base metal to ensure the anti-corrosion coating under slight bending, impact or collision. It does not fall off, does not lift up the skin, has a strong bond, and has a long-lasting antiseptic effect. This is not possible with any other surface anti-corrosion coating.
The principle of aluminum spraying and anti-corrosion coating of steel structure is cathodic protection. Under the corrosive environment, even if the anti-corrosion coating is partially damaged, it still has the effect of sacrificing its own protection of the steel matrix. The area ratio of the coating (anode) to the steel substrate (cathode) is ≥1; while the ratio of anode to cathode of the zinc-rich coating is <1, and the protective effect and the bonding force are also far lower than the arc spraying anti-corrosion coating.
Second, the technical advantages of aluminum spraying and zinc anticorrosion of steel structure Compared with the flame spraying, arc spraying adopts electric energy instead of gas combustion, which greatly improves work efficiency and work safety, especially the emergence of arc spraying mechanization equipment, arc spraying technology. It can fully meet the needs of the bridge construction period, and the arc temperature is much higher than the flame, the coating binding force is also much greater than the flame spraying, so the coating quality can fully meet the needs of long-term anti-corrosion. In the United States, due to the high labor cost, the cost of using arc spray anti-corrosion construction is even lower than that of heavy anti-corrosion paint. After decades of tests, it has been proved that spraying technology is a good method for long-term preservation of steel structures. This conclusion has been recognized by government departments and engineering circles in many countries around the world.
Third, the steel structure spray aluminum spraying and anti-corrosion construction process General arc spraying equipment from the rectifier power supply, control devices, spray guns, metal wire rack or wire feeding device, compressed air supply system and other components. The wire frame and the compressed air supply system are the same as the wire flame spray. The parameters of arc spraying and aluminum spraying are not only related to the spraying material, but also depend on the equipment used and the production efficiency requirements.
Application of Arc Sprayed Zinc-spraying Steel Structure in China The long-term anti-corrosion technology of arc spraying has been applied in metal spraying technology since the 1990s. Arc spraying is more common and its application prospects are more extensive. The principle of arc spray anti-corrosion is to use arc spraying equipment to heat, melt, atomize and spray two charged metal wires (such as zinc, aluminum, etc.) to form an anti-corrosion coating and a long-term anti-corrosion composite coating with an organic sealing coating. The salient features of this coating are:
Longer corrosion life The corrosion life can be up to 50 years and the anticorrosive coating does not need any other anticorrosive maintenance during the 30-year service period; after 30 years of maintenance, only the arc spray coating should be used to seal the coating; Re-spray to achieve a corrosion, the coating is effective for a long time.
The arc sprayed layer and the metal substrate have excellent coating adhesion (up to 10Mp or more). The metal sprayed layer is mechanically inlaid and combined with micro-metallurgy and matrix metal to ensure the anti-corrosion coating under slight bending, impact or collision. It does not fall off, does not lift up the skin, has a strong bond, and has a long-lasting antiseptic effect. This is not possible with any other surface anti-corrosion coating.
The anti-corrosion principle of arc spray zinc and aluminum coatings is cathodic protection. Under the corrosive environment, even if the anti-corrosion coating is partially damaged, it still sacrifices itself to protect the steel matrix. The area ratio of the coating (anode) to the steel substrate (cathode) is ≥1; while the ratio of anode to cathode of the zinc-rich coating is <1, and the protective effect and the bonding force are also far lower than the arc spraying anti-corrosion coating.
4. The application of aluminum spraying, zinc spraying and corrosion protection for steel structures has been widely used in coal mines, railways, water conservancy, port terminals, metallurgy, machinery, radio and television, medical treatment, electric power, and fire protection. For example, Baoshan Iron and Steel Group Majishan Harbor Steel Pilings, track functions of Shanghai Maglev fast trains, the Three Gorges Water Control Project on the Yangtze River, steel box girders and bridge decks of the Wuhan Junshan Yangtze River Bridge, and other national key construction projects, as well as Qian'an Qiandao Hunanpu Bridge, the Yangtze River Huangbaihe Bridge, and the Xiajiaxi Bridge, The steel bridges of Guangzhou Airport Sanyuanli overpass and Xulian Expressway Caozhou Canal Bridge have all been protected against arc corrosion by long-term anti-corrosion technology and have achieved good anti-corrosion effect. China has been fully capable of using arc spray long-term anti-corrosion technology to solve the problem of corrosion protection of large-scale steel bridges in the country.
The heavy-duty anti-corrosion technology of bridge steel structures has gradually formed two major development trends. The first is a rapidly developing heavy anti-corrosion system based on inorganic zinc-rich coatings, and the second is a relatively heavy-duty anti-corrosion system with a metal spray coating as a base. Because of their excellent corrosion resistance and environmental adaptability, these two systems are concerned with the corrosion of various types of steel bridges. In the next few decades, the country will save a lot of anti-corrosion maintenance costs for steel bridges, reduce environmental pollution, extend the service life of steel bridges, and generate huge economic and social benefits.