Research Status of Aluminum and Aluminum Alloy Brazing

【Summary Description】 Aluminum alloy has the advantages of low density, high strength and corrosion resistance, so it is widely used in automobile, high-speed railway vehicle, aerospace and military industry. Due to its unique physical and chemical properties, a series of difficulties will be encountered in the welding process, such as oxidation, thermal cracks and pores in the weld. For aluminum alloy welding, the traditional method is mainly fusion welding, the equipment is complex, and the technical requirements for welders are strict. As an important method of aluminum alloy connection, aluminum brazing has the characteristics of small deformation of brazed parts. The advantages of high dimensional accuracy have been widely used in China in recent years. The brazing technology of aluminum and aluminum alloys is a hot topic in recent years. With the continuous emergence of new materials and new methods, the brazing process of aluminum and aluminum alloys has developed rapidly, and the brazing methods, brazing materials and fluxes have made great progress. Aluminum and aluminum alloy brazing is one of the fields that have been studied and developed rapidly in recent years. This is mainly because it has a series of excellent properties, such as high strength, good corrosion resistance, high electrical conductivity and thermal conductivity, so it is widely used in aerospace, aviation, electronics, metallurgy, machinery manufacturing and light industry and other fields. Especially with the sharp rise in the price of copper, in order to reduce the quality, improve the efficacy and enhance the appearance, the technology of replacing copper with aluminum and steel with aluminum has been successfully applied in some fields. The most typical example is that the copper water tank of the car has been replaced by an aluminum water tank. There are few domestic manufacturers of large-scale production of aluminum flux, and most of the aluminum flux currently used is imported from abroad. Due to the low melting point of aluminum and aluminum alloy, strong chemical activity, high melting point, stable oxide film, can be firmly and densely attached to the surface of aluminum or aluminum alloy, the general brazing agent can not meet the requirements of brazing aluminum and aluminum alloy, must use special brazing agent-aluminum and aluminum alloy brazing agent. In addition, the corrosion resistance of aluminum and its alloy brazing joints is easily affected by the brazing filler metal and flux, which is mainly due to the large difference between the electrode potential of the brazing filler metal and the base metal, which reduces the corrosion resistance of the joint, especially the effect on the brazing joint is more obvious. In general, in order to remove the oxide film on the surface of aluminum and its alloys, most of the solder is filled with highly corrosive materials. Even if these materials are cleaned after brazing, it is difficult to completely remove the influence on the corrosion resistance of the joint.

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Brazing of aluminium and aluminium alloys

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