Copper brazing

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Copper and copper alloys are generally classified into four categories: copper (pure copper), brass, bronze and white copper. Copper brazing properties mainly depend on the stability of the surface oxide film and the influence of the brazing heating process on the material properties.

Copper oxide and cuprous oxide can be formed on the surface of pure copper. These two oxides are easily reduced by a reducing gas and are easily removed by a flux, so the brazing property of pure copper is excellent. In order to prevent hydrogen embrittlement, brazing cannot be performed in a reducing atmosphere containing hydrogen.

Brass containing only zinc can form oxides of cuprous oxide or zinc oxide on the surface. Although zinc oxide is relatively stable, it is not difficult to remove. Manganese oxide on the surface of manganese brass is relatively stable and difficult to remove. A strong flux should be used to ensure the wettability of the solder.

The oxide films on the surface of tin bronze and cadmium bronze are easily removed. Although the surface oxide films of silicon bronze and beryllium bronze are relatively stable, they are not difficult to remove. The aluminum bronze with w(A1) exceeding 10%, the surface is mainly aluminum oxide, which is difficult to remove, and a special flux must be used.

The oxide of nickel and the oxide of copper on the surface of the white copper are easily removed, but the brazing filler metal should be used for brazing to prevent self-cracking of the joint.
Vacuum brazing technology has become a promising welding technology since the 1940s. The first parts to braze copper and stainless steel in the electronics industry were later applied to the aerospace industry and the atomic energy industry. In 1959, they were applied to the manufacture of stainless steel plate-fin heat exchangers. It is now widely used in plate-fin heat exchangers and coolers in industrial sectors such as air separation plants, petrochemical plants, construction machinery, automobiles, boats and home appliances.

Vacuum Brazing Furnace

Due to the unparalleled advantages of vacuum brazing technology, it has been rapidly developed and widely used in industrialized countries around the world.

vacuum brazing advantage
1. Vacuum brazing, because it does not use flux, significantly improves the corrosion resistance of the product, eliminates all kinds of pollution, pollution-free processing equipment costs, and has good safety production conditions;
2. Vacuum brazing not only saves a lot of expensive metal flux, but also does not require complicated flux cleaning process, which reduces production cost;
3. Vacuum brazing solder has good wettability and fluidity, can weld more complicated and narrow channel devices, vacuum brazing improves product yield and obtains a firm and clean working surface;
4. Compared with other methods, the internal structure of the furnace and the fixture have a long service life, which can reduce the maintenance cost of the furnace;
5. Many materials suitable for vacuum brazing, such as: aluminum, aluminum alloy, copper, copper alloy, stainless steel, alloy steel, low carbon steel, titanium, nickel, Inconei, etc. can be brazed in a vacuum electric furnace Solder, the designer determines the material needed based on the purpose of the soldered device.