Vacuum brazing means the workpieces are heated and brazed in a vacuum chamber, mainly for joining of high product quality and oxidizable materials.

Vacuum brazing has several advantages: (1) This method will not use flux theoretically, which can significantly improve the corrosion resistance of the joint and eliminate various forms of pollutions. So, the kind of brazing method will not require complicated cleaning procedures after brazing, reducing production cost. (2) The brazing alloy in the vacuum brazing shows good ability in wettability and speading, making it join complicated or small apparatus and improve the finished product rate. (3) Comparing with other methods, the robust and cleaning joints are generally obtained by vacuum brazing. (4) Many kinds of materials can be joined through vacuum brazing, such as Al, Al alloy, Cu, Cu alloy, stainless steel, alloy steel, low carbon steel, Ti, Ni, Inconei and so on.

The general procedures for vacuum brazing are as followings:

Vacuum brazing requires higher than other joined methods and each process should contain complex controlling points. For example, the surface preparation of substrates should include the following procedures: removing oil and oxidation layer, obtaining a roughness of square root of 0.7-2μm, surface coating and so on.

The equipment for vacuum brazing is vacuum brazing furnace. The primary part in the vacuum furnace is a horizontal, single-room heating structure, which are made up of the furnace, heating chamber, vacuum system, air-cooled systems, pneumatic systems, partial pressure system and electrical controlling system and so on. Generally speaking, the service life of the internal structure in the vacuum furnace is usually long and the maintenance costs are less.