Vacuum Brazing: Unveiling the Benefits of Furnace Brazing

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Advantages of vacuum furnace brazing:

The main difference of vacuum furnace brazing is the difference in the heating furnace used. The effective space of the heating furnace is evacuated, and the welded parts assembled with brazing materials are heated in a vacuum environment to completely block oxygen and other impurities in the air. A series of physical and chemical reactions that are beneficial to brazing under vacuum conditions are used to achieve film removal and wetting. Brazing flux is generally not added during the brazing process. Under high temperature, the brazing material melts and fills to form a high-quality brazing seam.

In fact, in a vacuum environment, the oxidation phenomenon of the base material and the brazing material is significantly reduced. At the same time, the decrease in oxygen partial pressure will also cause the decomposition of the oxide film to be removed or destroyed, promote the wettability of the molten brazing material, and enhance the brazing material’s ability to fill the seam.

Classification of vacuum brazing furnaces:

At present, vacuum brazing furnaces can be divided into hot-wall vacuum brazing furnaces and cold-wall vacuum brazing furnaces. The former is composed of a vacuum container and a general resistance heating furnace (similar to the brazing equipment in the air furnace), and the product can be sent to the resistance heating furnace at different temperatures as needed; the latter is a heating furnace and a vacuum brazing chamber as a whole, rising from room temperature to the brazing temperature. Usually, cold wall vacuum brazing furnaces are used more.

Main features of vacuum furnace brazing:

Brazed parts will not have oxidation and other problems: because the air is removed in the vacuum environment, the elements such as oxygen, carbon, and nitrogen in the air are isolated during the melting and filling process of the brazing material, so that oxidation and carbon increase will not occur.

High quality of brazing seams: because brazing flux is not used, there will be no internal quality problems such as brazing flux residue and inclusions; and the brazing parts are in a vacuum environment, which improves the escape conditions of pores in the brazing material; the appearance quality of the brazing seams is greatly improved, and it is in a bright and non-oxidized state.

Low stress: because it is in a high temperature environment, the whole is heated and heated evenly, and the stress of uneven heating of parts is greatly reduced.

Wide adaptability: very suitable for the connection of dissimilar metals, the same metals, active metals and even non-metallic materials.

Not suitable for brazing of high vapor pressure elements: vacuum brazing is not recommended for metals with high vapor pressure such as manganese, lithium, and magnesium, and certain measures need to be taken to suppress the volatilization of elements.

Large one-time investment and high maintenance cost: It involves electronic control and other systems, and the operation and maintenance are relatively complicated, so the equipment cost and maintenance cost are high.

Vacuum Brazing Furnace