Vacuum brazing

Vacuum brazing characteristics
The development of vacuum brazing technology has been seventy-six years old and has become a promising welding technology. It was first used in the electronics industry to braze copper and stainless steel parts, and later applied to the aerospace industry and the atomic energy industry. In 1959, it was applied to the manufacture of stainless steel plate-fin heat exchangers. Now, it is widely used in various fields of life construction and industrial construction. Due to the incomparable advantages of vacuum brazing technology, it has been rapidly developed and widely used in the industrialized countries of the world.

Vacuum brazing needs attention
The speed of the pumping rate of the vacuum equipment directly affects the effective discharge of volatiles on the workpiece in the vacuum furnace. In the vacuum welding process, three volatiles such as oxygen, organic matter and brazing transition elements are mainly produced on the workpiece. The organic matter must be removed before 400 ° C, otherwise it will remain in the workpiece in the form of carbon, affecting the welding strength of the workpiece; oxygen and brazing transition elements must be removed before the melting point of the solder, otherwise it will oxidize The solder or residual residue in the workpiece affects the welding strength of the workpiece. The pumping rate of the vacuum equipment directly affects the clean elimination of the volatiles, so the pumping rate of the vacuum brazing furnace should be as fast as possible.
The ultimate vacuum value of a vacuum device can reflect two aspects. One is to indicate whether the volatiles on the workpiece are fully drained. The ultimate vacuum value of the vacuum equipment is relatively high, indicating that the volatiles on the workpiece are relatively clean. The second is to show whether there is air leakage in the vacuum equipment. The ultimate vacuum value of the vacuum equipment is relatively high, which means that there is no air leakage in the vacuum equipment, and it will not cause the base body, super hard abrasive grains, brazing material and organic glue on the workpiece. The secondary oxidation of the element greatly reduces the melting temperature of the brazing material, and the molten form of the brazing material is very good. Therefore, the ultimate vacuum value of the vacuum equipment must be high.
The uniformity of the thermal field temperature of the vacuum equipment directly affects the consistency of the welding quality of all the workpieces in the furnace. Because the melting temperature range of the brazing material is generally around 10 °C, and the uniformity of the thermal field temperature of the vacuum equipment is relatively poor, the phenomenon of under-fired welding and over-burning and damage to the abrasive will occur in the furnace, and defective products may appear. Therefore, the thermal field temperature uniformity of the vacuum equipment must be very good.

Advantages of vacuum brazing
Vacuum brazing, because of the lack of flux, significantly improves the corrosion resistance of the product, eliminating all kinds of pollution, pollution-free processing equipment costs, and good safety production conditions. It not only saves a lot of expensive metal flux, but also does not require complicated flux cleaning process, which reduces production cost. The solder has good wettability and mobility, and it can weld more complicated and narrow passage devices. Vacuum brazing improves the yield of the product and obtains a firm and clean working surface. Compared with other methods, the internal structure of the furnace and the fixture have a long life, which can reduce the maintenance cost of the furnace. Many materials suitable for vacuum brazing, such as: aluminum, aluminum alloy, copper, copper alloy, stainless steel, alloy steel, low carbon steel, titanium, nickel, Inconel, etc. can be brazed in a vacuum electric furnace, the designer according to The use of brazing devices determines the materials required, with aluminum and aluminum alloys being the most widely used.

Application of vacuum brazing on construction machinery
Vacuum brazing is a small example of small bits. Small and medium-sized bits are widely used in metallurgy, geology, coal, water, railway, military and other construction projects. According to statistics, in 1978, the country consumed about 10,000 small and medium-sized bits, but now the amount is even larger, playing an important role in the national economic construction.
Vacuum brazing is carried out in the absence of air, using a specialized furnace, and delivers significant advantages: extremely clean, flux-free braze joints of high integrity and superior strength. Improved temperature uniformity when heating in a vacuum, and lower residual stresses due to slow heating and cooling cycle, results in significantly improved thermal and mechanical properties of the material. Other benefits of vacuum brazing include heat treating or age hardening of the work piece as part of the metal-joining process, all in a single furnace cycle. Like conventional brazing, vacuum brazing is easily adapted to mass production.
-No oxidation, no weld flux, no pollution, no air hole;
-Low temperature brazing, high temperature brazing, continuous brazing;
-It works on Titanium (Ti), Zirconium (Zr), Niobium ( Nb), Molybdenum (Mo) refractory metal alloys and dissimilar metals too;
-High automation, easy operation, easy maintain.