Titanium Heat Exchanger Vacuum Brazing

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The material of the heat exchanger is TA2, as shown in the figure above. The heat exchanger is composed of a body and a cover plate. The cover plate is placed into the square groove of the body and forms a T-shaped brazed joint with the ribs of the body. After brazing, a sealed knot is formed. The width of the rib is 2mm. The thickness of the cover plate 1.9mm.

Solder used: (1) Ti-Zr-Ca-Ni system Ti-based solder, brazing temperature range of 910-960C. Used in the form of powder and quenched amorphous foil with a thickness of 0.05-0.07mm: (2) Pure Cu solder is used in the form of a 0.05mm thick cold rolling hall and a 10μm electroplated layer.

Equipment Applying

Vacuum brazing adopts SIMUWU vacuum brazing/diffusion welding furnace, the size of the uniform temperature zone is 600*600mm*900mm, and the operating temperature is 1230C. The thermal vacuum degree is better than 2x 10~2Pa.

The component analysis of the brazed joint adopts the electronic probe instrument of Beijing Research Institute, CAM SCAN3100 scanning electron microscope and OXFORDX-MAX energy spectrometer.

After cleaning the pure Cu solder foil, use an energy storage spot welder to position and spot weld the heat exchanger body to the ribs of the heat exchanger body. material. The assembly is placed on the brazing fixture and pressed so that the brazing material is pressed in the brazing gap. Each brazing seam is guaranteed to form a predetermined brazing gap to obtain a high brazing rate and air tightness. In order to prevent adhesion, the fixture and the titanium heat exchanger are separated with solder resist. Due to the large brazing parts, it is not convenient to use the hydraulic rod of the brazing furnace to uniformly pressurize. Therefore, the stainless steel pressure plate with fastening screws is used to uniformly pressurize at multiple points.

In Conclusion

Compared with pure Cu brazing filler metal, brazing titanium heat exchangers with Ti-Zr-Ni-Cu brazing can more easily obtain the isothermal solidification brazing seam structure. With pure Cu solder, the price is low. Dense and beautiful brazing joints can also be obtained, but the price is that the shape of the joint is lower.