PRODUCT CATEGORIES

Vacuum Heat Treatment Furnace

Vacuum Sintering Furnace

Vacuum Brazing Furnace

Research on titanium alloy plate-fin vacuum brazing

Plate fin heat exchangers are widely used in high-end equipment power and environmental control systems such as aerospace, submarines, and aircraft carriers due to their high heat transfer efficiency, high cost performance, compact and lightweight structure. Plate-fin heat exchangers are usually used in extreme environmental conditions such as high pressure, large load, and high temperature. Compared with traditional aluminum alloy and stainless steel materials, aluminum alloy materials are resistant to high temperatures, corrosion resistance, high strength, and can better handle high-temperature gases (470~870 K). The plate fin structure is the core component of the plate fin heat exchanger. The heat transfer process during the brazing process is relatively complex, involving thermal radiation between the material and the furnace body, as well as heat conduction between workpieces. The thermal process of welding directly determines the microstructure, residual stress and deformation after welding. However, since the temperature of the vacuum furnace is difficult to measure in actual production, the simulation method is more convenient, faster and less expensive, and can be used for actual production. Play a guiding role. At the same time, accurate calculation of the temperature field is the prerequisite for welding metallurgical analysis and integrated control of shape.

For the vacuum brazing process, more reasonable temperature field distribution and uniformity can lead to better and denser welded joints.
The vacuum brazing process uses a vacuum furnace to support the workpiece through pressure equipment, and radiatively heats the workpiece through heating bands distributed around the vacuum furnace wall. During the test, the vacuum degree of the environment is less than 8×10-3Pa to ensure the quality of welding. . At the same time, the experimental materials need to be pre-welded to ensure the flatness of the separator surface, and the fin structure needs to be ultrasonic cleaned. After surface cleaning, use absolute ethanol to further clean the material surface and dry it to ensure that the material surface is dry and clean before welding. The brazing temperature is 1150K. After reaching the maximum temperature, the holding time is 20 minutes. After the holding is completed, the furnace is cooled to room temperature. In order to maintain the uniformity of the temperature field in the furnace and the temperature field of the workpiece during the brazing process, and ensure that the brazing material can be fully heated, melted, spread, and filled with fiber seam gaps, the brazing process is not directly heated, but gradually heated through multiple times of heat preservation. to the brazing temperature, each holding time is 30 minutes.
Since during the entire vacuum brazing process, the temperature of the weldment will change with time and space, and during this process, the thermophysical properties of the material will also change non-linearly with temperature.

Research results on titanium alloy plate-fin vacuum brazing
1) Establish a temperature field model for the vacuum brazing process of the Chin alloy plate-fin heat exchanger. The simulated temperature curve change pattern is consistent with the thermal cycle curve of the test node, verifying the reliability of the model.
2) The distribution mode of the heating belt has a greater impact on the uniformity of the temperature field. The worse the directionality of the heat radiation received by the workpiece, the better its temperature uniformity will be. Among them, when the heating zones are spaced apart, the temperature field uniformity of the plate-fin structure is optimal.
3) By increasing the heating rate, the temperature difference of the plate-fin structure increases, and the uniformity of the temperature field becomes worse. Multiple heating and insulation can help improve the temperature unevenness caused by temperature lag.
4) The central area in the furnace has the highest temperature, the temperature field is symmetrically distributed along the center, and the temperature difference in the furnace is smaller than the temperature difference of the workpiece.