A vacuum brazing process for glass and metal

Mon Sep 19 14:49:09 CST 2022

A vacuum brazing process for glass and metal, the process includes the following steps: 1) surface treatment of glass and metal workpieces; 2) placing the processed welding workpieces in a vacuum brazing furnace, vacuum heating, and vacuuming Brazing; characterized in that, the above step 1) includes: step 1.1) roughening and cleaning the glass surface, and performing surface purification and smoothness treatment on the metal workpiece; step 1.2) chemical plating on the surface of the glass. The surface of the workpiece is plated with a uniform layer of copper; the vacuum brazing welding in the above step 2) includes the following process flow: placing the assembled welding workpiece in the vacuum heating chamber of the brazing furnace, and closing the furnace door; before brazing, start For the vacuum system of the brazing furnace, the furnace is evacuated below 4×10-2Pa; the heating system is started, and when the workpiece is heated to 550°C with the furnace heating, it is kept until the vacuum degree in the furnace is 4×10-2Pa, so that the workpiece is heated to 550°C. The temperature of each part is uniform, and the temperature in the brazing furnace continues to rise to the brazing temperature. After holding for 10 to 30 minutes, the heating is stopped, and the furnace is slowly cooled down. The temperature of the furnace is below 50°C. 2. The brazing process according to claim 1, wherein the above step 1.1 further comprises: sandblasting the glass surface, and then cleaning the surface with acetone, ethanol and clean water; placing the metal workpiece in a hydrogen burning furnace Carry out "burning hydrogen" purification treatment, and then use sandpaper and metallographic paper to polish the end face to obtain a certain roughness and smooth end face, then wash with acetone, ethanol and water respectively, and finally dry the glass and metal workpieces in the oven. Dry in dry box for later use. 3. brazing process according to claim 1, is characterized in that, the welding workpiece installation step in above-mentioned step 2) further comprises: step 2.1) utilizes high temperature and heat-resisting fixture to make glass, brazing filler metal and metal according to the brazing method. Craftsmanship requires assembly together. The brazing process of claim 3 is characterized in that the step 2.1) further comprises: disposing two layers of graphite plates between the upper and lower molds of the high-temperature and heat-resistant fixture, and placing the welded parts on the two-layer graphite plates In between, insert bolts into the screw holes of the upper and lower molds to connect the upper and lower molds together, and then use nuts to fix both ends of the bolts on the upper and lower molds of the high-temperature and heat-resistant fixture to set two layers of graphite between the upper and lower molds plate, place the weldment between the two layers of graphite plates, insert bolts into the screw holes of the upper and lower dies, connect the upper and lower dies together, and fix them with nuts at both ends of the bolts (please confirm whether there are any Order). Expanded graphite has the characteristics of high temperature resistance, corrosion resistance, thermal shock resistance, large expansion volume, excellent resilience and good contact with metal materials. The expansion and deformation of graphite at high temperature can be used to ensure the gap accuracy of the weld. , so as to ensure the wettability of the solder; in the cooling process, using the characteristics of good resilience, the pre-tightening force of the bolt gradually returns to the state before heating with the shrinkage and deformation of the fixture and the welding workpiece, which not only ensures the welding performance during the whole welding process. During the process, the welding parts are subject to small changes in the pre-tightening force of the bolts, and the graphite plate can be reused many times without being quickly scrapped, but the mechanical strength of the expanded graphite is not high. Mechanical strength, considering these factors, the graphite plate adopts expanded graphite material with metal skeleton. The brazing temperature of this process is generally around 680°C, and the maximum operating temperature of 1Cr18Ni9Ti is 870°C, which meets the process requirements of glass and metal vacuum brazing, so the metal skeleton material is 1Cr18Ni9Ti