A method for brazing an aluminothermically reduced surface-modified quartz fiber-reinforced silica composite material to an invar alloy

Abstract

A method for brazing aluminum hot reduction surface modified auxiliary quartz fiber reinforced silica composite and invar alloy, relates to a SiO 2f / SiO2 composite and invar alloy brazing method. In order to solve the problem of poor wettability of active filler metal on the surface of SiO 2f / SiO2 composite and low interface bonding strength, the present application reduces SiO2 on the surface of SiO 2f / SiO2 composite to Si and generates Al oxide, and the AgCuTi filler metal reacts with Al oxide to generate Ti3Al phase after brazing, which promotes the spread of AgCuTi filler metal on the surface of SiO 2f / SiO2 composite and improves wettability; AgCuTi / Nb / AgCu composite interlayer is used to assist brazing SiO 2f / SiO2 composite and invar alloy, Nb is used to prevent Ti element from reacting with Fe and Ni elements in invar alloy to generate brittle intermetallic compound, so as to optimize the microstructure of the weld, improve the strength of the brazed joint, and further improve the stability and reliability of the welded joint.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for brazing SiO 2f / SiO2 composite material and Invar alloy. BACKGROUND

[0002] With the rapid development of science and technology, the performance requirements of devices and components in the fields of aerospace vehicles, electronics and microelectronics, biomedicine, etc. are upgraded, and the requirements for materials are strict. Material research is important in many fields, especially in key areas, which requires materials to have multiple high-performance characteristics. The comprehensive performance of materials needs to be improved urgently, and composite materials have emerged as the times require. Composite materials combine the advantages of multiple materials and have excellent performance. SiO 2f / SiO2 composite material is a new type of composite material, which not only has the high hardness and high melting point of ceramic materials, but also has good wave permeability and thermal shock resistance. SiO 2f / SiO2 composite material has the advantages of light weight and high temperature resistance, and SiO 2f / SiO2 composite material has been widely used in high temperature fields, and SiO 2f / SiO2 composite material has the characteristics of low density and light weight, which greatly reduces the weight of the component. However, SiO 2f / SiO2 composite material has poor mechanical processing performance, and it is difficult to directly process components with complex structures, so it needs to be connected with other materials for use. SiO 2f / SiO2 composite material can be connected with Invar alloy by brazing, which can manufacture composite components with complex structure, not only greatly reducing the weight of the component, but also improving its working temperature.

[0003] There are two major difficulties in brazing SiO 2f / SiO2 composite material and Invar alloy: first, due to the poor wettability of active filler metal on the surface of SiO 2f / SiO2 composite material, the interfacial metallurgical reaction is difficult to proceed, which further leads to a significant reduction in the mechanical properties of the brazed joint; second, the Fe and Ni elements in Invar alloy are prone to react with the Ti element in the AgCuTi filler metal, which weakens the reactivity between the AgCuTi filler metal and the SiO 2f / SiO2 composite material interface, affecting the interfacial bonding strength. SUMMARY

[0004] The present application is to solve the problem of poor wettability of active filler metal on the surface of SiO 2f / SiO2 composite material and low interfacial bonding strength, a method for brazing SiO 2f / SiO2 composite material and Invar alloy by aluminum thermal reduction surface modification is proposed.

[0005] The application discloses an aluminum thermal reduction surface modification auxiliary SiO 2f The method for brazing the SiO

[0006] I. SiO 2f Pre-welding treatment of the SiO

[0007] 1. cutting the SiO 2f / SiO2 composite material to a predetermined size;

[0008] 2. ultrasonic cleaning the cut SiO 2f / SiO2 composite material;

[0009] 3. calcining the ultrasonic cleaned SiO 2f / SiO2 composite material;

[0010] The calcining process is as follows: heating at a heating rate of 5-10 ℃ / min to 700-800 ℃, maintaining for 60-120 min, and then cooling at a cooling rate of ≤5 ℃ / min to ≤150 ℃;

[0011] 4. polishing the welding surface of the SiO 2f / SiO2 composite material;

[0012] 5. ultrasonic cleaning the polished SiO 2f / SiO2 composite material;

[0013] 6. depositing an Al deposition layer on the welding surface of the SiO 2f / SiO2 composite material;

[0014] The deposition process of the Al deposition layer is as follows: clamping the SiO 2f / SiO2 composite material on a workbench of a magnetron sputtering device, adjusting the distance between a target material and the SiO 2f / SiO2 composite material, vacuumizing the magnetron sputtering device to ≤5×10 -3 Pa, then passing in 80-150 sccm of argon at a constant rate, keeping the working gas pressure at 0.1-0.8 Pa, setting the frequency of a pulse power source at f r = 500-700 Hz, setting the discharge pulse width at t ON = 200-400 μs, selecting a constant current mode, setting the average discharge current at 0.3-0.5 A, then gradually increasing the voltage applied on the target material until the target material is completely melted; then performing sputtering deposition to obtain the Al deposition layer on the welding surface of the SiO 2f / SiO2 composite material; and the target material is an aluminum target;

[0015] SiO 2f Aluminothermic reduction modification of SiO

[0016] SiO 2f / SiO2 composite material with Al deposition layer on the welding surface is placed in a vacuum furnace, first heated to 650-700℃ at a heating rate of 5-10℃ / min and kept for 1-4h for the reduction modification process, and then cooled to ≤150℃ at a cooling rate of ≤5℃ / min;

[0017] II. Pre-welding treatment of Invar alloy:

[0018] The Invar alloy is cut to a predetermined size, the welding surface of the Invar alloy is polished, and then ultrasonic cleaning is performed;

[0019] III. Pre-welding treatment of composite interlayer:

[0020] AgCuTi foil, AgCu foil and Nb foil are taken and cut to a predetermined size, and after cutting, polishing, flattening and ultrasonic cleaning are performed in sequence;

[0021] IV. Assembly of the welding test piece:

[0022] SiO 2f / SiO2 composite material obtained in step one, Invar alloy obtained in step two, and AgCuTi foil, AgCu foil and Nb foil obtained in step two are stacked to obtain a welding test piece; the stacking order is SiO 2f / SiO2 composite material, AgCuTi foil, Nb foil, AgCu foil, Invar alloy, SiO 2f / SiO2 composite material, the welding surface of the Invar alloy faces the AgCu foil;

[0023] V. Vacuum brazing connection: the assembled test piece is placed in a vacuum brazing furnace, the vacuum degree in the vacuum brazing furnace is 5×10 -3 Pa, heated to 840-900℃ at a heating rate of 5-10℃ / min, kept for 10-40min, and then cooled to ≤150℃ at a cooling rate of ≤5℃ / min.

[0024] The principles and benefits of the present application are:

[0025] The present application is based on the aluminothermic reduction modification of the surface of SiO 2f / SiO2 composite material, the SiO 2fThe SiO2 on the surface of the SiO2 / Si composite is reduced to Si and Al oxide is generated, the AgCuTi filler metal reacts with the Al oxide to generate Ti3Al phase after brazing, which promotes the AgCuTi filler metal to spread on the surface of the SiO2 / Si composite 2f wetting on the surface of the SiO2 / Si composite, thereby improving the spreading of the AgCuTi filler metal on the surface of the SiO2 / Si composite 2f wetting on the surface of the SiO2 / Si composite; in addition, the AgCuTi / Nb / AgCu composite interlayer is used to assist in brazing the SiO2 / Si composite and the Invar alloy 2f The Nb is used to prevent the Ti element from reacting with the Fe and Ni elements in the Invar alloy to generate brittle intermetallic compounds, so as to optimize the microstructure of the weld, improve the strength of the brazed joint, and further improve the stability and reliability of the welded joint. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 SiO2 / Si composite obtained in Example 1 2f Interface microstructure of the brazed joint of the SiO2 / Si composite and the Invar alloy

[0027] Figure 2 SiO2 / Si composite obtained in Example 2 2f Interface microstructure of the brazed joint of the SiO2 / Si composite and the Invar alloy DETAILED DESCRIPTION

[0028] The technical scheme of the present application is not limited to the following specific embodiments, and any reasonable combination of the specific embodiments is also included.

[0029] Specific embodiment one: in this embodiment, the surface of the SiO2 / Si composite is modified by the aluminum thermal reduction method to assist in brazing the SiO2 / Si composite and the Invar alloy 2f The method for brazing the SiO2 / Si composite and the Invar alloy is performed according to the following steps:

[0030] I. SiO2 / Si composite 2f Pre-welding treatment of the SiO2 / Si composite:

[0031] ①. The SiO2 / Si composite is cut to a predetermined size; 2f The SiO2 / Si composite is cut to a predetermined size;

[0032] ②. The cut SiO2 / Si composite is ultrasonically cleaned; 2f The cut SiO2 / Si composite is ultrasonically cleaned;

[0033] ③. The ultrasonically cleaned SiO2 / Si composite is calcined; 2f The ultrasonically cleaned SiO2 / Si composite is calcined;

[0034] The calcination process is: heating to 700-800℃ at a heating rate of 5-10℃ / min, holding for 60-120min, and then cooling to ≤150℃ at a cooling rate of ≤5℃ / min;

[0035] IV. Polishing SiO 2f / SiO2 composite material;

[0036] V. Ultrasonic cleaning the polished SiO 2f / SiO2 composite material;

[0037] VI. Depositing Al deposition layer on the welding surface of the SiO 2f / SiO2 composite material;

[0038] The deposition process of the Al deposition layer is: clamping the SiO 2f / SiO2 composite material on the workbench of the magnetron sputtering device, adjusting the distance between the target material and the SiO 2f / SiO2 composite material, vacuumizing the magnetron sputtering device to ≤5×10 -3 Pa, then passing in 80-150sccm of argon at a constant rate, keeping the working gas pressure at 0.1-0.8Pa, setting the frequency of the pulse power source at f r =500-700Hz, setting the discharge pulse width at t ON =200-400μs, selecting the constant current mode, setting the average discharge current at 0.3-0.5A, then gradually increasing the voltage applied on the target material until the target material is completely melted; then performing sputtering deposition on the welding surface of the SiO 2f / SiO2 composite material to obtain the Al deposition layer; the target material is an aluminum target;

[0039] VII. Surface aluminothermic reduction modification of SiO 2f / SiO2 composite material;

[0040] Placing the SiO 2f / SiO2 composite material with Al deposition layer on the welding surface in a vacuum furnace, first heating to 650-700℃ at a heating rate of 5-10℃ / min and holding for 1-4h to perform the reduction modification process, and then cooling to ≤150℃ at a cooling rate of ≤5℃ / min;

[0041] II. Pre-welding treatment of Invar alloy:

[0042] Cutting the Invar alloy to a predetermined size, polishing the welding surface of the Invar alloy, and then performing ultrasonic cleaning;

[0043] III. Pre-welding treatment of composite intermediate layer:

[0044] Take AgCuTi foil, AgCu foil and Nb foil, and cut to a predetermined size, and then sequentially polish, flatten and ultrasonic clean;

[0045] Four, assembly of the welding test piece:

[0046] The SiO 2f / SiO2 composite material obtained in step one, the Invar alloy obtained in step two, and the AgCuTi foil, AgCu foil and Nb foil obtained in step two are stacked to obtain a welding test piece; the stacking order is SiO 2f / SiO2 composite material, AgCuTi foil, Nb foil, AgCu foil, Invar alloy, SiO 2f The welding surface of the SiO

[0047] Five, vacuum brazing connection: place the assembled test piece into a vacuum brazing furnace, the vacuum degree in the vacuum brazing furnace is 5x10 -3 Pa, heat to 840-900℃ at a heating rate of 5-10℃ / min, keep for 10-40min, and then cool to ≤150℃ at a cooling rate of ≤5℃ / min.

[0048] The embodiment has the following beneficial effects:

[0049] The embodiment is based on the surface aluminothermic reduction modification of the SiO 2f / SiO2 composite material, the SiO 2f / SiO2 on the surface of the SiO 2f / SiO2 composite material is reduced to Si and generates the oxide of Al, the AgCuTi filler reacts with the oxide of Al to generate Ti3Al phase after brazing, which promotes the spreading and wetting of the AgCuTi filler on the surface of the SiO 2f / SiO2 composite material, thereby improving the wettability of the AgCuTi filler on the surface of the SiO 2f / SiO2 composite material and the Invar alloy, the Nb is used to block the reaction between Ti element and Fe and Ni elements in the Invar alloy to generate brittle intermetallic compounds, thereby optimizing the microstructure of the weld, improving the strength of the brazing connection joint, and further improving the stability and reliability of the welding joint.

[0050] Specific implementation method two: the difference between the embodiment and the specific implementation method one is that the ultrasonic cleaning process in step one ② is that the cleaning agent is anhydrous ethanol or acetone, the ultrasonic cleaning frequency is 70-150kHz, and the ultrasonic cleaning time is 5-60min.

[0051] Specific embodiment three: the difference between this embodiment and specific embodiment one or two is that: step one ④ said SiO 2f The surface to be welded of the / SiO2 composite is polished with 1000-3000 mesh sandpaper to remove surface impurities and ensure smoothness of the surface to be welded.

[0052] Specific embodiment four: the difference between this embodiment and one of specific embodiments one to three is that: the ultrasonic cleaning process in step one ⑤ is: using cleaning agent anhydrous ethanol or acetone, ultrasonic cleaning frequency is 70-150 kHz, ultrasonic cleaning time is 5-60 min, and repeated cleaning 2-3 times.

[0053] Specific embodiment five: the difference between this embodiment and one of specific embodiments one to four is that: the ultrasonic cleaning process in step two is: using cleaning agent anhydrous ethanol or acetone, ultrasonic cleaning frequency is 70-150 kHz, ultrasonic cleaning time is 5-60 min, and the surface to be welded of the invar alloy is polished with 400-1000 mesh sandpaper.

[0054] Specific embodiment six: the difference between this embodiment and one of specific embodiments one to five is that: in the process of polishing in step three, 1000-2000 mesh sandpaper is used to polish AgCuTi foil and AgCu foil, and 400-1000 mesh sandpaper is used to polish Nb foil.

[0055] Specific embodiment seven: the difference between this embodiment and one of specific embodiments one to six is that: the AgCuTi foil, AgCu foil and Nb foil in step three are cut to the edge greater than SiO 2f / SiO2 composite material to be welded.

[0056] Specific embodiment eight: the difference between this embodiment and one of specific embodiments one to seven is that: in the process of flattening in step three, a flat plate is used to clamp AgCuTi foil, AgCu foil and Nb foil, and a pressure of 5-10 MPa is applied.

[0057] Specific embodiment nine: the difference between this embodiment and one of specific embodiments one to eight is that: the ultrasonic cleaning process in step three is: using cleaning agent anhydrous ethanol or acetone, ultrasonic cleaning frequency is 70-150 kHz, ultrasonic cleaning time is 5-60 min, and repeated cleaning 2-3 times.

[0058] Specific embodiment ten: the difference between this embodiment and one of specific embodiments one to nine is that: the deposition process of Al deposition layer in step one ⑥ is: clamping SiO 2f / SiO2 composite material on the workbench of the magnetron sputtering device, adjusting the target material and SiO 2fThe distance between the SiO2 composite material and the magnetron sputtering device was 10 cm, and the magnetron sputtering device was vacuumized to 5×10 -3 Pa, then 100 sccm of argon was introduced at a constant rate, the working pressure was kept at 0.5 Pa, the frequency of the pulse power source was set to f r =600 Hz, the discharge pulse width was set to t ON =300 μs, the constant current mode was selected, the average discharge current was set to 0.4 A, then the voltage applied to the target was gradually increased until the target was completely melted, then sputtering deposition was performed for 60 min, and an Al deposition layer with a thickness of 6 μm was obtained on the surface of the SiO 2f 2 composite material to be welded.

[0059] Example 1:

[0060] In this embodiment, the SiO 2f 2 composite material was surface modified by the aluminothermic reduction method, and then was brazed with the Invar alloy.

[0061] I. SiO 2f 2 composite material before welding:

[0062] ① The SiO 2f 2 composite material was cut to 4 mm×4 mm×4 mm.

[0063] ② The cut SiO 2f 2 composite material was ultrasonically cleaned.

[0064] The ultrasonic cleaning process in step I ② is as follows: the cleaning agent is anhydrous ethanol, the ultrasonic cleaning frequency is 100 kHz, and the ultrasonic cleaning time is 10 min.

[0065] ③ The ultrasonically cleaned SiO 2f 2 composite material was calcined.

[0066] The calcination process is as follows: heating at a rate of 10 ℃ / min to 700 ℃, keeping the temperature for 60 min, and then cooling at a rate of 5 ℃ / min to 100 ℃; the calcination can remove the gum inside the SiO 2f 2 composite material.

[0067] ④ The surface to be welded of the SiO 2f 2 composite material was polished.

[0068] The surface to be welded of the SiO 2f 2 composite material in step I ④ was polished using 1500-mesh sandpaper to remove surface impurities and ensure that the surface to be welded was smooth and flat.

[0069] ⑤、ultrasonic cleaning of the polished SiO 2f / SiO2 composite material;

[0070] The ultrasonic cleaning process in step one ⑤ is as follows: the cleaning agent is anhydrous ethanol, the ultrasonic cleaning frequency is 100 kHz, the ultrasonic cleaning time is 10 min, and the cleaning is repeated 3 times;

[0071] ⑥, depositing an Al deposition layer on the SiO 2f / SiO2 composite material to be welded;

[0072] The deposition process of the Al deposition layer is as follows: the SiO 2f / SiO2 composite material is clamped on the workbench of the magnetron sputtering device, the distance between the target material and the SiO 2f / SiO2 composite material is adjusted to 10 cm, the magnetron sputtering device is vacuumed to 5 × 10 -3 Pa, then 100 sccm of argon gas is introduced at a constant rate, the working gas pressure is maintained at 0.5 Pa, the frequency of the pulse power source is set to f r = 600 Hz, the discharge pulse width is set to t ON = 300 μs, the constant current mode is selected, the average discharge current is set to 0.4 A, then the voltage applied to the target material is gradually increased until the target material is completely melted; then sputtering deposition is carried out for 60 min to obtain an Al deposition layer of 6 μm on the SiO 2f / SiO2 composite material to be welded; the target material is an aluminum target;

[0073] ⑦, surface aluminum thermal reduction modification of the SiO 2f / SiO2 composite material

[0074] The SiO 2f / SiO2 composite material with the Al deposition layer on the surface to be welded is placed in a vacuum furnace, first heated to 700℃ at a heating rate of 10℃ / min and kept for 2 h for the reduction modification process, then cooled to 100℃ at a cooling rate of 5℃ / min;

[0075] II. Pre-welding treatment of Invar alloy:

[0076] The Invar alloy is cut to a predetermined size, the surface to be welded of the Invar alloy is polished, and then ultrasonic cleaning is carried out;

[0077] The ultrasonic cleaning process is as follows: the cleaning agent is anhydrous ethanol, the ultrasonic cleaning frequency is 100 kHz, and the ultrasonic cleaning time is 10 min; the surface to be welded of the Invar alloy is polished with 600 mesh sandpaper;

[0078] III. Pre-welding treatment of the composite intermediate layer:

[0079] Take AgCuTi foil, AgCu foil and Nb foil, cut the AgCuTi foil to 5mm x 5mm, cut the AgCu foil to 6mm x 6mm, and cut the Nb foil to 6mm x 6mm; after cutting, polish, flatten, and ultrasonic clean in turn;

[0080] In the polishing process, 1500 mesh sandpaper is used to polish the AgCuTi foil and the AgCu foil, and 400 mesh sandpaper is used to polish the Nb foil;

[0081] In the flattening process, the AgCuTi foil, the AgCu foil and the Nb foil are clamped by a flat plate, and a pressure of 8MPa is applied;

[0082] The ultrasonic cleaning process is as follows: the cleaning agent is anhydrous ethanol, the ultrasonic cleaning frequency is 100kHz, the ultrasonic cleaning time is 10min, and the cleaning is repeated 3 times;

[0083] Four, assembly of the to-be-welded test piece:

[0084] The SiO 2f / SiO2 composite material obtained in step one, the Invar alloy obtained in step two, and the AgCuTi foil, the AgCu foil and the Nb foil obtained in step two are stacked to obtain a to-be-welded test piece; the stacking order is SiO 2f / SiO2 composite material, AgCuTi foil, Nb foil, AgCu foil, Invar alloy, SiO 2f The to-be-welded surface of the SiO

[0085] Five, vacuum brazing connection: place the assembled test piece into a vacuum brazing furnace, the vacuum degree in the vacuum brazing furnace is 5x10 -3 Pa, heat to 860℃ at a heating rate of 10℃ / min, keep for 20min, and then cool to 100℃ at a cooling rate of 5℃ / min.

[0086] The SiO 2f / SiO2 composite material obtained in example 1 has a shear strength of 54MPa when brazed and connected with the Invar alloy.

[0087] Example 2:

[0088] In this example, the SiO 2f / SiO2 composite material is surface modified by aluminum thermal reduction, and the method of brazing the SiO

[0089] One, SiO 2f Pre-welding treatment of the SiO / SiO2 composite material:

[0090] ①, cut the SiO 2f / SiO2 composite material to 4mm x 4mm x 4mm;

[0091] ②, ultrasonic cleaning of the cut SiO 2f / SiO2 composite material;

[0092] The ultrasonic cleaning process of step 1② is: using anhydrous ethanol as cleaning agent, ultrasonic cleaning frequency is 100kHz, ultrasonic cleaning time is 10min;

[0093] ③, calcination of the ultrasonic cleaned SiO 2f / SiO2 composite material;

[0094] The calcination process is: heating at a rate of 10℃ / min to 700℃, keeping for 60min, then cooling at a rate of 5℃ / min to 100℃; calcination can remove the gum inside the SiO 2f / SiO2 composite material;

[0095] ④, polishing the welding surface of SiO 2f / SiO2 composite material;

[0096] Step 1④ polishing the welding surface of SiO 2f / SiO2 composite material uses 1500 mesh sandpaper to remove surface impurities and ensure the smoothness of the welding surface;

[0097] ⑤, ultrasonic cleaning of the polished SiO 2f / SiO2 composite material;

[0098] The ultrasonic cleaning process of step 1⑤ is: using anhydrous ethanol as cleaning agent, ultrasonic cleaning frequency is 100kHz, ultrasonic cleaning time is 10min, repeated cleaning for 3 times;

[0099] ⑥, depositing Al deposition layer on the welding surface of SiO 2f / SiO2 composite material;

[0100] The deposition process of the Al deposition layer is: clamping the SiO 2f / SiO2 composite material on the workbench of the magnetron sputtering device, adjusting the distance between the target material and the SiO 2f / SiO2 composite material to 10cm, vacuumizing the magnetron sputtering device to 5x10 -3 Pa, then passing 100sccm of argon at a constant rate, keeping the working gas pressure at 0.5Pa, setting the frequency of the pulse power source to f r =600Hz, setting the discharge pulse width to tON =300μs, select constant current mode, set the average discharge current to 0.4A, and then gradually increase the voltage applied to the target until the target is completely melted; then perform sputtering deposition for 60min on SiO 2f A 6 μm Al deposition layer is obtained on the surface of the / SiO2 composite material to be welded; the target material is an aluminum target;

[0101] ⑦, SiO 2f / SiO2 composite surface aluminothermic reduction modification

[0102] SiO with an Al deposition layer on the surface to be welded 2f The SiO2 composite material was placed in a vacuum furnace and first heated to 700°C at a heating rate of 10°C / min and held for 2 hours for reduction modification. Then it was cooled to 100°C at a cooling rate of 5°C / min.

[0103] II. Pre-welding treatment of Invar alloy:

[0104] The Invar alloy is cut to the predetermined size, the surface of the Invar alloy to be welded is ground, and then ultrasonic cleaning is performed.

[0105] The ultrasonic cleaning process is as follows: anhydrous ethanol is used as the cleaning agent, the ultrasonic cleaning frequency is 100kHz, and the ultrasonic cleaning time is 10min; 600-grit sandpaper is used to polish the surface of the Invar alloy to be welded.

[0106] III. Pre-welding treatment of the composite intermediate layer:

[0107] Take AgCuTi foil, AgCu foil, and Nb foil. Cut the AgCuTi foil to 5mm×5mm, the AgCu foil to 6mm×6mm, and the Nb foil to 6mm×6mm. After cutting, perform grinding, flattening, and ultrasonic cleaning in sequence.

[0108] During the polishing process, 1500-grit sandpaper was used to polish the AgCuTi foil and AgCu foil, and 400-grit sandpaper was used to polish the Nb foil.

[0109] During the flattening process, a flat plate is used to clamp the AgCuTi foil, AgCu foil, and Nb foil, and a pressure of 8MPa is applied.

[0110] The ultrasonic cleaning process is as follows: the cleaning agent is anhydrous ethanol, the ultrasonic cleaning frequency is 100kHz, the ultrasonic cleaning time is 10min, and the cleaning is repeated 3 times.

[0111] IV. Assembly of the test specimens to be welded:

[0112] The SiO obtained in step one 2fThe SiO2 composite material, the Invar alloy obtained in step two, and the AgCuTi foil, AgCu foil, and Nb foil obtained in step two are stacked to form a test piece to be welded; the stacking order is SiO2, Invar, Invar, and Nb foil. 2f / SiO2 composite materials, AgCuTi foil, Nb foil, AgCu foil, Invar alloy, SiO 2f The surface to be soldered of the / SiO2 composite material faces the AgCuTi foil, and the surface to be soldered of the Invar alloy faces the AgCu foil.

[0113] V. Vacuum Brazing Connection: Place the assembled specimen into a vacuum brazing furnace, with a vacuum level of 5×10⁻⁶. -3 Pa was heated to 860°C at a heating rate of 10°C / min, held for 20 min, and then cooled to 100°C at a cooling rate of 5°C / min.

[0114] SiO obtained in Example 2 2f The shear strength of the brazed joint between the SiO2 composite material and the Invar alloy is 56 MPa.

[0115] from Figure 1 and Figure 2 As can be seen from the examples, in Example 1 and Example 2, SiO 2f The surface of the SiO2 composite material was modified to enhance the bonding between the solder and SiO2. 2f The interfacial reaction between the solder and SiO2 composite materials forms a dense and continuous reaction layer, significantly enhancing the bonding between the solder and SiO2. 2f Interfacial bonding strength between / SiO2 composite materials.

Claims

1. A method of brazing an aluminum thermally reduced surface modified SiO 2f / SiO2 composite to an Invar alloy, characterized by: Alumino-thermic reduction surface modification assisted SiO 2f A method of brazing a / SiO2 composite to an Invar alloy is carried out according to the following steps: I. SiO 2f Pre-weld treatment of SiO2 / SiO2 composites: ①, SiO 2f / SiO2 composite material is cut to a predetermined size; ii. The cut SiO 2f / SiO2 composite material is ultrasonically cleaned; ③ The SiO2 after ultrasonic cleaning 2f / SiO2 composite material is calcined; The calcination process is: heating at a heating rate of 5-10℃ / min to 700-800℃, holding for 60-120min, and then cooling at a cooling rate of ≤5℃ / min to ≤150℃; IV. Polishing SiO 2f welding surface of SiO2 composite 5. The polished SiO 2f / SiO2 composite material is ultrasonically cleaned; (6) depositing an Al deposition layer on the surface to be welded of the SiO 2f / SiO2 composite material; The deposition process of the Al deposition layer is: placing the SiO 2f / SiO2 composite on the worktable of a magnetron sputtering device, adjusting the distance between the target and the SiO 2f / SiO2 composite, vacuumizing the magnetron sputtering device to ≤5×10 -3 Pa, then passing 80-150 sccm of argon at a constant rate, keeping the working pressure at 0.1-0.8 Pa, setting the frequency of the pulse power source at f r =500-700 Hz, setting the discharge pulse width at t ON =200-400 μs, selecting the constant current mode, setting the average discharge current at 0.3-0.5 A, then gradually increasing the voltage applied on the target until the target is completely melted; then performing sputtering deposition on the welding surface of the SiO 2f / SiO2 composite to obtain the Al deposition layer; the target is an aluminum target; SiO 2f Surface modification of SiO2 / SiO2 composites by aluminothermic reduction SiO with an Al deposition layer on the surface to be welded 2f The SiO2 composite material is placed in a vacuum furnace and first heated to 650℃-700℃ at a heating rate of 5-10℃ / min and held for 1-4 hours for reduction modification. Then it is cooled to ≤150℃ at a cooling rate of ≤5℃ / min. II. Pre-welding treatment of Invar alloy: Cut the Invar alloy to a predetermined size, polish the welding surface of the Invar alloy, and then perform ultrasonic cleaning; III. Pre-welding treatment of composite interlayer: Take AgCuTi foil, AgCu foil and Nb foil, cut them to a predetermined size, and then polish, flatten and ultrasonically clean them in sequence; IV. Assembly of the welding test piece: SiO 2f / SiO2composite, Invar alloy obtained in step two, and AgCuTi foil, AgCu foil and Nb foil obtained in step three were stacked to obtain a welding test piece; the stacking order was SiO 2f / SiO2composite, AgCuTi foil, Nb foil, AgCu foil, Invar alloy, SiO 2f The welding surface of the SiO / SiO2composite faced the AgCuTi foil, and the welding surface of the Invar alloy faced the AgCu foil. V. Vacuum brazing: the assembled test piece is placed into a vacuum brazing furnace, the vacuum degree in the vacuum brazing furnace is 5x10 - 3 Pa, heated to 840-900℃ at a heating rate of 5-10℃ / min, kept for 10-40min, and then cooled to ≤150℃ at a cooling rate of ≤5℃ / min.

2. The aluminothermic reduction surface modification assisted SiO 2f A method of brazing an Invar alloy with a SiO2 / SiO2 composite material, characterized in that: The ultrasonic cleaning process in step I 2 is: using anhydrous ethanol or acetone as the cleaning agent, an ultrasonic cleaning frequency of 70-150kHz, and an ultrasonic cleaning time of 5-60min.

3. The aluminothermic reduction surface modification assisted SiO 2f A method of brazing an Invar alloy with a SiO2 / SiO2 composite material, characterized in that: The SiO 2f The surface to be welded of the SiO2 / SiO2 composite is polished with 1000-3000 mesh sandpaper to remove surface impurities and ensure smoothness of the surface to be welded.

4. The aluminothermic reduction surface modification assisted SiO 2f Process for brazing of SiO The ultrasonic cleaning process in step I 5 is: using anhydrous ethanol or acetone as the cleaning agent, an ultrasonic cleaning frequency of 70-150kHz, an ultrasonic cleaning time of 5-60min, and repeating the cleaning 2-3 times.

5. The aluminothermic reduction surface modification assisted SiO 2f Process for brazing of SiO The ultrasonic cleaning process in step II is: using anhydrous ethanol or acetone as the cleaning agent, an ultrasonic cleaning frequency of 70-150kHz, and an ultrasonic cleaning time of 5-60min; and 400-1000 mesh sandpaper is used to polish the welding surface of the Invar alloy.

6. The aluminothermic reduction surface modification assisted SiO 2f Process for brazing of SiO2 / SiO2 composites with Invar alloys, characterized in that: In the polishing process in step III, 1000-2000 mesh sandpaper is used to polish the AgCuTi foil and the AgCu foil, and 400-1000 mesh sandpaper is used to polish the Nb foil.

7. The aluminothermic reduction surface modification assisted SiO 2f Method for brazing of SiO The AgCuTi foil, AgCu foil and Nb foil of step three are cut to the edge of SiO 2f / SiO2 composite to be welded surface edge 1-2mm.

8. The aluminothermic reduction surface modification assisted SiO 2f Method for brazing of an / SiO2 composite material to an Invar alloy, characterized in that: In the flattening process in step III, the AgCuTi foil, the AgCu foil and the Nb foil are clamped by a flat plate, and a pressure of 5-10MPa is applied.

9. The aluminothermic reduction surface modification assisted SiO 2f Process for brazing of SiO The ultrasonic cleaning process in step III is: using anhydrous ethanol or acetone as the cleaning agent, an ultrasonic cleaning frequency of 70-150kHz, an ultrasonic cleaning time of 5-60min, and repeating the cleaning 2-3 times.

10. The aluminothermic reduction surface modification assisted SiO 2f Process for brazing of SiO The deposition process of the Al deposition layer in step one (6) is as follows: the SiO 2f / SiO2 composite material is clamped on the worktable of a magnetron sputtering device, the distance between the target and the SiO 2f / SiO2 composite material is adjusted to 10 cm, the magnetron sputtering device is vacuumized to 5×10 -3 Pa, then 100 sccm of argon is introduced at a constant rate, the working pressure is kept at 0.5 Pa, the frequency of the pulse power source is set to f r = 600 Hz, the discharge pulse width is set to t ON = 300 μs, the constant current mode is selected, the average discharge current is set to 0.4 A, then the voltage applied on the target is gradually increased until the target is completely melted; then sputtering deposition is performed for 60 min, and an Al deposition layer with a thickness of 6 μm is obtained on the welding surface of the SiO 2f / SiO2 composite material.

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