An indirect brazing method for surface-pre-metallized Y2O3-MgO ceramics to metals

Abstract

The application discloses an indirect brazing method for surface pre-metalized Y2O3-MgO ceramic and metal, and relates to a brazing method for Y2O3-MgO ceramic and metal. In order to solve the problem that Y2O3-MgO nano-composite ceramic and metal filler are difficult to generate metallurgical reaction and wetting, the application realizes pre-metalization by preparing an Ag-CuO-Al2O3 cladding layer on the surface of Y2O3-MgO ceramic to be welded, generates a metalized reaction layer by respectively reacting CuO and Al2O3 in the Ag-CuO-Al2O3 cladding layer with Y2O3 and MgO, so that the Ag-CuO-Al2O3 can realize complete paving on the surface of Y2O3-MgO ceramic and realize good metallurgical combination of the interface. In the vacuum brazing process, the Ag-based filler realizes good combination with the Ag-CuO-Al2O3 cladding layer, and also forms reliable connection with the metal on the other side, so that a brazing joint with good metallurgical combination and no defects is obtained. The shear strength of the connection joint obtained by the indirect brazing of Y2O3-MgO ceramic and metal reaches 67 MPa.

Description

Technical Field

[0001] This invention relates to a brazing method for Y2O3-MgO ceramics to metals. Background Technology

[0002] Infrared windows are crucial navigation components for aircraft, and the increasing speed of aircraft places higher demands on their high-temperature resistance and shock resistance. However, traditional infrared-transparent materials often suffer from strong spontaneous emission and significant loss of mechanical properties at high temperatures. Y₂O₃-MgO multiphase ceramics, with their excellent high-temperature infrared transmittance, mechanical strength, and thermal shock resistance, have high-temperature application potential and are expected to be widely used in ultra-high-speed aircraft such as UAVs in the future. However, in practical applications, it is often necessary to connect the infrared window with a metal to form a heterogeneous structure, thereby fully utilizing the advantages of both ceramics and metals. Since the connection between the infrared window and the metal shell of a UAV is susceptible to significant aerodynamic and aerothermal effects during high-speed flight, higher requirements are placed on the reliability of the joint between the Y₂O₃-MgO multiphase ceramic and the metal.

[0003] Currently, there are few reports on methods for joining Y2O3-MgO ceramics to metals. Due to the considerable brittleness of Y2O3-MgO ceramics, it is difficult to machine complete mechanical holes, making bolt connections unsuitable. Adhesive joints generally have an operating temperature not exceeding 200℃, making them unsuitable for the high-speed requirements of aircraft. Among various welding methods, fusion welding struggles to overcome the high melting point of Y2O3-MgO ceramics and the significant difference in melting point between them and metals. Pressure welding is ill-suited for the curved and thin-walled structures of infrared windows. In comparison, brazing is the most suitable method for joining Y2O3-MgO ceramic infrared windows.

[0004] However, metal oxide ceramics are mainly composed of covalent and ionic bonds, exhibiting very stable electronic coordination and chemical stability. Among many metal oxides such as SiO2, Al2O3, CaO, ZrO2, and Y2O3, Y2O3 exhibits the highest thermodynamic stability. Therefore, Y2O3-MgO nanocomposite ceramics, with Y2O3 and MgO as the main components, are difficult to react with traditional metal brazing fillers and form good wetting, thus affecting brazing quality. Summary of the Invention

[0005] To address the problem of the difficulty in achieving metallurgical reaction and wetting between Y2O3-MgO nanocomposite ceramics and metal brazing fillers, this invention proposes an indirect brazing method for surface-pre-metallized Y2O3-MgO ceramics and metals.

[0006] The indirect brazing method for surface-pre-metallized Y2O3-MgO ceramics to metals according to the present invention is carried out according to the following steps:

[0007] I. Pre-welding treatment of Y2O3-MgO ceramics:

[0008] The Y2O3-MgO ceramic surface to be welded was successively ground and ultrasonically cleaned.

[0009] II. Pre-welding treatment of metals:

[0010] The metal surfaces to be welded are sequentially ground and ultrasonically cleaned.

[0011] III. Preparation of Cladding Material:

[0012] Weigh Ag powder, CuO powder and Al2O3 powder, mix them and then ball mill them to obtain Ag-CuO-Al2O3 cladding material;

[0013] The molar concentration of CuO in the Ag-CuO-Al2O3 cladding material is 2-40%, and the molar concentration of Al2O3 is 4-16%.

[0014] IV. Preparation of Y2O3-MgO ceramic cladding layer:

[0015] The Ag-CuO-Al2O3 cladding material obtained in step 3 is dissolved in anhydrous ethanol to obtain Ag-CuO-Al2O3 cladding slurry, which is then uniformly coated on the surface of Y2O3-MgO ceramic to be welded and transferred to a muffle furnace for sintering to obtain an Ag-CuO-Al2O3 cladding layer on the surface of Y2O3-MgO ceramic to be welded.

[0016] The mass fraction of Ag-CuO-Al2O3 cladding material in the Ag-CuO-Al2O3 cladding slurry is 10-50%;

[0017] The sintering process is as follows: heating to 1000-1100℃ at a heating rate not exceeding 5℃ / min, holding at that temperature for 10-30min, and cooling to room temperature at a cooling rate not exceeding 5℃ / min; both heating and cooling rates not exceeding 5℃ / min can avoid excessive heating and cooling, which would cause excessive residual stress in the Y2O3-MgO ceramic, affecting the performance of the joint, or even causing the ceramic to crack.

[0018] V. Pre-soldering treatment of silver-based brazing foil:

[0019] The silver-based solder foil is cut to the predetermined size, then the two surfaces of the silver-based solder foil are polished, and finally ultrasonic cleaning is performed.

[0020] VI. Assembly of welding test pieces:

[0021] A silver-based brazing foil is placed between the Y2O3-MgO ceramic cladding layer and the metal surface to be soldered, and then fixed with a clamp to obtain an assembly.

[0022] VII. Vacuum Brazing: Place the assembly into a vacuum brazing furnace and perform vacuum brazing to complete the indirect brazing of the surface pre-metallized Y2O3-MgO ceramic with the metal.

[0023] The vacuum brazing process is as follows: the vacuum degree in the vacuum brazing furnace does not exceed 8×10⁻⁶. -3 Pa, heating rate not exceeding 15℃ / min, brazing temperature 840℃~900℃, holding time 10min~40min, after holding, cooling to room temperature, cooling rate not exceeding 10℃ / min.

[0024] The principle and beneficial effects of this invention are as follows:

[0025] This invention achieves pre-metallization by preparing an Ag-CuO-Al2O3 cladding layer on the surface of Y2O3-MgO ceramic to be soldered, thereby avoiding the problem of poor metallurgical reaction between traditional metal solders and Y2O3-MgO ceramics, which leads to poor weld joint quality. This invention utilizes CuO and Al2O3 in the Ag-CuO-Al2O3 cladding layer as active components to react with Y2O3 and MgO respectively to generate a metallization reaction layer. The composition of this metallization reaction layer is Y2Cu2O5 and MgO. 0.8 Cu 0.2 O and Y4Al2O9 achieve a good metallurgical bond with the ceramic interface, thereby realizing an Ag-dominant metallization process on the Y2O3-MgO ceramic surface. During vacuum brazing, the filler metal not only achieves a good bond with the Ag-CuO-Al2O3 cladding layer, but also forms a reliable connection with the metal on the other side, resulting in a well-metallurgically bonded, defect-free brazed joint. The joint obtained by indirect brazing of Y2O3-MgO ceramic and metal in this invention achieves a room temperature shear strength of 67 MPa. Attached Figure Description

[0026] Figure 1 The image shows the microstructure of the brazed joint obtained in Example 1;

[0027] Figure 2 The image shows the microstructure and elemental surface scan of the ceramic-side reaction layer of the brazed joint obtained in Example 1.

[0028] Figure 3 This is a microstructure image of the brazed joint obtained in Example 2. Detailed Implementation

[0029] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any reasonable combination of the specific embodiments.

[0030] Specific Implementation Method 1: The indirect brazing method between surface-pre-metallized Y2O3-MgO ceramic and metal in this implementation method is carried out according to the following steps:

[0031] I. Pre-welding treatment of Y2O3-MgO ceramics:

[0032] The Y2O3-MgO ceramic surface to be welded was successively ground and ultrasonically cleaned.

[0033] II. Pre-welding treatment of metals:

[0034] The metal surfaces to be welded are sequentially ground and ultrasonically cleaned.

[0035] III. Preparation of Cladding Material:

[0036] Weigh Ag powder, CuO powder and Al2O3 powder, mix them and then ball mill them to obtain Ag-CuO-Al2O3 cladding material;

[0037] The molar concentration of CuO in the Ag-CuO-Al2O3 cladding material is 2-40%, and the molar concentration of Al2O3 is 4-16%.

[0038] IV. Preparation of Y2O3-MgO ceramic cladding layer:

[0039] The Ag-CuO-Al2O3 cladding material obtained in step 3 is dissolved in anhydrous ethanol to obtain Ag-CuO-Al2O3 cladding slurry, which is then uniformly coated on the surface of Y2O3-MgO ceramic to be welded and transferred to a muffle furnace for sintering to obtain an Ag-CuO-Al2O3 cladding layer on the surface of Y2O3-MgO ceramic to be welded.

[0040] The mass fraction of Ag-CuO-Al2O3 cladding material in the Ag-CuO-Al2O3 cladding slurry is 10-50%;

[0041] The sintering process is as follows: heating to 1000-1100℃ at a heating rate not exceeding 5℃ / min, holding at that temperature for 10-30min, and cooling to room temperature at a cooling rate not exceeding 5℃ / min; both heating and cooling rates not exceeding 5℃ / min can avoid excessive heating and cooling, which would cause excessive residual stress in the Y2O3-MgO ceramic, affecting the performance of the joint, or even causing the ceramic to crack.

[0042] V. Pre-soldering treatment of silver-based brazing foil:

[0043] The silver-based solder foil is cut to the predetermined size, then the two surfaces of the silver-based solder foil are polished, and finally ultrasonic cleaning is performed.

[0044] VI. Assembly of welding test pieces:

[0045] A silver-based brazing foil is placed between the Y2O3-MgO ceramic cladding layer and the metal surface to be soldered, and then fixed with a clamp to obtain an assembly.

[0046] VII. Vacuum Brazing: Place the assembly into a vacuum brazing furnace and perform vacuum brazing to complete the indirect brazing of the surface pre-metallized Y2O3-MgO ceramic with the metal.

[0047] The vacuum brazing process is as follows: the vacuum degree in the vacuum brazing furnace does not exceed 8×10⁻⁶. -3 Pa, heating rate not exceeding 15℃ / min, brazing temperature 840℃~900℃, holding time 10min~40min, after holding, cooling to room temperature, cooling rate not exceeding 10℃ / min.

[0048] This embodiment achieves pre-metallization by preparing an Ag-CuO-Al2O3 cladding layer on the surface of Y2O3-MgO ceramic to be soldered, thereby avoiding the problem of poor metallurgical reaction between traditional metal solder and Y2O3-MgO ceramic, which leads to poor weld joint quality. This embodiment utilizes CuO and Al2O3 in the Ag-CuO-Al2O3 cladding layer as active components to react with Y2O3 and MgO respectively to generate a metallization reaction layer. The composition of this metallization reaction layer is Y2Cu2O5 and MgO. 0.8 Cu 0.2 O and Y4Al2O9 achieve a good metallurgical bond with the ceramic interface, thereby realizing an Ag-dominant metallization process on the Y2O3-MgO ceramic surface. During vacuum brazing, the filler metal not only achieves a good bond with the Ag-CuO-Al2O3 cladding layer, but also forms a reliable connection with the metal on the other side, resulting in a well-metallurgically bonded, defect-free brazed joint. The joint obtained by indirect brazing of Y2O3-MgO ceramic and metal in this invention achieves a room temperature shear strength of 67 MPa.

[0049] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that: when grinding the surface to be welded in step one, 400-3000 grit diamond sandpaper is used.

[0050] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that the ultrasonic cleaning time in step 1 is 5-60 minutes, and the cleaning agent used is anhydrous ethanol or acetone.

[0051] Specific Implementation Method Four: This implementation method differs from one of the specific implementation methods one to three in that: the metal surface to be welded in step two is polished using 400-3000 grit sandpaper.

[0052] Specific Implementation Method 5: This implementation method differs from one of the specific implementation methods 1 to 4 in that the ultrasonic cleaning time of the metal surface to be welded in step 2 is 5-60 minutes, and the cleaning agent used is anhydrous ethanol or acetone.

[0053] Specific Implementation Method Six: This implementation method differs from one of Specific Implementation Methods One to Five in that the metal mentioned in step two is a titanium alloy, a titanium-aluminum alloy, or niobium.

[0054] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the ball milling time in step three is 2-12 hours.

[0055] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: the ultrasonic cleaning time in step five is 5 to 60 minutes, the frequency is 80 to 120 kHz, and the cleaning is repeated 2 to 5 times.

[0056] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the cleaning agent used in the ultrasonic cleaning of step five is anhydrous ethanol or acetone.

[0057] Specific Implementation Method 10: This implementation method differs from Specific Implementation Methods 1 to 9 in that: the two surfaces of the silver-based brazing foil described in step 5 are polished using 400-3000 grit sandpaper.

[0058] Specific Implementation Method Eleven: This implementation method differs from Specific Implementation Methods One to Ten in that the silver-based solder foil is an Ag-Cu solder foil, an Ag-Cu-In solder foil, an Ag-Cu-Ni solder foil, or an Ag-Cu-Ti solder foil.

[0059] Example 1:

[0060] The indirect brazing method for surface-pre-metallized Y2O3-MgO ceramic to metal in this embodiment is carried out according to the following steps:

[0061] I. Pre-welding treatment of Y2O3-MgO ceramics:

[0062] The Y2O3-MgO ceramic with a diameter of 4mm×4mm×3mm was subjected to progressive grinding and ultrasonic cleaning of the surface to be welded.

[0063] The surface to be welded is polished step by step using diamond sandpaper of 400#, 800#, 1500#, and 2000#.

[0064] The ultrasonic cleaning time is 20 minutes, and the cleaning agent used is anhydrous ethanol.

[0065] II. Pre-welding treatment of metals:

[0066] The 15mm×10mm×3mm metal surface to be welded was successively ground and ultrasonically cleaned;

[0067] The metal surface to be welded is polished using 1500-grit sandpaper;

[0068] The ultrasonic cleaning time for the metal surface to be welded is 20 minutes, and the cleaning agent used is anhydrous ethanol.

[0069] The metal is a TC4 alloy;

[0070] III. Preparation of Cladding Material:

[0071] Weigh Ag powder, CuO powder and Al2O3 powder, mix them and then ball mill them to obtain Ag-CuO-Al2O3 cladding material;

[0072] The ball milling time is 7 hours;

[0073] The Ag-CuO-Al2O3 cladding material has a CuO molar concentration of 24% and an Al2O3 molar concentration of 8%.

[0074] IV. Preparation of Y2O3-MgO ceramic cladding layer:

[0075] The Ag-CuO-Al2O3 cladding material obtained in step 3 is dissolved in anhydrous ethanol to obtain Ag-CuO-Al2O3 cladding slurry, which is then uniformly coated on the surface of Y2O3-MgO ceramic to be welded and transferred to a muffle furnace for sintering to obtain an Ag-CuO-Al2O3 cladding layer on the surface of Y2O3-MgO ceramic to be welded.

[0076] The mass fraction of Ag-CuO-Al2O3 cladding material in the Ag-CuO-Al2O3 cladding slurry is 30%.

[0077] The sintering process is as follows: heating to 1000℃ at a heating rate of 5℃ / min, holding at that temperature for 30min, and cooling to room temperature at a cooling rate of 5℃ / min.

[0078] V. Pre-soldering treatment of silver-based brazing foil:

[0079] Cut the silver-based brazing foil to 6mm×6mm, then grind both surfaces of the silver-based brazing foil, and finally perform ultrasonic cleaning.

[0080] The silver-based solder foil is an Ag-Cu solder foil, with a mass ratio of Ag to Cu of 72:28.

[0081] Each ultrasonic cleaning session lasted 10 minutes, with a frequency of 100 kHz, and was repeated 3 times. The cleaning agent used was anhydrous ethanol.

[0082] The two surfaces of the silver-based brazing foil are polished using 1000-grit sandpaper;

[0083] VI. Assembly of welding test pieces:

[0084] A silver-based brazing foil is placed between the Y2O3-MgO ceramic cladding layer and the metal surface to be soldered, and then fixed with a clamp to obtain an assembly.

[0085] VII. Vacuum Brazing: Place the assembly into a vacuum brazing furnace and perform vacuum brazing to complete the indirect brazing of the surface pre-metallized Y2O3-MgO ceramic with the metal.

[0086] The vacuum brazing process is as follows: the vacuum degree in the vacuum brazing furnace is 3×10⁻⁶. -5 Pa, heating rate of 10℃ / min, brazing temperature of 860℃, holding time of 20min, cooling to room temperature after holding, cooling rate of 5℃ / min.

[0087] Shear tests were conducted using an electronic universal testing machine at a loading speed of 0.5 mm / min. The room temperature shear strength of the joint obtained in this embodiment reached 67 MPa.

[0088] Figure 1 The image shows the microstructure of the brazed joint obtained in Example 1. Figure 1 As can be seen, the indirect brazed joint obtained in this embodiment generates a distinct reaction layer on the ceramic side, indicating that the metallurgical bonding is good during the pre-metallization process and no defects are generated in the joint as a whole. Figure 2 The microstructure and elemental surface scan diagrams of the ceramic-side reaction layer of the brazed joint obtained in Example 1 are shown in Table 1; Table 1 shows the EDS analysis results (at.%) of each phase. Figure 2 As shown in Table 1, the dark black phase is Mg. 0.8 Cu 0.2 O compounds are distributed in a dotted pattern within the Y2Cu2O5 layer, while Y4Al2O9 is distributed between Y2Cu2O5 and Mg. 0.8 Cu 0.2 The outer side of O indicates that the ceramic side interface has achieved good metallurgical bonding.

[0089] Table 1

[0090]

[0091] Example 2:

[0092] The indirect brazing method for surface-pre-metallized Y2O3-MgO ceramic to metal in this embodiment is carried out according to the following steps:

[0093] I. Pre-welding treatment of Y2O3-MgO ceramics:

[0094] The Y2O3-MgO ceramic with a diameter of 4mm×4mm×3mm was subjected to progressive grinding and ultrasonic cleaning of the surface to be welded.

[0095] The surface to be welded is polished step by step using diamond sandpaper of 400#, 800#, 1500#, and 2000#.

[0096] The ultrasonic cleaning time is 20 minutes, and the cleaning agent used is anhydrous ethanol.

[0097] II. Pre-welding treatment of metals:

[0098] The 15mm×10mm×3mm metal surface to be welded was successively ground and ultrasonically cleaned;

[0099] The metal surface to be welded is polished using 1500-grit sandpaper;

[0100] The ultrasonic cleaning time for the metal surface to be welded is 20 minutes, and the cleaning agent used is anhydrous ethanol.

[0101] The metal is a TC4 alloy;

[0102] III. Preparation of Cladding Material:

[0103] Weigh Ag powder, CuO powder and Al2O3 powder, mix them and then ball mill them to obtain Ag-CuO-Al2O3 cladding material;

[0104] The ball milling time is 7 hours;

[0105] The molar concentration of CuO in the Ag-CuO-Al2O3 cladding material is 32%, and the molar concentration of Al2O3 is 6%.

[0106] IV. Preparation of Y2O3-MgO ceramic cladding layer:

[0107] The Ag-CuO-Al2O3 cladding material obtained in step 3 is dissolved in anhydrous ethanol to obtain Ag-CuO-Al2O3 cladding slurry, which is then uniformly coated on the surface of Y2O3-MgO ceramic to be welded and transferred to a muffle furnace for sintering to obtain an Ag-CuO-Al2O3 cladding layer on the surface of Y2O3-MgO ceramic to be welded.

[0108] The mass fraction of Ag-CuO-Al2O3 cladding material in the Ag-CuO-Al2O3 cladding slurry is 30%.

[0109] The sintering process is as follows: heating to 1000℃ at a heating rate of 5℃ / min, holding at that temperature for 30min, and cooling to room temperature at a cooling rate of 5℃ / min.

[0110] V. Pre-soldering treatment of silver-based brazing foil:

[0111] Cut the silver-based brazing foil to 6mm×6mm, then grind both surfaces of the silver-based brazing foil, and finally perform ultrasonic cleaning.

[0112] The silver-based solder foil is an Ag-Cu solder foil, with a mass ratio of Ag to Cu of 72:28.

[0113] Each ultrasonic cleaning session lasted 10 minutes, with a frequency of 100 kHz, and was repeated 3 times. The cleaning agent used was anhydrous ethanol.

[0114] The two surfaces of the silver-based brazing foil are polished using 1000-grit sandpaper;

[0115] VI. Assembly of welding test pieces:

[0116] A silver-based brazing foil is placed between the Y2O3-MgO ceramic cladding layer and the metal surface to be soldered, and then fixed with a clamp to obtain an assembly.

[0117] VII. Vacuum Brazing: Place the assembly into a vacuum brazing furnace and perform vacuum brazing to complete the indirect brazing of the surface pre-metallized Y2O3-MgO ceramic with the metal.

[0118] The vacuum brazing process is as follows: the vacuum degree in the vacuum brazing furnace is 3×10⁻⁶. -5 Pa, heating rate of 10℃ / min, brazing temperature of 880℃, holding time of 20min, cooling to room temperature after holding, cooling rate of 5℃ / min.

[0119] Shear tests were conducted using an electronic universal testing machine at a loading speed of 0.5 mm / min. The room temperature shear strength of the joint obtained in this embodiment reached 60 MPa. Figure 3 The image shows the microstructure of the brazed joint obtained in Example 2. Figure 3 As can be seen, the indirect brazed joint obtained in Example 2 has a distinct reaction layer on the ceramic side, indicating that the metallurgical bonding is good during the pre-metallization process and no defects are generated in the joint as a whole.

Claims

1. An indirect brazing method for surface-pre-metallized Y2O3-MgO ceramics to metals, characterized in that: The indirect brazing method for surface-pre-metallized Y2O3-MgO ceramics to metals is carried out according to the following steps: I. Pre-welding treatment of Y2O3-MgO ceramics: The Y2O3-MgO ceramic surface to be welded was successively ground and ultrasonically cleaned. II. Pre-welding treatment of metals: The metal surfaces to be welded are sequentially ground and ultrasonically cleaned. III. Preparation of Cladding Material: Weigh Ag powder, CuO powder and Al2O3 powder, mix them and then ball mill them to obtain Ag-CuO-Al2O3 cladding material; The molar concentration of CuO in the Ag-CuO-Al2O3 cladding material is 2-40%, and the molar concentration of Al2O3 is 4-16%. IV. Preparation of Y2O3-MgO ceramic cladding layer: The Ag-CuO-Al2O3 cladding material obtained in step 3 is dissolved in anhydrous ethanol to obtain Ag-CuO-Al2O3 cladding slurry, which is then uniformly coated on the surface of Y2O3-MgO ceramic to be welded and transferred to a muffle furnace for sintering to obtain an Ag-CuO-Al2O3 cladding layer on the surface of Y2O3-MgO ceramic to be welded. The mass fraction of Ag-CuO-Al2O3 cladding material in the Ag-CuO-Al2O3 cladding slurry is 10-50%; The sintering process is as follows: heating to 1000-1100℃ at a heating rate not exceeding 5℃ / min, holding at that temperature for 10-30min, and cooling to room temperature at a cooling rate not exceeding 5℃ / min; both heating and cooling rates not exceeding 5℃ / min can avoid excessive heating and cooling, which would cause excessive residual stress in the Y2O3-MgO ceramic, affecting the performance of the joint, or even causing the ceramic to crack. V. Pre-soldering treatment of silver-based brazing foil: The silver-based solder foil is cut to the predetermined size, then the two surfaces of the silver-based solder foil are polished, and finally ultrasonic cleaning is performed. VI. Assembly of welding test pieces: A silver-based brazing foil is placed between the Y2O3-MgO ceramic cladding layer and the metal surface to be soldered, and then fixed with a clamp to obtain an assembly. VII. Vacuum Brazing: Place the assembly into a vacuum brazing furnace and perform vacuum brazing to complete the indirect brazing of the surface pre-metallized Y2O3-MgO ceramic with the metal. The vacuum brazing process is as follows: the vacuum degree in the vacuum brazing furnace does not exceed 8×10⁻⁶. -3 Pa, heating rate not exceeding 15℃ / min, brazing temperature 840℃~900℃, holding time 10min~40min, after holding, cooling to room temperature, cooling rate not exceeding 10℃ / min.

2. The indirect brazing method for surface-pre-metallized Y₂O₃-MgO ceramics and metals according to claim 1, characterized in that: When grinding the surface to be welded in step one, use diamond sandpaper with a grit of 400 to 3000.

3. The indirect brazing method for surface-pre-metallized Y₂O₃-MgO ceramics and metals according to claim 1, characterized in that: The ultrasonic cleaning time in step one is 5-60 minutes, and the cleaning agent used is anhydrous ethanol or acetone.

4. The indirect brazing method between surface-pre-metallized Y₂O₃-MgO ceramic and metal according to claim 1, characterized in that: The metal surface to be welded in step two is polished using 400-3000 grit sandpaper.

5. The indirect brazing method for surface-pre-metallized Y₂O₃-MgO ceramics and metals according to claim 1, characterized in that: The ultrasonic cleaning time for the metal surface to be welded in step two is 5-60 minutes, and the cleaning agent used is anhydrous ethanol or acetone.

6. The indirect brazing method for surface-pre-metallized Y₂O₃-MgO ceramics to metal according to claim 1, characterized in that: The metal mentioned in step two is a titanium alloy, a titanium-aluminum alloy, or niobium.

7. The indirect brazing method for surface-pre-metallized Y₂O₃-MgO ceramics and metals according to claim 1, characterized in that: The ball milling time described in step three is 2-12 hours.

8. The indirect brazing method for surface-pre-metallized Y₂O₃-MgO ceramics to metal according to claim 1, characterized in that: Step 5: Each ultrasonic cleaning session lasts 5–60 minutes at a frequency of 80–120 kHz, and is repeated 2–5 times.

9. The indirect brazing method for surface-pre-metallized Y₂O₃-MgO ceramics to metals according to claim 1, characterized in that: The ultrasonic cleaning agent used in step five is anhydrous ethanol or acetone.

10. The indirect brazing method for surface-pre-metallized Y₂O₃-MgO ceramics and metals according to claim 1, characterized in that: Step five involves polishing the two surfaces of the silver-based solder foil using 400-3000 grit sandpaper.

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