CN101182230A - A method of vacuum diffusion bonding ceramics - Google Patents

Abstract

The invention relates to a method for joining ceramics by vacuum diffusion, which relates to a method for welding ceramics, and is especially suitable for the connection of ceramics and metals, and ceramics and ceramics. The invention solves the problems of high connection temperature, large metal deformation at the local part of the joint and poor performance of the joint existing in the existing method of diffusing and joining ceramics. The method for vacuum diffusion connecting ceramics of the present invention is carried out according to the following steps: 1. The surface of the base metal is cleaned; 2. The diffusion intermediate layer is evenly placed on the connecting surface of the base material to be welded; 3. The clip is installed Diffusion connection of the weldment; 4. Cool down; that is, the connected ceramic weldment is obtained. The connection temperature of the invention is reduced by 60°C to 150°C, the shear strength of ceramics and ceramics and ceramics and metals connected by the invention is increased by 20% to 80%, and the metal at the joint has no obvious deformation.

Description

A method of vacuum diffusion bonding ceramics

technical field

The invention relates to a method for welding ceramics, especially suitable for the connection of ceramics and metals, and ceramics and ceramics.

Background technique

Ceramics have excellent properties such as high hardness, low specific gravity, high strength, high temperature resistance, and corrosion resistance. They are recognized as the most promising high-temperature structural materials in the industrial fields of aerospace vehicles, weaponry, atomic energy, and automobiles. However, due to the poor plasticity of ceramics, it is not easy to make large or complex-shaped components. In order to solve this problem, it is necessary to develop the connection technology of other dissimilar materials such as ceramics and metals, in order to obtain ceramic-metal composite components with both excellent properties of ceramics and metals. At present, more researches are active brazing method and diffusion bonding method. Active brazing connection is a kind of brazing filler metal between ceramic and metal base material is melted at high temperature, and the active components in it chemically react with ceramic to form a stable reaction gradient layer and combine two different materials together. method. Brazing material for active metal brazing is made by adding active metal Ti, In, etc. to precious metal base materials such as Cu, Ag, and Au. However, the main problems of ceramic-metal brazing connection are: (1) low bonding strength; (2) poor comparability of joint performance evaluation; (3) high price of solder. Diffusion connection is generally under vacuum conditions, so that the finely processed surfaces to be connected are close together. Under a certain temperature and pressure, the atoms at the contact interface diffuse with each other to form a metal bond. It is a precise connection method. Connection quality is solid. Diffusion connection is suitable for the connection of various ceramics and metals. Diffusion connection overcomes the shortcomings of active brazing method. The main advantages of diffusion connection are high connection strength, stable joint quality and good corrosion resistance. It is especially suitable for the connection of ceramics and metals under high temperature and corrosion resistance conditions. However, when connecting ceramics and metals, the temperature used for diffusion bonding is generally high, and the metal deformation at the joint is large, and because of the high temperature during the connection, it often exceeds the phase transition point of the material or the precipitation temperature of the strengthening phase, making the joint Performance deteriorates. Especially for the connection of dissimilar materials such as ceramics and metals, due to the high connection temperature, intermetallic compounds are precipitated at the joint interface, and various brittle compounds are formed at the interface between ceramics and metals. The morphological distribution has a great influence on the performance of the joint, which directly affects the practical application of the ceramic-metal structure. At the same time, a large internal stress will be formed at the joint during cooling, which will deteriorate the performance of the joint.

Contents of the invention

The present invention provides a method for vacuum diffusion bonding ceramics in order to solve the problems of high connection temperature, large metal deformation at local joints and poor joint performance existing in the existing diffusion bonding ceramics method.

The method for vacuum diffusion bonding ceramics of the present invention is carried out according to the following steps: 1. Clean up the surface of the base material before the diffusion connection; The layer is hydrogenated titanium or titanium alloy foil, and the thickness of the middle layer of diffusion connection is 30-100 μm; 3. Place the clamped weldment in a vacuum diffusion welding machine for heating, and the vacuum degree is 1.33×10 ^-3 ～ 4. Diffusion connection is carried out under the condition of 0×10 ^-3 Pa; 4. After welding, the weldment is depressurized when the original vacuum condition is lowered to 100°C, and when the temperature is lowered to room temperature, the weldment is taken out; the connected ceramic weldment is obtained.

The hydrogen content of the hydrogenated titanium described in step 2 of the present invention is 0.1-0.6 wt.%.

The principle of the method of the present invention is as follows: use titanium or titanium alloy foil with a hydrogen content of 0.1% to 0.6% (percentage by weight) as the diffusion connection intermediate layer, and use titanium to absorb oxygen, nitrogen, carbon, and silicon in the ceramics at the diffusion connection temperature. Such elements have high chemical affinity, can interact with ceramics, undergo substitution reactions or compound reactions, form reaction products, and connect ceramics firmly together through the generated reaction products. At the same time, due to the decrease of the thermal deformation flow stress of titanium or titanium alloy caused by hydrogen, the thermoplasticity increases, so that the hydrogenated titanium or titanium alloy is easy to deform at high temperature; and the self-diffusion and solute diffusion capabilities of hydrogen in titanium or titanium alloy are relatively high , especially in the β phase, the diffusion ability is higher, so hydrogen can accelerate the diffusion of alloy elements, reduce the atomic binding energy, reduce the activation energy of diffusion, improve the ability of diffusion coordination and deformation, and can realize ceramic joints at relatively low temperatures Reliable diffusion connection. In addition, the hydrogenated titanium or titanium alloy undergoes dehydrogenation during the heating process of the vacuum diffusion connection. When the temperature reaches 600 ° C, the hydrogen begins to escape. When the temperature rises rapidly to reach the connection temperature, the hydrogen escapes sharply. The escaped hydrogen reacts with the oxide film on the surface of the material. This reduction reaction is very conducive to the removal of the oxide film, which helps to shorten the diffusion connection time and promote the diffusion connection process. For the vacuum diffusion connection of ceramics, compared with the conventional direct diffusion connection or the diffusion connection method using ordinary Ti foil as the intermediate layer, the vacuum diffusion connection method and process of the hydrogen-absorbing titanium alloy as the intermediate layer proposed by the present invention, the diffusion The connection temperature can be reduced by 60°C to 150°C, the shear strength of the joint can be increased by 20% to 80%, and the metal at the joint has no obvious deformation.

Description of drawings

Figure 1 is a schematic diagram of SiC/TC4 (hydrogen-containing titanium)/SiC diffusion bonding process curve; Figure 2 is a schematic diagram of Si ₃ N ₄ /TC4 (hydrogen-containing titanium)/Si ₃ N ₄ diffusion bonding process curve; Figure 3 is Al ₂ O ₃ /TC4 (hydrogenated titanium)/AISI304 stainless steel diffusion bonding process curve diagram; Figure 4 is a schematic diagram of Al ₂ O3/TC ₄ (hydrogenated titanium)/Kovar alloy diffusion bonding process curve; Figure 5 is SiC/TC4 (hydrogenated titanium )/TC4 titanium alloy diffusion bonding process curve; Figure 6 is a schematic diagram of SiC/Ti600 (hydrogen-containing titanium alloy foil)/GH128 nickel-based superalloy diffusion bonding process curve; T in Figure 1 to Figure 6 represents the diffusion bonding temperature, P represents the diffusion connection pressure, and t represents the diffusion connection time.

Detailed ways

Specific Embodiment 1: The method for vacuum diffusion bonding ceramics in this embodiment is carried out as follows: 1. Clean the surface of the base material before diffusion connection; 2. Place the diffusion intermediate layer evenly on the connection of the base material to be welded. On the surface, the middle layer of the diffusion connection is hydrogenated titanium or titanium alloy foil, and the thickness of the middle layer of the diffusion connection is 30-100 μm; 3. Place the clamped weldment in a vacuum diffusion welding machine for heating. Diffusion connection is carried out under the condition of 1.33×10 ^-3 ~ 4.0×10 ^-3 Pa; 4. After welding, the weldment is decompressed when the original vacuum condition drops to 100°C, and when the temperature is lowered to room temperature, the weldment is taken out; the connection is obtained Good ceramic weldments.

In this implementation method, the diffusion bonding process parameters should adopt the corresponding diffusion bonding temperature, diffusion bonding pressure and diffusion bonding time according to the difference of the base metal.

This embodiment is applicable to the connection of ceramics and ceramics, and ceramics and metals.

Embodiment 2: This embodiment differs from Embodiment 1 in that: in Step 2, the thickness of the diffusion-bonded intermediate layer is 40-80 μm. Other steps and parameters are the same as those in Embodiment 1.

Embodiment 3: The difference between this embodiment and Embodiment 1 is that in step 2, the thickness of the diffusion-bonded intermediate layer is 50 μm. Other steps and parameters are the same as those in Embodiment 1.

Embodiment 4: This embodiment is different from Embodiment 1 in that the thickness of the diffusion-bonded intermediate layer in step 2 is 60 μm. Other steps and parameters are the same as those in Embodiment 1.

Embodiment 5: This embodiment is different from Embodiment 1 in that: the hydrogen content of the hydrogenated titanium in step 2 is 0.1-0.6 wt.%. Other steps and parameters are the same as those in Embodiment 1.

Embodiment 6: This embodiment is different from Embodiment 1 in that: the hydrogen content of the hydrogenated titanium in step 2 is 0.2-0.5 wt.%. Other steps and parameters are the same as those in Embodiment 1.

Embodiment 7: This embodiment is different from Embodiment 1 in that: the hydrogen content of the hydrogenated titanium in step 2 is 0.3-0.4 wt.%. Other steps and parameters are the same as those in Embodiment 1.

Embodiment 8: This embodiment is different from Embodiment 1 in that: the hydrogen content of the hydrogenated titanium in step 2 is 0.35wt.%. Other steps and parameters are the same as those in Embodiment 1.

Specific embodiment nine: the difference between this embodiment and specific embodiment one is: in step 1, the surface of the parent material is cleaned by physical cleaning, chemical cleaning or first physical cleaning followed by chemical cleaning; the physical cleaning is followed by 400 ^# , 500 ^# , 600 ^# , 800 ^# and 1000 ^# metallographic sandpaper are polished step by step; the chemical cleaning is to prepare the corresponding corrosion solution according to the difference of the base material to remove the adsorption layer, impurities and/or oxide film on the surface of the base material , and then wipe the surface of the base metal to be welded with acetone or put the base metal in an acetone solution and use ultrasonic cleaning. Other steps and parameters are the same as those in Embodiment 1.

Embodiment 10: This embodiment is different from Embodiment 1 in that: in step 3, the heating method adopts induction heating or resistance heating. Other steps and parameters are the same as those in Embodiment 1.

Embodiment 11: In this embodiment, the method of diffusion bonding SiC ceramics and SiC ceramics is carried out as follows: 1. Before diffusion bonding, use 400 ^# , 500 ^# , 600 ^# , 800 ^# and 1000 # on the welded surface of the SiC base material in sequence ^{#Metallographic} sandpaper is polished step by step, and then placed in acetone solution and cleaned by ultrasonic waves; 2. Place the diffusion intermediate layer evenly on the connecting surface of the base material to be welded, and the diffusion connection intermediate layer is hydrogenated titanium (the hydrogen content is 0.3wt.%), the thickness of the diffusion-bonded intermediate layer is 30-50 μm; 3. Place the clamped weldment in a vacuum diffusion welding machine and heat it to 1350°C, at a vacuum degree of 1.33×10 ^-3 ～4.0× Diffusion connection is carried out under the condition of 10 ^-3 Pa, and the welding process specification parameter curve is shown in Figure 1; 4. After the welding is completed, the weldment is depressurized when the original vacuum condition drops to 100 ° C, and the weldment is taken out when the temperature is lowered to room temperature; That is, the weldment of connected SiC ceramics and SiC ceramics is obtained.

The diffusion connection of SiC/TC4 (titanium with hydrogen)/SiC in this embodiment shows that: the shear strength of the SiC/TC4 (titanium with hydrogen)/SiC diffusion connection at room temperature can reach 240-250 MPa, which is higher than that at the same diffusion connection temperature (1350 °C), diffusion bonding time (60min), and diffusion bonding pressure (10MPa), the SiC/Ti foil/SiC diffusion bonding joint strength (room temperature shear strength is 170-180MPa) is nearly 40% higher; (The diffusion bonding temperature is 1500°C, the diffusion bonding time is 60min, and the diffusion bonding pressure is 10MPa). The SiC/Ti foil/SiC diffusion bonding joint strength (room temperature shear strength is 240-250MPa) is equivalent, and the diffusion bonding temperature is reduced by 150°C. The fracture of the SiC/TiH ₂ /SiC diffusion bonded joint occurred on the SiC base metal near the joint; the interface microstructure of the joint was SiC/Ti ₃ SiC ₂ /Ti ₃ SiC ₂ +TiC/Ti ₃ SiC ₂ /SiC. The high temperature shear strength of SiC/TC4 (hydrogen)/SiC diffusion bonded joint can reach 220-230MPa at 800°C.

Embodiment 12: In this embodiment, the method for diffusion bonding Si ₃ N ₄ ceramics and Si ₃ N ₄ ceramics is carried out as follows: 1. Before diffusion bonding, use 400 ^# , 500 # on the welded surface of the Si ₃ N ₄ base material ^# , 600 ^# , 800 ^# and 1000 ^# metallographic sandpaper are polished step by step, and then placed in acetone solution and cleaned by ultrasonic waves; 2. Place the diffusion middle layer evenly on the connecting surface of the base metal to be welded, and the middle of the diffusion connection The layer is hydrogenated titanium (hydrogen content is 0.25wt.%), and the thickness of the diffusion connection intermediate layer is 50 μm; 3. Place the sandwiched weldment in a vacuum diffusion welding machine and heat it to 1400 ° C. At a vacuum degree of 1.33 ×10 ^-3 ~ 4.0×10 ^-3 Pa, the diffusion connection is carried out, and the welding process specification parameter curve is shown in Figure 2; 4. After welding, the weldment is decompressed when the temperature is lowered to 100°C under the original vacuum condition, and the temperature is lowered to At room temperature, the weldment is taken out; that is, the weldment of connected Si ₃ N ₄ ceramics and Si ₃ N ₄ ceramics is obtained.

The diffusion bonding of Si ₃ N ₄ /TC4 (titanium with hydrogen)/Si ₃ N ₄ in this embodiment shows that: the shear strength of Si ₃ N ₄ /TC4 (titanium with hydrogen)/Si ₃ N ₄ diffusion bonding at room temperature can reach 180～210MPa, compared with Si ₃ N ₄ /Ti foil/Si ₃ N ₄ diffusion bonding joint strength (room temperature shear The strength is 140-150MPa) is 30-50% higher; and Si ₃ N ₄ /Ti foil/Si ₃ N ₄ connected under high temperature conditions (diffusion connection temperature is 1500°C, diffusion connection time is 60min, diffusion connection pressure is 10MPa) The strength of diffusion bonding joints (shear strength at room temperature is 180-200MPa) is similar, and the diffusion bonding temperature is lowered by 100℃; the interface microstructure of the joints is Si ₃ N ₄ /Ti ₅ Si ₃ +TiN+TiSi/Si ₃ N ₄ . The high temperature shear strength of Si ₃ N ₄ /TiH ₂ /Si ₃ N ₄ diffusion bonded joints can reach 180-200 MPa at 800 °C.

Specific embodiment thirteen: In this embodiment, the method of diffusion bonding _Al2O3 ceramics and AISI304 stainless steel is carried out as follows: 1. Before diffusion _bonding , use 400 ^# _, 500 ^# , and 600 ^# on the welded surface of _Al2O3 ceramics in sequence , 800 ^# and 1000 ^# metallographic sandpapers are polished step by step, then placed in acetone solution and cleaned with ultrasonic waves, and the surface of the stainless steel to be welded is cleaned with acid; 2. Place the diffusion intermediate layer evenly on the connecting surface of the base metal to be welded Above, the diffusion bonding intermediate layer is hydrogenated titanium (hydrogen content is 0.4wt.%), and the thickness of the diffusion bonding intermediate layer is 50 μm; 3. Place the clamped weldment in a vacuum diffusion welding machine and heat it to 900 ° C. Diffusion connection is carried out under the condition of vacuum degree of 1.33×10 ^-3 ~ 4.0×10 ^-3 Pa, and the welding process specification parameter curve is shown in Figure 3; 4. After welding, when the weldment is cooled to 100°C under the original vacuum condition When the pressure is removed and the temperature is lowered to room temperature, the weldment is taken out; that is, the weldment of connected Al ₂ O ₃ ceramics and AISI304 stainless steel is obtained.

The diffusion connection of Al ₂ O ₃ /TC4 (hydrogen-containing titanium)/AISI304 stainless steel in this embodiment shows that the room temperature shear strength of the Al ₂ O ₃ /TC4 (hydrogen-containing titanium)/AISI304 stainless steel diffusion connection joint can reach 60-75 MPa, Compared with the joint strength of Al ₂ O ₃ /Ti foil/AISI304 stainless steel joint that uses the same thickness of Ti foil (the best welding specification is the diffusion bonding temperature of 900°C, the diffusion bonding time of 60min, and the diffusion bonding pressure of 15MPa) as the intermediate layer (room temperature shear The shear strength is 40-50MPa) which is 50%-80% higher, and the diffusion connection temperature is reduced by 60°C.

The composition of the Al ₂ O ₃ ceramics of this embodiment is shown in Table 1.

Table 1 Composition of Al ₂ O ₃ base material (wt.%)

Al ₂ O ₃ SiO ₂ CaO MgO K ₂ O Na ₂ O Impurities 94.58 3.55 0.12 0.92 0.05 0.53 margin

Specific Embodiment Fourteen: In this embodiment, _the method for diffusion bonding _Al2O3 ceramics and Kovar alloy is carried out as follows: 1. Before diffusion _bonding , use 400 ^# , 500 ^# , and 600 ^# on the welded surface of _Al2O3 ceramics in sequence , 800 ^# and 1000 ^# metallographic sandpapers are polished step by step, then placed in acetone solution and cleaned with ultrasonic waves, and the surface of the Kovar alloy to be welded is cleaned with acid; 2. The diffusion intermediate layer is evenly placed on the connection of the base metal to be welded On the surface, the diffusion bonding intermediate layer is hydrogenated titanium (hydrogen content is 0.35wt.%), and the thickness of the diffusion bonding intermediate layer is 50 μm; 3. Place the clamped weldment in a vacuum diffusion welding machine and heat it to 1100 °C , the diffusion connection is carried out under the condition of a vacuum degree of 1.33×10 ^-3 ~ 4.0×10 ^-3 Pa, and the welding process specification parameter curve is shown in Figure 4; 4. After welding, the weldment is cooled to 100°C under the original vacuum condition When the pressure is removed and the temperature is lowered to room temperature, the weldment is taken out; that is, the weldment of the connected Al ₂ O ₃ ceramic and Kovar alloy is obtained.

The diffusion bonding of Al ₂ O ₃ /TC4 (hydrogen-containing titanium)/Kovar alloy in this embodiment shows that: the room temperature shear strength of the Al ₂ O ₃ /TC4 (hydrogen-containing titanium)/Kovar alloy diffusion bonding joint can reach 160-180 MPa, Compared with the Al 2 O 3 /Ti foil/Kovar alloy joint strength (room temperature shear) of the same thickness of Ti foil (best welding specification is diffusion bonding temperature 1100 ℃, diffusion bonding time 60min, diffusion bonding pressure 10MPa) as the middle layer diffusion bonding Al ₂ O ₃ /Ti foil/Kovar alloy joint strength The shear strength is 120-150MPa) which is 10%-50% higher, and the diffusion connection temperature is reduced by 100°C.

The composition of the Kovar alloy of this embodiment is shown in Table 2.

Table 2 Composition of Kovar alloy base metal (wt.% weight percentage)

C P S Mg Mn Si Ni Co. Fe ≤0.05 ≤0.02 ≤0.02 - ≤0.40 ≤0.30 32.5-34 13.6-14.8 margin

Embodiment 15: In this embodiment, the method of diffusion bonding SiC ceramics and TC4 titanium alloy is carried out according to the following steps: 1. Before diffusion bonding, use 400 ^# , 500 ^# , 600 ^# , 800 ^# and 1000 # on the welded surface of SiC ceramics in sequence ^{#Metallographic} sandpaper is polished step by step, then placed in acetone solution and cleaned with ultrasonic waves, and the surface of TC4 titanium alloy to be welded is cleaned with acid; 2. Place the diffusion intermediate layer evenly on the connecting surface of the base metal to be welded, and diffuse The connecting intermediate layer is hydrogenated titanium (hydrogen content is 0.2wt.%), and the thickness of the diffusion connecting intermediate layer is 50 μm; 3. Place the clamped weldment in a vacuum diffusion welding machine and heat it to 850°C. Diffusion connection is carried out under the condition of 1.33×10 ^-3 ~ 4.0×10 ^-3 Pa, and the welding process specification parameter curve is shown in Figure 5; 4. After welding, the weldment is decompressed when the temperature drops to 100°C under the original vacuum condition. When the temperature is lowered to room temperature, the weldment is taken out; that is, the weldment of the connected SiC ceramic and TC4 titanium alloy is obtained.

The room temperature shear strength of the SiC/TC4 (hydrogen-containing titanium)/TC4 titanium alloy diffusion connection joint in this embodiment can reach 280-320 MPa.

Specific Embodiment 15: In this embodiment, the method of diffusion bonding SiC ceramics and nickel-based superalloy (GH128) is carried out as follows: 1. Before diffusion bonding, use 400 ^# , 500 ^# , 600 ^# , 800 ^# and 1000 ^# metallographic sandpaper are polished step by step, then placed in acetone solution and cleaned with ultrasonic waves, and the surface of the nickel-based superalloy to be welded is cleaned with acid; On the connection surface, the intermediate layer of diffusion bonding is a hydrogen-containing titanium alloy foil (hydrogen content is 0.45wt.%), and the thickness of the intermediate layer of diffusion bonding is 50 μm; 3. Place the clamped weldment in a vacuum diffusion welding machine Heat to 1050°C, and carry out diffusion connection under the condition of vacuum degree of 1.33×10 ^-3 ~ 4.0×10 ^-3 Pa. The welding process specification parameter curve is shown in Figure 6; 4. After welding, the weldment is under the original vacuum condition When the temperature is lowered to 100°C, the pressure is removed, and when the temperature is lowered to room temperature, the weldment is taken out; that is, the weldment of the connected SiC ceramic and nickel-based superalloy is obtained.

The room temperature shear strength of the SiC/Ti600 (hydrogen-containing titanium alloy foil)/GH128 nickel-based superalloy diffusion bonding joint in this embodiment can reach 210-260 MPa.

Claims (10)

1. A method for vacuum diffusion connecting ceramics is characterized in that the method for vacuum diffusion connecting ceramics is carried out as follows: one, before the diffusion connection, the base material surface is cleaned; two, the diffusion intermediate layer is evenly placed On the connecting surface of the welding base material, the intermediate layer of diffusion bonding is titanium or titanium alloy foil with hydrogen, and the thickness of the intermediate layer of diffusion bonding is 30-100 μm; 3. Place the clamped weldment in a vacuum diffusion welding machine for heating , Diffusion connection is carried out under the condition of vacuum degree of 1.33×10 ^-3 ~ 4.0×10 ^-3 Pa; 4. After welding, the weldment is depressurized when the original vacuum condition drops to 100°C, and when the temperature is lowered to room temperature, take out the weldment pieces; that is, the connected ceramic weldments are obtained. 2. A method for vacuum diffusion bonding ceramics according to claim 1, characterized in that the thickness of the diffusion bonding intermediate layer in step 2 is 40-80 μm. 3. A method for vacuum diffusion bonding ceramics according to claim 1, characterized in that the thickness of the diffusion bonding intermediate layer in step 2 is 50 μm. 4. A method for vacuum diffusion bonding ceramics according to claim 1, characterized in that the thickness of the diffusion bonding intermediate layer in step 2 is 60 μm. 5. A method for vacuum diffusion bonding ceramics according to claim 1, characterized in that the hydrogen content of the hydrogenated titanium in step 2 is 0.1-0.6 wt.%. 6. A method for vacuum diffusion bonding ceramics according to claim 1, characterized in that the hydrogen content of the hydrogenated titanium in step 2 is 0.2-0.5 wt.%. 7. A method for vacuum diffusion bonding ceramics according to claim 1, characterized in that the hydrogen content of the hydrogenated titanium in step 2 is 0.3-0.4 wt.%. 8. A method for vacuum diffusion bonding ceramics according to claim 1, characterized in that the hydrogen content of the hydrogenated titanium in step 2 is 0.35wt.%. 9. A method of vacuum diffusion bonding ceramics according to claim 1, characterized in that in step 1, the surface of the parent material is cleaned by physical cleaning, chemical cleaning or chemical cleaning after physical cleaning; the physical cleaning is sequentially Use 400 ^# , 500 ^# , 600 ^# , 800 ^# and 1000 ^# metallographic sandpaper to polish step by step; the chemical cleaning is to prepare the corresponding corrosion solution according to the difference of the base material to remove the adsorption layer, impurities and / or oxide film, and then wipe the surface of the base metal to be welded with acetone or put the base metal in an acetone solution and use ultrasonic cleaning. 10. A method for vacuum diffusion bonding ceramics according to claim 1, characterized in that the heating method in step 3 is induction heating or resistance heating.

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