CN113145830A

CN113145830A - Metal and ceramic connector and connecting method thereof

Info

Publication number: CN113145830A
Application number: CN202110272204.0A
Authority: CN
Inventors: 洪振军; 贺良; 杨炙坤; 于杰; 王静; 周晓龙
Original assignee: Kunming University of Science and Technology
Current assignee: Kunming University of Science and Technology
Priority date: 2021-03-12
Filing date: 2021-03-12
Publication date: 2021-07-23

Abstract

The invention discloses a metal-ceramic connecting body and a connecting method thereof, belonging to the field of metal-ceramic connecting. The ceramic is oxidized at high temperature, the surface-oxidized ceramic sheet is subjected to alloy vacuum casting, and finally the cast layered composite material is clamped and heat treated, so that the metallurgical bond between the sheet ceramic and the metal is produced. The invention utilizes the difference in thermal expansion coefficients between metals and ceramics and the interface compressive stress generated by lattice differences to encapsulate and bind the ceramics, improve its mechanical properties, and prevent the ceramics from splashing when fractured.

Description

Metal and ceramic connector and connecting method thereof

Technical Field

The invention relates to the technical field of ceramic-metal connection, in particular to a metal and ceramic connector and a connection method thereof.

Background

Engineering ceramics are high-performance structural materials, but ceramic parts have poor plasticity and poor impact resistance, so that the application of the engineering ceramics is limited. Metals have high strength, ductility and high temperature resistance, but sometimes have low stiffness. The metal and the ceramic are combined to form an ideal composite material, so that the respective excellent performances of the ceramic and the metal are exerted. Therefore, several ceramic and metal bonding techniques have been developed, such as solid phase bonding, brazing, precursor polymer bonding, ceramic powder and metal cast composite, and glass oxide bonding and diffusion bonding.

At present, a reinforcing material (such as SiC) and a buffer material (such as Al) are bonded together by metal casting porous ceramics, the porosity is not favorable for the flow filling of metal, and a large number of gaps or pores exist at the interface, so that the strength of the porous ceramic metal composite material is obviously lower than that of bulk ceramics. With bulk ceramics and metals for joining, residual stresses are created at the interface during fabrication and subsequent heat treatment due to differences in the thermal and mechanical properties of the materials. However, when the material is bent, the residual compressive stress in the material needs to be balanced firstly, so that larger force is needed for reaching the maximum deflection of the fracture, and the further evidence that the residual compressive stress of the surface layer in the material has a remarkable influence on the conventional mechanical properties of the material. Because the stress acts on the joint interface of the two, the requirement on the stability of the interface is higher, and the residual stress of the simple mechanical joint of the interface can be released immediately after the material is stressed. At the same time, excessive residual stress can cause stress concentrations, leading to interfacial bond fracture and possibly internal cracking of the ceramic. The strength of the bulk ceramic metal composite material is only improved if the metallurgical bonding problem of the metal and ceramic interface is solved. For the current connecting methods, no matter solid-phase bonding, brazing or other connecting methods, the process is complex, and the interface bonding performance is poor.

Disclosure of Invention

Aiming at the problems, the invention designs a simple and practical ceramic (especially SiC and B) which is simple and easy to operate and can be connected₄C and BN flake ceramics) and metals (particularly Al alloys) and connectors thereof.

In order to achieve the purpose, the invention provides the following scheme:

the invention provides a metal and ceramic connector, which is of a sandwich layered structure, wherein ceramic is coated inside metal.

The invention also provides a method for connecting the metal and the ceramic connector, which comprises the following steps: the method comprises the steps of pretreating ceramic, generating an oxide layer on the surface layer of the ceramic, using the oxide layer generated on the surface layer of the ceramic as a transition layer, carrying out alloy casting, and then carrying out clamping heat treatment.

Further, the ceramic comprises SiC and B₄C and BN.

Further, the pretreatment process comprises the step of keeping the temperature of the ceramic in an oxidizing gas atmosphere at 400-1400 ℃ for 5-20h to generate an oxide layer on the surface layer of the ceramic. Preferably, the ceramic is surface-oxidized in an oxygen atmosphere in a high temperature furnace with an oxygen flow rate of 100ml to 500 ml/min. Before an oxide layer is generated, the ceramic is subjected to ultrasonic cleaning by using an acetone solution, and the oiliness on the surface of the ceramic is removed. Then cleaning by using hydrofluoric acid, carrying out sand blasting (10-20 meshes of white corundum, sand blasting 0.8MPa) on the ceramic surface for roughening, removing corundum attached to the surface, and then carrying out surface oxidation on the roughened ceramic surface.

Further, the thickness of the oxide layer is 1-10 μm.

Further, the ceramic containing the oxide layer is cast in a vacuum casting mode, the casting liquid is Al-Mg-Si-Ni alloy liquid, and the casting temperature is 700 ℃.

Furthermore, the Al-Mg-Si-Ni alloy liquid contains 1-5 wt% of Mg, 5-10 wt% of Si, 1-5 wt% of Ni and the balance of Al. The Al-Mg-Si-Ni alloy liquid is prepared by mixing the raw materials and then smelting Al-Mg-Si-Ni alloy in a vacuum environment, wherein the smelting time is 0.5 h.

Further, the heat treatment temperature is 400-. And in the heat treatment process, a clamp is used for clamping the cast sample, the clamp and the sample are wrapped by aluminum foil and then placed into carbon powder, heat treatment is carried out at high temperature, and heat preservation is carried out for 5-10h at the temperature of 400-600 ℃.

The method comprises the steps of firstly carrying out high-temperature oxidation on ceramic, carrying out alloy vacuum casting on the ceramic wafer with the oxidized surface, and finally carrying out clamping heat treatment on the poured laminated composite material to enable the laminated ceramic and metal to be metallurgically bonded. The invention utilizes the difference of thermal expansion coefficients between metal and ceramic and the interface compressive stress generated by lattice difference, and balances the residual compressive stress in the material when the material is stressed and bent, thereby achieving the purpose of improving the bending strength of the composite material. The invention improves the bonding property of the ceramic chip-metal and improves the mechanical property of the ceramic chip by oxidizing the surface layer of the ceramic chip to form an oxide transition layer between the ceramic chip and the metal. Meanwhile, the ceramic is packaged and bound through metal compounding, and splashing of the ceramic during fracture is prevented.

The invention firstly forms an oxide film instead of an alloy film through the oxidation of the surface of the ceramic, and secondly adopts a vacuum metal Al alloy casting method to ensure that the oxide film on the surface of the ceramic reacts with molten aluminum alloy to realize metallurgical bonding, thereby realizing connection. According to the invention, compressive stress is generated on the surface of the ceramic through solidification and shrinkage of the metal after casting, and the compressive stress is balanced under the stress condition of the ceramic, so that the strength and the deformation resistance of the ceramic are improved.

Due to the difference of the thermal expansion coefficient and the lattice constant, the ceramic is subjected to the surface compressive stress within the range of 100-200 MPa. The invention provides a method for connecting SiC and B₄C and BN flake ceramics and metallic Al alloys. By pairing SiC and B₄Oxidizing the surfaces of the C and BN ceramic plates, then carrying out vacuum casting of Al-Mg-Si-Ni alloy, finally putting an aluminum foil wrapped sample into carbon powder and carrying out heat treatment by using a high-temperature furnace to realize SiC and B₄C and BN ceramic plates are connected with the metal Al alloy. By the connection mode, the adjustment of the compressive stress between the ceramic and the metal can be realized, and the bending strength and the deformation resistance of the composite material can be improved by balancing the compressive stress in the stress process of the composite material.

The invention discloses the following technical effects:

1. the invention realizes the metallurgical bonding of metal and block ceramic by combining metal casting and a ceramic transition layer, namely the connection of the metal and the block ceramic. During the use process, the bending strength and the deformation resistance of the composite material are improved. On the other hand, the existence of the packaging metal enables the ceramic to be tightly fixed in place, so that the broken ceramic cannot splash in the using process, and the ceramic is effectively packaged.

2. The invention has simple connection process, short time and easy operation through the steps of surface roughening treatment, surface oxidation, casting and heat treatment.

3. The bonding property of metal and ceramic is good, the oxide film is used as a transition layer for connecting the ceramic plate and the metal aluminum, the reaction of the alloy and the oxide film phase is realized in the casting process and the subsequent heat treatment process of the Al-Mg-Si-Ni alloy, the interface bonding is tighter, and no obvious transition layer exists.

4. The adjustment of the interface pressure stress can be realized by adjusting the thickness of the oxide layer on the surface of the block ceramic, so that the bending strength and the deformation resistance of the composite material are adjusted.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

FIG. 1 is a flow chart of a method of joining a metal to ceramic interconnect according to the present invention;

FIG. 2 is a graph comparing the results of three-point bending tests of SiC ceramic sheets of example 2 and comparative example 3, and comparative example 4 with cast samples before and after heat treatment;

FIG. 3 is a surface topography at the interface of the thermal treatment sample after the oxidized SiC ceramic wafer and the Al-Mg-Si-Ni alloy are cast in example 2 under different magnifications, wherein, the images b and d are partial magnified images of the images a and c respectively;

FIG. 4 is a diagram of the diffusion of elements at the interface of the thermal treatment sample after the oxidized SiC ceramic wafer and the Al-Mg-Si-Ni alloy are cast in example 2, wherein a is the interface morphology diagram, b is the element distribution diagram of four elements of Al, C, O and Si, and C, d, e and f are the distribution diagrams of the elements of Al, C, O and Si respectively;

FIG. 5 is the variation of lattice parameter of aluminum alloy at the interface of X-ray test composite in example 2;

FIG. 6 is the shape of the sample and the force applied to the sample in the three-point bending test in example 2;

FIG. 7 shows the results of X-ray tests conducted on the SiC ceramic of example 2 after oxidation at 1350 ℃ to form an oxide film.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The description and examples are intended to be illustrative only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

The flow chart of the method for connecting the metal and the ceramic connecting body is shown in figure 1.

Example 1

(1) Selecting a SiC ceramic wafer with pressureless sintering purity of more than 99 percent for testing, carrying out ultrasonic cleaning by using an acetone solution to remove the surface oiliness of the ceramic, then cleaning by using hydrofluoric acid, carrying out sand blasting and roughening (10-20 meshes of white corundum, sand blasting 0.8MPa) on the surface of the ceramic wafer, then removing the white corundum sand, and carrying out surface oxidation on the SiC ceramic wafer. And (3) preserving the heat of the ceramic wafer in an oxygen atmosphere (oxygen flow is 100ml/min) at 1350 ℃ for 5 hours by using a high-temperature furnace to perform surface oxidation, wherein the thickness of an oxide film is about 1 um.

(2) Fixing the SiC ceramic wafer in the middle of a die by using a customized die, then casting Al-Mg-Si-Ni alloy liquid by using a vacuum casting furnace, and mixing Al, Mg-Ni alloy and Al-Si alloy with the purity of more than 99.9%, wherein the Mg content is 1 wt%, the Si content is 2 wt%, the Ni content is 1 wt%, and the balance is Al. Putting the raw materials into a vacuum casting furnace, wherein the smelting temperature is 700 ℃, the smelting time is 0.5 hour, and carrying out vacuum casting after the smelting is finished.

(3) And after the cast sample is cooled, clamping the sample by using a customized clamp, putting the sample into carbon powder by using an aluminum foil wrapped clamp, pressurizing at 400 ℃ by using a high-temperature furnace, preserving heat for 10 hours under 100MPa, cooling along with the furnace, and taking out to obtain the metal and ceramic connector.

(4) And testing and calculating the interface compressive stress to be 160MPa, cutting the heat-treated sample to prepare a 21 x 40mm sample, and testing the bending strength of the sample by using a three-point bending tester. The bending strength of the sample reaches 330MPa, which is higher than 160MPa of the strength of the SiC ceramic chip, and the deformation amount reaches 0.25mm, and the ceramic is not broken.

Example 2

(1) Selecting a SiC ceramic wafer with pressureless sintering purity of more than 99 percent for testing, and using acetone solution for ultrasonic cleaning to remove the surface oiliness of the ceramic. And cleaning with hydrofluoric acid, performing sand blasting on the surface of the ceramic wafer to roughen the ceramic wafer (10-20 meshes of white corundum, and performing sand blasting at 0.8MPa), removing the white corundum sand, and performing surface oxidation on the SiC ceramic wafer. And (3) preserving the heat of the ceramic wafer for 10 hours in an oxygen atmosphere (oxygen flow is 200ml/min) at 1350 ℃ by using a high-temperature furnace, and oxidizing the surface of the ceramic wafer, wherein the thickness of an oxide film is 5 mu m.

(2) Fixing the SiC ceramic wafer in the middle of a die by using a customized die, then casting Al-Mg-Si-Ni alloy liquid by using a vacuum casting furnace, and mixing Al, Mg-Ni alloy and Al-Si alloy with the purity of more than 99.9%, wherein the Mg content is 2 wt%, the Si content is 6 wt%, the Ni content is 1.5 wt%, and the balance is Al. Putting the raw materials into a vacuum casting furnace, wherein the smelting temperature is 700 ℃, the smelting time is 0.5h, and carrying out vacuum casting after smelting is finished.

(3) After the cast sample is cooled, clamping the sample by using a customized clamp, putting the sample into carbon powder by using an aluminum foil wrapped clamp, pressurizing at 500 ℃ by using a high-temperature furnace under 120MPa, preserving heat for 5 hours, cooling along with the furnace, and taking out.

(4) The interface compressive stress is tested and calculated to be 150MPa, the heat-treated sample is cut to be made into a 21X 40mm sample, a three-point bending tester is used for testing the bending strength of the sample, the result is shown in figure 2, the surface appearance diagram of the thermal treatment sample interface after the oxidized SiC ceramic wafer and the Al-Mg-Si-Ni alloy are cast is shown in figure 3, the element diffusion diagram of the thermal treatment sample interface after the oxidized SiC ceramic wafer and the Al-Mg-Si-Ni alloy are cast is shown in figure 4, the lattice parameter change result of the aluminum alloy at the X-ray testing composite material interface is shown in figure 5, the shape of the sample and the stress condition of the three-point bending test are shown in figure 6, and the X-ray testing result after the SiC ceramic is oxidized at 1350 ℃ to form an oxide film is shown in figure 7. As can be seen from FIG. 2, the bending strength of the sample is higher than that of the SiC ceramic wafer by 160MPa, and the ceramic is not broken when the deformation reaches 0.60 mm. The bending strength of the sample reaches 300 MPa. The sample is cut, polished and polished to carry out interface scanning electron microscope analysis (see figure 3), so that the connection between the sample and the Al-Mg-Si-Ni alloy and the oxidized SiC ceramic wafer can be seen, and obvious metallurgical bonding exists at the interface. EDS elemental analysis indicated that the phenomenon of interfacial element interdiffusion was evident (see figure 4). As can be seen from FIG. 5, the X-ray test results of the samples obtained in step (2) and step (3) are compared with the diffraction peak shift, which indicates the presence of compressive stress. From FIG. 6, it can be confirmed that the desired oxide film was formed on the surface of SiC after the oxidation treatment.

According to the formula of the compressive stress, the bending strength of the 3-layer material with the surface layer being the compressive stress is as follows:

in the formula sigma_CIs interfacial compressive stress, d₂Is the SiC ceramic thickness and d is the total sample thickness, as shown in fig. 6.ν is Poisson's ratio of Al, E is elastic modulus of Al, and Δ ε is deformation amount of Al, and can be calculated according to difference of lattice constants before and after XRD detection heat treatment.

The value of d can be obtained by substituting the diffraction angle shown in fig. 5 into the bragg diffraction equation, and the specific algorithm is common knowledge in the art and does not belong to the essential point of the invention, and is not described herein.

The SiC surface oxidation process of this example is as follows:

SiC+3/2O₂→SiO₂+CO

SiC+2O₂→SiO₂+CO₂

SiC+O₂→SiO₂+C(g)；

melting Al alloy and SiO on the surface₂Reactions that may occur

Al+SiO₂→Al₂O₃+Si

Mg+SiO₂→MgO+Si

MgO+Al₂O₃→MgAl₂O₄。

Example 3

(1) Selecting a SiC ceramic wafer with pressureless sintering purity of more than 99 percent for testing, and using acetone solution for ultrasonic cleaning to remove the surface oiliness of the ceramic. And cleaning with hydrofluoric acid, performing sand blasting on the surface of the ceramic wafer to roughen the ceramic wafer (10-20 meshes of white corundum, and performing sand blasting at 0.8MPa), removing the white corundum sand, and performing surface oxidation on the SiC ceramic wafer. And (3) preserving the heat of the ceramic wafer for 10 hours in an oxygen atmosphere (oxygen flow is 300ml/min) at 1350 ℃ by using a high-temperature furnace, and oxidizing the surface of the ceramic wafer, wherein the thickness of an oxide film is about 10 mu m.

(2) Fixing the SiC ceramic wafer in the middle of a die by using a customized die, then casting Al-Mg-Si-Ni alloy liquid by using a vacuum casting furnace, and mixing Al, Mg-Ni alloy and Al-Si alloy with the purity of more than 99.9%, wherein the Mg content is 3 wt%, the Si content is 8 wt%, the Ni content is 2 wt%, and the balance is Al. Putting the raw materials into a vacuum casting furnace, wherein the smelting temperature is 700 ℃, the smelting time is 0.5 hour, and carrying out vacuum casting after the smelting is finished.

(3) After the cast sample is cooled, clamping the sample by using a customized clamp, putting the sample into carbon powder by using an aluminum foil wrapped clamp, pressurizing at 600 ℃ by using a high-temperature furnace under 200MPa, preserving heat for 10 hours, and taking out after cooling along with the furnace.

(4) The interfacial compressive stress was measured and calculated to be 90MPa, the heat-treated sample was cut to make 21 × 40mm samples, and the bending strength of the samples was measured using a three-point bending tester. The bending strength of the sample reaches 270MPa, which is higher than the strength of the SiC ceramic chip by 160MPa, and the deformation reaches 0.60mm, and the ceramic is not broken.

Example 4

(1) B with the pressureless sintering purity of more than 99 percent is selected₄And C, performing a test on the ceramic chip, and performing ultrasonic cleaning by using an acetone solution to remove the oiliness on the surface of the ceramic chip. Cleaning with hydrofluoric acid, roughening the ceramic wafer surface by sandblasting (10-20 mesh white corundum, sandblasting 0.8MPa), removing white corundum sand, and treating B₄And C, carrying out surface oxidation on the ceramic wafer. And (3) insulating for 15h in an oxygen atmosphere (oxygen flow is 400ml/min) at 800 ℃ by using a high-temperature furnace, and oxidizing the surface of the ceramic wafer, wherein the thickness of an oxide film is 5 um.

(2) Using a custom mold to form B₄Fixing the C ceramic wafer in the middle of the mold, then using a vacuum casting furnace to cast Al-Mg-Si-Ni alloy liquid, and adopting Al, Mg-Ni alloy and Al-Si alloy with the purity of more than 99.9% to carry out burdening, wherein the Mg content is 4 wt%, the Si content is 10 wt%, the Ni content is 3 wt%, and the balance is Al. Putting the raw materials into a vacuum casting furnace, wherein the smelting temperature is 700 ℃, the smelting time is 0.5 hour, and carrying out vacuum casting after the smelting is finished.

(3) After the cast sample is cooled, clamping the sample by using a customized clamp, putting the sample into carbon powder by using an aluminum foil wrapped clamp, pressurizing at 400 ℃ by using a high-temperature furnace and keeping the temperature at 200MPa for 5 hours, and taking out the sample after cooling along with the furnace.

(4) And testing and calculating the interface compressive stress to be 140MPa, cutting the heat-treated sample to prepare a 21 x 40mm sample, and testing the bending strength of the sample by using a three-point bending tester. The bending strength of the sample reaches 350MPa and is higher than B₄The strength of the ceramic wafer C is 250MPa, and the deformation amount reaches 0.20mm, so that the ceramic does not break.

Example 5

(1) BN ceramic plates with the pressureless sintering purity of more than 99% are selected for testing, and acetone solution is used for ultrasonic cleaning to remove the surface oiliness of the ceramic plates. Then cleaning the ceramic wafer by using hydrofluoric acid, carrying out sand blasting and roughening on the surface of the ceramic wafer (10-20 meshes of white corundum, and carrying out sand blasting at 0.8MPa), and then removing the white corundum sand to carry out surface oxidation. And (3) preserving the temperature for 20h in an oxygen atmosphere (oxygen flow is 500ml/min) at 1000 ℃ by using a high-temperature furnace to oxidize the surface of the ceramic wafer, wherein the thickness of the oxide film is 5 um.

(2) The method comprises the steps of fixing a BN ceramic wafer in the middle of a die by using a customized die, then casting Al-Mg-Si-Ni alloy liquid by using a vacuum casting furnace, and mixing Al, Mg-Ni alloy and Al-Si alloy with the purity of more than 99.9%, wherein the Mg content is 5 wt%, the Si content is 10 wt%, the Ni content is 5 wt%, and the balance is Al. Putting the raw materials into a vacuum casting furnace, wherein the smelting temperature is 700 ℃, the smelting time is 0.5 hour, and carrying out vacuum casting after the smelting is finished.

(4) The interfacial compressive stress was measured and calculated to be 150MPa, the heat-treated sample was cut to make 21 × 40mm samples, and the bending strength of the samples was measured using a three-point bending tester. The bending strength of the sample reaches 310MPa, which is 200MPa higher than that of the BN ceramic piece, and the ceramic with the deformation amount larger than 0.10mm is not broken.

Comparative example 1

The difference from example 1 is that the oxidation treatment is not performed in step (1), and the Al-Mg-Si-Ni alloy solution is directly vacuum cast on the ceramics treated with the acetone solution, the hydrofluoric acid, and the white corundum sand.

And testing and calculating the interface compressive stress to be 140MPa, cutting the heat-treated sample to prepare a 21 x 40mm sample, and testing the bending strength of the sample by using a three-point bending tester. The bending strength of the sample reaches 280MPa, and the deformation amount reaches 0.20mm, so that the ceramic is not broken.

Comparative example 2

The same as example 1 except that the heat treatment in step (3) was not performed, and the Al-Mg-Si-Ni alloy solution was vacuum-cast on the oxidized ceramics to obtain a sample for cutting test.

The interfacial compressive stress was measured and calculated to be 120MPa, the heat-treated sample was cut to make 21 × 40mm samples, and the bending strength of the samples was measured using a three-point bending tester. The bending strength of the sample reaches 250MPa, and the deformation amount reaches 0.15mm, so that the ceramic is not broken.

Comparative example 3

The difference from example 2 is that steps (1), (2) and (3) are not performed, and the cutting test is performed by directly using pure SiC plate-shaped ceramic which is not compounded by aluminum alloy.

Pure SiC ceramics were cut into 21 × 40mm and tested for bending strength using a three-point bending tester, and as a result, as shown in fig. 2, the bending strength of SiC was 160MPa, and partial fracture occurred when the deformation amount was 0.05mm or less.

Comparative example 4

The same as example 2, except that the heat treatment in step (3) was not performed, and the Al-Mg-Si-Ni alloy solution was vacuum-cast on the oxidized ceramics to obtain a sample for cutting test.

The interface compressive stress was measured and calculated to be 130MPa, the heat-treated sample was cut to make 21 × 40mm samples, and the bending strength of the samples was measured using a three-point bending tester, and the results are shown in fig. 2. The bending strength of the sample reaches 260MPa, and the deformation amount reaches 0.40mm, so that the ceramic is not broken.

From the comparison of the results of three-point bending tests of the SiC ceramic sheets in example 2, comparative example 3 and comparative example 4 and the cast samples before and after heat treatment, it can be seen that the bending strength of the samples after heat treatment is enhanced compared with that before heat treatment.

Comparative example 5

The difference from example 4 is that the Al-Mg-Si-Ni alloy solution was vacuum cast directly on ceramics treated with acetone solution, hydrofluoric acid and white corundum without oxidation treatment in step (1).

The interfacial compressive stress was measured and calculated to be 110MPa, the heat-treated sample was cut to make 21 × 40mm samples, and the bending strength of the samples was measured using a three-point bending tester. The bending strength of the sample reaches 200MPa, and the deformation amount reaches 0.175mm, so that the ceramic is not broken.

Comparative example 6

The difference from example 5 is that the Al-Mg-Si-Ni alloy solution was vacuum cast directly on the ceramics treated with acetone solution, hydrofluoric acid and white corundum without oxidation treatment in step (1).

The interfacial compressive stress was measured and calculated to be 120MPa, the heat-treated sample was cut to make 21 × 40mm samples, and the bending strength of the samples was measured using a three-point bending tester. The bending strength of the sample reaches 160MPa, and the deformation amount reaches 0.08mm, so that the ceramic is not broken.

COMPARATIVE EXAMPLE 7 (soldering Process)

The difference from embodiment 2 is that the connection is realized by using an aluminum brazing process, which is a conventional technique in the art and is not an inventive point, and thus, the details are not described herein.

The brazed samples were cut to make 21 x 40mm samples and tested for flexural strength using a three point bending tester. The bending strength of the sample reaches 170MPa, and the deformation reaches 0.40mm, so that the ceramic is broken.

Comparative example 8

The difference from the example 2 is that the process of the step (1) is to immerse the ceramic connection surface in the molten aluminum, move the ceramic connection surface relative to the molten aluminum so that the molten aluminum wets the ceramic connection surface, remove the ceramic connection surface from the molten aluminum, and cool the ceramic connection surface so that the aluminum liquid film adhered to the ceramic surface is naturally solidified to form the aluminum thin film.

The heat-treated sample was subjected to a cutting process to prepare a 21 x 40mm sample, and the bending strength of the sample was measured using a three-point bending tester. The bending strength of the sample reaches 150MPa, and the deformation reaches 0.40mm, so that the ceramic is broken.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.

Claims

1. A metal-ceramic connector, characterized in that the metal-ceramic connector is a sandwich layered structure, and the ceramic is coated inside the metal.

2. A method for connecting a metal and a ceramic connector as claimed in claim 1, characterized in that it comprises the steps of: pretreating the ceramic, generating an oxide layer on the surface of the ceramic, and using the oxide layer generated on the surface of the ceramic as a transition layer, alloy casting, and then clamp heat treatment.

3 . The connection method according to claim 2 , wherein the ceramics at least include three types of ceramics: SiC, B ₄ C and BN. 4 .

4 . The connection method according to claim 2 , wherein the pretreatment process comprises maintaining the ceramics in an oxidizing gas atmosphere at 400° C.-1400° C. for 5-20 hours to form an oxide layer on the ceramic surface. 5 .

5 . The connection method according to claim 4 , wherein the oxide layer has a thickness of 1-10 μm. 6 .

6 . The connection method according to claim 2 , wherein the ceramics containing the oxide layer is cast by means of vacuum casting, and the casting liquid is an Al-Mg-Si-Ni alloy liquid. 7 .

7. The connection method according to claim 6, characterized in that, in the Al-Mg-Si-Ni alloy liquid, the content of Mg is 1-5wt%, the content of Si is 5-10wt%, and the content of Ni is 1-5wt% %, the remainder is Al.

8 . The connection method according to claim 2 , wherein the heat treatment temperature is 400-600° C., the pressure is 100-200 MPa, and the holding time is 1-10 h. 9 .