Aluminum oxide ceramic heat-conducting material with high heat conductivity and preparation method of aluminum oxide ceramic heat-conducting material

Abstract

The invention relates to the technical field of heat-conducting ceramics, and particularly discloses a high-heat-conductivity aluminum oxide ceramic heat-conducting material and a preparation method thereof. The high-thermal-conductivity aluminum oxide ceramic heat conduction material comprises a tungsten slurry layer, a connecting layer and an aluminum oxide ceramic layer which are sequentially arranged from top to bottom, the connecting layer comprises graphene and metal particles, and the metal particles are selected from any one of Cu, Ag, Ni and Sn. The preparation method comprises the following steps: S1, preparing the connecting layer; s2, preparing tungsten slurry; and S3, preparing the heat conduction material. The high-heat-conductivity aluminum oxide ceramic heat conduction material can be used as an electronic device substrate material, and has the advantages of high heat conductivity, high mechanical strength and the like; in addition, the preparation method has the advantages of being simple in process, excellent in interlayer bonding performance and the like.

Description

Technical Field

[0001] The present application relates to the technical field of heat-conducting ceramics, and more specifically, to a high heat-conducting alumina ceramic heat-conducting material and a preparation method thereof. Background Art

[0002] Alumina ceramics have become one of the most widely used substrate materials in vacuum electronic devices due to their suitable dielectric constant, high dielectric strength, low dielectric loss, good thermal stability, low outgassing rate, and high mechanical strength.

[0003] Currently, the more common production process is to subject ceramic raw materials to steps such as ball milling, pressing, sintering, metallization, secondary sintering, nickel plating, and tungsten paste brushing. Among them, hot die casting is often used for pressing. The ceramic forms metallization of the ceramic by using tungsten paste, etc., but there are often problems such as low bonding strength and low density between the tungsten paste layer and the ceramic, which in turn leads to poor thermal conductivity of the ceramic. Summary of the Invention

[0004] In order to improve the thermal conductivity of the ceramic, the present application provides a high heat-conducting alumina ceramic heat-conducting material and a preparation method thereof.

[0005] A high heat-conducting alumina ceramic heat-conducting material provided by the present application adopts the following technical solutions:

[0006] In the first aspect, the present application provides a high heat-conducting alumina ceramic heat-conducting material, including a tungsten paste layer, a connection layer, and an alumina ceramic layer sequentially arranged from top to bottom. The connection layer includes graphene and metal particles, and the metal particles are selected from any one of Cu, Ag, Ni, and Sn.

[0007] By adopting the above technical solutions, the present application preferably provides a connection layer between the tungsten paste layer and the alumina ceramic layer. Graphene is used to connect the tungsten paste layer and the alumina ceramic layer. Graphene has a good bonding effect with both the tungsten paste and the ceramic layer. Graphene can not only capture tungsten vacancy defects and improve the ductility of tungsten, but also enhance the strength of the alumina ceramic, thereby effectively improving the bonding effect between the alumina ceramic and the tungsten paste layer. The connection layer in the present application also includes metal particles. The introduction of metal particles can enhance the roughness of the connection layer and further construct a metal heat-conducting network structure within the connection layer, which is beneficial to further enhancing the heat-conducting effect of the connection layer. And the introduction of metal particles can effectively reduce the interfacial reaction and agglomeration problems between graphene and the surface of the alumina ceramic, enabling graphene to stably serve as the connection layer for the alumina ceramic and the tungsten paste layer.

[0008] Optionally, the mass ratio of the graphene to the metal particles is 100:0.5 - 2.

[0009] By adopting the above technical solution, the mass ratio of metal particles to graphene is optimized, and a small amount of metal particles can be evenly distributed on the surface of graphene to reduce the interfacial reaction and agglomeration problems of graphene, and can also reduce the possibility of self-agglomeration of metal particles, enabling the connection layer to stably connect the alumina ceramic layer and the tungsten paste layer.

[0010] Optionally, the thickness of the connection layer is 0.1 - 0.3 μm.

[0011] By adopting the above technical solution, the thickness of the connection layer is optimized, making the overall thickness of the ceramic appropriate, which is beneficial to the subsequent use of the heat-conducting ceramic.

[0012] Optionally, the graphene includes graphene aerosol.

[0013] By adopting the above technical solution, the graphene sheets in the graphene aerosol are relatively evenly dispersed, and the graphene aerosol can adsorb metal particles, better enabling the metal particles to be loaded on the surface of the graphene sheets, which is beneficial to obtaining a more uniform dispersion effect of graphene and driving the metal particles attached thereto to construct a metal heat-conducting network in the connection layer to further improve the heat-conducting effect of the ceramic.

[0014] Optionally, the graphene aerosol is prepared by an electro-explosion method.

[0015] By adopting the above technical solution, the graphene aerosol prepared by the electro-explosion method all has a small sheet diameter and can act as a lubricating particle in the connection layer, which can improve the dispersion uniformity of each component in the connection layer and enhance the bonding effect between graphene and metal particles.

[0016] Optionally, graphite raw materials with a particle size of 20 - 25 μm are fed into an explosion detonation tube, and two discharge electrodes connected to a pulsed energy storage capacitor introduce a large current into the graphite raw materials through a gas discharge mode to heat and raise their temperature and cause an explosion to obtain graphene powder, and the graphene powder is dispersed in a protective atmosphere to obtain graphene aerosol.

[0017] Optionally, the graphene also includes heterostructure graphene, and the heterostructure graphene is a graphene / boron nitride heterostructure.

[0018] By adopting the above technical solution, in this application, graphene with a graphene / boron nitride heterostructure is preferably used as the connection layer, which can convert the excellent in-plane heat conduction of graphene into out-of-plane heat conduction and can further improve the heat-conducting effect of graphene.

[0019] Optionally, in the graphene / boron nitride heterostructure, the graphene is in a pre-folded structure and the boron nitride is in a cubic structure.

[0020] By adopting the above technical solution, graphene is prepared into a pre-folded form. The folded structure can promote the in-plane heat conduction of graphene to be converted into an out-of-plane heat conduction structure, and can form a van der Waals heterojunction with boron nitride, enabling the heterostructure to obtain ultra-high in-plane and out-of-plane heat conduction effects.

[0021] In a second aspect, the present application provides a method for preparing a highly thermally conductive alumina ceramic thermal conductive material, adopting the following technical solution:

[0022] A method for preparing a highly thermally conductive alumina ceramic thermal conductive material includes the following steps:

[0023] S1. Preparation of the connection layer: Respectively take metal particles, graphene, PVA and water, stir and mix them to prepare graphene slurry.

[0024] S2. Preparation of tungsten paste: Take tungsten powder, ethyl cellulose, polyvinyl butyral and terpineol, stir and mix them in a water bath to obtain tungsten paste.

[0025] S3. Preparation of the thermal conductive material: Coat the graphene slurry on the alumina ceramic sheet, dry it to obtain an intermediate product. On the surface of the intermediate product, screen-print the tungsten paste, degrease it, and sinter it by laser to obtain the thermal conductive material.

[0026] Optionally, the content of reduced tungsten powder in the tungsten powder is 30%.

[0027] By adopting the above technical solution, the content of reduced tungsten powder is optimized. The reduced tungsten powder has a finer particle size, can form a gradient particle size distribution in the tungsten paste layer, improve the density of the tungsten paste layer, and further improve the contact area between the tungsten paste layer and the connection layer to improve the bonding effect between the connection layer and the tungsten paste layer.

[0028] In summary, the present application has the following beneficial effects:

[0029] 1. Since the present application preferably adopts to set a connection layer between the tungsten paste layer and the alumina ceramic layer, and graphene is used to connect the tungsten paste layer and the alumina ceramic layer. Graphene has a good bonding effect with both the tungsten paste and the ceramic layer. Graphene can not only capture tungsten vacancy defects and improve the ductility of tungsten, but also enhance the strength of the alumina ceramic, thereby effectively improving the bonding effect between the alumina ceramic and the tungsten paste layer. The connection layer in the present application also includes metal particles. The introduction of metal particles can enhance the roughness of the connection layer, and can further construct a metal thermal conduction network structure in the connection layer, which is beneficial to further enhancing the thermal conduction effect of the connection layer. And the introduction of metal particles can effectively reduce the interfacial reaction and agglomeration problems between graphene and the surface of the alumina ceramic, enabling graphene to stably serve as a connection layer for the alumina ceramic and the tungsten paste layer.

[0030] 2. In this application, graphene aerosol is preferably added to the connection layer. The graphene sheets in the graphene aerosol are relatively evenly dispersed, and the graphene aerosol can adsorb metal particles, enabling the metal particles to be better loaded on the surface of the graphene sheets, which is conducive to obtaining a more uniform dispersion effect of the graphene and driving the metal particles attached thereto to construct a metal heat conduction network in the connection layer to further improve the heat conduction effect of the ceramic.

[0031] 3. In this application, by preparing graphene into a pre-folded form, the folded structure can promote the in-plane heat conduction of graphene to be converted into an out-of-plane heat conduction structure, and can form a van der Waals heterojunction with boron nitride, enabling the heterostructure to obtain an ultra-high in-plane and out-of-plane heat conduction effect. Detailed implementation manners

[0032] The following further elaborates on this application with reference to examples.

[0033] Preparation examples

[0034] Preparation examples of graphene aerosol

[0035] Preparation example 1

[0036] The preparation of the graphene aerosol is as follows: 12 mg of graphite raw material with a particle size of 20 μm is fed into an explosion detonation tube. Two discharge electrodes connected to a pulse energy storage capacitor introduce a large current into the graphite raw material through a gas discharge mode. Under the condition of 12 kV, it is heated and exploded to obtain graphene powder, and the graphene powder is dispersed in a protective atmosphere to obtain graphene aerosol.

[0037] Preparation example 2

[0038] The preparation of the graphene aerosol is as follows: 12 mg of graphite raw material with a particle size of 23 μm is fed into an explosion detonation tube. Two discharge electrodes connected to a pulse energy storage capacitor introduce a large current into the graphite raw material through a gas discharge mode. Under the condition of 12 kV, it is heated and exploded to obtain graphene powder, and the graphene powder is dispersed in a protective atmosphere to obtain graphene aerosol.

[0039] Preparation example 3

[0040] The preparation of the graphene aerosol is as follows: 12 mg of graphite raw material with a particle size of 25 μm is fed into an explosion detonation tube. Two discharge electrodes connected to a pulse energy storage capacitor introduce a large current into the graphite raw material through a gas discharge mode. Under the condition of 12 kV, it is heated and exploded to obtain graphene powder, and the graphene powder is dispersed in a protective atmosphere to obtain graphene aerosol.

[0041] Preparation examples of heterostructure graphene

[0042] Preparation example 4

[0043] Weigh 5 g of 50-mesh high-purity flake graphite into a conical flask, and successively add 150 mL of concentrated H 2 SO 4 and 50 mL of concentrated HNO 3 . After stirring at room temperature for 24 h, slowly pour it into 2 L of ionized water, and vacuum filter it 4 times with a circulating water type multi-purpose vacuum pump. Put the filtered product into a petri dish, flatten it without caking, place it in an oven at 60 °C until completely dry, and vacuum expand it at 1000 °C.

[0044] Put the expanded graphite powder into a conical flask, add 300 mL of concentrated H 2 SO 4 , ultrasonic dispersion, 4.2 g of potassium persulfate, and 6.2 g of phosphorus pentoxide. After stirring at 80 °C in a constant temperature water bath for 5 h, slowly pour it into 2 L of ionized water, and vacuum filter it 4 times with a circulating water type multi-purpose vacuum pump. Put the filtered product into a petri dish, flatten it without caking, place it in an oven at 80 °C until completely dry.

[0045] Divide the pre-oxidized graphite powder into two equal parts and put them into conical flasks. Add 300 mL of concentrated H 2 SO 4 at 0 °C to each conical flask, mix them evenly with ultrasonic dispersion, slowly add 10 g of potassium permanganate to it, stir well at 35 °C for 4 h, then add the mixture to 2 L of deionized water. After the mixed solution cools to room temperature, add 15 mL of 30 wt.% hydrogen peroxide to the beaker and react fully. Observe that the solution turns golden yellow. Let the above mixed solution stand and precipitate for 6 h, pour off the upper liquid, add 2 L of deionized water again, repeat 3 times, and after centrifugation, retain the upper clear liquid to prepare an aqueous solution of graphene oxide.

[0046] Prepare an aqueous solution of graphene oxide with a concentration of 2.0 mg / mL, fill it into an atomizing spray gun, spray graphene on a polyimide film at a rotation speed of 700 r / min, volatilize and dry it, and use a 10 wt% aqueous solution of hydroiodic acid to separate the polyimide film to obtain a graphene film.

[0047] Place the graphene film in a tubular furnace and heat-treat it at 1000 °C for 2 h under an argon atmosphere. Then clamp the graphene film between two mirror steel plates with a size of 8 cm × 8 cm, and apply pressure with a press. Keep the pressure at 50 MPa for 5 min, 100 MPa for 10 min, 150 MPa for 15 min, 200 MPa for 60 min, and 300 MPa for 120 min. Finally, obtain a flexible graphene film with a thickness of about 20 μm and a density of 1.32 g / cm3, that is, an in-plane superthermal conductive graphene film.

[0048] Put 5 mg of borane ammonia complex in two crucibles respectively, place them on both sides of the tube furnace, and place the in-plane thermally conductive graphene film prepared in the previous section in the center of the tube furnace. Set the heating program: heat to 130 °C in 60 min and hold for 60 min, heat to 500 °C in 20 min and hold for 60 min, heat to 1050 °C in 30 min and hold for 120 min. Run the heating program to deposit boron nitride on the graphene surface. When the temperature rises to 1050 °C, the pressure gauge shows -0.1 MPa. After the deposition is completed, wait for the tube furnace to cool down to 25 °C, and introduce argon to one atmosphere. Repeat this deposition step again until the thickness of the boron nitride coating can achieve electrical insulation to obtain the heterostructure graphene.

[0049] Preparation Example 5

[0050] Weigh 5 g of 50-mesh high-purity flake graphite into a conical flask, and successively add 150 mL of concentrated H 2 SO 4 and 50 mL of concentrated HNO 3 . After stirring at room temperature for 24 h, slowly pour it into 2 L of ionized water, and vacuum filter 4 times with a circulating water type multi-purpose vacuum pump. Put the filtered product into a petri dish, flatten it, and make sure it does not form lumps. Place it in an oven at 60

[0051] °C until it is completely dry, and expand it under vacuum at 1000 °C.

[0052] Put the expanded graphite powder into a conical flask, add 300 mL of concentrated H 2 SO 4 , ultrasonic dispersion, 4.2 g of potassium persulfate, and 6.2 g of phosphorus pentoxide. After stirring at 80 °C in a constant temperature water bath for 5 h, slowly pour it into 2 L of ionized water, and vacuum filter 4 times with a circulating water type multi-purpose vacuum pump. Put the filtered product into a petri dish, flatten it, and make sure it does not form lumps. Place it in an oven at 80 °C until it is completely dry.

[0053] Divide the pre-oxidized graphite powder into two equal parts and put them into conical flasks. Add 300 mL of concentrated H 2 SO 4 to each conical flask, mix them evenly by ultrasonic dispersion, slowly add 10 g of potassium permanganate to it, stir well at 35 °C for 4 h, then add the mixture to 2 L of deionized water. After the mixed solution cools down to room temperature, add 15 mL of 30 wt.% hydrogen peroxide to the beaker and react fully. Observe that the solution turns golden yellow. Let the above mixed solution stand and precipitate for 6 h, pour off the upper liquid, add 2 L of deionized water again, repeat 3 times, and after centrifugation, retain the upper clear liquid to prepare an aqueous solution of graphene oxide.

[0054] Prepare an aqueous solution of graphene oxide with a concentration of 2.0 mg / mL, fill it into an atomizing spray gun, spray graphene on a polyimide film at a rotation speed of 700 r / min, volatilize and dry it, and use a 10 wt% aqueous solution of hydroiodic acid to separate the polyimide film to obtain a graphene film.

[0055] Heat-treat the graphene film in an argon atmosphere in a tube furnace at 1000 °C for 2 hours. Then, clamp the graphene film between two mirror steel plates with dimensions of 8 cm × 8 cm, and apply pressure with a press. Keep the pressure at 50 MPa for 5 min, 100 MPa for 10 min, 150 MPa for 15 min, 200 MPa for 60 min, and 300 MPa for 120 min. Finally, obtain a flexible graphene film with a thickness of about 20 μm and a density of 1.32 g / cm³, that is, an in-plane ultra-high thermal conductivity graphene film.

[0056] Apply a shear force around the in-plane ultra-high thermal conductivity graphene film to form pre-folded graphene, and then laterally compress this wrinkled structure to obtain a dense integral graphene film. After obtaining the pre-folded graphene film, place it between two flat mirror steel plates, use a steel sheet with a thickness of 450 μm, fix the positions of the upper and lower mirror steel plates, and push the steel sheet to compress the wrinkles from both sides to the middle, and keep it for 3 min. Repeat this step 8 times. Finally, obtain an out-of-plane ultra-high thermal conductivity graphene film with a thickness of 450 μm and a density of 1.70 g / cm 3 ³.

[0057] Put 5 mg of borane ammonia complex in two crucibles respectively, place them on both sides of the tube furnace, and place the out-of-plane ultra-high thermal conductivity graphene film prepared in the previous section in the center of the tube furnace. Set the heating program: heat up to 130 °C in 60 min and keep it warm for 60 min, heat up to 500 °C in 20 min and keep it warm for 60 min, heat up to 1050 °C in 30 min and keep it warm for 120 min. Run the heating program to deposit boron nitride on the graphene surface. When the temperature rises to 1050 °C, the pressure gauge shows -0.1 MPa. After the deposition is completed, wait for the tube furnace to cool down to 25 °C, and introduce argon until the pressure reaches one atmosphere. Repeat this deposition step again until the thickness of the boron nitride coating can achieve electrical insulation to obtain a heterostructure graphene.

[0058] Examples

[0059] Example 1

[0060] On the one hand, the present application provides a high thermal conductivity alumina ceramic thermal conductive material, which includes a tungsten paste layer, a connection layer, and an alumina ceramic layer arranged in sequence from top to bottom; the connection layer is composed of graphene and metal particles, and the metal particles can be any one of Cu, Ag, Ni, and Sn.

[0061] In this embodiment, the metal particles are made of metal Cu, and the graphene is graphene with a purity of 98% from Qingdao Hexinda Carbon Materials Co., Ltd.

[0062] On the other hand, the present application provides a method for preparing a highly thermally conductive alumina ceramic thermal conductive material, comprising the following steps:

[0063] S1. Preparation of the bonding layer: Respectively take metal particles, graphene, 2% PVA and water, stir and mix them to prepare a graphene slurry; the mass ratio of metal particles, graphene and PVA is 0.5:100:101.

[0064] S2. Preparation of the tungsten paste: Take tungsten powder, ethyl cellulose, polyvinyl butyral and terpineol, stir and mix them in a water bath to obtain a tungsten paste; among them, take 92% by weight of terpineol, 3% by weight of polyvinyl butyral and 5% by weight of ethyl cellulose, stir and mix them to obtain a mixed solution, take 85 parts by weight of tungsten powder and 10 parts by weight of the mixed solution, mix them, and obtain the tungsten paste through ball milling.

[0065] S3. Preparation of the thermal conductive material: Coat the graphene slurry on the alumina ceramic sheet, dry it to obtain an intermediate product, the thickness of the bonding layer is 0.1 μm, screen-print the tungsten paste on the surface of the intermediate product, degrease it, and sinter it by laser to obtain the thermal conductive material.

[0066] Example 2

[0067] On the one hand, the present application provides a highly thermally conductive alumina ceramic thermal conductive material, comprising a tungsten paste layer, a bonding layer and an alumina ceramic layer sequentially arranged from top to bottom; the bonding layer is composed of graphene and metal particles, and the metal particles can be any one of Cu, Ag, Ni, Sn.

[0068] In this embodiment, the metal particles are made of metal Cu, and the graphene is graphene with a purity of 98% from Qingdao Hexinda Carbon Materials Co., Ltd.

[0069] On the other hand, the present application provides a method for preparing a highly thermally conductive alumina ceramic thermal conductive material, comprising the following steps:

[0070] S1. Preparation of the bonding layer: Respectively take metal particles, graphene, 2% PVA and water, stir and mix them to prepare a graphene slurry; the mass ratio of metal particles, graphene and PVA is 1:100:101.

[0071] S2. Preparation of the tungsten paste: Take tungsten powder, ethyl cellulose, polyvinyl butyral and terpineol, stir and mix them in a water bath to obtain a tungsten paste; among them, take 92% by weight of terpineol, 3% by weight of polyvinyl butyral and 5% by weight of ethyl cellulose, stir and mix them to obtain a mixed solution, take 85 parts by weight of tungsten powder and 10 parts by weight of the mixed solution, mix them, and obtain the tungsten paste through ball milling.

[0072] S3. Preparation of thermal conductive material: Coat graphene slurry on the alumina ceramic sheet, dry it to obtain an intermediate product. The thickness of the connection layer is 0.1 μm. Screen-print tungsten paste on the surface of the intermediate product, degrease it, and then sinter it by laser to obtain the thermal conductive material.

[0073] Example 3

[0074] On the one hand, the present application provides a highly thermal conductive alumina ceramic thermal conductive material, which includes a tungsten paste layer, a connection layer, and an alumina ceramic layer sequentially arranged from top to bottom; the connection layer is composed of graphene and metal particles, and the metal particles can be any one of Cu, Ag, Ni, and Sn.

[0075] In this embodiment, the metal particles are selected as metal Cu, and the graphene is graphene with a purity of 98% from Qingdao Hexinda Carbon Materials Co., Ltd.

[0076] On the other hand, the present application provides a preparation method of a highly thermal conductive alumina ceramic thermal conductive material, which includes the following steps:

[0077] S1. Preparation of connection layer: Respectively take metal particles, graphene, 2% PVA, and water, stir and mix them to prepare graphene slurry; the mass ratio of metal particles, graphene, and PVA is 2:100:101.

[0078] S2. Preparation of tungsten paste: Take tungsten powder, ethyl cellulose, polyvinyl butyral, and terpineol, stir and mix them in a water bath to obtain tungsten paste; among them, take 92% by weight of terpineol, 3% by weight of polyvinyl butyral, and 5% by weight of ethyl cellulose, stir and mix them to obtain a mixed solution, take 85 parts by weight of tungsten powder and 10 parts by weight of the mixed solution, mix them, and then obtain tungsten paste through ball milling.

[0079] S3. Preparation of thermal conductive material: Coat graphene slurry on the alumina ceramic sheet, dry it to obtain an intermediate product. The thickness of the connection layer is 0.1 μm. Screen-print tungsten paste on the surface of the intermediate product, degrease it, and then sinter it by laser to obtain the thermal conductive material.

[0080] Example 4

[0081] On the one hand, the present application provides a highly thermal conductive alumina ceramic thermal conductive material, which includes a tungsten paste layer, a connection layer, and an alumina ceramic layer sequentially arranged from top to bottom; the connection layer is composed of graphene and metal particles, and the metal particles can be any one of Cu, Ag, Ni, and Sn.

[0082] In this embodiment, the metal particles are selected as metal Cu, and the graphene is graphene with a purity of 98% from Qingdao Hexinda Carbon Materials Co., Ltd.

[0083] On the other hand, the present application provides a method for preparing a highly thermally conductive alumina ceramic thermal conductive material, comprising the following steps:

[0084] S1. Preparation of the connecting layer: respectively take metal particles, graphene, 2% PVA and water, stir and mix them to prepare graphene slurry; the mass ratio of metal particles, graphene and PVA is 1:100:101.

[0085] S2. Preparation of tungsten paste: take tungsten powder, ethyl cellulose, polyvinyl butyral and terpineol, stir and mix them in a water bath to obtain tungsten paste; among them, take 92% by weight of terpineol, 3% by weight of polyvinyl butyral and 5% by weight of ethyl cellulose, stir and mix them to obtain a mixed solution, take 85 parts by weight of tungsten powder (70% conventional tungsten powder, 30% reduced tungsten powder) and 10 parts by weight of the mixed solution, mix them, and obtain tungsten paste through ball milling.

[0086] S3. Preparation of the thermal conductive material: coat the graphene slurry on the alumina ceramic sheet, dry it to obtain an intermediate product, the thickness of the connecting layer is 0.1 μm, screen-print the tungsten paste on the surface of the intermediate product, degrease it, and sinter it by laser to obtain the thermal conductive material.

[0087] Example 5

[0088] On the one hand, the present application provides a highly thermally conductive alumina ceramic thermal conductive material, comprising a tungsten paste layer, a connecting layer and an alumina ceramic layer sequentially arranged from top to bottom; the connecting layer is composed of graphene and metal particles, and the metal particles can be any one of Cu, Ag, Ni, and Sn.

[0089] In this example, the metal particles are selected as metal Cu, and the graphene is graphene with a purity of 98% from Qingdao Hexinda Carbon Materials Co., Ltd.

[0090] On the other hand, the present application provides a method for preparing a highly thermally conductive alumina ceramic thermal conductive material, comprising the following steps:

[0091] S1. Preparation of the connecting layer: respectively take metal particles, graphene, 2% PVA and water, stir and mix them to prepare graphene slurry; the mass ratio of metal particles, graphene and PVA is 1:100:101.

[0092] S2. Preparation of tungsten paste: take tungsten powder, ethyl cellulose, polyvinyl butyral and terpineol, stir and mix them in a water bath to obtain tungsten paste; among them, take 92% by weight of terpineol, 3% by weight of polyvinyl butyral and 5% by weight of ethyl cellulose, stir and mix them to obtain a mixed solution, take 85 parts by weight of tungsten powder and 10 parts by weight of the mixed solution, mix them, and obtain tungsten paste through ball milling.

[0093] S3. Preparation of thermal conductive material: Coat graphene slurry on the alumina ceramic sheet, dry it to obtain an intermediate product with a connection layer thickness of 0.2 μm. Screen-print tungsten paste on the surface of the intermediate product, degrease it, and then sinter it by laser to obtain the thermal conductive material.

[0094] Example 6

[0095] On the one hand, the present application provides a highly thermally conductive alumina ceramic thermal conductive material, which includes a tungsten paste layer, a connection layer, and an alumina ceramic layer arranged in sequence from top to bottom; the connection layer is composed of graphene and metal particles, and the metal particles can be any one of Cu, Ag, Ni, and Sn.

[0096] In this embodiment, the metal particles are selected as metal Cu, and the graphene is graphene with a purity of 98% from Qingdao Hexinda Carbon Materials Co., Ltd.

[0097] On the other hand, the present application provides a preparation method for a highly thermally conductive alumina ceramic thermal conductive material, which includes the following steps:

[0098] S1. Preparation of connection layer: Respectively take metal particles, graphene, 2% PVA, and water, stir and mix them to prepare graphene slurry; the mass ratio of metal particles, graphene, and PVA is 1:100:101.

[0099] S2. Preparation of tungsten paste: Take tungsten powder, ethyl cellulose, polyvinyl butyral, and terpineol, stir and mix them in a water bath to obtain tungsten paste; among them, take 92% by weight of terpineol, 3% by weight of polyvinyl butyral, and 5% by weight of ethyl cellulose, stir and mix them to obtain a mixed solution, take 85 parts by weight of tungsten powder and 10 parts by weight of the mixed solution, mix them, and obtain tungsten paste through ball milling.

[0100] S3. Preparation of thermal conductive material: Coat graphene slurry on the alumina ceramic sheet, dry it to obtain an intermediate product with a connection layer thickness of 0.3 μm. Screen-print tungsten paste on the surface of the intermediate product, degrease it, and then sinter it by laser to obtain the thermal conductive material.

[0101] Example 7

[0102] On the one hand, the present application provides a highly thermally conductive alumina ceramic thermal conductive material, which includes a tungsten paste layer, a connection layer, and an alumina ceramic layer arranged in sequence from top to bottom; the connection layer is composed of graphene and metal particles, and the metal particles can be any one of Cu, Ag, Ni, and Sn.

[0103] In this embodiment, the metal particles are selected as metal Cu, and the graphene includes graphene with a purity of 98% from Qingdao Hexinda Carbon Materials Co., Ltd. and the graphene aerosol prepared in Preparation Example 1 with a mass ratio of 1:1.

[0104] On the other hand, the present application provides a method for preparing a highly thermally conductive alumina ceramic thermal conductive material, comprising the following steps:

[0105] S1. Preparation of the connecting layer: respectively take metal particles, graphene, 2% PVA and water, stir and mix them to prepare graphene slurry; the mass ratio of metal particles, graphene and PVA is 1:100:101.

[0106] S2. Preparation of tungsten paste: take tungsten powder, ethyl cellulose, polyvinyl butyral and terpineol, stir and mix them in a water bath to obtain tungsten paste; among them, take 92% by weight of terpineol, 3% by weight of polyvinyl butyral and 5% by weight of ethyl cellulose, stir and mix them to obtain a mixed solution, take 85 parts by weight of tungsten powder and 10 parts by weight of the mixed solution, mix them, and obtain tungsten paste through ball milling.

[0107] S3. Preparation of the thermal conductive material: coat the graphene slurry on the alumina ceramic sheet, dry it to obtain an intermediate product, the thickness of the connecting layer is 0.1 μm, screen-print the tungsten paste on the surface of the intermediate product, degrease it, and perform laser sintering to obtain the thermal conductive material.

[0108] Examples 8-9

[0109] On the one hand, the present application provides a highly thermally conductive alumina ceramic thermal conductive material, comprising a tungsten paste layer, a connecting layer and an alumina ceramic layer which are sequentially arranged from top to bottom; the connecting layer is composed of graphene and metal particles, and the metal particles can be any one of Cu, Ag, Ni, and Sn.

[0110] In this embodiment, the metal particles are selected as metal Cu, and the graphene includes graphene with a purity of 98% from Qingdao Hexinda Carbon Materials Co., Ltd. with a mass ratio of 1:1 and the graphene aerosol prepared in Preparation Examples 2-3.

[0111] On the other hand, the present application provides a method for preparing a highly thermally conductive alumina ceramic thermal conductive material, comprising the following steps:

[0112] S1. Preparation of the connecting layer: respectively take metal particles, graphene, 2% PVA and water, stir and mix them to prepare graphene slurry; the mass ratio of metal particles, graphene and PVA is 1:100:101.

[0113] S2. Preparation of tungsten paste: take tungsten powder, ethyl cellulose, polyvinyl butyral and terpineol, stir and mix them in a water bath to obtain tungsten paste; among them, take 92% by weight of terpineol, 3% by weight of polyvinyl butyral and 5% by weight of ethyl cellulose, stir and mix them to obtain a mixed solution, take 85 parts by weight of tungsten powder and 10 parts by weight of the mixed solution, mix them, and obtain tungsten paste through ball milling.

[0114] S3. Preparation of thermal conductive material: Coat graphene slurry on an alumina ceramic sheet, dry it to obtain an intermediate product. The thickness of the connection layer is 0.1 μm. Screen-print tungsten paste on the surface of the intermediate product, degrease it, and then sinter it by laser to obtain the thermal conductive material.

[0115] Example 10

[0116] On the one hand, the present application provides a highly thermally conductive alumina ceramic thermal conductive material, which includes a tungsten paste layer, a connection layer, and an alumina ceramic layer arranged in sequence from top to bottom; the connection layer is composed of graphene and metal particles, and the metal particles can be any one of Cu, Ag, Ni, and Sn.

[0117] In this example, the metal particles are selected as metal Cu. The graphene includes graphene with a purity of 98% from Qingdao Hexinda Carbon Materials Co., Ltd., graphene aerosol prepared in Preparation Example 2, and heterostructured graphene prepared in Preparation Example 4, with a mass ratio of 1:1:1.

[0118] On the other hand, the present application provides a preparation method of a highly thermally conductive alumina ceramic thermal conductive material, which includes the following steps:

[0119] S1. Preparation of connection layer: Respectively take metal particles, graphene, 2% PVA, and water, stir and mix them to prepare graphene slurry; the mass ratio of metal particles, graphene, and PVA is 1:100:101.

[0120] S2. Preparation of tungsten paste: Take tungsten powder, ethyl cellulose, polyvinyl butyral, and terpineol, stir and mix them in a water bath to obtain tungsten paste; among them, take 92% by weight of terpineol, 3% by weight of polyvinyl butyral, and 5% by weight of ethyl cellulose, stir and mix them to obtain a mixed solution, take 85 parts by weight of tungsten powder and 10 parts by weight of the mixed solution, mix them, and ball mill them to obtain tungsten paste.

[0121] S3. Preparation of thermal conductive material: Coat graphene slurry on an alumina ceramic sheet, dry it to obtain an intermediate product. The thickness of the connection layer is 0.1 μm. Screen-print tungsten paste on the surface of the intermediate product, degrease it, and then sinter it by laser to obtain the thermal conductive material.

[0122] Example 11

[0123] On the one hand, the present application provides a highly thermally conductive alumina ceramic thermal conductive material, which includes a tungsten paste layer, a connection layer, and an alumina ceramic layer arranged in sequence from top to bottom; the connection layer is composed of graphene and metal particles, and the metal particles can be any one of Cu, Ag, Ni, and Sn.

[0124] In this embodiment, the metal particles are selected as metal Cu, and the graphene includes graphene with a purity of 98% from Qingdao Hexinda Carbon Materials Co., Ltd., graphene aerosol prepared in Preparation Example 2, and hetero-structured graphene prepared in Preparation Example 5, with a mass ratio of 1:1:1.

[0125] On the other hand, the present application provides a method for preparing a highly thermally conductive alumina ceramic thermal conductive material, comprising the following steps:

[0126] S1. Preparation of the connecting layer: Metal particles, graphene, 2% PVA, and water are respectively taken and stirred and mixed to prepare a graphene slurry; the mass ratio of the metal particles, graphene, and PVA is 1:100:101.

[0127] S2. Preparation of the tungsten paste: Tungsten powder, ethyl cellulose, polyvinyl butyral, and terpineol are taken and stirred and mixed in a water bath to obtain a tungsten paste; among them, 92% by weight of terpineol, 3% by weight of polyvinyl butyral, and 5% by weight of ethyl cellulose are stirred and mixed to obtain a mixed solution, 85 parts by weight of tungsten powder and 10 parts by weight of the mixed solution are mixed, and after ball milling, a tungsten paste is obtained.

[0128] S3. Preparation of the thermal conductive material: The graphene slurry is coated on the alumina ceramic sheet and dried to obtain an intermediate product. The thickness of the connecting layer is 0.1 μm. On the surface of the intermediate product, the tungsten paste is screen-printed, degreased, and laser sintered to obtain the thermal conductive material.

[0129] Comparative example

[0130] Comparative example 1

[0131] The difference between this comparative example and Example 1 is that no connecting layer is provided in this comparative example.

[0132] Comparative example 2

[0133] The difference between this comparative example and Example 1 is that the connecting layer in this comparative example only contains graphene.

[0134] Performance detection test

[0135] (1) Viscosity test: Test of thermal conductivity: The thermal conductivity is measured using a DRL-Ⅲ type thermal conductivity meter from Xiangtan Xiangyi Instrument Co., Ltd. Its principle is based on ASTM D5470-2012 (Test standard for heat transfer performance of thin thermally conductive solid electrical insulating materials), GB / T 29313—2012 "Test method for thermal conductivity of electrical insulating materials", etc. The size of the test sample is D = 30 m.

[0136] (2) Bonding performance test: Observe whether the product shrinks uniformly and whether warping occurs.

[0137] Table 1 Performance detection

[0138]

[0139] It can be found by combining the performance detection and comparison in Table 1 that:

[0140] 1. By comparing Examples 1-3 with Comparative Examples 1-2, it can be found that the thermal conductivity of the alumina ceramics prepared in Examples 1-3 has been improved. This shows that in this application, by connecting the tungsten paste layer and the alumina ceramic layer with graphene, graphene has a good bonding effect with both the tungsten paste and the ceramic layer. Graphene can not only capture tungsten vacancy defects and improve the ductility of tungsten, but also enhance the strength of the alumina ceramics, thereby effectively improving the bonding effect between the alumina ceramics and the tungsten paste layer. The connecting layer in this application also includes metal particles. The introduction of metal particles can enhance the roughness of the connecting layer and further construct a metal thermal conduction network structure within the connecting layer, which is beneficial to further enhancing the thermal conduction effect of the connecting layer. And the introduction of metal particles can effectively reduce the interfacial reaction and agglomeration problems between graphene and the surface of the alumina ceramics, enabling graphene to stably serve as the connecting layer for the alumina ceramics and the tungsten paste layer.

[0141] 2. By comparing Example 4 with Example 2, it can be found that the thermal conductivity of the alumina ceramics prepared in Example 4 has been improved. This shows that in this application, the reduced tungsten powder has a finer particle size, which can form a gradient particle size distribution in the tungsten paste layer, improve the density of the tungsten paste layer, and further increase the contact area between the tungsten paste layer and the connecting layer to improve the bonding effect between the connecting layer and the tungsten paste layer.

[0142] 3. By comparing Examples 7-9 with Example 2, it can be found that the thermal conductivity of the alumina ceramics prepared in Examples 7-9 has been improved. This shows that in this application, the graphene aerosols prepared by the electro-explosion method all have a smaller sheet diameter and can act as lubricating particles in the connecting layer, which can improve the dispersion uniformity of each component in the connecting layer and the bonding effect between graphene and metal particles.

[0143] 4. By comparing Examples 10-11 with Example 2, it can be found that the thermal conductivity of the alumina ceramics prepared in Examples 10-11 has been improved. This shows that in this application, by preparing graphene into a pre-folded form, the folded structure can promote the in-plane thermal conduction of graphene to be converted into an out-of-plane thermal conduction structure and can form a van der Waals heterojunction with boron nitride, enabling the heterostructure to obtain ultra-high in-plane and out-of-plane thermal conduction effects.

[0144] This specific embodiment is only an explanation of this application and is not a limitation of this application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as they are within the scope of the claims of this application, they are protected by the patent law.

Claims

1. A high thermal conductivity alumina ceramic thermal conductive material, characterized in that: It comprises a tungsten slurry layer, a connection layer and an alumina ceramic layer which are arranged in sequence from top to bottom. The connection layer comprises graphene and metal particles. The metal particles are selected from any one of Cu, Ag, Ni and Sn.

2. The high thermal conductivity alumina ceramic thermal conductive material according to claim 1, characterized in that: The mass ratio of the graphene to the metal particles is 100:0.5-2.

3. The high thermal conductivity alumina ceramic thermal conductive material according to claim 1, characterized in that: The thickness of the connecting layer is 0.1-0.3 μm.

4. The high thermal conductivity alumina ceramic thermal conductive material according to claim 1, characterized in that: The graphene includes graphene aerosol.

5. The high thermal conductivity alumina ceramic thermal conductive material according to claim 1, characterized in that: The graphene aerosol is prepared by an electric explosion method.

6. The high thermal conductivity alumina ceramic thermal conductive material according to claim 1, characterized in that: The graphene aerosol is prepared as follows: a graphite raw material with a particle size of 20-25 μm is fed into an explosion detonation tube, two discharge electrodes connected to a pulse energy storage capacitor introduce a large current into the graphite raw material through a gas discharge mode, so that the graphite raw material is heated and exploded to obtain graphene powder, and the graphene powder is dispersed in a protective atmosphere to obtain graphene aerosol.

7. The high thermal conductivity alumina ceramic thermal conductive material according to claim 1, characterized in that: The graphene also includes heterostructure graphene, and the heterostructure graphene is a graphene / boron nitride heterostructure.

8. The high thermal conductivity alumina ceramic thermal conductive material according to claim 1, characterized in that: In the graphene / boron nitride heterostructure, the graphene is a pre-wrinkled structure, and the boron nitride is a cubic structure.

9. The method for preparing a high thermal conductivity alumina ceramic thermal conductive material according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Preparation of connecting layer: taking metal particles, graphene, PVA and water respectively, stirring and mixing to prepare graphene slurry; S2. Preparation of tungsten slurry: tungsten powder, ethyl cellulose, polyvinyl butyral and pinene alcohol are mixed in a water bath and stirred to obtain tungsten slurry; S3. Preparation of thermal conductive material: coating graphene slurry on an alumina ceramic sheet, drying to obtain an intermediate product, screen printing tungsten slurry on the surface of the intermediate product, degreasing, and laser sintering to obtain a thermal conductive material.

10. The method for preparing a high thermal conductivity alumina ceramic thermal conductive material according to claim 9, characterized in that: The content of reduced tungsten powder in the tungsten powder is 30%.

Images