A three-dimensional continuous diamond / metal composite material, its preparation method and application

Abstract

The present invention provides a three-dimensional continuous diamond / metal composite material, its preparation method and application. More specifically, the three-dimensional continuous diamond / metal composite material is constructed by a three-dimensional continuous diamond network and a metal network in an interpenetrating manner. The three-dimensional continuous diamond network is formed by diamond particles with a silicon carbide protective layer on the surface connected through diamond-silicon carbide phase boundaries. Among them, the metal in the metal network is copper, aluminum, magnesium, copper alloy, aluminum alloy or magnesium alloy. The preparation method provided by the present invention also solves the problems of preparing a porous blank body of diamond material and an interfacial protective layer. The prepared composite material not only has an adjustable diamond volume fraction, high thermal conductivity, low expansion and high strength, but also meets the requirements of low cost and short process rapid preparation, and shows broad application prospects in the fields of heat dissipation materials, wear-resistant materials, functional structure integrated materials and bulletproof materials, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and particularly to a three-dimensional continuous diamond / metal composite material, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of fields such as the electronics industry, the military field, and aerospace, the demand for high-power density and high-reliability power electronic devices is increasing continuously, which puts forward higher requirements for high-thermal-conductivity and low-expansion heat dissipation materials. Traditional metal heat dissipation materials can no longer meet the heat dissipation requirements of these high-power devices. Metal matrix composites, because they combine the mechanical properties of metals and the high-thermal-conductivity properties of reinforcements, have gradually replaced traditional heat dissipation materials. Common metal matrix composite heat dissipation materials include aluminum silicon, silicon carbide / aluminum, diamond / aluminum, and diamond / copper, etc.

[0003] Diamond / metal composite materials, also known as diamond particle-reinforced metal matrix composite materials, are a type of particle-reinforced metal matrix composite materials formed by uniformly dispersing diamond particles in metals. This composite material combines the advantages of metal and diamond materials. Diamond is one of the materials with excellent thermal conductivity and low thermal expansion coefficient in nature, while copper, aluminum, magnesium, etc. also have excellent thermal conductivity.

[0004] However, due to the special crystal structure of diamond, the interface optimization mechanism and process between it and the metal matrix are very complex, which limits the transfer and transformation of the excellent properties of diamond to the composite material. Through the improvement and innovation of forming technologies, achieving the best optimization of the two-phase interface is the key to promoting the research, development, and application of diamond / metal composite materials. For traditional diamond / metal composite materials, the interface properties and thermal conductivity of the composite material are improved through surface modification treatment of diamond particles, but the surface modification process is complex, costly, inefficient, the bonding between the modified layer and diamond is poor, and the surface modified layer is uneven. At the same time, forming processes such as hot press sintering and spark plasma sintering have long process flows, low efficiency, instability, and low yield, and it is difficult to prepare composite materials with complex structures. Therefore, it is urgent to develop a diamond / metal composite material with low cost and high performance and its preparation process, which can meet the requirements of low cost and short process preparation while achieving high thermal conductivity, low expansion, and high strength. Summary of the Invention

[0005] To solve the problems in the prior art, the present invention provides a three-dimensional continuous diamond / metal composite material, its preparation method and applications. By constructing a three-dimensional continuous silicon carbide-bonded diamond network and a metal network, this method solves the problems in the preparation of porous green bodies and interfacial protective layers of diamond materials. The prepared composite material not only has adjustable diamond volume fraction, thermal conductivity and thermal expansion coefficient, but also can be rapidly prepared at low cost and with a short process. Especially in the fields of heat dissipation materials, wear-resistant materials, functional structure integrated materials and bulletproof materials, etc., it shows broad application prospects.

[0006] In the first aspect, the present invention provides a three-dimensional continuous diamond / metal composite material, which is constructed by mutually penetrating a three-dimensional continuous diamond network and a metal network. The three-dimensional continuous diamond network is formed by connecting diamond particles with a silicon carbide protective layer on the surface through diamond-silicon carbide phase boundaries.

[0007] Among them, the metal in the metal network is copper, aluminum, magnesium, copper alloy, aluminum alloy or magnesium alloy.

[0008] Preferably, the volume fraction of the three-dimensional continuous diamond network is 40%-80%, the porosity of the three-dimensional continuous diamond network is 20%-60%, the volume fraction of the diamond particles is 30%-75%, and the volume fraction of the silicon carbide protective layer is 5%-30%.

[0009] Preferably, the volume fraction of the three-dimensional continuous diamond network is 45%-72%, the porosity of the three-dimensional continuous diamond network is 28%-55%, the volume fraction of the diamond particles is 34%-65%, and the volume fraction of the silicon carbide protective layer is 7%-29%.

[0010] Preferably, the volume fraction of the three-dimensional continuous diamond network is 72%, the porosity of the three-dimensional continuous diamond network is 28%, the volume fraction of the diamond particles is 65%, and the volume fraction of the silicon carbide protective layer is 7%.

[0011] Preferably, the volume fraction of the three-dimensional continuous diamond network is 64%, the porosity of the three-dimensional continuous diamond network is 36%, the volume fraction of the diamond particles is 51%, and the volume fraction of the silicon carbide protective layer is 13%.

[0012] Preferably, the volume fraction of the three-dimensional continuous diamond network is 65%, the porosity of the three-dimensional continuous diamond network is 35%, the volume fraction of the diamond particles is 36%, and the volume fraction of the silicon carbide protective layer is 29%.

[0013] Preferably, the volume fraction of the three-dimensional continuous diamond network is 45%, the porosity of the three-dimensional continuous diamond network is 55%, the volume fraction of the diamond particles is 34%, and the volume fraction of the silicon carbide protective layer is 11%.

[0014] Preferably, a silicon carbide protective layer is formed on the surface of the diamond particles in the three-dimensional continuous diamond network. The thickness of the silicon carbide protective layer is 100 nm - 1.0 μm, and the silicon carbide protective layer covers an area of more than 90% of the surface area of the diamond particles.

[0015] More preferably, the thickness of the silicon carbide protective layer is 200 nm - 0.8 μm.

[0016] Preferably, the pore size of the three-dimensional continuous diamond network is 50 nm - 300 μm, and the size of the diamond particles is 50 μm - 700 μm.

[0017] More preferably, the pore size of the diamond network is 50 nm - 200 μm, and the size of the diamond particles is 100 μm - 500 μm.

[0018] Preferably, the magnesium alloy is selected from magnesium-aluminum alloys, magnesium-manganese alloys, magnesium-lithium alloys, magnesium-rare earth alloys, magnesium-silver alloys or magnesium-thorium alloys; the copper alloy is selected from brass, cupronickel or bronze; the aluminum alloy is selected from aluminum-silicon alloys, aluminum-magnesium-silicon alloys, aluminum-copper alloys, aluminum-magnesium alloys, aluminum-manganese alloys, aluminum-zinc alloys or aluminum-lithium alloys.

[0019] In a second aspect, the present invention provides a method for preparing the above three-dimensional continuous diamond / metal composite material, which includes the following steps:

[0020] Step 1, preparation of the slurry: Mix diamond particles, silicon-based powder, binder, curing agent and solvent evenly to obtain the slurry;

[0021] Step 2, granulation process: Remove the solvent from the slurry, crush it and then screen it to obtain particulate matter;

[0022] Step 3, forming process: Press the particulate matter obtained in Step 2 into a preform;

[0023] Step 4, pyrolysis process: Pyrolyze the preform obtained in Step 3 to obtain a pyrolyzed preform;

[0024] Step 5, sintering process: Perform high-temperature sintering on the pyrolyzed preform obtained in Step 4 to prepare a three-dimensional continuous diamond network;

[0025] Step 6, composite process: Pour or infiltrate the molten metal into the three-dimensional continuous diamond network obtained in Step 5 to prepare a three-dimensional continuous diamond / metal composite material.

[0026] Preferably, in step 1, the ratio of diamond particles, silicon-based powder, binder, curing agent, and solvent is as follows: for every 500 g of diamond particles, 50 g - 200 g of silicon-based powder, 50 g - 200 g of binder, 10 g - 100 g of curing agent, and 500 mL - 1000 mL of solvent are used.

[0027] Preferably, the silicon-based powder is one or both of metallic silicon powder and silicon dioxide powder.

[0028] Preferably, the binder is one or more of phenolic resin, epoxy resin, polyvinyl alcohol, polyvinyl butyral, furan resin, polyurethane, polycarbosilane, polyborazane, polyborosiloxane, polyborosilazane, and polyzirconium borosilazane.

[0029] Preferably, the curing agent is a substance that can react with the binder and transform the binder from a liquid or semi-fluid state to a solid state.

[0030] Preferably, the curing agent is one type of amine curing agent, acid anhydride curing agent, phenolic curing agent, imidazole curing agent, acidic curing agent, and mercaptan curing agent.

[0031] The amine curing agents are selected from ethylenediamine, triethylenetetramine, m-phenylenediamine, 4,4'-diaminodiphenylmethane, aliphatic diamine substances, aliphatic polyamine substances, aromatic polyamine substances, dicyandiamide substances, melamine, trimethylmelamine, and hexamethylenetetramine.

[0032] The acid anhydride curing agents are, for example, selected from phthalic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, maleic anhydride, and trimellitic anhydride.

[0033] The phenolic curing agents are selected from p-phenylenedimethylaldehyde, phenol, hydroquinone, cresol, bisphenol A, bisphenol F, nonylphenol, resorcinol, formaldehyde, and glutaraldehyde.

[0034] The imidazole curing agents are selected from imidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-methylimidazole, 2-phenylimidazole, 4,5-dihydroxyimidazole, 2-isopropylimidazole, 2-aminoimidazole, N-ethylimidazole, and imidazole salts.

[0035] The acidic curing agents are selected from p-toluenesulfonic acid, citric acid, sulfuric acid, hydrochloric acid, phosphoric acid, oxalic acid, adipic acid, benzenesulfonic acid, petroleum sulfonic acid, acetic acid, formic acid, glycolic acid, lactic acid, hydroxybutanedioic acid, propionic acid, fatty acids, boric acid, succinic acid, and p-azidobenzoic acid.

[0036] The mercaptan curing agent is selected from 1,2,3-propanetrithiol, 1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 2-mercaptoethanol, 2-mercaptopropionic acid, mercaptopropanol, mercaptoacetic acid, bis(mercaptomethyl)benzene (DMDE), mercaptoacetamide, and polyacrylate mercaptan.

[0037] Preferably, the solvent is one or more of ethanol, acetone, ethylene glycol, toluene, xylene, and water.

[0038] Preferably, in step 2, the method for removing the solvent from the slurry is selected from natural drying, freeze drying, spray drying, fluidized bed drying, belt drying, hollow paddle drying, disk drying, boiling drying, pneumatic drying, vacuum drying, or hot air circulation drying.

[0039] Preferably, in step 2, the pulverization method is mechanical pulverization. For example, a crusher is used for pulverization, and the crusher is selected from jaw crushers, cone crushers, or impact crushers.

[0040] Preferably, in step 2, pulverization is carried out until a powder with a particle size less than 0.5 mm is obtained.

[0041] Preferably, in step 2, the granular material obtained after screening has a mesh size of less than 150 mesh.

[0042] Preferably, in step 2, the granular material obtained after screening has a mesh size of less than 120 mesh.

[0043] Preferably, in step 3, the pressing pressure used for pressing into a preform is 50 MPa - 100 MPa, the pressure holding time is 10 min - 60 min, and the temperature is 20 °C - 240 °C.

[0044] Preferably, in step 4, the pyrolysis temperature is 600 °C - 1000 °C, and the heat preservation pyrolysis time is 30 min - 60 min.

[0045] Preferably, in step 4, an inert gas is used for protection during pyrolysis. More preferably, the inert gas is selected from helium, neon, and argon.

[0046] Preferably, in step 5, the high-temperature sintering is carried out in a protective atmosphere or under vacuum conditions. The protective atmosphere is selected from one or both of argon protection and nitrogen protection.

[0047] Preferably, in step 5, the high-temperature sintering temperature is 1450 °C - 1750 °C, and the sintering time is 5 min - 60 min.

[0048] Preferably, in step 6, the metal of the molten metal is selected from copper, aluminum, magnesium, copper alloy, aluminum alloy or magnesium alloy; wherein the magnesium alloy is selected from magnesium-aluminum alloy, magnesium-manganese alloy, magnesium-lithium alloy, magnesium-rare earth alloy, magnesium-silver alloy, magnesium-thorium alloy; the copper alloy is selected from brass, cupronickel and bronze; the aluminum alloy is selected from aluminum-silicon alloy, aluminum-magnesium-silicon alloy, aluminum-copper alloy, aluminum-magnesium alloy, aluminum-manganese alloy, aluminum-zinc alloy and aluminum-lithium alloy.

[0049] Preferably, in step 6, the casting method is to preheat the three-dimensional continuous diamond network, the preheating temperature is 600°C - 1000°C, under inert gas protection; at the same time, preheat the mold to 200°C - 400°C; then place the preheated three-dimensional continuous diamond network into the mold, and at the same time pour the molten metal into the mold, the pouring temperature is 500°C - 1450°C; pressurize for filling, the pressure applied is 80 MPa - 200 MPa, the pressurizing time is greater than 5 s, and the holding pressure time is greater than 5 s.

[0050] The infiltration is pressureless infiltration. Place the three-dimensional continuous diamond network into the mold, place the metal on the upper part of the three-dimensional continuous diamond network, and use N 2 protection. The infiltration temperature is 600°C - 1400°C, keep warm for 0.1 h - 2 h, melt the metal into molten metal, and the molten metal infiltrates into the three-dimensional continuous diamond network.

[0051] The infiltration is pressure infiltration. Place the three-dimensional continuous diamond network into the mold, and place the metal on its upper part, evacuate, the infiltration temperature is 500°C - 1400°C, keep warm for 0.1 h - 2 h, inflate and pressurize, the pressure is 0.1 MPa - 12 MPa, and the molten metal infiltrates into the three-dimensional continuous diamond network.

[0052] In the third aspect, the present invention provides an application of a three-dimensional continuous diamond / metal composite material, and the three-dimensional continuous diamond / metal composite material is used for heat dissipation materials, wear-resistant materials, functional structure integrated materials, and bulletproof materials.

[0053] Among them, the functional structure integrated material is a kind of composite material that not only has load-bearing capacity (structural function), but also can achieve specific physical, chemical or biological functions. It breaks through the separate design between structure and function of traditional materials, and through the collaborative design of materials and structures, enables it to meet the requirements of functionality and structure at the same time. The composite material of the present invention not only has good mechanical properties, but also has good thermal conductivity, and can be used as a functional structure integrated material, heat dissipation material, wear-resistant material, and bulletproof material.

[0054] To sum up, the present invention has the following beneficial effects:

[0055] 1. The three-dimensional continuous diamond / metal composite material of the present invention is constructed by a three-dimensional continuous diamond network and a metal network in an interpenetrating manner. Among them, the diamond network is formed by connecting diamond particles with a silicon carbide protective layer on the surface through diamond-silicon carbide phase boundaries. By using the preparation method of the present invention, a high thermal conductivity diamond / metal composite material with highly adjustable diamond volume fraction, thermal conductivity, and thermal expansion coefficient can be obtained. Among them, the thermal conductivity ranges from 423 W / m·K to 572 W / m·K, and the linear expansion coefficient (0 - 100 o °C) is 5.9×10 -6 / K - 7.0×10 -6 / K, and the flexural strength ranges from 323 MPa to 378 MPa.

[0056] 2. The three-dimensional continuous diamond network prepared by the present invention is formed by connecting through diamond-silicon carbide phase boundaries to ensure the high strength of the three-dimensional continuous diamond network. At the same time, the silicon carbide layer formed on the surface of the diamond particles plays a surface modification role.

[0057] 3. For the three-dimensional continuous diamond / metal composite material prepared by the present invention, the diamond volume fraction and porosity are adjustable, which is beneficial for adapting to different application environments.

[0058] 4. The three-dimensional continuous diamond / metal composite material prepared by the present invention has the characteristics of high mechanical properties, low expansion coefficient, high thermal conductivity, etc., and is isotropic. The preparation process has a short process flow and low cost, and can meet the market demand.

[0059] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the protection scope of the present invention. Brief Description of the Drawings

[0060] Figure 1 This is the scanning electron microscope result diagram of the three-dimensional continuous diamond network obtained by the sintering process in Example 1 of the present invention, which shows the microscopic morphology of the diamond network with a silicon carbide protective layer obtained after sintering at 1650 °C.

[0061] Figure 2 This is the scanning electron microscope result diagram of the three-dimensional continuous diamond network obtained by the sintering process in Example 1 of the present invention, which shows the microscopic morphology of the silicon carbide protective layer on the surface of the diamond network obtained after sintering at 1650 °C. Detailed Embodiments

[0062] The present invention will be further described in detail below with reference to the embodiments.

[0063] Example 1

[0064] In this embodiment, the preparation process of the three-dimensional continuous diamond / metal composite material is as follows:

[0065] Step 1, preparation of slurry: Diamond particles (particle size 100 μm), metal silicon powder (average particle size 3.5 μm), phenolic resin (binder), p-toluenesulfonic acid (curing agent), and ethanol are mixed in a ratio of 500 g: 80 g: 100 g: 10 g: 1000 mL, and the slurry is prepared by sufficient ball milling and mixing.

[0066] Step 2, granulation process

[0067] Step 2-1 Drying: The slurry obtained in Step 1 is dried to remove the solvent, and dry material is obtained. The drying process uses a vacuum drying process at a temperature of 80 °C and holds for 4 hours.

[0068] Step 2-2 Crushing: The material obtained in Step 2-1 is crushed into powder with a particle size less than 0.5 mm using an impact crusher.

[0069] Step 2-3 Screening: The material obtained in Step 2-2 is screened to obtain material with a mesh size less than 120.

[0070] Step 3, forming process

[0071] The material with a mesh size less than 120 screened in Step 2-3 is pressed into a preform using a mold at a temperature of 25 °C, a pressure of 100 MPa, and a holding pressure of 10 min.

[0072] Step 4, pyrolysis process

[0073] The preform is pyrolyzed under the protection of an inert gas to obtain a pyrolyzed preform; during the pyrolysis process, the pyrolysis temperature of 850 °C is reached at a heating rate of 1 °C / min, and the pyrolysis is held for 45 min.

[0074] Step 5, sintering process

[0075] The pyrolyzed preform obtained in Step 4 is sintered at a high temperature under vacuum conditions at a temperature of 1650 °C and a holding time of 60 min to obtain a three-dimensional continuous diamond network.

[0076] Step 6, composite process

[0077] The three-dimensional continuous diamond network is preheated in a box furnace at a preheating temperature of 700 °C under the protection of an inert gas; at the same time, the mold is preheated to 300 °C; then the preheated three-dimensional continuous diamond network is placed in the mold, and the molten aluminum alloy ZL101 is poured into the mold at a pouring temperature of 700 °C; pressure is applied for filling, the applied pressure is 100 MPa, the pressurization time is 30 s, and the holding pressure time is greater than 30 s; after cooling, a three-dimensional continuous diamond / metal composite material is obtained.

[0078] As Figure 1 shown, by observing the microstructure of the three-dimensional continuous diamond network obtained after the sintering process in Step 5 of Example 1 through a scanning electron microscope, it can be seen that the diamond network is a porous network structure with uniform pore distribution. The pore size of the diamond network is about 50 nm - 200 μm.

[0079] As Figure 2 shown, by observing the microstructure of the three-dimensional continuous diamond network obtained after the sintering process in Step 5 of Example 1 through a scanning electron microscope, it can be seen that a silicon carbide protective layer is formed on the surface of the diamond particles. The thickness of the silicon carbide protective layer is about 0.2 μm - 0.8 μm, and the silicon carbide protective layer basically covers the surface area of the diamond particles, covering more than 90% of the surface area of the diamond particles.

[0080] It can be seen therefrom that the diamond particles with a silicon carbide protective layer formed on the surface are connected through the diamond-silicon carbide phase boundary to form a three-dimensional continuous diamond network. The three-dimensional continuous diamond network and the metal alloy network penetrate each other through the composite process in Step 6 to form a three-dimensional continuous diamond / metal composite material.

[0081] In this embodiment, the technical indicators of the three-dimensional continuous diamond / metal composite material are as follows:

[0082] The thermal conductivity is 437 W / m·K, the linear expansion coefficient (0 - 100 °C) is 6.1×10 -6 / K, and the flexural strength is 357 MPa. Among them, the volume fraction of the three-dimensional continuous diamond network is 72%, the porosity of the three-dimensional continuous diamond network is 28%, the volume fraction of the diamond particles is 65%, and the volume fraction of the silicon carbide protective layer is 7%. The volume fraction of the three-dimensional continuous diamond network is the percentage of the volume of the three-dimensional continuous diamond network in the volume of the three-dimensional continuous diamond / metal composite material. The porosity of the three-dimensional continuous diamond network is the percentage of the volume of the part other than the three-dimensional continuous diamond network in the three-dimensional continuous diamond / metal composite material. The sum of the porosity of the three-dimensional continuous diamond network and the volume fraction of the three-dimensional continuous diamond network is 100%; the volume fraction of the diamond particles is the percentage of the volume of the diamond particles in the three-dimensional continuous diamond network in the volume of the three-dimensional continuous diamond / metal composite material; the volume fraction of the silicon carbide protective layer is the percentage of the volume of the silicon carbide protective layer on the surface of the diamond particles in the three-dimensional continuous diamond network in the volume of the three-dimensional continuous diamond / metal composite material.

[0083] Example 2

[0084] The difference between this embodiment and Example 1 is that the phenolic resin in Step 1 is replaced with a mixture of phenolic resin, epoxy resin, and polyvinyl alcohol.

[0085] Step 1 is replaced by making a slurry by mixing diamond particles (particle size 200 μm), metallic silicon powder (average particle size 10 μm), phenolic resin, epoxy resin and a mixture of polyvinyl alcohol (binder), p-toluenesulfonic acid (curing agent), and ethanol in a ratio of 500 g:50 g:50 g:10 g:1000 mL through sufficient ball milling and mixing.

[0086] In this embodiment, the technical indicators of the three-dimensional continuous diamond / metal composite are as follows:

[0087] The thermal conductivity is 572 W / m·K, the linear expansion coefficient (0 - 100 °C) is 6.7×10 -6 / K, and the flexural strength is 323 MPa.

[0088] Among them, the volume fraction content of the three-dimensional continuous diamond network is 64%, the porosity of the three-dimensional continuous diamond network is 36%, the volume fraction of diamond particles is 51%, and the volume fraction of the silicon carbide protective layer is 13%.

[0089] Example 3

[0090] The difference between this embodiment and Example 1 is that the conditions for pressing into a preform in Step 3 are replaced by a temperature of 180 °C, a pressure of 50 MPa, and a pressure holding time of 20 min.

[0091] In this embodiment, the technical indicators of the three-dimensional continuous diamond / metal composite are as follows:

[0092] The thermal conductivity is 456 W / m·K, the linear expansion coefficient (0 - 100 o °C) is 5.9×10 -6 / K, and the flexural strength is 378 MPa.

[0093] Among them, the volume fraction content of the three-dimensional continuous diamond network is 72%, the porosity of the three-dimensional continuous diamond network is 28%, the volume fraction of diamond particles is 65%, and the volume fraction of the silicon carbide protective layer is 7%.

[0094] Example 4

[0095] The difference between this embodiment and Example 1 is that Step 6 is replaced by placing the three-dimensional continuous diamond network into a mold, putting aluminum alloy on the upper part of the three-dimensional continuous diamond network, performing vacuum infiltration, with an infiltration temperature of 100 °C, holding for 0.1 h, inflating and pressurizing, with a pressure of 12 MPa; after cooling, a three-dimensional continuous diamond / metal composite is obtained.

[0096] In this embodiment, the technical indicators of the three-dimensional continuous diamond / metal composite are as follows:

[0097] The thermal conductivity is 479 W / m·K, and the linear expansion coefficient (0 - 100 o °C) is 6.0×10 -6 / K, and the flexural strength is 365 MPa.

[0098] Among them, the volume fraction content of the three-dimensional continuous diamond network is 72%, the porosity of the three-dimensional continuous diamond network is 28%, the volume fraction of diamond particles is 65%, and the volume fraction of the silicon carbide protective layer is 7%.

[0099] Example 5

[0100] The difference between this example and Example 4 is that the phenolic resin in Step 1 is replaced by a mixture of phenolic resin and epoxy resin.

[0101] Step 6 is replaced by putting the three-dimensional continuous diamond into a mold, putting magnesium alloy AZ31 on the upper part of the three-dimensional continuous diamond, evacuating and infiltrating, the infiltration temperature is 500 °C, holding for 2 h, inflating and pressurizing, the pressure is 0.1 MPa; after cooling, a three-dimensional continuous diamond / metal composite material is obtained.

[0102] In this example, the technical indexes of the three-dimensional continuous diamond / metal composite material are as follows:

[0103] The thermal conductivity is 423 W / m·K, and the linear expansion coefficient (0 - 100 o °C) is 7.0×10 -6 / K, and the flexural strength is 363 MPa.

[0104] Among them, the volume fraction content of the three-dimensional continuous diamond network is 72%, the porosity of the three-dimensional continuous diamond network is 28%, the volume fraction of diamond particles is 65%, and the volume fraction of the silicon carbide protective layer is 7%.

[0105] Example 6

[0106] The difference between this example and Example 1 is that Step 1 is replaced by making a slurry by ball milling a mixture of diamond particles (particle size 100 μm), silica powder (average particle size 100 nm), epoxy resin (binder), terephthalaldehyde (curing agent), and ethanol according to the ratio of 500 g:50 g:50 g:25 g:500 mL.

[0107] Among them, the volume fraction of the three-dimensional continuous diamond network is 45%, the porosity of the three-dimensional continuous diamond network is 55%, the volume fraction of diamond particles is 34%, and the volume fraction of the silicon carbide protective layer is 11%.

[0108] Example 7

[0109] The difference between this embodiment and Embodiment 1 is that in Step 1, it is replaced by making a slurry by mixing diamond particles (particle size 500 μm), metallic silicon powder (average particle size 10 μm), polyvinyl butyral (binder), glutaraldehyde (curing agent), and ethanol according to the ratio of 500 g: 200 g: 200 g: 100 g: 1000 mL through sufficient ball milling and mixing.

[0110] Among them, the volume fraction content of the three-dimensional continuous diamond network is 65%, the porosity of the three-dimensional continuous diamond network is 35%, the volume fraction of diamond particles is 36%, and the volume fraction of the silicon carbide protective layer is 29%.

[0111] Embodiment 8

[0112] The difference between this embodiment and Embodiment 1 is that in Step 1, it is replaced by making a slurry by mixing diamond particles (particle size 200 μm), silicon dioxide powder (average particle size 10 μm), furan resin (binder), phthalic anhydride (curing agent), and ethanol according to the ratio of 500 g: 100 g: 100 g: 50 g: 1000 mL through sufficient ball milling and mixing.

[0113] In Step 4, the pyrolysis temperature is 600 °C, and the pyrolysis is carried out with heat preservation for 60 min.

[0114] In Step 5, the temperature of high-temperature sintering is 1450 °C, and the sintering time is 60 min.

[0115] In Step 6, non-pressure infiltration is used to compound metal and diamond. The three-dimensional continuous diamond network is placed in a mold, and metal is placed on the upper part of the three-dimensional continuous diamond network. Using N 2 protection, the infiltration temperature is 1400 °C, and the heat preservation is 0.1 h. The metal melts into a metal melt, and the metal melt infiltrates into the three-dimensional continuous diamond network.

[0116] Embodiment 9

[0117] The difference between this embodiment and Embodiment 1 is that in Step 1, phenolic resin is replaced by polyvinyl alcohol; p-toluenesulfonic acid is replaced by phenol.

[0118] In Step 3, the conditions for pressing into a preform are replaced by a temperature of 200 °C, a pressure of 100 MPa, and a pressure holding time of 20 min;

[0119] In Step 4, the pyrolysis temperature is 1000 °C, and the pyrolysis is carried out with heat preservation for 30 min.

[0120] In Step 5, the temperature of high-temperature sintering is 1750 °C, and the sintering time is 5 min.

[0121] In Step 6, the composite metal and diamond are infiltrated without pressure. The three-dimensional continuous diamond network is placed in a mold, and metal is placed on top of the three-dimensional continuous diamond network. Using N 2 protection, the infiltration temperature is 600 °C, and it is held for 2 h. The metal melts into a metal melt, and the metal melt infiltrates into the three-dimensional continuous diamond network.

[0122] Example 10

[0123] The difference between this example and Example 1 is that the phenolic resin in Step 1 is replaced with polyurethane; p-toluenesulfonic acid is replaced with ethylenediamine.

[0124] The conditions for pressing into a preform in Step 3 are replaced with a temperature of 220 °C, a pressure of 50 MPa, and a pressure holding time of 30 min.

[0125] Example 11

[0126] The difference between this example and Example 1 is that the phenolic resin in Step 1 is replaced with polycarbosilane; p-toluenesulfonic acid is replaced with imidazole.

[0127] Step 6 is replaced with placing the three-dimensional continuous diamond in a mold, placing aluminum alloy on top of the three-dimensional continuous diamond, vacuum infiltration, with an infiltration temperature of 1000 °C, holding for 1 hour, inflating and pressurizing, with a pressure of 8 MPa, and the aluminum alloy melt infiltrates into the three-dimensional continuous diamond network.

[0128] Example 12

[0129] The difference between this example and Example 1 is that the phenolic resin in Step 1 is replaced with polyboron nitride; p-toluenesulfonic acid is replaced with 1,2,3-propanetrithiol.

[0130] Step 6 is replaced with placing the three-dimensional continuous diamond in a mold, placing aluminum alloy on top of the three-dimensional continuous diamond, vacuum infiltration, with an infiltration temperature of 1200 °C, holding for 1 hour, inflating and pressurizing, with a pressure of 8 MPa, and the aluminum alloy melt infiltrates into the three-dimensional continuous diamond network.

[0131] Example 13

[0132] The difference between this example and Example 4 is that the phenolic resin in Step 1 is replaced with polyboron nitride; p-toluenesulfonic acid is replaced with succinic acid.

[0133] The metal used is an aluminum-magnesium-silicon alloy.

[0134] Example 14

[0135] The difference between this example and Example 4 is that the phenolic resin in Step 1 is replaced with polyborosiloxane; p-toluenesulfonic acid is replaced with mercaptoacetic acid.

[0136] The metal used is a magnesium-thorium alloy.

[0137] Example 15

[0138] The difference between this example and Example 4 is that the phenolic resin in Step 1 is replaced by polyborosilazane; p-toluenesulfonic acid is replaced by 2-methylimidazole.

[0139] The metal used is an aluminum-zinc alloy.

[0140] By observing the three-dimensional continuous diamond network blocks obtained in the sintering process of Step 5 in the above examples through a scanning electron microscope, the microscopic morphology of silicon carbide-bonded diamond similar to that of Figure 1-2 can be observed, indicating that a three-dimensional continuous diamond network bonded with silicon carbide can be obtained by the method of the present invention. When the metal is combined with this three-dimensional continuous diamond network, a structure in which the three-dimensional continuous diamond network and the metal alloy network penetrate each other will inevitably be formed. At the same time, it can be found through observation that due to the formation of a silicon carbide protective layer on the surface of diamond particles and the connection through the diamond-silicon carbide phase boundary, the diamond particles form a three-dimensional continuous diamond network.

[0141] In the present invention, by arranging silicon-based powder, binder, and curing agent on the outer surface of diamond particles, and through the forming process, pyrolysis process, and sintering process, the mixture of silicon-based powder, binder, and curing agent can form a silicon carbide protective layer on the surface of diamond particles, and the diamond particles are connected through the diamond-silicon carbide phase boundary to form a three-dimensional continuous diamond network. The binder and curing agent used in the present invention mainly serve the purpose of bonding diamond and providing a carbon source in silicon carbide, and carbon-containing binders and compatible curing agents known in the art with similar functions can be selected for use.

[0142] The results of Examples 1-15 show that for the three-dimensional continuous diamond / metal composite material of the present invention, since the diamond particles are connected through the diamond-silicon carbide phase boundary to form a three-dimensional continuous diamond network, the preparation process of the three-dimensional continuous diamond preform is short, the cost is low, and a three-dimensional continuous diamond preform with a complex shape can be prepared. At the same time, the three-dimensional continuous diamond / metal composite material has excellent thermophysical properties and mechanical properties, and is isotropic, and has great application value in the preparation of the third-generation semiconductor heat dissipation material "diamond / metal composite material".

[0143] Comparative Example 1

[0144] A nano-SiC coating was prepared on the surface of diamond by combining the sol-gel method and in-situ reduction technology. SiO with a pH value of 7.5 and a molar concentration of 0.2 mol / L was used. 2 The sol was coated on diamond particles (particle size 100 μm); after coating SiO 2The diamond in the sol form was loaded into a vacuum furnace for sintering. The heating rate was 5 °C / min, and it was kept at 1450 °C for 2 h and then cooled with the furnace. Then, 60% diamond by volume with a nano-SiC coating and 50 μm 6061 aluminum alloy powder were mechanically mixed and hot-pressed at a hot-pressing temperature of 620 °C and a pressure of 50 MPa to obtain a 60% diamond-aluminum composite material.

[0145] In this comparative example, the technical indexes of the 60% diamond / aluminum composite material are as follows:

[0146] The thermal conductivity is 373 W / m·K, and the linear expansion coefficient (0 - 100 o °C) is 7.5×10 -6 / K, and the flexural strength is 180 MPa.

[0147] Comparative Example 2

[0148] The nano-TiC coating was prepared on the diamond surface by the sol-gel method. The TiO 2 sol with a pH value of 7.5 and a molar concentration of 0.2 mol / L was used to coat the diamond particles (size 200 μm), and it was sintered at 1450 °C for 2 hours to form a uniform TiC coating on the diamond surface. Then, 60% diamond with a nano-TiC coating and 50 μm 6061 aluminum alloy powder were mechanically mixed and hot-pressed at a hot-pressing temperature of 620 °C and a pressure of 50 MPa to obtain a 60% diamond-aluminum composite material.

[0149] In this comparative example, the technical indexes of the 60% diamond / metal composite material are as follows:

[0150] The thermal conductivity is 300 W / m·K, and the linear expansion coefficient (0 - 100 o °C) is 7.0×10 -6 / K, and the flexural strength is 200 MPa.

[0151] Comparative Example 3

[0152] The nano-SiC coating was prepared on the diamond surface by combining the sol-gel method with in-situ reduction technology. The SiO 2 sol with a pH value of 7.5 and a molar concentration of 0.15 mol / L was used to coat the diamond particles (particle size 100 μm). The diamond coated with the SiO 2 sol was loaded into a vacuum furnace for sintering. The heating rate was 10 °C / min, and it was kept at 1500 °C for 3 h and then cooled with the furnace. Then, 60% diamond with a nano-SiC coating and 50 μm 6061 aluminum alloy powder were mechanically mixed and hot-pressed at a hot-pressing temperature of 620 °C and a pressure of 80 MPa to obtain a 60% diamond-aluminum composite material.

[0153] In this comparative example, the technical indicators of the 60% diamond / metal composite material are as follows:

[0154] The thermal conductivity is 415 W / m·K, and the linear expansion coefficient (0 - 100 o °C) is 7.1×10 -6 / K, and the flexural strength is 230 MPa.

[0155] Comparative Example 4

[0156] The nano-SiC coating was prepared on the diamond surface by combining the sol-gel method and in-situ reduction technology. The SiO 2 sol with a pH value of 7.5 and a molar concentration of 0.2 mol / L was used to coat diamond particles (particle size 100 μm). The diamond coated with SiO 2 sol was loaded into a vacuum furnace for sintering. The heating rate was 5 °C / min, and it was kept at 1450 °C for 2 h and then cooled with the furnace. Then, 60% of the diamond with a nano-SiC coating was mechanically mixed with 60 μm AZ31 magnesium alloy powder and hot-pressed at a hot-pressing temperature of 570 °C and a pressure of 100 MPa to obtain a 60% diamond metal composite material.

[0157] In this comparative example, the technical indicators of the 60% diamond / metal composite material are as follows:

[0158] The thermal conductivity is 269 W / m·K, and the linear expansion coefficient (0 - 100 o °C) is 7.4×10 -6 / K, and the flexural strength is 170 MPa.

[0159] By comparing with the comparative example, it can be seen that since a method different from the preparation method of the present invention was used in the comparative example, a three-dimensional continuous diamond network could not be obtained. From the perspective of technical indicators, although both are diamond and metal composite materials, because the comparative example does not contain a three-dimensional continuous diamond network, its ability to resist bending stress is weaker than that of the composite material of the present invention. At the same time, because it is constructed by the interpenetration of the three-dimensional continuous diamond network and the metal network, its thermal conductivity performance is significantly improved. Therefore, although the same type of metal and the same size of diamond as in Examples 1 - 5 were used in the comparative example, since a three-dimensional continuous diamond network was not formed, the thermal conductivity is low.

[0160] As described above, the above are only exemplary specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for preparing a three-dimensional continuous diamond / metal composite material, characterized in that: The three-dimensional continuous diamond / metal composite material is constructed by a three-dimensional continuous diamond network and a metal network in a mutually penetrating manner, and the three-dimensional continuous diamond network is formed by diamond particles with a silicon carbide protective layer formed on the surface connected through a diamond-silicon carbide phase boundary; Wherein, the metal in the metal network is copper, aluminum, magnesium, copper alloy, aluminum alloy or magnesium alloy; The volume fraction of the three-dimensional continuous diamond network is 40%-80%, the porosity of the three-dimensional continuous diamond network is 20%-60%, the volume fraction of the diamond particles is 30%-75%, and the volume fraction of the silicon carbide protective layer is 5%-30%; A silicon carbide protective layer is formed on the surface of diamond particles in the three-dimensional continuous diamond network. The thickness of the silicon carbide protective layer is 100 nm -1.0 μm, and the silicon carbide protective layer covers more than 90% of the surface area of ​​the diamond particles. The linear expansion coefficient of the three-dimensional continuous diamond / metal composite material at 0-100℃ is 5.9×10 -6 / K -7.0×10 -6 / K; The preparation method comprises the following steps: Step 1, preparation of slurry: diamond particles, silicon-based powder, binder, curing agent and solvent are mixed evenly to obtain slurry; Step 2, granulation process: removing the solvent in the slurry, crushing and screening to obtain granular materials; Step 3, forming process: pressing the granular material obtained in step 2 into a preform; Step 4, pyrolysis process: pyrolyzing the preform obtained in step 3 to obtain a pyrolyzed preform; Step 5, sintering process: sintering the pyrolysis preform obtained in step 4 at high temperature to obtain a three-dimensional continuous diamond network; Step 6, composite process: pouring or infiltrating the molten metal into the three-dimensional continuous diamond network prepared in step 5 to prepare a three-dimensional continuous diamond / metal composite material; In step 1, the ratio of diamond particles, silicon-based powder, binder, curing agent, and solvent is 50 g to 200 g of silicon-based powder, 50 g to 200 g of binder, 10 g to 100 g of curing agent, and 500 mL to 1000 mL of solvent for every 500 g of diamond particles; The silicon-based powder is one or both of metallic silicon powder and silicon dioxide powder; In step 5, high temperature sintering is performed in a protective atmosphere or in a vacuum condition, wherein the protective atmosphere is selected from one or both of argon protection and nitrogen protection; the high temperature sintering temperature is 1450°C-1750°C, and the sintering time is 5 min-60 min.

2. The preparation method according to claim 1, characterized in that: The binder is selected from one or more of phenolic resin, epoxy resin, polyvinyl alcohol, polyvinyl butyral, furan resin, polyurethane, polycarbosilane, polyborazane, polyborosiloxane, polyborosilazane, and polyzirconium borosilazane; the curing agent is selected from amine curing agents, acid anhydride curing agents, phenolic curing agents, imidazole curing agents, acidic curing agents, or thiol curing agents.

3. The preparation method according to claim 1, characterized in that: In step 2, the method for removing the solvent in the slurry is selected from natural drying, freeze drying, spray drying, fluidized bed drying, belt drying, hollow paddle drying, disc drying, boiling drying, air flow drying, vacuum drying or hot air circulation drying; the pulverizing method is mechanical pulverization, pulverizing to obtain a powder with a particle size of less than 0.5 mm; and sieving to obtain a granular material below 150 mesh.

4. The preparation method according to claim 1, characterized in that: In step 3, the pressing pressure used for pressing into the preform is 50 MPa-100 MPa, the holding time is 10 min-60 min, and the temperature is 20 ℃-240 ℃.

5. The preparation method according to claim 1, characterized in that: In step 6, the metal of the molten metal is selected from copper, aluminum, magnesium, copper alloy, aluminum alloy or magnesium alloy; the magnesium alloy is selected from magnesium-aluminum alloy, magnesium-manganese alloy, magnesium-lithium alloy, magnesium rare earth alloy, magnesium-silver alloy or magnesium-thorium alloy; the copper alloy is selected from brass, nickel silver or bronze; the aluminum alloy is selected from aluminum-silicon alloy, aluminum-magnesium-silicon alloy, aluminum-copper alloy, aluminum-magnesium alloy, aluminum-manganese alloy, aluminum-zinc alloy or aluminum-lithium alloy.

6. The preparation method according to claim 1, characterized in that: In step 6, the pouring method is to preheat the three-dimensional continuous diamond network at a temperature of 600°C-1000°C under inert gas protection; at the same time, preheat the mold to 200°C-400°C; then place the preheated three-dimensional continuous diamond network into the mold, and pour the molten metal into the mold at a pouring temperature of 500°C-1450°C; pressurize and fill the mold, the applied pressure is 80 MPa-200 MPa, the pressurization time is greater than 5 s, and the pressure holding time is greater than 5 s; The infiltration is pressureless infiltration, where the three-dimensional continuous diamond network is placed in a mold, and metal is placed on the upper part of the three-dimensional continuous diamond network. N2 protection is used, and the infiltration temperature is 600℃-1400℃. The temperature is kept for 0.1 h-2 h. The metal is melted into molten metal, and the molten metal is infiltrated into the three-dimensional continuous diamond network; or The impregnation is pressure impregnation, where a three-dimensional continuous diamond network is placed in a mold, and metal is placed on top of it, and then vacuumed. The infiltration temperature is 500℃-1400℃, the insulation time is 0.1h-2h, the pressure is inflated and pressurized to 0.1MPa-12MPa, and the molten metal infiltrates into the three-dimensional continuous diamond network.

7. The three-dimensional continuous diamond / metal composite material prepared by the preparation method according to any one of claims 1 to 6; The three-dimensional continuous diamond / metal composite material is constructed by a three-dimensional continuous diamond network and a metal network in a mutually penetrating manner. The three-dimensional continuous diamond network is formed by diamond particles with a silicon carbide protective layer formed on the surface connected by a diamond-silicon carbide phase boundary. The metal in the metal network is copper, aluminum, magnesium, a copper alloy, an aluminum alloy or a magnesium alloy.

8. The three-dimensional continuous diamond / metal composite material according to claim 7, characterized in that: The volume fraction of the three-dimensional continuous diamond network is 40%-80%, the porosity of the three-dimensional continuous diamond network is 20%-60%, the volume fraction of diamond particles is 30%-75%, and the volume fraction of the silicon carbide protective layer is 5%-30%.

9. The three-dimensional continuous diamond / metal composite material according to claim 7, characterized in that: A silicon carbide protective layer is formed on the surface of the diamond particles in the three-dimensional continuous diamond network. The thickness of the silicon carbide protective layer is 100 nm-1.0 μm, and the silicon carbide protective layer covers more than 90% of the surface area of ​​the diamond particles.

10. An application of a three-dimensional continuous diamond / metal composite material, characterized in that: The three-dimensional continuous diamond / metal composite material described in any one of claims 7 to 9 is used for heat dissipation materials, wear-resistant materials, functional structure integrated materials, and bulletproof materials.

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