A method for preparing a low-density and high-thermal-conductivity copper-based graphite heat sink material

Abstract

The invention discloses a method for preparing a low-density and high-thermal-conductivity copper-based graphite heat sink material, the method comprising: 1. selecting one or more copper alloy powders of CuZr powder, CuCr powder and CuCrZr powder as matrix powder, and mixing with graphite powder by mechanical ball milling; 2. sintering the mixed powder to obtain a sintered body; 3. subjecting the sintered body to aging heat treatment to obtain a low-density and high-thermal-conductivity copper-based graphite heat sink material. The invention adds the reinforcing phase raw material graphite powder to the copper alloy powder, mixes and sinters, generates a carbide ceramic phase in situ and forms a ceramic phase transition layer, improves the interface bonding ability between the copper matrix and the graphite, forms a heterogeneous structure matrix structure by using copper alloy powders of different compositions and sizes at the same time, improves the strength and plasticity of the copper-based graphite heat sink material, makes the copper-based graphite heat sink material have both excellent mechanical properties and thermal conductivity, has a simple process, is low in cost, and is suitable for the field of heat sink materials.

Description

Technical Field

[0001] The invention relates to the technical field of copper-based composite materials, and in particular to a method for preparing a low-density and high-thermal-conductivity copper-graphite heat sink material. Background Art

[0002] Copper-graphite composite material is a composite material prepared by special means with copper or copper alloy as the matrix and graphite. This type of composite material has excellent thermal and electrical conductivity, good friction and wear performance, arc erosion resistance, and wide raw material sources and low prices, and is highly concerned by market applications. Copper-graphite composite materials can often meet different application requirements by changing their composition, additive phase, and molding process, such as being used in engine sealing rings, motor rotors, electrodes, rail tram pantograph slides, etc. In particular, in recent years, with the development of electronic devices towards lightweight and high energy density, higher requirements have been put forward for heat dissipation materials. Copper-based composite materials with high graphite content prepared by powder metallurgy have excellent characteristics of low density and high thermal conductivity. Compared with traditional copper alloys, molybdenum-copper composite materials, etc., it is a very potential heat sink material. However, due to the great incompatibility between copper and graphite, the high wetting angle of liquid copper to graphite, the large difference in the linear expansion coefficient of copper and graphite, and the large difference in density between the two, all of which greatly affect the preparation and comprehensive performance of composite materials.

[0003] Relevant research shows that the continuous optimization and development of powder metallurgy preparation technology can improve the comprehensive performance of composite materials, such as bending strength and thermal conductivity, by achieving uniform dispersion of graphite in the copper matrix and improving the bonding ability of the copper-graphite interface. Mechanical mixing methods are often used to improve the dispersibility of graphite, such as adding powder to the fluid and stirring it evenly to form a slurry and then drying it, or directly grinding the powder in a ball mill. Although the former makes it easier to disperse graphite evenly, it is also easy to oxidize the metal powder and introduce pores during the sintering process, affecting the performance of the composite material. The most common method to improve the bonding strength between the matrix and the graphite interface is to modify the graphite surface. The methods for modifying graphite include electroplating, chemical plating, chemical vapor deposition, magnetron sputtering, etc. Through this method, metal coatings, such as copper and nickel coatings, or metal carbide ceramic coatings, such as TiC and ZrC, can be formed on the graphite surface. Although the dense coating formed on the graphite surface can improve the density and comprehensive mechanical properties of the composite material, the mechanical properties and processing properties of the composite material with high graphite content are still low and cannot meet the use requirements. In addition, such modification methods are often complicated and cumbersome, require special equipment and are costly, and are not suitable for industrial large-scale production and use. Therefore, it is necessary to develop a preparation method for copper-graphite heat sink materials with simple process and low cost to obtain high-performance copper-graphite heat sink materials. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing a low-density and high-thermal-conductivity copper-based graphite heat sink material in view of the deficiencies of the above-mentioned prior art. The method directly adds the reinforcing phase raw material graphite powder to the copper alloy powder for mixing and sintering to generate a carbide ceramic phase in situ and form a ceramic phase transition layer, thereby improving the interface bonding ability between the copper matrix and the graphite, and forming a heterogeneous structure at the same time, improving the strength and plasticity of the copper-based graphite heat sink material, so that the copper-based graphite heat sink material has both excellent mechanical properties and thermal conductivity, solving the problem that the prior art is complex in process, high in cost, and the performance of the composite material cannot meet the use requirements.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a low-density and high-thermal-conductivity copper-based graphite heat sink material, characterized in that the method comprises the following steps:

[0006] Step 1, selecting one or more copper alloy powders of CuZr powder, CuCr powder and CuCrZr powder as base powder, and mixing them with graphite powder by mechanical ball milling to obtain a powder in which copper alloy powder and graphite powder are uniformly mixed;

[0007] Step 2: Put the copper alloy powder and graphite powder obtained in step 1 into a graphite mold for pressure sintering to obtain a sintered body;

[0008] Step three: subjecting the sintered body obtained in step two to aging heat treatment to obtain a low-density and high-thermal-conductivity copper-based graphite heat sink material.

[0009] The present invention adds low-density graphite powder to the copper matrix, so that the overall density of the copper-based graphite heat sink material is lower than the density of copper. At the same time, the addition of high thermal conductivity graphite powder improves the thermal conductivity of the copper matrix, so that the thermal conductivity of the copper-based graphite heat sink material is higher than the thermal conductivity of copper, thereby obtaining a copper-based graphite heat sink material with low density and high thermal conductivity. Generally, the density of the copper-based graphite heat sink material is less than 8.96g / cm 3 , thermal conductivity is greater than 400W / mK.

[0010] The above-mentioned method for preparing a low-density and high-thermal conductivity copper-based graphite heat sink material is characterized in that the CuZr powder, CuCr powder and CuCrZr powder in step one are prepared by a gas atomization method, a rotating electrode method or a mechanical alloying method, and have a particle size of 10 μm to 100 μm, and the graphite powder is flake graphite or spherical graphite, and has a particle size of 5 μm to 200 μm.

[0011] The above-mentioned method for preparing a low-density and high-thermal conductivity copper-based graphite heat sink material is characterized in that the mass content of Zr in the CuZr powder in step one is 0.1%~2.0%, and the balance is Cu, the mass content of Cr in the CuCr powder is 1.0%~10.0%, and the balance is Cu, the mass content of Zr in the CuCrZr powder is 0.1%~1.0%, the mass content of Cr is 0.1%~1.0%, and the balance is Cu.

[0012] The above-mentioned method for preparing a low-density and high-thermal conductivity copper-based graphite heat sink material is characterized in that, in step one, when CuZr powder and CuCr powder are selected as the base powder, the mass content of Zr in the base powder is 0.01%~1.8%, the mass content of Cr is 0.1%~9%, and the balance is Cu; when CuZr powder and CuCrZr powder are selected as the base powder, the mass content of Zr in the base powder is 0.1%~1.9%, the mass content of Cr is 0.01%~0.9%, and the balance is Cu; when CuCr powder and CuCrZr powder are selected as the base powder, the mass content of Zr in the base powder is 0.01%~0.9%, the mass content of Cr is 0.19%~9.1%, and the balance is Cu.

[0013] The above-mentioned method for preparing a low-density and high-thermal conductivity copper-based graphite heat sink material is characterized in that the volume content of graphite powder in the powder uniformly mixed with the copper alloy powder and graphite powder in step one is 20%~80%, and the volume content of the matrix powder is 20%~80%.

[0014] The above-mentioned method for preparing a low-density and high-thermal conductivity copper-based graphite heat sink material is characterized in that the ball-to-material ratio of the mechanical ball milling mixing in step one is 5~10:1, the ball milling speed is 150rpm~300rpm, and the ball milling time is 6h~12h.

[0015] The above-mentioned method for preparing a low-density and high-thermal-conductivity copper-based graphite heat sink material is characterized in that the pressure sintering treatment in step 2 is vacuum hot pressing sintering or spark plasma sintering.

[0016] The above-mentioned method for preparing a low-density and high-thermal conductivity copper-based graphite heat sink material is characterized in that the sintering temperature of the pressure sintering treatment in step 2 is 800°C~1000°C, the insulation time is 0.15h~2h, the sintering environment is vacuum, and the sintering pressure is 30MPa~50MPa.

[0017] The above-mentioned method for preparing a low-density and high-thermal-conductivity copper-based graphite heat sink material is characterized in that the temperature of the aging heat treatment in step three is 400° C.~600° C., and the time is 1h~3h.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. In view of the defects of the prior art in that the coating process on the graphite surface is complicated and the cost is high, the present invention directly mixes graphite powder and copper alloy powder and then sinters them. By controlling the sintering process, an intermediate carbide ceramic layer is generated in situ between the copper alloy and the graphite by utilizing element diffusion. The method is simple, the preparation cost is low, and the elements are evenly distributed. The interface of the intermediate carbide ceramic layer formed by diffusion is compact and uniform, so that the copper-based graphite heat sink material has both excellent mechanical properties and thermal conductivity.

[0020] 2. The present invention uses copper alloy powders of different compositions and particle sizes as matrix raw materials to form a heterogeneous structure with different strengths and sizes, that is, a copper alloy matrix with a large powder particle size as the skeleton, and the gaps are filled with copper alloys with small powder particle sizes. Graphite is evenly distributed in the matrix of the heterogeneous structure. By changing the composition and particle size ratio of the copper alloy powder, the strong plasticity and size difference of the "soft zone" and "hard zone" of the heterogeneous structure matrix can be regulated to give play to the advantages of high strength and plasticity of the heterogeneous structure. In addition, small-sized copper alloy powders can provide a larger surface area for contact with graphite to improve density. The heterogeneous structure ensures the stress transmission of the copper-based graphite heat sink material when it is deformed by external force, avoids brittle fracture, and further improves the strong plasticity of the material.

[0021] 3. The present invention reduces the content of solid solution elements in the copper alloy skeleton and promotes the uniform precipitation of the second phase by adjusting the temperature and time of aging heat treatment, and can also regulate the growth of the intermediate layer, thereby further improving the thermal conductivity and mechanical properties of the copper-based graphite heat sink material.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a micrograph of the organizational morphology of the copper-based graphite heat sink material prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0024] The CuZr powder, CuCr powder and CuCrZr powder used in Examples 1 to 10 of the present invention and Comparative Examples 1 to 2 are prepared by a gas atomization method, a rotating electrode method or a mechanical alloying method, and have a particle size of 10 μm to 100 μm. The graphite powder used is flake graphite or spherical graphite, and has a particle size of 5 μm to 200 μm.

[0025] Example 1

[0026] This embodiment includes the following steps:

[0027] Step 1, select 96.09g of CuZr powder with an average particle size D50 of 50μm as the base powder. The preparation method and composition of the CuZr powder are shown in B of Table 1 below. Put it into a stainless steel ball mill with 23.91g of spherical graphite powder with an average particle size D50 of 20μm, and configure stainless steel grinding balls according to a ball-to-material ratio of 8:1. Perform mechanical ball milling and mixing at a speed of 200rpm for 8h to obtain a powder in which copper alloy powder and graphite powder are uniformly mixed; the volume content of graphite powder in the powder in which copper alloy powder and graphite powder are uniformly mixed is 50%, and the volume content of base powder is 50%;

[0028] Step 2: The copper alloy powder and graphite powder obtained in step 1 are uniformly mixed and loaded into a graphite mold for vacuum hot pressing sintering at a sintering temperature of 900° C., a holding time of 1 h, a vacuum sintering environment, and a sintering pressure of 40 MPa to obtain a sintered body;

[0029] Step 3: Place the sintered body obtained in step 2 into a heat treatment furnace for aging heat treatment at a temperature of 500° C. for 2 h to obtain a copper-based graphite heat sink material.

[0030] According to tests, the copper-based graphite heat sink material prepared in this embodiment has a bending strength of 78.7 MPa, a thermal conductivity of 153.4 W / mK, and a density of 95.0%.

[0031] Figure 1 This is a micrograph of the structure morphology of the copper-based graphite heat sink material prepared in this embodiment. Figure 1 It can be seen that the copper alloy powder in the bright area is basically interconnected, the black area is graphite, and most of the graphite is evenly dispersed and filled between the copper alloy skeletons. This morphology structure ensures that the copper-based graphite heat sink material has good machinability and bending resistance.

[0032] Example 2

[0033] This embodiment includes the following steps:

[0034] Step 1: 112.97 g of CuCr powder with an average particle size D50 of 10 μm is selected as the base powder. The preparation method and composition of the CuCr powder are shown in D of Table 1 below. The powder and 7.03 g of flake graphite powder with an average particle size D50 of 5 μm are placed in a stainless steel ball mill, and stainless steel grinding balls are configured according to a ball-to-material ratio of 5:1. The powder is mechanically ball milled and mixed at a speed of 150 rpm for 6 hours to obtain a powder in which the copper alloy powder and graphite powder are uniformly mixed. The volume content of the graphite powder in the powder in which the copper alloy powder and graphite powder are uniformly mixed is 20%, and the volume content of the base powder is 80%;

[0035] Step 2: The copper alloy powder and graphite powder obtained in step 1 are uniformly mixed and loaded into a graphite mold for spark plasma sintering at a sintering temperature of 800° C., a holding time of 0.15 h, a sintering pressure of 30 MPa, and a vacuum sintering environment to obtain a sintered body;

[0036] Step 3: Place the sintered body obtained in step 2 into a heat treatment furnace for aging heat treatment at a temperature of 400° C. for 1 h to obtain a copper-based graphite heat sink material.

[0037] According to tests, the copper-based graphite heat sink material prepared in this embodiment has a bending strength of 98.3 MPa, a thermal conductivity of 164.1 W / mK, and a density of 93.7%.

[0038] Example 3

[0039] This embodiment includes the following steps:

[0040] Step 1: 60.13 g of CuCrZr powder with an average particle size D50 of 100 μm is selected as the base powder. The preparation method and composition of the CuCrZr powder are shown in H of Table 1 below. The powder is placed in a stainless steel ball mill with 59.87 g of flaky graphite powder with an average particle size D50 of 200 μm. Stainless steel grinding balls are configured according to a ball-to-material ratio of 10:1. The powder is mechanically ball-milled at a speed of 300 rpm for 12 hours to obtain a powder in which the copper alloy powder and graphite powder are uniformly mixed. The volume content of the graphite powder in the powder in which the copper alloy powder and graphite powder are uniformly mixed is 80%, and the volume content of the base powder is 20%;

[0041] Step 2: The copper alloy powder and graphite powder obtained in step 1 are uniformly mixed and loaded into a graphite mold for vacuum hot pressing sintering. The sintering temperature is 1000° C., the holding time is 2 h, the sintering environment is vacuum, and the sintering pressure is 50 MPa to obtain a sintered body;

[0042] Step 3: Place the sintered body obtained in step 2 into a heat treatment furnace for aging heat treatment at a temperature of 600° C. for 3 hours to obtain a copper-based graphite heat sink material.

[0043] According to tests, the copper-based graphite heat sink material prepared in this embodiment has a bending strength of 22.7 MPa, a thermal conductivity of 425.9 W / mK, and a density of 92.6%.

[0044] Example 4

[0045] This embodiment includes the following steps:

[0046] Step 1: 11.30 g of CuZr powder with an average particle size D50 of 10 μm and 101.67 g of CuCr powder with an average particle size D50 of 100 μm were selected as base powders. The preparation methods and compositions of CuZr powder and CuCr powder are shown in A and F of Table 1 below. They were placed in a stainless steel ball mill with 7.03 g of flake graphite powder with an average particle size D50 of 5 μm, and stainless steel grinding balls were configured according to a ball-to-material ratio of 5:1. Mechanical ball milling was performed at a speed of 150 rpm for 6 hours to obtain a powder in which copper alloy powder and graphite powder were evenly mixed.

[0047] Step 2: The copper alloy powder and graphite powder obtained in step 1 are uniformly mixed and loaded into a graphite mold for spark plasma sintering at a sintering temperature of 800° C., a holding time of 0.15 h, a sintering pressure of 30 MPa, and a vacuum sintering environment to obtain a sintered body;

[0048] Step 3: Place the sintered body obtained in step 2 into a heat treatment furnace for aging heat treatment at a temperature of 400° C. for 1 h to obtain a copper-based graphite heat sink material.

[0049] According to tests, the copper-based graphite heat sink material prepared in this embodiment has a bending strength of 132.8 MPa, a thermal conductivity of 174.5 W / mK, and a density of 97.9%.

[0050] Example 5

[0051] This embodiment includes the following steps:

[0052] Step 1: 86.48 g of CuZr powder with an average particle size D50 of 50 μm and 9.61 g of CuCr powder with an average particle size D50 of 50 μm are selected as base powders. The preparation methods and compositions of CuZr powder and CuCr powder are shown in B and E of Table 1 below. They are placed in a stainless steel ball mill with 23.91 g of spherical graphite powder with an average particle size D50 of 20 μm, and stainless steel grinding balls are configured according to a ball-to-material ratio of 8:1. Mechanical ball milling is performed at a speed of 200 rpm for 8 hours to obtain a powder in which copper alloy powder and graphite powder are evenly mixed.

[0053] Step 2: The copper alloy powder and graphite powder obtained in step 1 are uniformly mixed and loaded into a graphite mold for vacuum hot pressing sintering at a sintering temperature of 900° C., a holding time of 1 h, a sintering pressure of 40 MPa, and a vacuum sintering environment to obtain a sintered body;

[0054] Step 3: Place the sintered body obtained in step 2 into a heat treatment furnace for aging heat treatment at a temperature of 500° C. for 2 h to obtain a copper-based graphite heat sink material.

[0055] According to tests, the copper-based graphite heat sink material prepared in this embodiment has a bending strength of 105.3 MPa, a thermal conductivity of 183.6 W / mK, and a density of 95.1%.

[0056] Example 6

[0057] This embodiment includes the following steps:

[0058] Step 1, select 54.12g of CuZr powder with an average particle size D50 of 100μm and 6.01g of CuCr powder with an average particle size D50 of 10μm as the base powder, the preparation method and composition of the CuZr powder and the CuCr powder are shown in C and D of Table 1 below, put them into a stainless steel ball mill with 59.87g of flake graphite powder with an average particle size D50 of 200μm, and configure stainless steel grinding balls according to a ball-to-material ratio of 10:1, and perform mechanical ball milling at a speed of 300rpm for 12h to obtain a powder in which copper alloy powder and graphite powder are evenly mixed;

[0059] Step 2: The copper alloy powder and graphite powder obtained in step 1 are uniformly mixed and loaded into a graphite mold for vacuum hot pressing sintering at a sintering temperature of 1000° C., a holding time of 2 h, a sintering pressure of 50 MPa, and a vacuum sintering environment to obtain a sintered body;

[0060] Step 3: Place the sintered body obtained in step 2 into a heat treatment furnace for aging heat treatment at a temperature of 600° C. for 3 hours to obtain a copper-based graphite heat sink material.

[0061] According to tests, the copper-based graphite heat sink material prepared in this embodiment has a bending strength of 56.4 MPa, a thermal conductivity of 487.2 W / mK, and a density of 98.5%.

[0062] Example 7

[0063] This embodiment includes the following steps:

[0064] Step 1: 11.30 g of CuZr powder with an average particle size D50 of 10 μm and 101.67 g of CuCrZr powder with an average particle size D50 of 50 μm were selected as base powders. The preparation methods and compositions of CuZr powder and CuCrZr powder are shown in A and G of Table 1 below. They were placed in a stainless steel ball mill with 7.03 g of flake graphite powder with an average particle size D50 of 5 μm, and stainless steel grinding balls were configured according to a ball-to-material ratio of 5:1. Mechanical ball milling was performed at a speed of 150 rpm for 6 hours to obtain a powder in which copper alloy powder and graphite powder were evenly mixed.

[0065] Step 2: The copper alloy powder and graphite powder obtained in step 1 are uniformly mixed and loaded into a graphite mold for spark plasma sintering at a sintering temperature of 800° C., a holding time of 0.15 h, a sintering pressure of 30 MPa, and a vacuum sintering environment to obtain a sintered body;

[0066] Step 3: Place the sintered body obtained in step 2 into a heat treatment furnace for aging heat treatment at a temperature of 400° C. for 1 h to obtain a copper-based graphite heat sink material.

[0067] According to tests, the copper-based graphite heat sink material prepared in this embodiment has a bending strength of 116.7 MPa, a thermal conductivity of 152.5 W / mK, and a density of 96.4%.

[0068] Example 8

[0069] This embodiment includes the following steps:

[0070] Step 1, 86.48g of CuZr powder with an average particle size D50 of 100μm and 9.61g of CuCrZr powder with an average particle size D50 of 10μm are selected as base powders. The preparation methods and compositions of CuZr powder and CuCrZr powder are shown in C and I of Table 1 below. They are placed in a stainless steel ball mill with 23.91g of spherical graphite powder with an average particle size D50 of 20μm, and stainless steel grinding balls are configured according to a ball-to-material ratio of 8:1. Mechanical ball milling is performed at a speed of 200rpm for 8h to obtain a powder in which copper alloy powder and graphite powder are evenly mixed.

[0071] Step 2: The copper alloy powder and graphite powder obtained in step 1 are uniformly mixed and loaded into a graphite mold for vacuum hot pressing sintering at a sintering temperature of 900° C., a holding time of 1 h, a sintering pressure of 40 MPa, and a vacuum sintering environment to obtain a sintered body;

[0072] Step 3: Place the sintered body obtained in step 2 into a heat treatment furnace for aging heat treatment at a temperature of 500° C. for 2 h to obtain a copper-based graphite heat sink material.

[0073] According to tests, the copper-based graphite heat sink material prepared in this embodiment has a bending strength of 114.5 MPa, a thermal conductivity of 158.1 W / mK, and a density of 97.2%.

[0074] Example 9

[0075] This embodiment includes the following steps:

[0076] Step 1: 30.06 g of CuZr powder with an average particle size D50 of 50 μm and 30.07 g of CuCrZr powder with an average particle size D50 of 100 μm are selected as base powders. The preparation methods and compositions of CuZr powder and CuCrZr powder are shown in Table 1 B and H below. They are placed in a stainless steel ball mill with 59.87 g of flake graphite powder with an average particle size D50 of 200 μm, and stainless steel grinding balls are configured according to a ball-to-material ratio of 10:1. Mechanical ball milling is performed at a speed of 300 rpm for 12 hours to obtain a powder in which copper alloy powder and graphite powder are evenly mixed.

[0077] Step 2: The copper alloy powder and graphite powder obtained in step 1 are uniformly mixed and loaded into a graphite mold for vacuum hot pressing sintering at a sintering temperature of 1000° C., a holding time of 2 h, a sintering pressure of 50 MPa, and a vacuum sintering environment to obtain a sintered body;

[0078] Step 3: Place the sintered body obtained in step 2 into a heat treatment furnace for aging heat treatment at a temperature of 600° C. for 3 hours to obtain a copper-based graphite heat sink material.

[0079] According to tests, the copper-based graphite heat sink material prepared in this embodiment has a bending strength of 45.3 MPa, a thermal conductivity of 473.5 W / mK, and a density of 98.1%.

[0080] Example 10

[0081] This embodiment includes the following steps:

[0082] Step 1: 11.30 g of CuCr powder with an average particle size D50 of 10 μm and 101.67 g of CuCrZr powder with an average particle size D50 of 10 μm were selected as base powders. The preparation methods and compositions of the CuCr powders and CuCrZr powders are shown in D and I of Table 1 below. The powders were put into a stainless steel ball mill with 7.03 g of flake graphite powder with an average particle size D50 of 5 μm, and stainless steel grinding balls were configured according to a ball-to-material ratio of 5:1. The powders were mechanically ball-milled at a speed of 150 rpm for 6 hours to obtain a powder in which the copper alloy powder and the graphite powder were evenly mixed.

[0083] Step 2: The copper alloy powder and graphite powder obtained in step 1 are uniformly mixed and loaded into a graphite mold for spark plasma sintering at a sintering temperature of 800° C., a holding time of 0.15 h, a sintering pressure of 30 MPa, and a vacuum sintering environment to obtain a sintered body;

[0084] Step 3: Place the sintered body obtained in step 2 into a heat treatment furnace for aging heat treatment at a temperature of 400° C. for 1 h to obtain a copper-based graphite heat sink material.

[0085] According to tests, the copper-based graphite heat sink material prepared in this embodiment has a bending strength of 109.8 MPa, a thermal conductivity of 158.3 W / mK, and a density of 95.9%.

[0086] Comparative Example 1

[0087] The difference between this comparative example and Example 1 is that in step 1, no copper alloy powder is used, and the copper powder and the graphite powder are directly mechanically ball-milled.

[0088] According to tests, the copper-based graphite heat sink material prepared in this comparative example has a bending strength of 51.3 MPa, a thermal conductivity of 161.8 W / mK, and a density of 93.7%.

[0089] Comparative Example 2

[0090] The difference between this comparative example and Example 1 is that in step 2, the powder uniformly mixed with copper alloy powder and graphite powder is pressed into shape by cold isostatic pressing at a pressure of 100 MPa, and then vacuum pressureless sintering is carried out in a tubular furnace at a sintering temperature of 800°C and a holding time of 0.5 h.

[0091] According to tests, the copper-based graphite heat sink material prepared in this comparative example has a bending strength of 40.8 MPa, a thermal conductivity of 143.9 W / mK, and a density of 91.2%.

[0092] Table 1

[0093]

[0094] "Bal." in Table 1 indicates a margin.

[0095] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a low-density and high-thermal-conductivity copper-based graphite heat sink material, characterized in that: The method comprises the following steps: Step 1, selecting two copper alloy powders of CuZr powder, CuCr powder and CuCrZr powder as base powder, and the two copper alloy powders have different particle sizes, and mechanically ball milling and mixing with graphite powder to obtain a powder in which copper alloy powder and graphite powder are evenly mixed; the volume content of graphite powder in the powder in which copper alloy powder and graphite powder are evenly mixed is 20%~80%, and the volume content of base powder is 20%~80%; the ball-to-material ratio of the mechanical ball milling mixing is 5~10:1, the ball milling speed is 150rpm~300rpm, and the ball milling time is 6h~12h; Step 2: Put the copper alloy powder and graphite powder obtained in step 1 into a graphite mold for pressure sintering to obtain a sintered body; Step three: subjecting the sintered body obtained in step two to aging heat treatment to obtain a low-density and high-thermal-conductivity copper-based graphite heat sink material.

2. The method for preparing a low-density and high-thermal-conductivity copper-based graphite heat sink material according to claim 1, characterized in that: The CuZr powder, CuCr powder and CuCrZr powder in step 1 are prepared by gas atomization, rotating electrode or mechanical alloying, and have a particle size of 10 μm to 100 μm. The graphite powder is flake graphite or spherical graphite, and has a particle size of 5 μm to 200 μm.

3. The method for preparing a low-density and high-thermal-conductivity copper-based graphite heat sink material according to claim 1, characterized in that: The mass content of Zr in the CuZr powder in step 1 is 0.1%~2.0%, and the balance is Cu. The mass content of Cr in the CuCr powder is 1.0%~10.0%, and the balance is Cu. The mass content of Zr in the CuCrZr powder is 0.1%~1.0%, the mass content of Cr is 0.1%~1.0%, and the balance is Cu.

4. The method for preparing a low-density and high-thermal-conductivity copper-based graphite heat sink material according to claim 1, characterized in that: In step one, when CuZr powder and CuCr powder are selected as the base powder, the mass content of Zr in the base powder is 0.01%~1.8%, the mass content of Cr is 0.1%~9%, and the balance is Cu; when CuZr powder and CuCrZr powder are selected as the base powder, the mass content of Zr in the base powder is 0.1%~1.9%, the mass content of Cr is 0.01%~0.9%, and the balance is Cu; when CuCr powder and CuCrZr powder are selected as the base powder, the mass content of Zr in the base powder is 0.01%~0.9%, the mass content of Cr is 0.19%~9.1%, and the balance is Cu.

5. The method for preparing a low-density and high-thermal-conductivity copper-based graphite heat sink material according to claim 1, characterized in that: The pressure sintering process in step 2 is vacuum hot pressing sintering or spark plasma sintering.

6. The method for preparing a low-density and high-thermal-conductivity copper-based graphite heat sink material according to claim 1, characterized in that: The sintering temperature of the pressure sintering treatment in step 2 is 800° C. to 1000° C., the holding time is 0.15 h to 2 h, the sintering environment is vacuum, and the sintering pressure is 30 MPa to 50 MPa.

7. The method for preparing a low-density and high-thermal-conductivity copper-based graphite heat sink material according to claim 1, characterized in that: The temperature of the aging heat treatment in step 3 is 400°C to 600°C, and the time is 1h to 3h.

Images