Preparation method of high-thermal-conductivity diamond-based composite material

Abstract

The invention discloses a preparation method of a high-thermal-conductivity diamond-based composite material. Comprising the following steps: (1) preparing an ordered layered diamond framework by adopting diamond powder as a raw material and an organic binder as an additive and utilizing a bidirectional freezing ice template method; and (2) an ultrathin metal protection layer is controllably deposited on the inner surface and the outer surface of the layered diamond framework through an atomic layer deposition process. And (3) metal melt is infiltrated into the coated diamond framework material, and the layered diamond / metal composite material is prepared after pressure maintaining and cooling. A layered diamond framework is constructed through an ice template method, a complete path is provided for heat conduction, and scattering of phonons on a metal / diamond interface is reduced. And meanwhile, the interlayer wettability problem of the framework is solved through the technologies such as atomic layer deposition and chemical plating, the metal infiltration process is optimized, the defects of the formed composite material are reduced, and finally the heat conductivity and strength of the diamond-based composite material are effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of thermal conductive materials, and more specifically to a method for preparing a high thermal conductivity diamond-based composite material. Background Art

[0002] With the rapid development of science and technology, the demand for electronic devices in many fields such as advanced manufacturing and aviation is increasing day by day. With the increase in the integration degree of electronic components, the heat generation of components has also increased significantly, and the heat dissipation problem has become an important factor affecting the performance and life of equipment.

[0003] Diamond has both extremely high thermal conductivity (2200–2600 W / (m·K)) and extremely low coefficient of thermal expansion, and is a very promising heat sink material. In recent years, with the maturity of the artificial synthesis diamond technology, the price of diamond powder has dropped significantly and has certain industrial application value. Generally, diamond is used as a reinforcing phase, and the thermal conductivity of the composite material is improved by dispersing diamond in a metal matrix. In particular, diamond / copper composites and diamond / aluminum composites are regarded as the next-generation electronic packaging materials and have important potential applications in the field of thermal management.

[0004] However, the wettability of diamond with most metals is very poor. In particular, the discrete spatial distribution structure of diamond in the metal matrix leads to the formation of a large number of diamond / metal interfaces, and a high interfacial thermal resistance is formed during the heat conduction process, resulting in the thermal conductivity of the diamond / metal composite material being much lower than that of diamond and unable to meet the current heat dissipation requirements of equipment.

[0005] Therefore, developing a thermally conductive network structure that can be composed of pure diamond and avoiding the formation of diamond / metal interfaces in the heat conduction path is of great significance for the development of new high thermal conductivity diamond / metal composite materials for current advanced equipment. Based on this, the present invention constructs a three-dimensional layered and continuous pure diamond thermally conductive network through bionic design of the structure, improves the thermal conductivity of the composite material, and improves the mechanical properties of the composite material through layered structure design and interlayer interface modification. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for preparing a base composite material with high thermal conductivity and adjustable coefficient of thermal expansion, which can solve the problems of low efficiency, immature processing technology and complex preparation process of traditional melt infiltration method for producing composite thermal conductive materials, resulting in low product density and diamond graphitization, and can also solve the problems that the contact interfaces between diamond and metal are not wetted with each other, resulting in insufficient firmness of the interfacial bonding between the reinforcing phase and the metal matrix, and there will be defects such as holes and cracks at the two-phase bonding interface of the product after sintering and forming, as well as the interfacial thermal resistance restricting the heat conduction of the material.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing a high thermal conductivity diamond-based composite material, comprising the following steps:

[0009] (1) Weigh diamond powder and perform pickling treatment to remove surface impurities;

[0010] (2) Dissolve the organic binder in water and stir to obtain a homogeneous solution;

[0011] (3) Add the diamond powder treated in step (1) to the solution obtained in step (2) and stir to obtain a uniformly mixed suspension slurry;

[0012] (4) Pour the suspension slurry obtained in step (3) into a mold and place it on a copper rack, and perform freeze forming under the action of a cold source to obtain a frozen sample;

[0013] (5) After the frozen sample obtained in step (4) is dried by low-temperature vacuum drying, perform heat treatment under argon protection or in a vacuum environment to obtain a layered diamond skeleton;

[0014] (6) Through a plating process, controllably deposit a layer of ultra-thin metal protective layer on the inner and outer surfaces of the layered diamond skeleton obtained in step (5) to obtain a diamond skeleton after plating, or directly infiltrate the metal into the diamond skeleton for compounding, and further optimize the compounding strength and the diamond / metal interface through high temperature and high pressure;

[0015] (7) Perform infiltration compounding of the layered diamond skeleton after plating obtained in step (6) and molten metal under normal pressure / negative pressure to obtain a layered diamond / metal composite material.

[0016] Preferably, in step (1), the pickling is to treat the diamond powder with aqua regia; the particle size of the diamond powder is 10 nm - 500 μm.

[0017] Preferably, in step (2), the organic binder is a polymer containing only carbon, hydrogen, and oxygen.

[0018] Preferably, in step (2), the organic binder is polyvinyl alcohol. The available organic polymer additives in the present invention are polyvinyl alcohol (degree of alcoholysis is 87% - 89%), chitosan, and sucrose, with a content of about 3 wt%, a viscosity of 80 - 110 mPa·s, having high solubility and high viscosity, and the purpose is to ensure that the slurry reaches sufficient viscosity, but not limited thereto.

[0019] Preferably, in step (3), the mass percentage of diamond powder in the suspension slurry is 10% - 60%.

[0020] Preferably, the freeze forming in step (4) is carried out in a bi-directional freezing mold.

[0021] Preferably, the low-temperature vacuum drying in step (5) is carried out at -40°C to -60°C.

[0022] Preferably, the heat treatment in step (5) is carried out in a tube furnace at 500 - 1000°C for 1 - 10 h.

[0023] Preferably, the coating process in step (6) is atomic layer deposition or electroless plating; the metal protective layer is tungsten, chromium or titanium.

[0024] Preferably, the high temperature in step (6) is 700°C and the high pressure is 100 MPa.

[0025] Preferably, the molten metal in step (7) is copper, aluminum or silver.

[0026] As can be seen from the above technical solutions, compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. By adopting a biomimetic layered structure design, a layered continuous and through pure diamond heat conduction network is directly constructed, avoiding the formation of diamond / metal interfaces in the heat transfer path;

[0028] 2. The present invention uses processes such as atomic layer deposition and electroless plating to metallize the surface of the formed diamond skeleton, effectively solving the problem of poor wettability at the copper / diamond interface.

[0029] 3. The ordered layered diamond / metal composite material prepared by the present invention has a microscale microstructure, so the physical and mechanical properties of the composite material are greatly improved.

[0030] 4. The ice template method adopted by the present invention has low cost, simple operation, low requirements for the particle size of raw materials and no pollution to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0032] Figure 1 It is a schematic diagram of the process for preparing the diamond-based composite material in Embodiment 1 and Embodiment 2 of the present invention;

[0033] Figure 2SEM photograph of the ordered-layer diamond framework obtained after freeze-forming and drying in Example 1 of the present invention;

[0034] Figure 3 SEM photograph of the ordered-layer diamond framework obtained after high-temperature heat treatment in Example 1 of the present invention;

[0035] Figure 4 SEM photograph of the diamond / Cu composite material prepared in Example 1 of the present invention;

[0036] Figure 5 SEM photograph of the diamond / Al composite material prepared in Example 2 of the present invention;

[0037] Figure 6 SEM photograph of the ordered-layer diamond framework obtained after freeze-forming and drying in Example 3 of the present invention;

[0038] Figure 7 SEM photograph of the ordered-layer diamond framework obtained after high-temperature heat treatment in Example 3 of the present invention;

[0039] Figure 8 SEM photograph of the diamond / Al composite material prepared in Example 3 of the present invention. Detailed implementation manners

[0040] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0041] Example 1

[0042] This example provides a preparation method of a high-thermal-conductivity diamond-based composite material, including the following steps:

[0043] In the first step, an aqueous solution of sodium carboxymethylcellulose is prepared. Weigh 0.10 g of sodium carboxymethylcellulose, disperse it in 4 mL of water, and stir for 4 h until it is completely dissolved to obtain a 4 mL uniformly mixed colorless and transparent solution.

[0044] In the second step, take the 4 mL of the aqueous solution of sodium carboxymethylcellulose obtained in the first step, add 2 g of diamond powder with a nanoscale size, and stir for 24 h to obtain a uniformly mixed suspension slurry.

[0045] In the third step, pour the suspension slurry obtained in the second step into a two-way freezing mold for freeze-forming to obtain a frozen sample.

[0046] Step 4: Transfer the frozen sample obtained in Step 3 into a freeze dryer and dry for 40 h. After removing the ice layer, an ordered layered metal framework precursor with a binder is obtained ( Figure 2 ).

[0047] Step 5: Heat the ordered layered metal framework obtained in Step 4 in a tubular furnace under argon protection at 800 °C for 2 h to obtain a bulk ordered layered diamond framework with a side length of about 2.0 cm ( Figure 3 ).

[0048] Step 6: Deposit a Cr layer on the surface of the framework by atomic layer deposition (precursor: Cr(thd)3; temperature: 280 °C; pulse: 1.5 s, reaction gases: mixed gas of H2 and Ar).

[0049] Step 7: Infiltrate and composite the layered diamond framework with the deposited layer obtained in Step 6 with molten Cu under atmospheric pressure to obtain a layered diamond / Cu composite material ( Figure 4 ).

[0050] Example 2

[0051] This example provides a method for preparing a high thermal conductivity diamond-based composite material, including the following steps:

[0052] Step 1: Prepare an aqueous solution of sodium carboxymethylcellulose. Weigh 0.10 of sodium carboxymethylcellulose, disperse it in 4 mL of water, and stir for 4 h until it is completely dissolved to obtain a 4 mL uniformly mixed colorless transparent solution.

[0053] Step 2: Take the 4 mL aqueous solution of sodium carboxymethylcellulose obtained in Step 1, add 2 g of nano-sized diamond powder, and stir for 24 h to obtain a uniformly mixed suspension slurry.

[0054] Step 3: Pour the suspension slurry obtained in Step 2 into a two-way freezing mold for freeze molding to obtain a frozen sample.

[0055] Step 4: Transfer the frozen sample obtained in Step 3 into a freeze dryer and dry for 40 h. After removing the ice layer, an ordered layered metal framework precursor with a binder is obtained.

[0056] Step 5: Heat the ordered layered metal framework obtained in Step 4 in a tubular furnace under argon protection at 800 °C for 2 h to obtain a bulk ordered layered diamond framework with a side length of about 2.0 cm.

[0057] Step 6: By pressure infiltration (pressure is ~2 MPa), composite the molten metal Al with the diamond framework, and further optimize the composite material under high temperature and high pressure conditions (700 °C, 100 MPa) to obtain the final diamond / Al composite material ( Figure 5)。

[0058] Example 3

[0059] This example provides a method for preparing a high thermal conductivity diamond-based composite material, which includes the following steps:

[0060] In the first step, an aqueous solution of polyvinyl alcohol is prepared. Weigh 00.20 g of polyvinyl alcohol, disperse it in 4 mL of water, and completely dissolve it by heating in a water bath at 60 °C for 2 h. Then cool it naturally to room temperature to obtain 4 mL of a uniformly mixed colorless and transparent solution.

[0061] In the second step, take the 4 mL of the aqueous solution of polyvinyl alcohol obtained in the first step, add 2.0 g of submicron-sized diamond powder, and stir for 48 h to obtain a uniformly mixed suspension slurry.

[0062] In the third step, pour the suspension slurry obtained in the second step into a two-way freezing mold for freeze molding to obtain a frozen sample.

[0063] In the fourth step, transfer the frozen sample obtained in the third step into a freeze dryer and dry it for 45 h. After removing the ice layer, an ordered layered metal skeleton precursor with a binder is obtained ( Figure 6 )。

[0064] In the fifth step, heat the ordered layered metal skeleton obtained in the fourth step in a tubular furnace under argon protection at 800 °C for 2 h to obtain a block-shaped ordered layered diamond skeleton with a side length of about 12.0 cm ( Figure 7 )。

[0065] In the sixth step, deposit a Cr layer on the surface of the skeleton by atomic layer deposition (precursor: Cr(thd)3; temperature: 280 °C; pulse: 1.5 s, reaction gas: a mixture of H2 and Ar).

[0066] In the seventh step, infiltrate and composite the layered diamond skeleton with the obtained coating with molten Al at atmospheric pressure to obtain a layered diamond / Al composite material ( Figure 8 )。

[0067] In this specification, each example is described in a progressive manner. The key point of each example is to illustrate the differences from other examples. For the same or similar parts among the examples, reference can be made to each other. For the device disclosed in the example, since it corresponds to the method disclosed in the example, the description is relatively simple, and reference can be made to the method part for the relevant parts.

[0068] The foregoing description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a high thermal conductivity diamond-based composite material, characterized in that, It includes the following steps: (1) Weigh diamond powder and conduct pickling treatment to remove surface impurities; (2) Dissolve the organic binder in water and stir to obtain a uniform solution; (3) Add the diamond powder treated in step (1) to the solution obtained in step (2) and stir to obtain a uniformly mixed suspension slurry; (4) Pour the suspension slurry obtained in step (3) into a mold and place it on a copper frame, and conduct freeze forming under the action of a cold source to obtain a frozen sample; (5) After the frozen sample obtained in step (4) is dried by low-temperature vacuum drying, place it in an argon protection or vacuum environment for heat treatment to obtain a layered diamond skeleton; (6) Through a plating process, controllably deposit a layer of ultra-thin metal protective layer on the inner and outer surfaces of the layered diamond skeleton obtained in step (5) to obtain a diamond skeleton after plating; or directly infiltrate the metal into the diamond skeleton for compounding, and further optimize the compounding strength and the diamond / metal interface through high temperature and high pressure; (7) Conduct infiltration compounding of the layered diamond skeleton after plating obtained in step (6) and the molten metal under normal pressure / negative pressure to obtain a layered diamond / metal composite material.

2. The preparation method of a high thermal conductivity diamond-based composite material according to claim 1, characterized in that, The pickling in step (1) is to treat the diamond powder with aqua regia; the particle size of the diamond powder is 10 nm - 500 μm.

3. The preparation method of a high thermal conductivity diamond-based composite material according to claim 1, characterized in that, The organic binder in step (2) is a polymer containing only carbon, hydrogen, and oxygen.

4. The preparation method of a high thermal conductivity diamond-based composite material according to claim 1, characterized in that, The organic binder in step (2) is polyvinyl alcohol.

5. The preparation method of a high thermal conductivity diamond-based composite material according to claim 1, characterized in that, The mass percentage of diamond powder in the suspension slurry in step (3) is 10% - 60%.

6. The preparation method of a high thermal conductivity diamond-based composite material according to claim 1, wherein The freeze forming in step (4) is freeze forming in a two-way freezing mold.

7. The preparation method of a high thermal conductivity diamond-based composite material according to claim 1, characterized in that, The low-temperature vacuum drying in step (5) is carried out at -40°C to -60°C.

8. The preparation method of an ordered layered diamond skeleton / copper composite material according to claim 1, characterized in that, The heat treatment in step (5) is to heat in a tube furnace at 500 - 1000°C for 1 - 10 h.

9. The preparation method of a high thermal conductivity diamond-based composite material according to claim 1, characterized in that, The plating process in step (6) is atomic layer deposition or electroless plating; the metal protective layer is tungsten, chromium, or titanium.

10. The preparation method of a high thermal conductivity diamond-based composite material according to claim 1, characterized in that, The molten metal in step (7) is copper, aluminum, or silver.

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