Preparation method of novel porous foam metal copper material with high thermal conductivity and heat dissipation

Abstract

The invention relates to the technical field of foam metal preparation, in particular to a preparation method of a novel high-heat-conduction heat-dissipation porous foam metal copper material, which comprises the following steps: S1, preparing two parts of mixtures containing copper powder and additives, and respectively mixing the mixtures with polystyrene microspheres and modified polystyrene microspheres to obtain a mixed material A and a mixed material B; s2, the mixed material B is put into a mold C, isostatic pressing is conducted, and a green body X is obtained; s3, loading the green body X into a mold D, filling the mixed material A into a gap between the green body X and the mold D, and performing isostatic pressing to obtain a green body Y; and S4, in the inert protective gas atmosphere, the green body Y is pre-sintered and sintered, and the novel high-heat-conduction and heat-dissipation porous foam metal copper material is obtained. The porous foam metal copper material disclosed by the invention is prepared by adopting a microsphere calcining process, has relatively high porosity and impact resistance, and is excellent in heat-conducting property at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of metallic foams, and particularly relates to a preparation method of a novel highly thermally conductive and heat dissipating porous metallic copper foam material. Background Art

[0002] With the development of electronic devices towards high performance, miniaturization and integration, the power density of chips and electronic components has been continuously increasing, and the heat dissipation problem has become increasingly prominent. Porous metallic copper foam materials have broad application prospects in the field of heat dissipation of electronic devices due to their light weight, large specific surface area, good thermal conductivity and other characteristics.

[0003] At present, the methods for preparing porous metallic copper foam materials mainly include powder metallurgy, melt foaming, electrodeposition, metal deposition, etc. Among them, the powder metallurgy method forms a porous structure by mixing metal powder with a foaming agent and then heating and sintering. Although this method has relatively simple process, the obtained product has a low porosity, uneven pore size distribution, and poor mechanical strength; the melt foaming method adds a foaming agent to molten metal and prepares metallic foam through the processes of bubble formation and solidification, but this method has problems such as difficult process control and unstable product quality; the electrodeposition method deposits metallic copper on a porous template and then removes the template to obtain a porous structure. This method can precisely control the pore size and distribution, but has disadvantages such as long preparation period and high cost; the metal deposition method deposits metal on the surface of the template by means of chemical vapor deposition or physical vapor deposition. Although a high porosity can be obtained, it requires high equipment requirements and is difficult to achieve large-scale production.

[0004] Patent Publication No. CN107552796B discloses "a method for preparing metallic foam by packing resin microspheres". In this method, a kind of PMMA hollow microspheres are first prepared, the PMMA hollow microspheres are packed, and then a slurry prepared by mixing metal powder and water is filled. After steps such as drying and sintering and curing, metallic foam is obtained. The porosity and size of the metallic foam obtained by this method are effectively controlled, and the compressive capacity is enhanced. However, the metallic foam obtained by this method is not applicable to some solid-state battery fields with harsh conditions.

[0005] Therefore, there is an urgent need to develop a novel preparation method of porous metallic copper foam materials to solve the problems such as poor mechanical properties and narrow application range existing in the prior art. Summary of the Invention

[0006] The main object of the present invention is to provide a preparation method of a novel highly thermally conductive and heat dissipating porous metallic copper foam material. The metallic copper foam material is prepared by adopting a microsphere calcination process, has a high porosity and impact resistance, and excellent thermal conductivity at the same time.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows: The present invention provides a preparation method of a novel high thermal conductivity and heat dissipation porous foam metal copper material, comprising the following steps: S1. Prepare two mixtures containing copper powder and additives, and mix them with polystyrene microspheres and modified polystyrene microspheres respectively to obtain mixed materials A and B; S2. Load the mixed material B into mold C and perform isostatic pressing to obtain a green body X; S3. Load the green body X into mold D, and then fill the pores between the green body X and mold D with the mixed material A, and perform isostatic pressing to obtain a green body Y; S4. Under an inert protective gas atmosphere, pre-sinter and sinter the green body Y to obtain a novel high thermal conductivity and heat dissipation porous foam metal copper material.

[0008] Previous foam metal materials often used a single sodium chloride for mixing and calcining to prepare foam metal copper materials. Although this method has a simple process, the products obtained have a low porosity and poor impact resistance, resulting in a narrow scope of application of the products. Therefore, it is necessary to improve the process. Previously, a preparation process of foam metal was disclosed in Patent CN105903968A, which was prepared by processes such as mixing, rubber mixing, calendering, pre-drying, precision rolling, sintering, cleaning, drying, and slicing, reducing the production time and improving the processing accuracy at the same time. With the continuous in-depth research and development of the company, it was found that the performance of the foam metal materials in the aforementioned application still had room for improvement, so that the foam metal could be applicable to the more demanding solid-state battery field and prevent cracks from appearing in the foam metal due to poor mechanical properties during the pressure encapsulation process, which would affect the battery performance.

[0009] In this application, first, the composite pore-forming agent, additive and copper powder are respectively mixed with polystyrene microspheres and modified polystyrene microspheres of different particle sizes. Then, the mixed material B containing smaller particle size modified polystyrene microspheres is first pressed into a green body X, and then the mixed material A containing larger particle size polystyrene microspheres is filled and compounded and pressed to obtain a green body Y. During this process, the outer layer of the mixed material B is wrapped and compacted by the mixed material A. Under specific conditions, the green body Y is subjected to a step-by-step calcination process of microsphere calcination. First, during the two-stage pre-calcination process, the outermost polystyrene microspheres in the first calcination process decompose to generate pores. Subsequently, when the temperature is raised again, the inner layer of modified polystyrene microspheres will start to decompose to generate gas. Due to the existence of larger pores in the outer layer, internal aggregation and expansion will not occur, resulting in uneven pores in the internal structure of the foam metal. Finally, a foam metal with a gradient pore size distribution is formed. When the outer layer structure of this structure is subjected to impact or extrusion, it can undergo a small elastic deformation to absorb energy, and the inner layer structure has a higher density and plays a role of rigid support to improve the stability of the structure, thereby improving the impact resistance and compressive performance of the foam metal.

[0010] In some embodiments, the mass ratio of the copper powder, the additive, and the polystyrene microspheres is 1:(0.2~0.6):(0.1~0.3).

[0011] In some embodiments, the width of the mold C is greater than the width of the mold D.

[0012] In some embodiments, the average particle size of the polystyrene microspheres is 30~50μm; the average particle size of the modified polystyrene microspheres is 20~30μm.

[0013] By regulating the average particle size of the polystyrene microspheres and the modified polystyrene microspheres in this application, a foam metal copper material with a pore size gradient distribution can be formed during the preparation of the foam metal. And in combination with a specific preparation process, it can prevent the problem of uneven pore size distribution caused by microspheres of different particle sizes. At the same time, the existence of the gradient pore distribution can improve the thermal conductivity of the foam metal. The reason may be that the large-pore pores can improve the convective heat transfer performance of the material, and the small-pore pores can enhance the heat conduction path, and the synergistic effect of the two improves the thermal conductivity of the material.

[0014] In some embodiments, the preparation method of the modified polystyrene microspheres includes the following steps: A1. Mix acryloyl chloride and melamine, add a first solvent and a deacidifying agent, stir at a constant temperature at room temperature for 2~4h, then add epichlorohydrin, continue to stir at a constant temperature for 3~5h, extract after the reaction ends, concentrate the organic phase under reduced pressure, and perform column chromatography to obtain the compound shown in formula Ⅰ (Ⅰ); A2. Under an inert protective gas atmosphere, mix styrene, divinylbenzene, and the compound shown in formula Ⅰ in step A1, add a second solvent, add an initiator, raise the temperature to 70~90℃, stir at a constant temperature for 12~14h, centrifuge, filter, wash, and dry after the reaction ends, and place at 170~200℃ for 1~3h to obtain the modified polystyrene microspheres.

[0015] In some embodiments, the molar ratio of the acryloyl chloride, melamine, epichlorohydrin, and deacidifying agent is (0.8~1):1:(2~2.3):(3.4~4).

[0016] Preferably, the molar ratio of the acryloyl chloride, melamine, epichlorohydrin, and deacidifying agent is 0.9:1:2.2:3.7.

[0017] By regulating the molar ratios of acryloyl chloride, melamine, epichlorohydrin, and acid-binding agents, this application can prevent crosslinking of modified polystyrene microspheres, which increases the particle size of the microspheres and is not conducive to obtaining a foam metal material with a pore size distribution that gradually increases from the inside to the outside. In addition, it can also prevent the decomposition temperatures of the modified polystyrene microspheres and the polystyrene microspheres from being too close, so that the gas generated by the decomposition of the internal microspheres during the preparation process cannot be discharged in time, reducing the structural strength of the foam metal and causing uneven pore distribution inside the foam metal.

[0018] In some embodiments, in step A2, the molar ratio of styrene, divinylbenzene, and the compound shown in formula I is 1:(0.2 - 0.4):(0.3 - 0.6).

[0019] Preferably, in step A2, the molar ratio of styrene, divinylbenzene, and the compound shown in formula I is 1:0.3:0.4.

[0020] In some embodiments, the preparation method of the additive includes the following steps: B1. Ball-mill kaolin at a speed of 500 rpm for 1 - 2 h to obtain activated kaolin with an average particle size of 1 - 2 μm. B2. Immerse the activated kaolin in step B1 in dimethyl sulfoxide for 22 - 24 h, then add cetyltrimethylammonium bromide and heat to 60 - 80 °C for constant-temperature soaking for 4 - 8 h, and filter to obtain intercalated modified kaolin. B3. Immerse the intercalated modified kaolin in an ethanol dispersion of heptadecafluorodecyltrimethoxysilane and carboxylated carbon nanotubes, heat to 55 - 65 °C for constant-temperature stirring for 4 - 8 h, and after the reaction, centrifuge, filter, and dry to obtain the product.

[0021] In this application, it is found in the research that kaolin will generate mullite phase during the high-temperature sintering process, enhancing the mechanical properties of the foam metal. However, the compatibility between conventional kaolin and copper powder is poor and prone to agglomeration. By modifying kaolin, on the one hand, the synergistic pretreatment of kaolin with dimethyl sulfoxide and cetyltrimethylammonium bromide can increase the spacing between kaolin interlayers, enabling carboxylated carbon nanotubes to effectively enter between the kaolin interlayers. At the same time, the synergistic effect with heptadecafluorodecyltrimethoxysilane can form a multi-level micro-nano hydrophobic structure, enhancing the compatibility between the modified kaolin and copper powder. At the same time, carboxylated carbon nanotubes can enter the interlayers of kaolin, enhancing the mechanical strength of each interlayer and further improving the mechanical properties and thermal conductivity of the foam metal.

[0022] In some embodiments, in step B2, the mass ratio of the activated kaolin, dimethyl sulfoxide, and cetyltrimethylammonium bromide is 1:(5 - 8):(1 - 1.5).

[0023] Preferably, in step B2, the mass ratio of the activated kaolin, dimethyl sulfoxide, and cetyltrimethylammonium bromide is 1:6:1.3.

[0024] In some embodiments, in step B3, the mass ratio of the heptadecafluorodecyltrimethoxysilane to the carboxylated carbon nanotubes is 1:(0.2 - 0.7).

[0025] Preferably, in step B3, the mass ratio of the heptadecafluorodecyltrimethoxysilane to the carboxylated carbon nanotubes is 1:0.5.

[0026] In some embodiments, in step S4, the specific operation of the pre - sintering is as follows: First, heat at a heating rate of 5 - 10 °C / min to 300 - 400 °C, hold for 1 - 2 h, and then heat at a heating rate of 5 - 10 °C / min to 500 - 700 °C, hold for 0.5 - 1.5 h.

[0027] In some embodiments, in step S4, the sintering temperature is 800 - 950 °C and the time is 3 - 4 h.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The porous foam metal copper material of the present invention is prepared by using a microsphere calcination process, has a gradient pore size distribution structure, and has a high porosity and impact resistance, and at the same time has excellent thermal conductivity.

[0029] (2) A large number of epoxy groups are contained in the structure of the modified polystyrene microspheres of the present invention, which increases the decomposition temperature of the modified polystyrene microspheres, enabling them to decompose after the polystyrene microspheres. When the larger - sized polystyrene microspheres decompose first on the outer layer of the foam metal to form a larger pore structure, the gas formed by the subsequent decomposition of the slightly smaller - sized modified polystyrene microspheres inside can be smoothly discharged, preventing the risk of gas aggregation increasing the pore size of the inner layer and also preventing cracks from occurring in the internal structure of the foam metal due to pressure, resulting in a decrease in mechanical strength.

[0030] (3) The additive of the present invention is prepared by synergistically pretreating modified kaolin with dimethyl sulfoxide and cetyltrimethylammonium bromide, which increases the spacing between the kaolin interlayers, enables the carboxylated carbon nanotubes to effectively enter between the kaolin interlayers, and then can form a multi - level micro - nano hydrophobic structure in cooperation with the heptadecafluorodecyltrimethoxysilane, enhancing the compatibility between the modified kaolin and the copper powder. At the same time, the carboxylated carbon nanotubes can enter the interlayers of the kaolin, enhancing the mechanical strength of each interlayer, and further improving the mechanical properties and thermal conductivity of the foam metal. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic structural diagram of the green body Y prepared in Example 1; Figure 2 Schematic structural diagram of green body X prepared in Example 1; Figure 3 1H NMR spectrum of the compound shown in Formula I prepared in Preparation Example 1; Figure 4 1H NMR spectrum of the compound shown in Formula II prepared in Preparation Example 2. Detailed Description of the Invention

[0032] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be construed as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0033] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0034] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. Without departing from the scope or spirit of the present invention, various modifications and variations can be made to the specific embodiments of the present invention specification, which will be obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention will be obvious to those skilled in the art. The specification and examples of the present application are merely exemplary.

[0035] Among them, the polystyrene microspheres were purchased from Zhongke Leiming (Beijing) Technology Co., Ltd.

[0036] Preparation Example 1 Preparation method of modified polystyrene microspheres, comprising the following steps: A1. Mix 270 mmol of acryloyl chloride and 300 mmol of melamine, add 550 mL of toluene and 1110 mmol of sodium bicarbonate, stir at a constant temperature at room temperature for 3 h, then add 630 mmol of epichlorohydrin, continue to stir at a constant temperature for 4 h, extract after the reaction ends, concentrate the organic phase under reduced pressure, and perform column chromatography to obtain the compound shown in Formula I (I) (1H NMR spectrum is shown in the appendix Figure 3 ); A2. Under an N2 atmosphere, 750 mmol of styrene, 225 mmol of divinylbenzene, and 300 mmol of the compound shown in Formula I in Step A1 were mixed and added to 1 L of tetrahydrofuran. 1 g of azobisisobutyronitrile was added, and the temperature was raised to 80 °C and stirred at a constant temperature for 13 h. After the reaction was completed, centrifugation, filtration, washing, and drying were carried out, and it was placed at 180 °C for 2 h to obtain modified polystyrene microspheres.

[0037] Preparation Example 2 A method for preparing modified polystyrene microspheres, comprising the following steps: A1. 630 mmol of acryloyl chloride and 300 mmol of melamine were mixed and added to 550 mL of toluene and 1110 mmol of sodium bicarbonate, and stirred at a constant temperature at room temperature for 3 h. Subsequently, 270 mmol of epichlorohydrin was added, and stirring was continued at a constant temperature for 4 h. After the reaction was completed, extraction was carried out, the organic phase was concentrated under reduced pressure, and column chromatography was carried out to obtain the compound shown in Formula II (II) (See the attached 1H NMR spectrum Figure 4 ); A2. Under an N2 atmosphere, 750 mmol of styrene, 225 mmol of divinylbenzene, and 300 mmol of the compound shown in Formula II in Step A1 were mixed and added to 1 L of tetrahydrofuran. 1 g of azobisisobutyronitrile was added, and the temperature was raised to 80 °C and stirred at a constant temperature for 13 h. After the reaction was completed, centrifugation, filtration, washing, and drying were carried out, and it was placed at 180 °C for 2 h to obtain modified polystyrene microspheres.

[0038] Preparation Example 3 A method for preparing modified polystyrene microspheres, the specific implementation method is the same as that of Preparation Example 1, except that in Step A2, the amount of the compound shown in Formula I is 200 mmol.

[0039] Preparation Example 4 A method for preparing an additive, comprising the following steps: B1. Kaolin was ball-milled at a speed of 500 rpm for 1.5 h to obtain activated kaolin with an average particle size of 2 μm; B2. 10 g of the activated kaolin in Step B1 was soaked in 60 g of dimethyl sulfoxide for 23 h, and then 13 g of cetyltrimethylammonium bromide was added and soaked at a constant temperature of 70 °C for 6 h, and the intercalated modified kaolin was obtained by filtration; B3. 10 g of the intercalated modified kaolin in Step B2 was soaked in 300 mL of an ethanol dispersion containing 10 g of 1H,1H,2H,2H-perfluorodecyltrimethoxysilane and 5 g of carboxylated carbon nanotubes, and stirred at a constant temperature of 60 °C for 6 h. After the reaction was completed, centrifugation and filtration were carried out, and drying was carried out to obtain the product.

[0040] Preparation Example 5 The preparation method of the additive is the same as that of Preparation Example 3, except that cetyltrimethylammonium bromide is not added.

[0041] Preparation Example 6 The preparation method of the additive is the same as that of Preparation Example 3, except that in the operation step of B2, 10 g of the activated kaolin in step B1 is soaked in a mixture of 60 g of dimethyl sulfoxide and 13 g of cetyltrimethylammonium bromide for 24 h, and then filtered to obtain the product.

[0042] Example 1 A preparation method of a novel highly thermally conductive and heat dissipating porous foam copper material includes the following steps: S1. Mix two portions of a mixture containing 100 g of copper powder and 40 g of an additive with 20 g of polystyrene microspheres with an average particle size of 40 μm and 20 g of modified polystyrene microspheres with an average particle size of 25 μm respectively to obtain mixed materials A and B; S2. Load the mixed material B into mold C and perform isostatic pressing to obtain a green compact X (see attachment Figure 2 ); S3. Load the green compact X into mold D, and then fill the pores between the green compact X and mold D with the mixed material A, and perform isostatic pressing to obtain a green compact Y (see attachment Figure 1 ); S4. Under a N2 atmosphere, pre-sinter the green compact Y and sinter it at 900 °C for 3.5 h to obtain the novel highly thermally conductive and heat dissipating porous foam copper material.

[0043] The width of mold C is greater than the width of mold D.

[0044] Among them, the specific operation steps of the pre-sintering are as follows: First, heat up at a heating rate of 7 °C / min to 350 °C, hold for 1.5 h, and then heat up at a heating rate of 7 °C / min to 600 °C and hold for 1 h.

[0045] The modified polystyrene microspheres are prepared from Preparation Example 1, and the additive is prepared from Preparation Example 3.

[0046] Example 2 A preparation method of a novel highly thermally conductive and heat dissipating porous foam copper material includes the following steps: S1. Mix two portions of a mixture containing 100 g of copper powder and 20 g of an additive with 10 g of polystyrene microspheres with an average particle size of 50 μm and 10 g of modified polystyrene microspheres with an average particle size of 30 μm respectively to obtain mixed materials A and B; S2. Load the mixed material B into mold C and perform isostatic pressing to obtain a green compact X; S3. Place the green body X into the mold D, then fill the pores between the green body X and the mold D with the mixed material A, and perform isostatic pressing to obtain the green body Y; S4. Under the N2 atmosphere, pre-sinter the green body Y and sinter it at 800 °C for 4 h to obtain the novel high thermal conductivity and heat dissipation porous foam copper material.

[0047] The width of the mold C is greater than the width of the mold D.

[0048] Among them, the specific operation steps of the pre-sintering are as follows: First, heat up to 300 °C at a heating rate of 5 °C / min and keep the temperature for 2 h, and then heat up to 500 °C at a heating rate of 5 °C / min and keep the temperature for 1.5 h.

[0049] The modified polystyrene microspheres are obtained from Preparation Example 1, and the additive is obtained from Preparation Example 3.

[0050] Example 3 A preparation method of a novel high thermal conductivity and heat dissipation porous foam copper material, comprising the following steps: S1. Mix two portions of the mixture containing 100 g of copper powder and 60 g of additive with 30 g of polystyrene microspheres with an average particle size of 30 μm and 30 g of modified polystyrene microspheres with an average particle size of 20 μm respectively to obtain the mixed material A and the mixed material B; S2. Place the mixed material B into the mold C and perform isostatic pressing to obtain the green body X; S3. Place the green body X into the mold D, then fill the pores between the green body X and the mold D with the mixed material A, and perform isostatic pressing to obtain the green body Y; S4. Under the N2 atmosphere, pre-sinter the green body Y and sinter it at 950 °C for 3 h to obtain the novel high thermal conductivity and heat dissipation porous foam copper material.

[0051] The width of the mold C is greater than the width of the mold D.

[0052] Among them, the specific operation steps of the pre-sintering are as follows: First, heat up to 400 °C at a heating rate of 10 °C / min and keep the temperature for 1 h, and then heat up to 700 °C at a heating rate of 10 °C / min and keep the temperature for 0.5 h.

[0053] The modified polystyrene microspheres are obtained from Preparation Example 1, and the additive is obtained from Preparation Example 3.

[0054] Example 4 A preparation method of a novel high thermal conductivity and heat dissipation porous foam copper material, the specific implementation manner is the same as that of Example 1, the difference is that the modified polystyrene microspheres are obtained from Preparation Example 2.

[0055] Example 5 A preparation method of a novel highly thermally conductive and heat-dissipating porous foam metal copper material. The specific implementation manner is the same as that of Example 1, except that the modified polystyrene microspheres are prepared from Preparation Example 3.

[0056] Example 6 A preparation method of a novel highly thermally conductive and heat-dissipating porous foam metal copper material. The specific implementation manner is the same as that of Example 1, except that the additive is prepared from Preparation Example 5.

[0057] Example 7 A preparation method of a novel highly thermally conductive and heat-dissipating porous foam metal copper material. The specific implementation manner is the same as that of Example 1, except that the additive is prepared from Preparation Example 6.

[0058] Example 8 A preparation method of a novel highly thermally conductive and heat-dissipating porous foam metal copper material. The specific implementation manner is the same as that of Example 1, except that the specific operation steps of pre-sintering are as follows: heating to 600 °C at a heating rate of 10 °C / min and holding for 1.5 h.

[0059] Comparative Example 1 A preparation method of a novel highly thermally conductive and heat-dissipating porous foam metal copper material, comprising the following steps: S1. After mixing 100 g of copper powder and 40 g of additive, further mix with 20 g of polystyrene microspheres with an average particle size of 40 μm to obtain a mixed material A; S2. Isostatically press the mixed material A to obtain a green body M; S4. Under a N2 atmosphere, pre-sinter the green body M and sinter at 900 °C for 3.5 h to obtain the novel highly thermally conductive and heat-dissipating porous foam metal copper material.

[0060] Among them, the specific operation steps of pre-sintering are as follows: heating to 350 °C at a heating rate of 7 °C / min and holding for 1.5 h.

[0061] The additive is prepared from Preparation Example 3.

[0062] Comparative Example 2 A preparation method of a novel highly thermally conductive and heat-dissipating porous foam metal copper material. The specific implementation manner is the same as that of Example 1, except that an equal mass of kaolin is used to replace the additive.

[0063] Performance test: (1) Thermal conductivity: The porous foam metal copper is made into a cylindrical specimen with a diameter of Φ12.7 mm, and the thermal conductivity of the specimen is tested with a laser thermal conductivity meter; (2) Porosity: The porosity of the porous foam metal copper is tested by the gas adsorption method (BET method); (3)Compressive strength test: The compressive strength of porous copper foam was tested according to the test method of GB / T 31930-2015 standard; (4)Impact resistance test: Tested according to the standard of GB / T 229-2020. The porous copper foam was made into a standard part with a thickness of 200 mm, and a 0.5 KG metal ball was used to vertically impact the standard part at a speed of 300 km / h to observe the depression situation.

[0064] The porous copper foams of each example and comparative example were tested according to the above method, and the test results are shown in Table 1.

[0065] Table 1

[0066] According to the data in Table 1, it can be seen that the porous foam copper materials prepared in Examples 1 to 3 have high porosity, thermal conductivity and compressive strength, and at the same time have good impact resistance; in Example 4, due to the change in the molar ratio of acryloyl chloride, melamine, epichlorohydrin and acid-binding agent, crosslinking occurred during the preparation of the modified polystyrene microspheres, resulting in an increase in particle size, thereby weakening the effect of the pore size gradient distribution of the foam copper, and the thermal conductivity, compressive strength and impact strength decreased; in Example 5, due to the change in the molar ratio of styrene, divinylbenzene and the compound shown in Formula I, the contents of epoxy groups and amide groups in the structure of the modified polystyrene microspheres decreased, resulting in a decrease in the high-temperature resistance of the modified polystyrene microspheres, and the effect of forming a gradient pore size distribution became worse, which was not conducive to improving the compressive strength and impact strength of the foam metal; in Example 6, due to the absence of cetyltrimethylammonium bromide, the ability of single dimethyl sulfoxide to expand the interlayer spacing of kaolin was weak, resulting in a decrease in the amount of copper powder and carboxylated carbon nanotubes entering the kaolin interlayer, and at the same time reducing the compressive strength and impact strength of the internal structure of the foam copper; in Example 7, due to the change in the preparation method of the additive, during the modification of kaolin with dimethyl sulfoxide and cetyltrimethylammonium bromide, a competitive adsorption phenomenon occurred when the two competed for the active sites of kaolin, and cetyltrimethylammonium bromide would hinder dimethyl sulfoxide from entering deeper into the kaolin to expand the interlayer spacing, thereby making the adsorption capacity and dispersibility of kaolin worse, so that the thermal conductivity, compressive strength and impact strength of the foam copper all became weaker; in Example 8, due to the change in the pre-sintering method, the structural effect of the foam metal to form a gradient pore size distribution became worse, resulting in a significant decrease in the porosity of the foam metal, and at the same time the compressive strength and impact strength decreased; in Comparative Example 1, due to the absence of modified polystyrene microspheres during the preparation of the foam copper, the porosity and thermal conductivity of the foam copper decreased, and the impact strength and compressive strength increased slightly; in Comparative Example 2, due to the use of equal-mass kaolin instead of the additive, its dispersibility and adsorption capacity in the system were poor, resulting in uneven pore size distribution of the foam copper, thereby reducing the thermal conductivity, compressive strength and impact strength of the foam copper.

[0067] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the examples, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A preparation method of a novel high - thermal - conductivity heat - dissipating porous foam copper material, characterized in that, It includes the following steps: S1. Prepare two mixtures containing copper powder and additives, and mix them with polystyrene microspheres and modified polystyrene microspheres respectively to obtain mixed materials A and B; S2. Load the mixed material B into mold C and perform isostatic pressing to obtain a green body X; S3. Load the green body X into mold D, and then fill the pores between the green body X and mold D with the mixed material A, and perform isostatic pressing to obtain a green body Y; S4. Under the atmosphere of inert protective gas, pre-sinter and sinter the green body Y to obtain a novel high-thermal-conductivity and heat-dissipating porous foam copper material; The preparation method of the modified polystyrene microspheres includes the following steps: A1. Mix acryloyl chloride and melamine, add them to the first solvent and an acid-binding agent, stir at a constant temperature at room temperature for 2 - 4 h, then add epichlorohydrin, and continue to stir at a constant temperature for 3 - 5 h. After the reaction ends, perform extraction, concentrate the organic phase under reduced pressure, and perform column chromatography to obtain the compound shown in formula I; （Ⅰ）； A2. Under the atmosphere of inert protective gas, mix styrene, divinylbenzene, and the compound shown in formula I in step A1, add them to the second solvent, add an initiator, heat up to 70 - 90 °C and stir at a constant temperature for 12 - 14 h. After the reaction ends, centrifuge, filter, wash, dry, and place at 170 - 200 °C for 1 - 3 h to obtain modified polystyrene microspheres; The preparation method of the additive includes the following steps: B1. Ball-mill kaolin at a rotation speed of 500 rpm for 1 - 2 h to obtain activated kaolin with an average particle size of 1 - 2 μm; B2. Immerse the activated kaolin in step B1 in dimethyl sulfoxide for 22 - 24 h, then add cetyltrimethylammonium bromide and heat up to 60 - 80 °C and soak at a constant temperature for 4 - 8 h, and filter to obtain intercalated modified kaolin; B3. Immerse the intercalated modified kaolin in an ethanol dispersion of 1H,1H,2H,2H-perfluorodecyltrimethoxysilane and carboxylated carbon nanotubes, heat up to 55 - 65 °C and stir at a constant temperature for 4 - 8 h. After the reaction ends, centrifuge and filter, and dry to obtain the product.

2. The preparation method of the novel high thermal conductivity porous foam metal copper material according to claim 1, characterized in that, The average particle size of the polystyrene microspheres is 30 - 50 μm; the average particle size of the modified polystyrene microspheres is 20 - 30 μm.

3. The preparation method of the novel high thermal conductivity heat dissipation porous foam metal copper material according to claim 1, characterized in that, The molar ratio of acryloyl chloride, melamine, epichlorohydrin, and the acid-binding agent is (0.8 - 1):1:(2 - 2.3):(3.4 - 4).

4. The preparation method of the novel highly thermally conductive and heat dissipating porous foam metal copper material according to claim 1, characterized in that, In step A2, the molar ratio of styrene, divinylbenzene, and the compound shown in formula I is 1:(0.2 - 0.4):(0.3 - 0.6).

5. The preparation method of the novel high thermal conductivity and heat dissipating porous foam metal copper material according to claim 1, characterized in that, In step B2, the mass ratio of the activated kaolin, dimethyl sulfoxide, and cetyltrimethylammonium bromide is 1:(5 - 8):(1 - 1.5).

6. The preparation method of the novel high thermal conductivity heat dissipation porous foam metal copper material according to claim 1, characterized in that, In step B3, the mass ratio of 1H,1H,2H,2H-perfluorodecyltrimethoxysilane and carboxylated carbon nanotubes is 1:(0.2 - 0.7).

7. The preparation method of the novel high thermal conductivity porous foam copper material according to claim 1, characterized in that, In step S4, the specific operation of the pre-sintering is: first heat up at a heating rate of 5 - 10 °C / min to 300 - 400 °C, keep warm for 1 - 2 h, and then heat up at a heating rate of 5 - 10 °C / min to 500 - 700 °C, and keep warm for 0.5 - 1.5 h.

8. The preparation method of the novel high thermal conductivity heat dissipation porous foam metal copper material according to claim 1, characterized in that, In step S4, the sintering temperature is 800 - 950 °C, and the time is 3 - 4 h.

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