An in-situ aluminum nitride frame / polymer composite material and a preparation method thereof

Abstract

The application relates to the technical field of composite materials, in particular to an in-situ aluminum nitride framework / polymer composite material and a preparation method thereof. The preparation method comprises the following steps: A) uniformly mixing an aluminum source, a solid nitrogen source, a sintering aid and an additive in a solvent to obtain an aluminum-containing suspension; B) performing directional freeze forming on the aluminum-containing suspension, and obtaining an aluminum-containing raw material powder framework through freeze drying; C) performing an in-situ nitriding reaction on the aluminum-containing raw material powder framework under a nitrogen-containing gas condition, and obtaining an in-situ aluminum nitride framework after carbon removal; and D) vacuum impregnating a polymer into the in-situ aluminum nitride framework, and then performing solidification to obtain the in-situ aluminum nitride framework / polymer composite material. The three-dimensional aluminum nitride framework with a directional network channel is constructed through the ice template method and the in-situ nitriding reaction sintering of aluminum powder, and the aluminum nitride framework / polymer composite material with excellent thermal conductivity is obtained on the basis.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, and in particular to an in-situ aluminum nitride framework / polymer composite material and its preparation method. Background Technology

[0002] In recent years, due to the integration, miniaturization and increasing power density of electronic products, the components of electronic products will generate a lot of heat during operation. If the heat cannot be dissipated as soon as possible, it will reduce the service life and operating speed of electronic devices. This urgently requires the preparation of materials with high thermal conductivity, low coefficient of expansion, light weight and low cost to obtain electronic devices with high thermal conductivity.

[0003] Polymers possess excellent properties such as low specific gravity, good processability, low cost, good chemical stability, and high adhesion, making them widely used in various fields. However, polymer materials themselves have poor thermal conductivity, resulting in poor heat dissipation in the thermal interface materials prepared from them, which greatly limits their application in electronic products. Taking epoxy resin as an example, due to its ease of processing, low cost, and light weight, it is currently widely used in the preparation of electrical insulation and electronic packaging materials. However, its thermal conductivity is only about 0.2 W / (m·K), far from meeting the heat dissipation requirements of rapidly developing electronic components. Research has found that the addition of high thermal conductivity inorganic fillers can effectively improve the thermal properties of polymers. Currently, metal oxides (such as Al2O3, SiO2, MgO, ZnO), carbides (SiC), nitrides (such as AlN, BN, Si3N4), metal powders and fibers, as well as carbon materials such as graphite, graphene, carbon fiber, and carbon black are widely used as fillers in polymer composites. Among various thermally conductive fillers, AlN has high thermal conductivity, is non-toxic, has a stable crystal structure, low dielectric constant, and relatively stable mechanical properties, making it a very promising thermally conductive filler.

[0004] For polymer composites, inorganic fillers are arranged in three main ways within the polymer: random dispersion, anisotropic arrangement, and directional thermally conductive channels. Pre-constructing a three-dimensional framework structure for the filler can reduce the contact thermal resistance between fillers in the composite, achieving high thermal conductivity with relatively low ceramic filler content. The ice-templating method is widely used in the preparation of oriented porous materials due to its advantages such as controllable pores, low processing shrinkage, and high strength. Studies have found that in the preparation of directional aluminum nitride channels using the ice-templating method, due to the high hydrolysis tendency of aluminum nitride, the surface of aluminum nitride needs to be modified beforehand when using water as a solvent to prevent hydrolysis, which is detrimental to improving the thermal conductivity of the subsequent polymer composite. Using organic substances (such as tert-butanol) as a solvent instead of water can avoid aluminum nitride hydrolysis, but the use of non-aqueous solvents increases the material preparation cost. Therefore, finding a more suitable preparation technology for directional aluminum nitride channels is crucial for obtaining high thermal conductivity aluminum nitride / polymer composites. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide an in-situ aluminum nitride framework / polymer composite material and its preparation method. The in-situ aluminum nitride framework / polymer composite material prepared by the present invention has excellent thermal conductivity.

[0006] This invention provides a method for preparing an in-situ aluminum nitride framework / polymer composite material, comprising the following steps:

[0007] A) Mix the aluminum source, solid nitrogen source, sintering aid and additives in a solvent to obtain an aluminum-containing suspension;

[0008] B) After the aluminum-containing suspension is subjected to directional freeze-forming, an aluminum-containing raw material powder framework is obtained by freeze-drying.

[0009] C) The aluminum-containing raw material powder framework is subjected to an in-situ nitriding reaction under nitrogen-containing gas conditions to remove carbon and obtain an in-situ aluminum nitride framework.

[0010] D) After vacuum impregnating the polymer into the in-situ aluminum nitride framework, it is then cured to obtain an in-situ aluminum nitride framework / polymer composite material.

[0011] Preferably, in step A), the aluminum source is aluminum powder.

[0012] Preferably, in step A), the solid nitrogen source includes at least one of melamine, dicyandiamide, and cyanamide;

[0013] The mass ratio of the solid nitrogen source to the aluminum source is 1-3:1-2.

[0014] Preferably, in step A), the sintering aid includes at least one of Y2O3, CaF2, and YF3;

[0015] The sintering aid accounts for 2-5% of the mass of the aluminum source.

[0016] Preferably, in step A), the additive includes a binder and a dispersant;

[0017] The adhesive comprises at least one of sodium carboxymethyl cellulose and polyvinyl alcohol;

[0018] The dispersant includes at least one of citric acid, polyacrylamide, chitosan, and acetic acid.

[0019] Preferably, in step A), the solvent is deionized water.

[0020] Preferably, in step A), the volume of the aluminum source is calculated from the volume of the in-situ aluminum nitride framework, and the volume ratio of the in-situ aluminum nitride framework to the volume of the solvent is 10-50:90-50.

[0021] Preferably, in step B), the temperature for directional freezing is -50 to -180°C, and the time is 3 to 10 minutes.

[0022] Preferably, in step B), the freeze-drying temperature is -50°C and the time is 12 to 24 hours.

[0023] Preferably, in step C), the in-situ nitriding reaction is carried out at a temperature of 900–1400 °C for a time of 120–180 min.

[0024] The flow rate of the nitrogen-containing gas is 80–100 sccm.

[0025] Preferably, in step C), the carbon removal is carried out in air;

[0026] The carbon removal temperature is 600–700℃, and the time is 120–180 min.

[0027] Preferably, in step D), the impregnation solution for vacuum impregnation includes a polymer, a curing agent, and a catalyst;

[0028] The polymer includes at least one of resin, polyimide, polytetrafluoroethylene, and silicone rubber;

[0029] The curing agent is 4-methylhexahydrophthalic anhydride;

[0030] The catalyst is 1-(p-methylbenzenesulfonyl)imidazole.

[0031] Preferably, in step D), the vacuum impregnation time is 1 to 2 hours;

[0032] The vacuum degree of the vacuum impregnation is less than 10. -1Pa;

[0033] The curing process includes first curing at 80–90°C for 2–3 hours, and then curing at 120–130°C for 2–3 hours.

[0034] The present invention also provides an in-situ aluminum nitride framework / polymer composite material prepared by the preparation method described above.

[0035] This invention eliminates the need for pre-synthesizing aluminum nitride powder before constructing the aluminum nitride framework. Instead, it prepares a three-dimensional aluminum nitride framework in situ in one step through the nitridation reaction and sintering of aluminum powder. This shortens the material preparation process and avoids the problem of easy hydrolysis of aluminum nitride during the preparation of suspensions before conventional freeze molding. In addition, the ice template method combined with the directional network channels mainly constructed by aluminum nitride powder after in-situ nitridation reaction and sintering is beneficial for obtaining aluminum nitride / polymer composite materials with excellent surface thermal conductivity.

[0036] This invention provides a method for preparing an in-situ aluminum nitride framework / polymer composite material, comprising the following steps: A) mixing an aluminum source, a solid nitrogen source, a sintering aid, and additives in a solvent to obtain an aluminum-containing suspension; B) subjecting the aluminum-containing suspension to directional freeze-forming, followed by freeze-drying to obtain an aluminum-containing raw material powder framework; C) subjecting the aluminum-containing raw material powder framework to an in-situ nitriding reaction under nitrogen-containing gas conditions to remove carbon and obtain an in-situ aluminum nitride framework; D) vacuum impregnating the polymer into the in-situ aluminum nitride framework, followed by curing to obtain the in-situ aluminum nitride framework / polymer composite material. Compared with existing preparation processes, this invention eliminates the need for pre-preparation or purchase of aluminum nitride powder, greatly simplifying the complex preparation process of the entire thermally conductive composite material from aluminum nitride powder preparation to aluminum nitride / polymer composite material preparation. Furthermore, it solves the problem of easy hydrolysis of aluminum nitride during the preparation of existing aluminum nitride / polymer composite materials, thereby reducing the thermal conductivity of the composite material. The prepared in-situ aluminum nitride framework mainly consists of oriented vertical channels formed by aluminum nitride particles, with aluminum nitride whiskers interspersed between adjacent channels, interconnecting to form thermally conductive channels. After vacuum impregnation with a polymer, an in-situ aluminum nitride framework / polymer composite material with excellent surface thermal conductivity can be obtained. Furthermore, the in-situ aluminum nitride framework / polymer composite material prepared by this invention exhibits excellent mechanical properties. Attached Figure Description

[0037] Figure 1 The images show the XRD patterns of the aluminum-containing raw material powder framework in step 2) and the in-situ aluminum nitride framework in step 3) of Embodiment 1 of the present invention.

[0038] Figure 2 This is an SEM image of the fracture cross section of the in-situ aluminum nitride framework in step 3) of Embodiment 1 of the present invention.

[0039] Figure 3This is an EDS-Mapping diagram of the fracture cross section of the in-situ aluminum nitride framework / polymer composite material of Example 1 of the present invention. Detailed Implementation

[0040] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] This invention provides a method for preparing an in-situ aluminum nitride framework / polymer composite material, comprising the following steps:

[0042] A) Mix the aluminum source, solid nitrogen source, sintering aid and additives in a solvent to obtain an aluminum-containing suspension;

[0043] B) After the aluminum-containing suspension is subjected to directional freeze-forming, an aluminum-containing raw material powder framework is obtained by freeze-drying.

[0044] C) The aluminum-containing raw material powder framework is subjected to an in-situ nitriding reaction under nitrogen-containing gas conditions to remove carbon and obtain an in-situ aluminum nitride framework.

[0045] D) After vacuum impregnating the polymer into the in-situ aluminum nitride framework, it is then cured to obtain an in-situ aluminum nitride framework / polymer composite material.

[0046] In step A):

[0047] In some embodiments of the present invention, the aluminum source is aluminum powder. In some embodiments, the size of the aluminum powder is 1–2 μm. The present invention does not have special requirements for the shape of the aluminum powder.

[0048] In some embodiments of the present invention, the aluminum powder is spherical and / or flake-shaped. In some embodiments, the aluminum powder comprises spherical aluminum powder and flake-shaped aluminum powder, wherein the volume ratio of the spherical aluminum powder to the flake-shaped aluminum powder is 1:1. In the present invention, the aluminum powder can be commercially available.

[0049] In some embodiments of the present invention, the solid nitrogen source includes at least one selected from melamine, dicyandiamide, and cyanamide. The mass ratio of the solid nitrogen source to the aluminum source is 1–3:1–2. In some embodiments, the mass ratio of the solid nitrogen source to the aluminum source is 1:2, 1:1, 2:1, or 3:1. The solid nitrogen source can decompose into ammonia gas at high temperatures, which participates in the aluminum powder nitriding reaction to generate aluminum nitride, while preventing the aluminum powder from melting and closing the channel at high temperatures.

[0050] In some embodiments of the present invention, the sintering aid includes at least one of Y₂O₃, CaF₂, and YF₃. The sintering aid accounts for 2% to 5% of the mass of the aluminum source. In some embodiments, the sintering aid accounts for 5% of the mass of the aluminum source. In some embodiments, the sintering aid includes CaF₂ and YF₃, with a mass ratio of CaF₂ to YF₃ of 3:2. The addition of the sintering aid can promote the nitriding reaction and lower the nitriding reaction temperature.

[0051] In some embodiments of the invention, the additive includes a binder and a dispersant. The binder includes at least one of sodium carboxymethyl cellulose and polyvinyl alcohol. The binder accounts for 0.5 to 2% of the mass of the aluminum source. In some embodiments, the binder accounts for 1% of the mass of the aluminum source.

[0052] In some embodiments of the present invention, the dispersant comprises at least one selected from citric acid, polyacrylamide, chitosan, and acetic acid. The dispersant accounts for 1-4% of the mass of the aluminum source. In some embodiments, the dispersant accounts for 2% of the mass of the aluminum source.

[0053] In some embodiments of the present invention, the solvent is deionized water. The volume of the aluminum source is calculated from the volume of the in-situ aluminum nitride framework, and the volume ratio of the in-situ aluminum nitride framework to the solvent is 10-50:90-50. In some embodiments, the volume ratio of the in-situ aluminum nitride framework to the solvent is 40:60, 20:80, 40:60, or 30:70. In some embodiments of the present invention, the solvent is deionized water. After freeze-drying, a three-dimensional aluminum-containing raw material powder framework can be obtained.

[0054] In some embodiments of the present invention, the mixing is performed by magnetic stirring. In some embodiments, the magnetic stirring time is 24 hours.

[0055] In step B):

[0056] In some embodiments of the present invention, the directional freeze-forming temperature is -50 to -180°C, and the time is 3 to 10 minutes. In some embodiments, the freeze-forming temperature is -70°C. In some embodiments, the freeze-forming time is 5 minutes.

[0057] In some embodiments of the present invention, after freeze-forming, the process further includes freeze-drying. The freeze-drying temperature is -50°C, and the time is 12–24 hours. In some embodiments, the freeze-drying time is 24 hours. Freeze-drying can remove ice crystals formed by water within the three-dimensional aluminum-containing raw material powder framework during the freeze-forming process.

[0058] In step C):

[0059] In some embodiments of the present invention, the nitrogen-containing gas is at least one of nitrogen and ammonia. In some embodiments, the nitrogen-containing gas is nitrogen.

[0060] In some embodiments of the present invention, the flow rate of the nitrogen-containing gas is 80–100 sccm. In some embodiments, the flow rate of the nitrogen-containing gas is 100 sccm.

[0061] In some embodiments of the present invention, the nitriding reaction is carried out at a temperature of 900–1400°C for a time of 120–180 min. In some embodiments, the nitriding reaction is carried out at a temperature of 1400°C. In some embodiments, the nitriding reaction is carried out for a time of 180 min.

[0062] In some embodiments of the present invention, the decarbonization is carried out in air at a temperature of 600–700°C for a time of 120–180 min. In some embodiments, the decarbonization temperature is 700°C. In some embodiments, the decarbonization time is 120 min. After decarbonization, a high-purity porous aluminum nitride three-dimensional framework can be obtained.

[0063] In step D):

[0064] The impregnation solution used in the vacuum impregnation process includes a polymer, a curing agent, and a catalyst.

[0065] In some embodiments of the present invention, the polymer includes at least one of resin, polyimide, polytetrafluoroethylene, and silicone rubber.

[0066] In some embodiments of the present invention, the curing agent is 4-methylhexahydrophthalic anhydride.

[0067] In some embodiments of the present invention, the catalyst is 1-(p-methylbenzenesulfonyl)imidazole.

[0068] In some embodiments of the present invention, the mass ratio of the polymer, curing agent, and catalyst is 90–110:80–90:0.5–1.5. In some embodiments, the mass ratio of the polymer, curing agent, and catalyst is 100:86:1.

[0069] In some embodiments of the present invention, the impregnation solution for vacuum impregnation is prepared according to the following method:

[0070] The polymer, curing agent, and catalyst are stirred and mixed to obtain a vacuum impregnation solution.

[0071] The mixing temperature is 50–70°C, and the mixing time is 30–90 minutes. In some embodiments, the mixing temperature is 60°C. In some embodiments, the mixing time is 60 minutes.

[0072] The stirring speed is 700–900 r / min. In some embodiments, the stirring speed is 700 r / min.

[0073] The mixing method is magnetic stirring.

[0074] In some embodiments of the present invention, the volume ratio of the in-situ aluminum nitride frame to the impregnation liquid is 10–50:90–50. In some embodiments, the volume ratio of the in-situ aluminum nitride frame to the impregnation liquid is 40:60, 20:80, or 30:70.

[0075] In some embodiments of the present invention, the vacuum impregnation temperature is 55–65°C. In some embodiments of the present invention, the vacuum impregnation temperature is 60°C.

[0076] In some embodiments of the present invention, the vacuum degree of the vacuum impregnation is less than 10. -1 Pa.

[0077] In some embodiments of the present invention, the vacuum impregnation time is 1 to 2 hours. In some embodiments, the vacuum impregnation time is 2 hours.

[0078] In some embodiments of the present invention, the curing includes first curing at 80–90°C for 2–3 hours, and then curing at 120–130°C for 2–3 hours. In some embodiments, the curing includes first curing at 90°C for 3 hours, and then curing at 120°C for 3 hours.

[0079] The present invention does not impose any special restrictions on the source of the raw materials used above, and they can be commercially available.

[0080] The present invention also provides an in-situ aluminum nitride framework / polymer composite material prepared by the preparation method described above.

[0081] This invention uses aluminum powder as the main raw material. First, a suspension containing aluminum powder is prepared, and then frozen and freeze-dried using an ice template method to obtain a three-dimensional framework constructed from the aluminum-containing raw material powder. After nitriding and removal of residual carbon, the three-dimensional framework of the aluminum-containing raw material powder is transformed in situ into an aluminum nitride three-dimensional framework. Finally, an in-situ aluminum nitride framework / polymer composite material is obtained using a vacuum infiltration method. Compared with existing preparation processes, this invention does not require the pre-preparation or purchase of aluminum nitride powder, greatly simplifying the complex preparation process of the entire thermally conductive composite material from aluminum nitride powder preparation to aluminum nitride / composite material preparation. Furthermore, it solves the problem of easy hydrolysis of aluminum nitride in the existing aluminum nitride / polymer composite material preparation process, which reduces the thermal conductivity of the composite material. The prepared in-situ aluminum nitride three-dimensional framework mainly consists of vertical channels formed by the oriented arrangement of aluminum nitride particles, while aluminum nitride whiskers are interspersed between adjacent channels, interconnecting to form multiple thermally conductive channels. After vacuum infiltration of the polymer, an in-situ aluminum nitride framework / polymer composite material with excellent thermal conductivity can be obtained. Meanwhile, the in-situ aluminum nitride framework / polymer composite material prepared by this invention exhibits excellent mechanical properties.

[0082] To further illustrate the present invention, the following detailed description of an in-situ aluminum nitride framework / polymer composite material and its preparation method provided by the present invention is provided in conjunction with embodiments, but it should not be construed as limiting the scope of protection of the present invention.

[0083] In the embodiments, the size of the aluminum powder is 1 to 2 μm.

[0084] Example 1

[0085] 1) Add spherical aluminum powder, sintering aid (including YF3 and CaF2 in a mass ratio of 2:3), solid nitrogen source (melamine), and additives (including binder sodium carboxymethyl cellulose and dispersant citric acid) to deionized water as solvent, and stir magnetically for 24 hours to obtain an aluminum-containing suspension.

[0086] The volume of the aluminum powder is calculated from the volume of the in-situ aluminum nitride framework. The volume ratio of the in-situ aluminum nitride framework to the solvent is 40:60. The sintering aid accounts for 5% of the mass of the spherical aluminum powder. The mass ratio of melamine to the aluminum powder is 1:2. The binder accounts for 1% of the mass of the spherical aluminum powder. The dispersant accounts for 2% of the mass of the spherical aluminum powder.

[0087] 2) After the suspension was directionally frozen at -70℃ for 5 min, it was then freeze-dried at -50℃ for 24 h to remove ice crystals and obtain an aluminum-containing raw material powder framework.

[0088] 3) The aluminum-containing raw material powder frame obtained in step 2) is placed in a tube furnace and nitrided at 1400℃ under normal pressure for 3 hours in a flowing nitrogen atmosphere of 100 sccm. Then, it is decarbonized in air at 700℃ for 2 hours to obtain an in-situ aluminum nitride frame.

[0089] 4) Epoxy resin, 4-methylhexahydrophthalic anhydride and 1-(p-methylbenzenesulfonyl)imidazole were mixed at a mass ratio of 100:86:1 and magnetically stirred at 60°C (700 r / min) for 1 h to obtain an impregnation solution.

[0090] The in-situ aluminum nitride framework was immersed in the impregnation solution and vacuum impregnated at 60°C for 2 hours, and then cured at 90°C and 120°C for 3 hours respectively to obtain the in-situ aluminum nitride framework / polymer composite material.

[0091] The aluminum-containing raw material powder framework from step 2) and the in-situ aluminum nitride framework from step 3) were characterized using X-ray diffraction (XRD; Smart Lab, Rigaku, Japan). The results are as follows: Figure 1 As shown. From Figure 1 It can be seen that in the aluminum-containing raw material powder framework, in addition to the main raw materials Al, melamine and additives YF3 and CaF2, a small amount of AlO(OH) is generated due to the hydrolysis of the aluminum powder surface during the preparation of the suspension. However, after nitriding reaction and sintering, the aluminum powder reacts completely and all of it is converted into aluminum nitride, as well as trace oxides YAlO3 and Ca3Al2O6 generated by the reaction with the additives. The aluminum-containing raw material powder framework is transformed into an aluminum nitride framework in situ.

[0092] The fracture cross-section of the in-situ aluminum nitride framework in step 3) was analyzed using a scanning electron microscope (FESEM; Hitachi S-4800, Japan). The results are as follows: Figure 2 As shown. Figure 2 Figures a and b show SEM images of the fracture cross-sections of the in-situ aluminum nitride framework at low and high magnification, respectively. From... Figure 2 It can be seen that the in-situ aluminum nitride framework prepared by ice template method combined with nitriding reaction sintering has obvious vertical channels formed by the directional arrangement of aluminum nitride particles. At the same time, aluminum nitride whiskers are interspersed between adjacent channels and can form multiple heat conduction channels.

[0093] The fracture cross-section of the in-situ aluminum nitride framework / polymer composite material obtained in step 4) was analyzed using a scanning electron microscope (FESEM; Hitachi S-4800, Japan). The results are as follows: Figure 3 As shown. From Figure 3 The EDS-Mapping diagram shows that the thermally conductive channels, mainly formed by aluminum nitride particles, were not destroyed after vacuum impregnation of epoxy resin.

[0094] The surface thermal conductivity of the in-situ aluminum nitride framework / polymer composite material was tested using a laser thermal conductivity meter (model LFA427); the flexural strength was measured using a universal testing machine (AGS-X, Shimadzu, 13 Japan). The test results show that the thermal conductivity of the in-situ aluminum nitride framework / polymer composite material is 4.30 W·m. -1 ·k -1 The bending strength is 98.26 MPa.

[0095] Example 2

[0096] 1) Add spherical aluminum powder, sintering aid (including YF3 and CaF2 in a mass ratio of 2:3), solid nitrogen source (melamine), and additives (including binder sodium carboxymethyl cellulose and dispersant citric acid) to deionized water as solvent, and stir magnetically for 24 hours to obtain a uniformly mixed suspension.

[0097] The volume of the aluminum powder is calculated from the volume of the in-situ aluminum nitride framework. The volume ratio of the in-situ aluminum nitride framework to the volume of the solvent is 20:80. The sintering aid accounts for 5% of the mass of the aluminum powder. The mass ratio of melamine to the aluminum powder is 1:2. The binder accounts for 1% of the mass of the aluminum powder. The dispersant accounts for 2% of the mass of the aluminum powder.

[0098] 2) After the suspension is directionally frozen at -70℃ for 5 minutes to form a solid, it is then freeze-dried at -50℃ for 24 hours to remove ice crystals and obtain an aluminum-containing raw material powder framework.

[0099] 3) The aluminum-containing raw material powder frame obtained in step 2) is placed in a tube furnace and nitrided at 1400℃ under normal pressure for 3 hours in a flowing nitrogen atmosphere of 100 sccm. Then, it is decarbonized in air at 700℃ for 2 hours to obtain an in-situ aluminum nitride frame.

[0100] 4) Epoxy resin, 4-methylhexahydrophthalic anhydride and 1-(p-methylbenzenesulfonyl)imidazole were mixed at a mass ratio of 100:86:1 and magnetically stirred at 60°C (700 r / min) for 1 h to obtain an impregnation solution.

[0101] The in-situ aluminum nitride framework was immersed in the impregnation solution and vacuum impregnated at 60°C for 2 hours, and then cured at 90°C and 120°C for 3 hours respectively to obtain the in-situ aluminum nitride framework / polymer composite material.

[0102] The surface thermal conductivity of the in-situ aluminum nitride framework / polymer composite material was tested using a laser thermal conductivity meter (model LFA427); the flexural strength was measured using a universal testing machine (AGS-X, Shimadzu, 13 Japan). The test results show that the surface thermal conductivity of the in-situ aluminum nitride framework / polymer composite material is 1.23 W·m.-1 ·k -1 The bending strength is 111.28 MPa.

[0103] Example 3

[0104] 1) Add spherical aluminum powder, sintering aid (including YF3 and CaF2 in a mass ratio of 2:3), solid nitrogen source (melamine), and additives (including binder sodium carboxymethyl cellulose and dispersant citric acid) to deionized water as solvent, and stir magnetically for 24 hours to obtain a uniformly mixed suspension.

[0105] The volume of the aluminum powder is calculated from the volume of the in-situ aluminum nitride framework. The volume ratio of the in-situ aluminum nitride framework to the volume of the solvent is 40:60. The sintering aid accounts for 5% of the mass of the aluminum powder. The mass ratio of melamine to the aluminum powder is 1:2. The binder accounts for 1% of the mass of the aluminum powder. The dispersant accounts for 2% of the mass of the aluminum powder.

[0106] 2) After the suspension is directionally frozen at -70℃ for 5 minutes to form a solid, it is then freeze-dried at -50℃ for 24 hours to remove ice crystals and obtain an aluminum-containing raw material powder framework.

[0107] 3) The aluminum-containing raw material powder frame obtained in step 2) is placed in a tube furnace and nitrided at 1200℃ under normal pressure for 3 hours in a flowing nitrogen atmosphere of 100 sccm. Then, it is decarbonized in air at 700℃ for 2 hours to obtain an in-situ aluminum nitride frame.

[0108] 4) Epoxy resin, 4-methylhexahydrophthalic anhydride and 1-(p-methylbenzenesulfonyl)imidazole were mixed at a mass ratio of 100:86:1 and magnetically stirred at 60°C (700 r / min) for 1 h to obtain an impregnation solution.

[0109] The in-situ aluminum nitride framework was immersed in the impregnation solution and vacuum impregnated at 60°C for 2 hours, and then cured at 90°C and 120°C for 3 hours respectively to obtain the in-situ aluminum nitride framework / polymer composite material.

[0110] The surface thermal conductivity of the in-situ aluminum nitride framework / polymer composite material was tested using a laser thermal conductivity meter (model LEA427); the flexural strength was measured using a universal testing machine (AGS-X, Shimadzu, 13 Japan). The test results show that the surface thermal conductivity of the in-situ aluminum nitride framework / polymer composite material is 1.52 W·m. -1 ·k -1 The flexural strength is 96.48 MPa.

[0111] Example 4

[0112] 1) The flake aluminum powder, sintering aid (including YF3 and CaF2 in a mass ratio of 2:3), solid nitrogen source (melamine), and additives (binder sodium carboxymethyl cellulose and dispersant citric acid) are added to the solvent deionized water and magnetically stirred for 24 hours to obtain a uniformly mixed suspension.

[0113] The volume of the aluminum powder is calculated from the volume of the in-situ aluminum nitride framework. The volume ratio of the in-situ aluminum nitride framework to the volume of the solvent is 40:60. The sintering aid accounts for 5% of the mass of the aluminum powder. The mass ratio of melamine to the aluminum powder is 1:2. The binder accounts for 1% of the mass of the aluminum powder. The dispersant accounts for 2% of the mass of the aluminum powder.

[0114] 2) After the suspension is directionally frozen at -70℃ for 5 minutes to form a solid, it is then freeze-dried at -50℃ for 24 hours to remove ice crystals and obtain an aluminum-containing raw material powder framework.

[0115] 3) The aluminum-containing raw material powder frame obtained in step 2) is placed in a tube furnace and nitrided at 1400℃ under normal pressure for 3 hours in a flowing nitrogen atmosphere of 100 sccm. Then, it is decarbonized in air at 700℃ for 2 hours to obtain an in-situ aluminum nitride frame.

[0116] 4) Epoxy resin, 4-methylhexahydrophthalic anhydride and 1-(p-methylbenzenesulfonyl)imidazole were mixed at a mass ratio of 100:86:1 and magnetically stirred at 60°C (700 r / min) for 1 h to obtain an impregnation solution.

[0117] The in-situ aluminum nitride framework was immersed in the impregnation solution and vacuum impregnated at 60°C for 2 hours, and then cured at 90°C and 120°C for 3 hours to obtain the in-situ aluminum nitride framework / polymer composite material.

[0118] The surface thermal conductivity of the in-situ aluminum nitride framework / polymer composite material was tested using a laser thermal conductivity meter (model LFA427); the flexural strength was measured using a universal testing machine (AGS-X, Shimadzu, 13 Japan). The test results show that the thermal conductivity of the in-situ aluminum nitride framework / polymer composite material is 2.25 W·m. -1 ·k -1 The bending strength is 89.13 MPa.

[0119] Example 5

[0120] 1) Add flake aluminum powder, sintering aid (including YF3 and CaF2 in a mass ratio of 2:3), solid nitrogen source (melamine), and additives (including binder sodium carboxymethyl cellulose and dispersant citric acid) to deionized water as solvent. After magnetic stirring for 24 hours, a uniformly mixed suspension is obtained.

[0121] The volume of the aluminum powder is calculated from the volume of the in-situ aluminum nitride framework. The volume ratio of the in-situ aluminum nitride framework to the volume of the solvent is 30:70. The sintering aid accounts for 5% of the mass of the aluminum powder. The mass ratio of melamine to the aluminum powder is 1:2. The binder accounts for 1% of the mass of the aluminum powder. The dispersant accounts for 2% of the mass of the aluminum powder.

[0122] 2) After the suspension is directionally frozen at -70℃ for 5 minutes to form a solid, it is then freeze-dried at -50℃ for 24 hours to remove ice crystals and obtain an aluminum-containing raw material powder framework.

[0123] 3) The aluminum-containing raw material powder frame obtained in step 2) is placed in a tube furnace and nitrided at 1400℃ under normal pressure for 3 hours in a flowing nitrogen atmosphere of 100 sccm. Then, it is decarbonized in air at 700℃ for 2 hours to obtain an in-situ aluminum nitride frame.

[0124] 4) Epoxy resin, 4-methylhexahydrophthalic anhydride and 1-(p-methylbenzenesulfonyl)imidazole were mixed at a mass ratio of 100:86:1 and magnetically stirred at 60°C (700 r / min) for 1 h to obtain an impregnation solution.

[0125] The in-situ aluminum nitride framework was immersed in the impregnation solution and vacuum impregnated at 60°C for 2 hours, and then cured at 90°C and 120°C for 3 hours respectively to obtain the in-situ aluminum nitride framework / polymer composite material.

[0126] The surface thermal conductivity of the in-situ aluminum nitride framework / polymer composite material was tested using a laser thermal conductivity meter (model LFA427); the flexural strength was measured using a universal testing machine (AGS-X, Shimadzu, 13 Japan). The test results show that the surface thermal conductivity of the in-situ aluminum nitride framework / polymer composite material is 1.772 W·m. -1 ·k -1 The bending strength is 94.82 MPa.

[0127] Example 6

[0128] 1) Add spherical aluminum powder, flake aluminum powder, sintering aid (including YF3 and CaF2 in a mass ratio of 2:3), solid nitrogen source (melamine), and additives (binder sodium carboxymethyl cellulose and dispersant citric acid) to deionized water as solvent. After magnetic stirring for 24 hours, a uniformly mixed suspension is obtained.

[0129] The volume of the aluminum powder is calculated from the volume of the in-situ aluminum nitride framework. The volume ratio of the in-situ aluminum nitride framework to the volume of the solvent is 40:60. The sintering aid accounts for 5% of the total aluminum powder mass. The mass ratio of melamine to the total aluminum powder mass is 1:2. The binder accounts for 1% of the total aluminum powder mass. The dispersant accounts for 2% of the total aluminum powder mass.

[0130] 2) After the suspension is oriented frozen at -70℃ for 5 minutes to form a solid, it is then freeze-dried at -50℃ for 24 hours to remove ice crystals and obtain an aluminum-containing raw material powder framework.

[0131] 3) The aluminum-containing raw material powder frame obtained in step 2) is placed in a tube furnace and nitrided at 1400℃ under normal pressure for 3 hours in a nitrogen atmosphere with a flow rate of 100 sccm. Then, carbon is removed at 700℃ for 2 hours to obtain an in-situ aluminum nitride frame.

[0132] 4) Epoxy resin, 4-methylhexahydrophthalic anhydride and 1-(p-methylbenzenesulfonyl)imidazole were mixed at a mass ratio of 100:86:1 and magnetically stirred at 60°C (700 r / min) for 1 h to obtain an impregnation solution.

[0133] The in-situ aluminum nitride framework was immersed in the impregnation solution and vacuum impregnated at 60°C for 2 hours, and then cured at 90°C and 120°C for 3 hours to obtain the in-situ aluminum nitride framework / polymer composite material.

[0134] The surface thermal conductivity of the in-situ aluminum nitride framework / polymer composite material was tested using a laser thermal conductivity meter (model LFA427); the flexural strength was measured using a universal testing machine (AGS-X, Shimadzu, 13 Japan). The test results show that the thermal conductivity of the in-situ aluminum nitride framework / polymer composite material is 2.05 W·m. -1 ·k -1 The bending strength is 91.56 MPa.

[0135] Example 7

[0136] 1) Add spherical aluminum powder, flake aluminum powder, sintering aid (including YF3 and CaF2 in a mass ratio of 2:3), solid nitrogen source (melamine), and additives (binder sodium carboxymethyl cellulose and dispersant citric acid) to deionized water as solvent. After magnetic stirring for 24 hours, a uniformly mixed suspension is obtained.

[0137] The volume ratio of spherical aluminum powder to flake aluminum powder is 1:1. The total volume of aluminum powder is calculated from the volume of the in-situ aluminum nitride framework. The volume ratio of the in-situ aluminum nitride framework to the solvent is 30:70. The sintering aid accounts for 5% of the total aluminum powder mass. The mass ratio of melamine to the total aluminum powder is 1:2. The binder accounts for 1% of the total aluminum powder mass. The dispersant accounts for 2% of the total aluminum powder mass.

[0138] 2) After the suspension is directionally frozen at -70℃ for 5 minutes to form a solid, it is then freeze-dried at -50℃ for 24 hours to remove ice crystals and obtain an aluminum-containing raw material powder framework.

[0139] 3) The aluminum-containing raw material powder frame obtained in step 2) is placed in a tube furnace and nitrided at 1200℃ under normal pressure for 3 hours under a flowing nitrogen atmosphere of 100 sccm. Then, it is decarbonized in air at 700℃ for 2 hours to obtain an in-situ aluminum nitride frame.

[0140] 4) Epoxy resin, 4-methylhexahydrophthalic anhydride and imidazole were mixed at a mass ratio of 100:86:1 and magnetically stirred at 60°C (700 r / min) for 1 h to obtain an impregnation solution.

[0141] The in-situ aluminum nitride framework was immersed in the impregnation solution and vacuum impregnated at 60°C for 2 hours, and then cured at 90°C and 120°C for 3 hours to obtain the in-situ aluminum nitride framework / polymer composite material.

[0142] The surface thermal conductivity of the in-situ aluminum nitride framework / polymer composite material was tested using a laser thermal conductivity meter (model LFA427); the flexural strength was measured using a universal testing machine (AGS-X, Shimadzu, 13 Japan). The test results show that the thermal conductivity of the in-situ aluminum nitride framework / polymer composite material is 1.42 W·m. -1 ·k -1 The flexural strength is 94.79 MPa.

[0143] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not 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 an in-situ aluminum nitride framework / polymer composite material, comprising the following steps: A) mixing aluminum powder, a solid nitrogen source, a sintering aid, and an additive in deionized water to obtain an aluminum-containing suspension; B) performing directional freeze forming on the aluminum-containing suspension, and then obtaining an aluminum-containing raw material powder framework by freeze drying; C) performing an in-situ nitriding reaction on the aluminum-containing raw material powder framework in a nitrogen-containing gas, and then obtaining an in-situ aluminum nitride framework after carbon removal; D) vacuum impregnating an impregnating solution into the in-situ aluminum nitride framework, and then performing solidification to obtain an in-situ aluminum nitride framework / polymer composite material.

2. The production method according to claim 1, characterized by, In step A), the solid nitrogen source comprises at least one of melamine, dicyandiamide, and cyanamide. The mass ratio of the solid nitrogen source to the aluminum powder is 1-3:1-2.

3. The preparation method according to claim 1, characterized in that, In step A), the sintering aid comprises at least one of Y2O3, CaF2, and YF3. The sintering aid accounts for 2-5% of the mass of the aluminum powder.

4. The method of claim 1, wherein, In step A), the additive comprises a binder and a dispersant. The binder comprises at least one of sodium carboxymethyl cellulose and polyvinyl alcohol. The dispersant comprises at least one of citric acid, polyacrylamide, chitosan, and acetic acid.

5. The preparation method according to claim 1, characterized in that, In step A), the volume of the aluminum powder is converted from the volume of the in-situ aluminum nitride framework, and the volume ratio of the in-situ aluminum nitride framework to the deionized water is 10-50:90-50.

6. The method of claim 1, wherein, In step B), the temperature of the directional freeze forming is -50 to -180℃, and the time is 3-10 min.

7. The preparation method according to claim 1, characterized in that, In step B), the temperature of the freeze drying is -50℃, and the time is 12-24 h.

8. The method of claim 1, wherein, In step C), the temperature of the in-situ nitriding reaction is 900-1400℃, and the time is 120-180 min. The gas flow of the nitrogen-containing gas is 80-100 sccm.

9. The method of claim 1, wherein, In step C), the carbon removal is performed in air. The temperature of the carbon removal is 600-700℃, and the time is 120-180 min.

10. The method of claim 1, wherein, In step D), the impregnating solution for vacuum impregnation comprises a polymer, a curing agent, and a catalyst. The polymer is an epoxy resin. The curing agent is 4-methyl hexahydrophthalic anhydride. The catalyst is 1-(p-methylbenzenesulfonyl)imidazole.

11. The method of claim 1, wherein, In step D), the time for vacuum impregnation is 1-2 h. The vacuum infiltration has a vacuum degree less than 10 -1 Pa; The solidification comprises first solidifying at 80-90℃ for 2-3 h, and then solidifying at 120-130℃ for 2-3 h. 12.An in-situ aluminum nitride framework / polymer composite material prepared by the method of any one of claims 1-11.

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