Flake aluminum nitride and its preparation method

Abstract

This invention provides a method for preparing flake-shaped aluminum nitride. The method includes: a paste-making step, in which nano-alumina powder, modified cellulose, and an organic solvent are mixed and dispersed to obtain a pre-dispersed paste; a carbon-containing porous body preparation step, in which the pre-dispersed paste is subjected to a first heat treatment to obtain a carbon-containing porous body; a carbothermal reduction step, in which the carbon-containing porous body is subjected to carbothermal reduction treatment under a nitrogen atmosphere to obtain carbon-containing aluminum nitride; and a decarburization step, in which the carbon-containing aluminum nitride is decarburized to obtain flake-shaped aluminum nitride. By preparing nano-alumina powder, modified cellulose, and an organic solvent into a paste, and through stepwise carbonization and carbothermal reaction, flake-shaped aluminum nitride can be prepared on a large scale, with a simple process flow and low cost.

Description

Technical Field

[0001] This invention relates to the field of ceramic powders, and particularly to a sheet-like aluminum nitride and its preparation method. Background Technology

[0002] 5G and intelligent technologies have driven the miniaturization and integration of electronic devices, and the resulting high heat flux density has made heat dissipation design a key constraint on device performance. Against this backdrop, the importance of thermal interface materials (TIMs) used to fill the micro-gap between chips and heat sinks is increasingly evident. To overcome the bottleneck of insufficient thermal conductivity of polymer-based thermal interface materials (TIMs), incorporating highly thermally conductive functional fillers is the mainstream technical approach. Among them, aluminum nitride, due to its excellent thermal conductivity and physical properties compatible with semiconductor processes, is considered one of the ideal fillers for solving the heat dissipation problems of next-generation high-power-density electronic devices, especially in the semiconductor and integrated circuit manufacturing fields where material purity is critical.

[0003] Flake-shaped aluminum nitride has unique advantages in some application areas. In related technologies, CN104828792A discloses a method for preparing flake-shaped aluminum nitride by first decomposing a precursor using water-soluble inorganic aluminum salts in combination with amine organic compounds, water-soluble carbon sources, and auxiliary agents, followed by nitriding. CN115010100A discloses a method for obtaining flake-shaped aluminum nitride powder by ball milling spherical aluminum powder as raw material and then in-situ nitriding the flake aluminum. CN120965343A discloses a method for preparing flake-shaped aluminum nitride by ball milling and uniformly mixing Al2O3 powder, carbon black, and cryolite (Na3AlF6) followed by carbothermic reduction. However, in these related technologies, the production of flake-shaped aluminum powder using the carbothermic reduction of water-soluble aluminum salts results in a low content of aluminum powder with flake morphology in the product, and the raw material process is complex. The quality of aluminum nitride powder prepared by nitriding metallic aluminum sheets is not high. The preparation of sheet aluminum nitride using cryolite inevitably introduces impurities such as Na, making it impossible to guarantee high purity. Summary of the Invention

[0004] In view of the problems existing in the prior art, the present invention provides a method for preparing sheet-like aluminum nitride, which can at least improve one of the problems of low production efficiency, complex process and Na impurities in the prior art.

[0005] The first aspect of this invention provides a method for preparing sheet-like aluminum nitride, the method comprising:

[0006] In the ointment preparation process, nano-alumina powder, modified cellulose, and organic solvent are mixed and dispersed to obtain a pre-dispersed ointment;

[0007] The carbon-containing porous body preparation process involves subjecting a pre-dispersed paste to a first heat treatment to obtain a carbon-containing porous body.

[0008] The carbothermal reduction process involves carbothermizing carbon-containing porous materials under a nitrogen atmosphere to obtain carbon-containing aluminum nitride.

[0009] The decarburization process involves decarburizing carbon-containing aluminum nitride to obtain flake aluminum nitride.

[0010] The above method for preparing sheet-like aluminum nitride avoids the sol-gel method, thus preventing the reduction in industrial production efficiency caused by the rapid volume expansion of the sol-gel method and improving production efficiency. First, nano-alumina powder, modified cellulose, and organic solvents are prepared into a paste. The paste has a high solid content and low fluidity, which allows for control over the amount of organic solvent used, avoiding significant solvent loss and reducing costs. Furthermore, the absence of carbon black components minimizes the impact of carbon black structure on the carbon-containing porous structure. Simultaneously, utilizing the characteristics of the paste, limited organic solvent volatilization occurs during heating, leading to carbonization of the modified cellulose and the formation of a carbon-containing porous structure conducive to the growth of sheet-like aluminum nitride. This enables large-scale, simple, and low-cost preparation of sheet-like aluminum nitride.

[0011] In some embodiments, the particle size D50 of the nano-alumina powder is 100-500 nm.

[0012] In some embodiments, the modified cellulose is one or more of methylcellulose, ethylcellulose, and cellulose acetate butyrate.

[0013] In some embodiments, the mass ratio of nano-alumina powder, modified cellulose, and organic solvent is 1:(1~3):(5~7).

[0014] In some embodiments, the organic solvent is at least one selected from terpineol, diethylene glycol butyl ether acetate, ethyl acetate, and ethylene glycol ethyl ether.

[0015] In some embodiments, the process of mixing and dispersing nano-alumina powder, modified cellulose, and organic solvent to obtain a pre-dispersed paste includes: mixing modified cellulose and organic solvent to form an organic carrier dispersion, mixing nano-alumina powder with the organic carrier dispersion to form a dispersion slurry, and introducing the dispersion slurry into a three-roll mill for rolling to obtain a pre-dispersed paste.

[0016] In a further embodiment, mixing modified cellulose and an organic solvent to form an organic carrier dispersion includes: heating the organic solvent to 60-90°C and adding modified cellulose in batches to the stirred organic solvent at a stirring rate of 500-800 rpm to disperse the modified cellulose and obtain an organic carrier dispersion.

[0017] In a further embodiment, mixing nano-alumina powder with an organic carrier dispersion to form a dispersion slurry includes: adding nano-alumina powder to the organic carrier dispersion in batches at a stirring rate of 500-700 rpm until no dry powder remains, and then cooling to obtain the dispersion slurry.

[0018] In some embodiments, the first heat treatment of the pre-dispersed paste to obtain a carbon-containing porous body includes: heating the pre-dispersed paste to 300-400°C at a rate of 5-15°C / min in a nitrogen atmosphere and holding it at that temperature for 1-3 hours to obtain a carbon-containing porous body.

[0019] In some embodiments, the carbonothermic reduction treatment of carbon-containing porous bodies to obtain aluminum carbon nitride under a nitrogen atmosphere includes: heating the carbon-containing porous body to 1550-1750°C at a rate of 15-30°C / min under a nitrogen atmosphere and holding it at that temperature for 5-7 hours to generate aluminum carbon nitride.

[0020] In some embodiments, decarburizing aluminum nitride to obtain flake aluminum nitride includes: placing aluminum nitride containing carbon at 650-750°C in an oxygen-containing atmosphere for 5-7 hours to obtain flake aluminum nitride.

[0021] A second aspect of the present invention provides a sheet-like aluminum nitride, which is prepared by the above-described preparation method.

[0022] Other further beneficial effects of the present invention can be seen in the description of the specific embodiments. Attached Figure Description

[0023] Figure 1 An optical photograph of the pre-dispersed paste obtained in Example 1 of the present invention is shown;

[0024] Figure 2 An optical photograph of the carbon-containing porous body obtained in Example 1 of the present invention is shown;

[0025] Figure 3 The image shown is a SEM image of the sheet-like aluminum nitride obtained in Example 1 of the present invention;

[0026] Figure 4 The SEM image of aluminum nitride obtained in Comparative Example 1 of the present invention is shown. Detailed Implementation

[0027] The "range" disclosed in this invention is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0028] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0029] Unless otherwise specified, all technical features and optional technical features of this invention can be combined to form new technical solutions.

[0030] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, optionally sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0031] Unless otherwise specified, the terms "comprising" and "including" as used in this invention are open-ended but can also be closed-ended. For example, "comprising" and "including" may also include or contain other components not listed, or may include only or contain the listed components.

[0032] Unless otherwise specified, the term "or" is inclusive in this invention. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0033] In this article, in the semantic context of representing time, "h" represents hours.

[0034] In this article, paste refers to a semi-solid material with poor flowability or almost no flowability.

[0035] As mentioned above, the relevant technologies suffer from problems such as low production efficiency of aluminum nitride, complex processes, and sodium impurities.

[0036] In view of this, a first aspect of the present invention provides a method for preparing sheet-like aluminum nitride, the method comprising:

[0037] In the ointment preparation process, nano-alumina powder, modified cellulose, and organic solvent are mixed and dispersed to obtain a pre-dispersed ointment;

[0038] The carbon-containing porous body preparation process involves subjecting a pre-dispersed paste to a first heat treatment to obtain a carbon-containing porous body.

[0039] The carbothermal reduction process involves carbothermizing carbon-containing porous materials under a nitrogen atmosphere to obtain carbon-containing aluminum nitride.

[0040] The decarburization process involves decarburizing carbon-containing aluminum nitride to obtain flake aluminum nitride.

[0041] In this embodiment of the invention, nano-alumina powder is used in combination with modified cellulose, without employing the sol-gel method. This avoids the reduction in industrial production efficiency caused by the rapid volume expansion of the sol-gel method, thus improving production efficiency. In the above preparation method, nano-alumina powder, modified cellulose, and organic solvent are first prepared into a paste. The paste has a high solid content and low fluidity. On the one hand, this allows for control over the amount of organic solvent used, avoiding significant solvent loss and reducing costs. On the other hand, the absence of carbon black components reduces the impact of carbon black structure on the carbon-containing porous structure. Simultaneously, utilizing the characteristics of the paste, a small amount of organic solvent evaporates during heating, and the modified cellulose carbonizes, forming a carbon-containing porous structure conducive to the growth of sheet-like aluminum nitride. Based on this, a carbothermal reduction process and a decarburization process are sequentially performed to obtain sheet-like aluminum nitride. This enables large-scale, low-cost preparation of high-quality sheet-like aluminum nitride.

[0042] In some embodiments, the particle size D50 of the nano-alumina powder is 100-500 nm. For example, the particle size D50 of the nano-alumina powder can be 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, or any value within the range of 100-500 nm, or a range consisting of any two of the above values.

[0043] In some embodiments, the modified cellulose is one or more of methylcellulose, ethylcellulose, and cellulose acetate butyrate.

[0044] In some embodiments, the mass ratio of nano-alumina powder, modified cellulose, and organic solvent is 1:(1~3):(5~7). Modified cellulose serves as a dispersion medium for forming the paste and also as a carbon source. Through a first heat treatment, it forms a carbon-containing porous structure that coats the nano-alumina powder and restricts the growth direction of the aluminum nitride subsequently converted from the nano-alumina, promoting the formation of plate-like aluminum nitride. Excessive addition of modified cellulose reduces production efficiency, while insufficient addition fails to form a suitable carbon-containing porous structure, hindering the formation of plate-like aluminum nitride. Insufficient organic solvent prevents uniform dispersion of the nano-alumina powder and modified cellulose, ultimately affecting the particle size of the plate-like aluminum nitride. Excessive organic solvent hinders paste formation, preventing the formation of a suitable carbon-containing porous structure through the first heat treatment, thus affecting the formation of plate-like aluminum nitride powder. Simultaneously, excessive organic solvent during the first heat treatment also leads to significant heat and solvent loss, impacting industrial production efficiency and cost.

[0045] In some embodiments, the organic solvent is at least one selected from terpineol, diethylene glycol butyl ether acetate, ethyl acetate, and ethylene glycol ethyl ether. Using this organic solvent facilitates complete evaporation during heating, leaving almost no residue, and also exhibits good compatibility with modified cellulose, promoting the formation of a paste in which nano-alumina powder and modified cellulose are uniformly dispersed.

[0046] Understandably, there are many ways to mix and disperse nano-alumina powder, modified cellulose, and organic solvents to obtain a pre-dispersed paste, as long as the final mixture presents a paste-like form.

[0047] In some embodiments, the process of mixing and dispersing nano-alumina powder, modified cellulose, and organic solvent to obtain a pre-dispersed paste includes: mixing modified cellulose and organic solvent to form an organic carrier dispersion, mixing nano-alumina powder with the organic carrier dispersion to form a dispersion slurry, and introducing the dispersion slurry into a three-roll mill for rolling to obtain the pre-dispersed paste.

[0048] In the above embodiments, the steps of mixing modified cellulose and organic solvent to form an organic carrier dispersion, and mixing nano-alumina powder with the organic carrier dispersion to form a dispersion slurry, can be performed in a dispersion container. Exemplarily, the dispersion container is a container equipped with a stirring device, such as a dispersion tank with a stirring device. Pre-mixing the modified cellulose and organic solvent to form an organic carrier dispersion, and then mixing the nano-alumina with the organic carrier dispersion to form a dispersion slurry, facilitates the uniform mixing of nano-alumina and modified cellulose.

[0049] In a further embodiment, mixing modified cellulose and an organic solvent to form an organic carrier dispersion includes: heating the organic solvent to 60-90°C and adding modified cellulose in batches to the stirred organic solvent at a stirring rate of 500-800 rpm to disperse the modified cellulose and obtain the organic carrier dispersion. Suitable temperature and stirring rate facilitate the rapid and complete dissolution of modified cellulose in the organic solvent, thereby benefiting the subsequent dispersion of nano-alumina powder.

[0050] In a further embodiment, mixing the nano-alumina powder with the organic carrier dispersion to form a dispersion slurry includes: adding the nano-alumina powder in batches to the organic carrier dispersion at a stirring rate of 500-700 rpm until no dry powder remains, and then cooling to obtain the dispersion slurry. It is understood that the temperature of the organic carrier dispersion is generally between 60-90°C. After the nano-alumina powder is added in batches, it remains at a relatively high temperature; cooling is beneficial for the next processing step. The final cooling temperature can be selected according to the requirements of the subsequent slurry-making equipment; for example, cooling to room temperature can be used.

[0051] Understandably, the primary objective of the heat treatment is to evaporate the organic solvent while simultaneously carbonizing the modified cellulose, thereby forming a carbon-containing porous body. To achieve this objective, it is advantageous to conduct the treatment in a vacuum or inert atmosphere, and preferably in a nitrogen atmosphere.

[0052] In some implementations, the first heat treatment of the pre-dispersed paste to obtain a carbon-containing porous body includes: heating the pre-dispersed paste to 300-400°C at a rate of 5-15°C / min in a nitrogen atmosphere and holding it at that temperature for 1-3 hours to obtain the carbon-containing porous body. For example, the heating rate can be 5°C / min, 8°C / min, 10°C / min, 12°C / min, or 15°C / min. The endpoint temperature of the first heat treatment, 300°C, 320°C, 340°C, 360°C, 380°C, or 400°C, is any value within the range of 300-400°C or a range consisting of any two of the above values.

[0053] During the heating process, the organic solvent evaporates, and during the holding process, the modified cellulose decomposes into amorphous carbon that uniformly coats the nano-alumina powder, generating gas that is released, forming a loose porous structure. A suitable heating rate helps control the evaporation rate of the organic solvent; an excessively high heating rate leads to rapid evaporation, forming an undesirable macroporous structure, which is detrimental to obtaining the desired carbon-containing porous structure. Similarly, a suitable holding temperature helps control the carbonization rate, thereby controlling the evaporation rate of the gases generated during carbonization, which also helps control the morphology of the carbon-containing porous body. A suitable carbon-containing porous structure is beneficial for further improving the yield of plate-like aluminum nitride.

[0054] In some embodiments, the carbothermic reduction treatment of carbon-containing porous bodies to obtain aluminum carbon nitride under a nitrogen atmosphere includes: heating the carbon-containing porous body to 1550-1750°C at a rate of 15-30°C / min under a nitrogen atmosphere and holding it at that temperature for 5-7 hours to generate aluminum carbon nitride. The holding temperature is chosen to facilitate the carbothermic reduction reaction and control grain growth. If the temperature is too low, the reaction will be incomplete; if the temperature is too high, the generated aluminum nitride will grow abnormally, resulting in aluminum nitride particles with excessively large sizes.

[0055] In some embodiments, decarburizing aluminum carbonitride to obtain flake aluminum nitride includes: placing the aluminum carbonitride in an oxygen-containing atmosphere at 650-750°C for 5-7 hours to obtain flake aluminum nitride. It is understood that in an oxygen-containing atmosphere, carbon can react with oxygen and thus be removed. Exemplarily, the oxygen-containing atmosphere can be an air atmosphere.

[0056] A second aspect of the present invention provides a sheet-like aluminum nitride, which is prepared by the above-described preparation method.

[0057] The following embodiments describe the disclosure of this invention in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of this disclosure. Unless otherwise stated, all reagents and raw materials used in the embodiments are commercially available or synthesized by conventional methods, and the instruments used in the embodiments are also commercially available.

[0058] In the following embodiments, the morphology of the sheet-like aluminum nitride was observed using a FESEM with the model number MAIA3TESCAN.

[0059] In the following examples, the nano-alumina powder was AKP-30 purchased from Sumitomo Corporation of Japan;

[0060] In the following examples, the ethyl cellulose was ETHOCEL Standard 4 purchased from Dow Chemical.

[0061] Example 1

[0062] (1) Add 600g of terpineol to a beaker, place it in a water bath at 85℃, turn on the stirrer, and set the speed to 500RPM.

[0063] (2) Add 200g of ethyl cellulose slowly in batches until it is completely dispersed to obtain an organic carrier dispersion;

[0064] (3) Add nano alumina powder (100g in total) to the organic carrier dispersion in batches until there is no dry powder. Remove and let cool naturally to obtain the dispersion slurry.

[0065] (4) The dispersion slurry is rolled in a three-roll mill to obtain a uniform and fine pre-dispersed paste;

[0066] (5) The pre-dispersed paste was placed in a muffle furnace and heated at 350°C for 2 hours under a nitrogen atmosphere at a preset heating rate of 10°C / min to obtain a carbon-containing porous body.

[0067] (6) The carbon-containing porous body was placed in a sintering furnace to reduce alumina. The temperature was raised to 1650℃ at a rate of 25℃ / min under a nitrogen atmosphere and held for 6 hours to obtain carbon-containing aluminum nitride.

[0068] (7) Carbon-containing aluminum nitride is placed in a muffle furnace for decarburization and kept at 650°C for 6 hours in air atmosphere to obtain flake aluminum nitride powder.

[0069] refer to Figure 3 It can be seen that the obtained aluminum nitride powder is in the form of flakes.

[0070] Example 2

[0071] (1) Add 700g of ethylene glycol ethyl ether to a beaker, place it in a water bath at 85℃ and keep it at a constant temperature. Turn on the stirrer and set the speed to 500RPM.

[0072] (2) Add 300g of ethyl cellulose slowly in batches until it is completely dispersed to obtain an organic carrier dispersion;

[0073] (3) Add nano alumina powder (100g in total) to the organic carrier dispersion in batches until there is no dry powder. Remove and let cool naturally to obtain the dispersion slurry.

[0074] (4) The dispersion slurry is rolled in a three-roll mill to obtain a uniform and fine pre-dispersed paste;

[0075] (5) Place the pre-dispersed paste into a muffle furnace and heat it at 300°C for 3 hours under a nitrogen atmosphere at a preset heating rate of 5°C / min to obtain a carbon-containing porous body.

[0076] (6) The carbon-containing porous body was placed in a sintering furnace to reduce alumina. The temperature was raised to 1700℃ at a rate of 25℃ / min under a nitrogen atmosphere and held for 5 hours to obtain carbon-containing aluminum nitride.

[0077] (7) Carbon-containing aluminum nitride is placed in a muffle furnace for decarburization and kept at 700°C for 6 hours in air atmosphere to obtain flake aluminum nitride powder.

[0078] Comparative Example 1

[0079] (1) Mix 300g terpineol, 100g nano carbon black and 100g nano alumina powder to obtain a mixture;

[0080] (2) The mixture was heated at a preset heating rate of 10℃ / min and kept at 350℃ for 2h under nitrogen atmosphere to obtain a dry mixture;

[0081] (3) The carbon-containing porous body was placed in a sintering furnace to reduce alumina. The temperature was raised to 1650℃ at a rate of 25℃ / min under a nitrogen atmosphere and held for 6 hours to obtain carbon-containing aluminum nitride.

[0082] (4) Carbon-containing aluminum nitride is placed in a muffle furnace for decarburization and kept at 650°C for 6 hours in air atmosphere to obtain aluminum nitride powder.

[0083] The aluminum nitride powder obtained in this comparative example was in granular form and did not exhibit a flake-like morphology.

[0084] Comparative Example 2

[0085] (1) Mix 300g terpineol, 100g nano alumina powder and 80g ethyl cellulose to obtain a mixture;

[0086] (2) The mixture was heated at a preset heating rate of 10℃ / min and kept at 350℃ for 2h under nitrogen atmosphere to obtain a dry mixture;

[0087] (3) The carbon-containing porous body was placed in a sintering furnace to reduce alumina. The temperature was raised to 1650℃ at a rate of 25℃ / min under a nitrogen atmosphere and held for 6 hours to obtain carbon-containing aluminum nitride.

[0088] (4) Carbon-containing aluminum nitride is placed in a muffle furnace for decarburization and kept at 650°C for 6 hours in air atmosphere to obtain aluminum nitride powder.

[0089] The aluminum nitride powder obtained in this comparative example was in granular form and did not exhibit a flaky morphology. Furthermore, the aluminum nitride had low purity and contained some unreduced aluminum oxide.

[0090] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0091] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing sheet-like aluminum nitride, characterized in that, The preparation method includes: In the ointment preparation process, nano-alumina powder, modified cellulose, and organic solvent are mixed and dispersed to obtain a pre-dispersed ointment; The carbon-containing porous body preparation process involves subjecting the pre-dispersed paste to a first heat treatment to obtain the carbon-containing porous body; The carbothermal reduction process involves treating the carbon-containing porous body under a nitrogen atmosphere to obtain carbon-containing aluminum nitride. The decarburization process involves decarburizing the carbon-containing aluminum nitride to obtain flake-shaped aluminum nitride. The mass ratio of the nano-alumina powder, the modified cellulose, and the organic solvent is 1:(1~3):(5~7); The method of mixing and dispersing nano-alumina powder, modified cellulose, and organic solvent to obtain a pre-dispersed paste includes: mixing the modified cellulose and the organic solvent to form an organic carrier dispersion, mixing the nano-alumina powder with the organic carrier dispersion to form a dispersion slurry, and introducing the dispersion slurry into a three-roll mill for rolling to obtain the pre-dispersed paste. The first heat treatment of the pre-dispersed paste to obtain a carbon-containing porous body includes: heating the pre-dispersed paste to 300-400°C at a rate of 5-15°C / min in a nitrogen atmosphere and holding it at that temperature for 1-3 hours to obtain a carbon-containing porous body. The process of obtaining aluminum carbon nitride by carbothermic reduction of carbon-containing porous body under nitrogen atmosphere includes: heating the carbon-containing porous body to 1550-1750℃ at a rate of 15-30℃ / min under nitrogen atmosphere and holding it at that temperature for 5-7h to generate aluminum carbon nitride.

2. The method for preparing sheet-like aluminum nitride according to claim 1, characterized in that: The particle size D50 of the nano-alumina powder is 100-500 nm.

3. The method for preparing sheet-like aluminum nitride according to claim 1, characterized in that: The modified cellulose is one or more of methylcellulose, ethylcellulose, and cellulose acetate butyrate.

4. The method for preparing sheet-like aluminum nitride according to claim 1, characterized in that: The organic solvent is at least one of terpineol, diethylene glycol butyl ether acetate, ethyl acetate, and ethylene glycol ethyl ether.

5. The method for preparing sheet-like aluminum nitride according to claim 1, characterized in that: The step of mixing the modified cellulose and the organic solvent to form an organic carrier dispersion includes: heating the organic solvent to 60-90°C and adding the modified cellulose in batches to the stirred organic solvent at a stirring rate of 500-800 rpm to disperse the modified cellulose and obtain the organic carrier dispersion.

6. The method for preparing sheet-like aluminum nitride according to claim 1, characterized in that: The step of mixing the nano-alumina powder with the organic carrier dispersion to form a dispersion slurry includes: adding the nano-alumina powder to the organic carrier dispersion in batches at a stirring rate of 500-700 rpm until no dry powder remains, and then cooling to obtain the dispersion slurry.

7. The method for preparing sheet-like aluminum nitride according to claim 1, characterized in that: The process of decarburizing the carbon-containing aluminum nitride to obtain flake aluminum nitride includes: placing the carbon-containing aluminum nitride in an oxygen-containing atmosphere at 650-750°C for 5-7 hours to obtain the flake aluminum nitride.

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