Method for regulating carbon content in aluminum nitride, product and application

Abstract

The application belongs to the field of aluminum nitride preparation, and discloses a method for regulating carbon content in aluminum nitride, a product and application thereof, which comprises the following steps: mixing a glucose alcohol solution with aluminum nitride powder, performing ball milling to obtain slurry with uniform mixing; drying the slurry to obtain dry powder; and performing heat treatment on the dry powder under vacuum or inert atmosphere to regulate the carbon content in the aluminum nitride. The method solves the problem that, when regulating the carbon content in the preparation process of aluminum nitride powder, carbon black is often used as a carbon source, the carbon source is not easy to disperse and is prone to agglomeration, the use amount of the carbon source is relatively large, and the uniformity of the obtained aluminum nitride powder cannot meet the requirements.

Description

Technical Field

[0001] This invention belongs to the field of aluminum nitride preparation, specifically relating to a method, product, and application for controlling the carbon content in aluminum nitride. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] A standard sample, sometimes called a standard substance, is a material or substance with one or more sufficiently homogeneous and well-defined characteristic values ​​used to calibrate measuring devices, evaluate measuring methods, or assign values ​​to materials. It can be a pure or mixed gas, fluid, or solid. ISO Guide 30:1992 also defines a certified standard sample as a standard sample with a certificate that one or more characteristic values ​​are determined using a traceable procedure, making it traceable to an accurately reproducible unit of measurement for expressing that characteristic value, and each standard value is accompanied by an uncertainty at a given confidence level. Standard samples are widely used in measurement quality assurance, product quality management, evaluation of measurement methods, and the scientific formulation and effective implementation of regulations. In recent years, standard samples have played an increasingly important role in the development of a market economy, requiring a growing variety and higher quality of standard samples.

[0004] Aluminum nitride (AlN) has high thermal conductivity (theoretically up to 320 W·m). -1 K -1 It exhibits good insulation (>10" Q·cm), low dielectric constant (8.0 under 1MHz testing conditions), and low dielectric loss (dielectric loss angle is tanδ=10). -4 ), and its coefficient of thermal expansion matches that of silicon (3.2 × 10⁻⁶). -6 K -1 Aluminum nitride (ANU) possesses excellent chemical stability and is non-toxic, making it widely used in semiconductors, vacuum electronic devices, and other fields. It is also a key material for electronic components in automotive electronics, aerospace, and military defense. The properties of ANU change depending on its carbon content, and different carbon contents lead to different applications. Therefore, controlling the carbon content of ANU to obtain standard samples with corresponding carbon contents is of great significance.

[0005] Currently, the commonly used method for adjusting the carbon content in aluminum nitride is to adjust the amount of carbon black added during the aluminum nitride preparation process. However, carbon black is difficult to disperse and prone to agglomeration, requiring measures to ensure thorough mixing. For example, patent CN 117800737A discloses a method for preparing high-purity aluminum nitride powder in batches. Dispersants and binders are added to a mixture of carbon black and aluminum nitride, followed by dry and wet milling to obtain a precursor slurry. This slurry is then combined with high-temperature nitriding and decarburization treatments to obtain high-purity aluminum nitride powder. This method is often used for batch production in workshops. However, it involves adding additives to disperse carbon black, requiring a large amount of carbon black and multiple operations such as dry and wet milling. The carbon black dispersion process is cumbersome and time-consuming. Furthermore, the large amount of carbon black used can cause the slurry to adhere to the inner walls of the dry milling container and the high-temperature furnace, affecting the accuracy of the carbon content in the aluminum nitride. Additionally, the poor uniformity of the carbon black slurry means that the resulting aluminum nitride cannot meet the requirements of standard samples. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method, product, and application for regulating the carbon content in aluminum nitride. The method provided by the present invention solves at least one of the aforementioned problems.

[0007] In a first aspect, the present invention provides a method for controlling the carbon content in aluminum nitride, comprising:

[0008] A glucose alcohol solution was mixed with aluminum nitride powder and ball-milled to obtain a uniformly mixed slurry.

[0009] The slurry is dried to obtain a dry powder;

[0010] The carbon content in aluminum nitride can be controlled by heat treatment of dried powder under vacuum or inert atmosphere.

[0011] Preferably, the heat treatment temperature is 600–1500℃ and the holding time is 15–60 min.

[0012] Preferably, the inert atmosphere is either nitrogen or argon.

[0013] Preferably, the glucose alcohol solution is an anhydrous ethanol solution of glucose.

[0014] Preferably, the mass ratio of glucose alcohol solution to aluminum nitride powder is 40.99:0.1 to 0.3.

[0015] Preferably, the glucose alcohol solution and aluminum nitride powder are mixed and then ball-milled at a speed of 250-350 r / min; more preferably, the ball-to-material ratio is 3-5:1 and the ball-milling time is 20-28 h; even more preferably, the ball milling is a wet ball milling process.

[0016] Preferably, the drying is vacuum drying at a temperature of 35-45°C.

[0017] In a second aspect, the present invention provides aluminum nitride prepared by the method described in the first aspect.

[0018] Thirdly, the application of the method described in the first aspect in the preparation of aluminum nitride.

[0019] The beneficial effects achieved by one or more technical solutions of the present invention are as follows:

[0020] 1. This invention mixes glucose alcohol solution with aluminum nitride powder by ball milling and drying, thereby improving the uniformity of the mixture. Furthermore, it achieves uniform dispersion of glucose without the need for dispersants or other additives. Subsequent heat treatment yields high-quality aluminum nitride. This method helps improve the accuracy and uniformity of carbon content in aluminum nitride. The method is simple, has a straightforward process, requires minimal equipment, is low-cost, and allows for small-batch control of the carbon content in aluminum nitride powder.

[0021] 2. Since the carbon content of aluminum nitride needs to be controlled with high precision during the carbon source introduction process, an ethanol-soluble carbon source is selected. A glucose alcohol solution is mixed with aluminum nitride and ball-milled. After the glucose is mixed evenly with aluminum nitride, it is first carbonized and then dissolved into aluminum nitride. At the same time, the wet ball milling method is more conducive to the uniform dispersion of glucose alcohol solution and aluminum nitride powder. Then, heat treatment is performed to further improve the uniformity of aluminum nitride. Detailed Implementation

[0022] Given that existing aluminum nitride powder preparation processes often use carbon black as a carbon source to control carbon content, but carbon sources are not easily dispersed and tend to agglomerate, and the amount of carbon source used is relatively large, the uniformity of the obtained aluminum nitride powder cannot meet the requirements, this invention proposes a method, product, and application for controlling the carbon content in aluminum nitride.

[0023] A typical embodiment of the present invention provides a method for controlling the carbon content in aluminum nitride, comprising: mixing a glucose alcohol solution with aluminum nitride powder, ball milling to obtain a uniformly mixed slurry; drying the slurry to obtain a dried powder; and heat-treating the dried powder under vacuum or an inert atmosphere at a temperature of 600–1500°C for a holding time of 15–60 min, thereby controlling the carbon content in aluminum nitride.

[0024] Since the doping of C into AlN is a p-type substitution, the original lattice undergoes a slight deformation after doping, and its geometric parameters and electronic structure also change. The doping can effectively increase the mean free path of phonons, thereby improving the lattice thermal conductivity of intrinsic AlN.

[0025] Another embodiment of the present invention provides aluminum nitride, which is prepared by the method described in the first aspect.

[0026] A third embodiment of the present invention provides the application of the method as described in the first aspect in the preparation of aluminum nitride.

[0027] The following will describe in detail the implementation of the present invention with reference to specific embodiments, so that the process of how the present invention uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0028] Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art, and the reagents and products used are all commercially available.

[0029] Example 1

[0030] Add glucose to anhydrous ethanol and stir until homogeneous to obtain a 0.125 wt% glucose-ethanol solution.

[0031] Aluminum nitride powder with a purity of 99% and glucose alcohol solution were mixed at a weight ratio of 0.3:40.99, and then ball-milled for 24 hours at a ball mill speed of 300 r / min and a ball-to-material ratio of 4:1.

[0032] The mixed slurry was placed in a vacuum drying oven and dried at 40°C. The drying was stopped when the slurry turned into powder.

[0033] The dried powder was placed in an alumina crucible and heat-treated at 1000℃ for 45 minutes under a vacuum atmosphere to obtain the treated aluminum nitride powder.

[0034] Example 2

[0035] Add glucose to anhydrous ethanol and stir until homogeneous to obtain a 0.175 wt% glucose-ethanol solution.

[0036] Aluminum nitride powder with a purity of 99% and glucose alcohol solution were mixed at a weight ratio of 0.3:40.99, and then ball-milled for 24 hours at a ball mill speed of 300 r / min and a ball-to-material ratio of 4:1.

[0037] The mixed slurry was placed in a vacuum drying oven and dried at 40°C. The drying was stopped when the slurry turned into powder.

[0038] The dried powder was placed in an alumina crucible and heat-treated at 1000℃ for 45 minutes under a vacuum atmosphere to obtain the treated aluminum nitride powder.

[0039] Example 3

[0040] Add glucose to anhydrous ethanol and stir until homogeneous to obtain a 0.225 wt% glucose-ethanol solution.

[0041] Aluminum nitride powder with a purity of 99% and glucose alcohol solution were mixed at a weight ratio of 0.2:40.99, and then ball-milled for 24 hours at a ball mill speed of 300 r / min and a ball-to-material ratio of 4:1.

[0042] The mixed slurry was placed in a vacuum drying oven and dried at 40°C. The drying was stopped when the slurry turned into powder.

[0043] The dried powder was placed in an alumina crucible and heat-treated at 1000℃ for 45 minutes under a vacuum atmosphere to obtain the treated aluminum nitride powder.

[0044] Example 4

[0045] Add glucose to anhydrous ethanol and stir until homogeneous to obtain a 0.275 wt% glucose-ethanol solution.

[0046] Aluminum nitride powder with a purity of 99% and glucose alcohol solution were mixed at a weight ratio of 0.2:40.99, and then ball-milled for 24 hours at a ball mill speed of 300 r / min and a ball-to-material ratio of 4:1.

[0047] The mixed slurry was placed in a vacuum drying oven and dried at 40°C. The drying was stopped when the slurry turned into powder.

[0048] The dried powder was placed in an alumina crucible and heat-treated at 1000℃ for 45 minutes under a vacuum atmosphere to obtain the treated aluminum nitride powder.

[0049] Example 5

[0050] Add glucose to anhydrous ethanol and stir until homogeneous to obtain a 0.325 wt% glucose-ethanol solution.

[0051] Aluminum nitride powder with a purity of 99% and glucose alcohol solution were mixed at a weight ratio of 0.1:40.99, and then ball-milled for 24 hours at a ball mill speed of 300 r / min and a ball-to-material ratio of 4:1.

[0052] The mixed slurry was placed in a vacuum drying oven and dried at 40°C. The drying was stopped when the slurry turned into powder.

[0053] The dried powder was placed in an alumina crucible and heat-treated at 1000℃ for 45 minutes under a vacuum atmosphere to obtain the treated aluminum nitride powder.

[0054] Example 6

[0055] Add glucose to anhydrous ethanol and stir until homogeneous to obtain a 0.375 wt% glucose-ethanol solution.

[0056] Aluminum nitride powder with a purity of 99% and glucose alcohol solution were mixed at a weight ratio of 0.1:40.99, and then ball-milled for 24 hours at a ball mill speed of 300 r / min and a ball-to-material ratio of 4:1.

[0057] The mixed slurry was placed in a vacuum drying oven and dried at 40°C. The drying was stopped when the slurry turned into powder.

[0058] The dried powder was placed in an alumina crucible and heat-treated at 1000℃ for 45 minutes under a vacuum atmosphere to obtain the treated aluminum nitride powder.

[0059] Example 7

[0060] Add glucose to anhydrous ethanol and stir until homogeneous to obtain a 0.325 wt% glucose-ethanol solution.

[0061] Aluminum nitride powder with a purity of 99% and glucose alcohol solution were mixed at a weight ratio of 0.1:40.99, and then ball-milled for 28 hours at a ball mill speed of 250 r / min and a ball-to-material ratio of 3:1.

[0062] The mixed slurry was placed in a vacuum drying oven and dried at 35°C. The drying was stopped when the slurry turned into powder.

[0063] The dried powder was placed in an alumina crucible and heat-treated at 600℃ for 60 minutes under nitrogen atmosphere to obtain the treated aluminum nitride powder.

[0064] Example 8

[0065] Add glucose to anhydrous ethanol and stir until homogeneous to obtain a 0.375 wt% glucose-ethanol solution.

[0066] Aluminum nitride powder with a purity of 99% and glucose alcohol solution were mixed at a weight ratio of 0.1:40.99, and then ball-milled for 20 hours at a ball mill speed of 350 r / min and a ball-to-material ratio of 5:1.

[0067] The mixed slurry was placed in a vacuum drying oven and dried at 45°C. The drying was stopped when the slurry turned into powder.

[0068] The dried powder was placed in an alumina crucible and heat-treated at 1500℃ for 45 minutes under an argon atmosphere to obtain the treated aluminum nitride powder.

[0069] The elemental content of the aluminum nitride powders obtained from Examples 1-8 was tested, and the changes in carbon content in the aluminum nitride powders are shown in Table 1.

[0070] Table 1. Changes in carbon content before and after treatment (in mass percentage)

[0071]

[0072] As shown in Table 1, and as demonstrated in Examples 1-6, the higher the concentration of the glucose solution, the higher the carbon content in the aluminum nitride. Therefore, the carbon content in the final aluminum nitride can be controlled by adjusting the concentration of the glucose solution.

[0073] The preparation method of the present invention involves high-temperature and atmospheric-pressure heat treatment of AlN powder doped with C. The original AlN lattice undergoes slight deformation, and its geometric parameters and electronic structure also change. The doping of C can effectively increase the mean free path of phonons, thereby improving the lattice thermal conductivity of intrinsic AlN and further improving the performance of aluminum nitride.

[0074] Comparative Example 1

[0075] The difference from Example 1 is that glucose is replaced with sucrose, and the sucrose alcohol solution is mixed with aluminum nitride powder; the rest of the steps are the same.

[0076] The elemental content of the aluminum nitride powder obtained by the above treatment was tested. The results showed that sucrose is almost insoluble in ethanol, and the carbon content of the treated aluminum nitride powder remained almost unchanged.

[0077] Comparative Example 2

[0078] The difference from Example 1 is that the glucose alcohol solution is replaced with a 0.125 wt% glucose aqueous solution, and the sucrose alcohol solution is mixed with aluminum nitride powder, while the rest of the steps are the same.

[0079] The elemental content of the aluminum nitride powder obtained by the above treatment was tested. The results showed that although the carbon content of the treated aluminum nitride powder increased, most of the aluminum nitride was oxidized to aluminum oxide. This was due to the severe hydrolysis of aluminum nitride caused by prolonged grinding in aqueous solution.

[0080] Since aluminum nitride hydrolyzes upon contact with water, resulting in its oxidation to aluminum oxide, anhydrous ethanol is chosen as the solvent. Because the amount of carbon source introduced is very small, glucose, which is soluble in ethanol, is selected as the carbon source to ensure more uniform mixing of the raw materials.

[0081] Since glucose is carbonized after being mixed with aluminum nitride and then dissolved into aluminum nitride, the carbon content is very small. Direct addition would lead to uneven mixing of raw materials. Therefore, it is chosen to dissolve glucose in alcohol, mix the alcohol solution with aluminum nitride powder, and then perform heat treatment to make it more uniform.

[0082] Comparative Example 3

[0083] The comparative example is Embodiment 1 of patent CN 117800737 A, which includes the following steps:

[0084] S1: Place 1200g of alumina and 530g of carbon black into a horizontal ball mill and dry grind for 20 minutes at a speed of 30r / min. Then add 6800g of water, 8.5g of acrylic copolymer dispersant, 46.5g of polyethylene glycol, 40g of polyvinyl alcohol mixed binder and 6g of sintering aid, and wet grind for 60 minutes at a speed of 80r / min to obtain a precursor slurry. Spray granulation is then performed to obtain precursor granulated powder with a particle size of about 100μm.

[0085] S2: The granulated precursor powder obtained in S1 is fed into the large tube of a high-temperature rotary kiln via an automatic feeder; the high-temperature rotary kiln is evacuated to a vacuum of 97 kPa, and held for 20 minutes. Nitrogen gas is then introduced until the pressure inside the kiln reaches a slightly positive pressure. This gas purging operation is repeated twice before the kiln heating program is started. The temperature is increased to 1550℃ at a rate of 10℃ / min, held for 4 hours, with the kiln tube rotation speed at 2 r / min and the nitrogen flow rate at 150 L / h; high-temperature nitriding yields gray aluminum nitride powder containing trace amounts of carbon.

[0086] S3: The gray aluminum nitride powder obtained in S2 is sent to a decarburization rotary furnace at 650°C for 3 hours for air decarburization. After being crushed by an air jet mill, high-purity aluminum nitride powder is obtained.

[0087] The target carbon content of the obtained high-purity aluminum nitride was 300 ppm, the actual carbon content was 270 ppm, the error was 10%, and the uniformity was 3.17.

[0088] Comparative Example 4

[0089] This comparative example is an adjustment to Example 1 of patent CN 117800737 A. Since the patent describes the steps for mass production, the raw materials of this scheme are adjusted proportionally. The specific steps are as follows:

[0090] S1: Place 120g of alumina and 53g of carbon black into a horizontal ball mill and dry grind for 20 minutes at a speed of 30 r / min. Then add 680g of water, 0.85g of acrylic copolymer dispersant, 4.65g of polyethylene glycol, 4g of polyvinyl alcohol mixed binder and 0.6g of sintering aid, and wet grind for 60 minutes at a speed of 80 r / min to obtain a precursor slurry. Spray granulation is then performed to obtain precursor granulated powder with a particle size of about 100μm.

[0091] The precursor granulated powder was placed in an alumina crucible and heat-treated at 1000℃ for 45 minutes under an argon atmosphere to obtain the treated aluminum nitride powder.

[0092] The target carbon content of the aluminum nitride powder obtained in Comparative Example 3 was expected to be 400 ppm. However, the actual carbon content of the obtained aluminum nitride powder was found to be 467 ppm, with an error of 16.75% and a uniformity of 3.77.

[0093] As can be seen from the examples and Comparative Example 3, the nitrogen content control of aluminum nitride in the present invention is more accurate and the uniformity is better. Comparative Example 3 is actually a batch control of carbon content in aluminum nitride in the production workshop, while the present invention prepares standard samples of aluminum nitride in the laboratory and applies the batch preparation method to the laboratory. As shown in Comparative Example 4, due to the poor dispersibility of carbon black, even if dispersion is performed, the uniformity of the obtained aluminum nitride still cannot meet the requirements of the standard sample. At the same time, carbon black slurry is easy to adhere to the container wall. Due to adhesion loss, residue and other reasons, the accuracy of nitrogen content control of aluminum nitride powder is affected.

[0094] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for controlling the carbon content in aluminum nitride, characterized in that, A glucose alcohol solution was mixed with aluminum nitride powder and ball-milled to obtain a uniformly mixed slurry; the mass ratio of glucose alcohol solution to aluminum nitride powder was 40.99:0.1~0.

3. The slurry is dried to obtain a dry powder; the drying is vacuum drying at a temperature of 35-45℃. The carbon content in aluminum nitride is controlled by heat treatment of the dried powder under vacuum or inert atmosphere; the heat treatment temperature is 600~1500℃ and the holding time is 15~60min.

2. The method for controlling the carbon content in aluminum nitride as described in claim 1, characterized in that, The inert atmosphere is either nitrogen or argon. Alternatively, glucose alcohol solution is an anhydrous ethanol solution of glucose.

3. The method for controlling the carbon content in aluminum nitride as described in claim 1, characterized in that, After mixing glucose alcohol solution with aluminum nitride powder, the mixture is ball-milled at a speed of 250-350 r / min.

4. The method for controlling the carbon content in aluminum nitride as described in claim 3, characterized in that, The ball-to-material ratio is 3-5:1, and the ball milling time is 20-28 hours.

5. The method for controlling the carbon content in aluminum nitride as described in claim 1, characterized in that, The ball milling process is a wet ball milling process.

6. An aluminum nitride, characterized in that, It is prepared by the method of controlling the carbon content in aluminum nitride as described in any one of claims 1-5.

7. The application of the method for controlling the carbon content in aluminum nitride as described in any one of claims 1-5 in the preparation of aluminum nitride.

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