Preparation method of aluminum nitride powder
By using methylbenzoyl chloride compound as an additive and staged calcination during the preparation of aluminum nitride powder, the problem of increased oxygen content caused by carbon black residue in the carbothermic reduction method was solved, thereby improving the performance of aluminum nitride ceramic substrates and making them suitable for high-power electronic devices.
Patent Information
- Application Number
- CN202511330470.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-17
- Publication Date
- 2025-12-12
AI Technical Summary
The carbothermal reduction method produces excessive carbon black residue during the preparation of aluminum nitride powder, which leads to an increase in oxygen content and affects the thermal conductivity, dielectric properties, and mechanical strength of aluminum nitride ceramic substrates, failing to meet the heat dissipation and signal transmission requirements of high-power electronic devices.
Methylbenzoyl chloride compound was used as an additive, and the oxygen content of aluminum nitride powder was reduced by centrifugation and staged controlled calcination.
It effectively removes carbon black, reduces the oxygen content of aluminum nitride powder, improves the thermal conductivity and dielectric properties of ceramic substrates, enhances mechanical strength, and meets the requirements of high-power electronic devices.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of ceramic materials technology, specifically to a method for preparing aluminum nitride powder. Background Technology
[0002] Currently, the main methods for synthesizing aluminum nitride powder include direct nitriding of aluminum powder, chemical vapor deposition, and carbothermal reduction. Among these, carbothermal reduction is widely used in the preparation of aluminum nitride powder due to its advantages such as low raw material cost, relatively simple process operation, high production efficiency, and ease of large-scale production.
[0003] However, there are still some problems to be solved in the practical application of carbothermal reduction. During the reaction process, excessive carbon black residue is easily generated. The carbon content of this residue will cause combustion and exothermic reaction during the subsequent high-temperature calcination, which will trigger a local high-temperature oxidation reaction and cause the oxygen content in silicon nitride powder to increase significantly.
[0004] Increased oxygen content negatively impacts several key properties of aluminum nitride ceramic substrates. For instance, elevated oxygen content leads to a significant decrease in thermal conductivity, deteriorating heat dissipation performance and failing to meet the heat dissipation efficiency requirements of high-power electronic devices. Furthermore, the introduction of oxygen impurities affects the dielectric properties of the ceramic substrate, increasing dielectric loss and interfering with the transmission quality of electronic signals. In addition, excessive oxygen content reduces the mechanical strength of the ceramic substrate, making it more prone to cracking under mechanical stress, severely affecting the reliability and lifespan of devices.
[0005] Therefore, it is necessary to propose a method for preparing aluminum nitride powder with low oxygen content. Summary of the Invention
[0006] This invention proposes a method for preparing aluminum nitride powder, which solves the problem of high oxygen content in aluminum nitride powder in related technologies.
[0007] The technical solution of this invention is as follows: This invention proposes a method for preparing aluminum nitride powder, comprising the following steps: S1. Disperse the aluminum nitride semi-finished product prepared by carbothermal reduction in a solvent, add triethylamine and additives in sequence, and mix to obtain a mixture; S2. After separation, the mixture yields aluminum nitride slurry, which is then dried and calcined to obtain aluminum nitride powder. The auxiliary agent is a methylbenzoyl chloride compound.
[0008] As a further technical solution, in step S2, the separation is centrifugal separation, the centrifugal separation speed is 5000 rpm, and the centrifugal separation time is 10 min.
[0009] As a further technical solution, the mass ratio of the aluminum nitride semi-finished product to the solvent is 1:3~5, for example, it can be 1:3, 1:3.2, 1:3.5, 1:3.8, 1:4, 1:4.5, 1:5, preferably 1:4.
[0010] As a further technical solution, in step S1, the mixing time is 30~60min, for example, it can be 30min, 35min, 40min, 45min, 50min, 55min, or 60min, preferably 60min.
[0011] As a further technical solution, the methylbenzoyl chloride compound includes one or more of o-methylbenzoyl chloride, m-methylbenzoyl chloride, and p-methylbenzoyl chloride; preferably p-methylbenzoyl chloride.
[0012] In the preparation method of aluminum nitride powder of the present invention, the methylbenzoyl chloride compound used as an auxiliary agent is preferably p-methylbenzoyl chloride. Compared with o-methylbenzoyl chloride and m-methylbenzoyl chloride, the methyl group and acyl chloride group of p-methylbenzoyl chloride are in the para position, resulting in high molecular symmetry. The non-polar effect of the benzene ring and methyl group can be better distributed on the carbon black surface, reducing the surface polarity of the carbon black and promoting the separation of aluminum nitride and carbon black in the aluminum nitride semi-finished product.
[0013] As a further technical solution, in step S1, the mass ratio of triethylamine to the aluminum nitride semi-finished product is 2~3:100.
[0014] In the preparation process of aluminum nitride powder of this invention, in order to further promote the interaction between methylbenzoyl chloride compound and carbon black, triethylamine is added to convert the carboxyl groups on the surface of carbon black into carboxylate salts. Utilizing the strong nucleophilicity of the carboxylate group, the binding of methylbenzoyl chloride compound and carbon black is promoted. When the content of triethylamine is too high, the hydroxyl groups on the surface of aluminum nitride will also be excessively neutralized, thereby reducing the polarity of aluminum nitride and hindering the subsequent separation of aluminum nitride and carbon black based on their polarity. However, if the amount of triethylamine added is too low, the conversion of carboxyl groups on the surface of carbon black will not be sufficient, which is not conducive to reducing the polarity of the carbon black surface. Therefore, when the mass ratio of triethylamine to aluminum nitride semi-finished product is 2~3:100, the conversion of carboxyl groups on the surface of carbon black can be better achieved without excessively neutralizing the hydroxyl groups on the surface of aluminum nitride, thus better widening the polarity difference between aluminum nitride and carbon black and promoting their separation.
[0015] As a further technical solution, the mass ratio of the additive to the aluminum nitride semi-finished product is 3~4:100.
[0016] In the preparation method of aluminum nitride powder of the present invention, when the mass ratio of additive to aluminum nitride semi-finished product is 3~4:100, the additive can undergo a sufficient nucleophilic substitution reaction with the carboxylate group on the surface of carbon black. This can avoid the problem of insufficient reaction caused by too low additive content, and also avoid the problem of abnormal modification of aluminum nitride surface caused by too high additive content.
[0017] As a further technical solution, the solvent includes one or more of acetone, tetrahydrofuran, and acetonitrile.
[0018] In the preparation method of aluminum nitride powder of the present invention, a polar solvent is selected. Aluminum nitride powder has high polarity and can be fully dispersed in a polar solution. However, the polarity of carbon black treated with methyl benzoyl chloride compound will decrease. In a polar solvent, carbon black will aggregate and precipitate, thereby achieving the separation of aluminum nitride and carbon black.
[0019] As a further technical solution, the solvent also includes 18-crown-6, which is composed of acetone, acetonitrile and 18-crown-6 in a mass ratio of 20:7:1~2.
[0020] In the preparation method of aluminum nitride powder of this invention, the solvent further includes 18-crown-6. 18-crown-6 can disrupt the carboxyl groups formed on the surfaces of triethylamine and carbon black, destroying the ion-pair structure and promoting the dissociation of more carboxyl groups into carboxylate groups, thus creating conditions for subsequent nucleophilic substitution reactions. When the solvent is formed by a combination of these three components, the polarity and reaction environment of the mixed solvent are conducive to the separation of aluminum nitride and carbon black, reducing the oxygen content of the aluminum nitride powder.
[0021] As a further technical solution, in step S2, the calcination heating process includes a first heating stage, a second heating stage, and a third heating stage, and the heating rates of the first heating stage, the second heating stage, and the third heating stage are different.
[0022] In the preparation method of aluminum nitride powder of the present invention, calcination is carried out in three stages. By controlling the heating rate in stages, the problem of increased oxygen content caused by the exothermic reaction of carbon black is reduced.
[0023] As a further technical solution, the heating rate of the first stage of heating is greater than the heating rate of the second stage of heating, which is greater than the heating rate of the third stage of heating.
[0024] As a further technical solution, the heating rate of the first stage of heating is 8~10℃ / min, for example, it can be 8℃ / min, 8.5℃ / min, 9℃ / min, 9.5℃ / min, 10℃ / min, preferably 10℃ / min; the heating rate of the second stage of heating is 4~6℃ / min, for example, it can be 4℃ / min, 4.5℃ / min, 5℃ / min, 5.5℃ / min, 6℃ / min, preferably 5℃ / min; the heating rate of the third stage of heating is 1~3℃ / min, for example, it can be 1℃ / min, 1.5℃ / min, 2℃ / min, 2.5℃ / min, 3℃ / min, preferably 3℃ / min.
[0025] As a further technical solution, the calcination process includes the following steps: the dried aluminum nitride slurry is heated to 200-250°C at a heating rate of 8-10°C / min, for example, 200°C, 210°C, 220°C, 230°C, 240°C, or 250°C, preferably 250°C; the temperature is then raised to 400-450°C at a heating rate of 4-6°C / min, for example, 400°C, 410°C, 420°C, 430°C, 440°C, or 450°C. The temperature is 50℃, preferably 450℃; the temperature is increased to 600-650℃ at a heating rate of 1-3℃ / min and then held for 2-3 hours, for example, 600℃, 610℃, 620℃, 630℃, 640℃, or 650℃, preferably 650℃, for example, 2 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours, or 3 hours, preferably 3 hours; after cooling, aluminum nitride powder is obtained.
[0026] The working principle and beneficial effects of this invention are as follows: In the preparation method of aluminum nitride powder of this invention, the addition of methyl benzoyl chloride compound as an auxiliary agent helps to separate aluminum nitride and carbon black in the aluminum nitride semi-finished product, reduces the carbon black content, and lowers the oxygen content of the aluminum nitride powder. In the prior art, when preparing aluminum nitride using the carbothermic reduction method, the aluminum nitride semi-finished product often contains carbon black due to the excessive use of carbon black. High carbon black content during the subsequent calcination and decarbonization process can cause combustion exothermics, increasing the oxygen content of the aluminum nitride powder, which is detrimental to the later use of the aluminum nitride powder. In this invention, to better achieve the separation of aluminum nitride and carbon black in the aluminum nitride semi-finished product during the preparation process, methyl benzoyl chloride is added... Benzoyl chloride is used as an additive. When triethylamine is added, the carboxyl groups on the surface of carbon black form carboxylates, converting the carboxyl groups into carboxylate groups. Since the nucleophilicity of carboxylate groups is greater than that of hydroxyl groups on the surface of aluminum nitride, methyl benzoyl chloride will preferentially undergo a nucleophilic substitution reaction with carbon black, introducing methyl and benzene rings on the surface of carbon black, further reducing the polarity of carbon black. Aluminum nitride, on the other hand, has higher polarity. By utilizing the difference in polarity between the two, the separation of aluminum nitride and carbon black in the mixture can be better achieved. Carbon black can be effectively removed before calcination, thereby reducing the increase in oxygen content caused by the exothermic reaction of carbon black during the calcination process of aluminum nitride, and further reducing the oxygen content of aluminum nitride powder. Detailed Implementation
[0027] The technical solutions 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0028] In the following embodiments and comparative examples: The aluminum nitride semi-finished product prepared by carbothermic reduction method is specifically prepared by mixing alumina and carbon black, sintering at 1500℃, holding at that temperature for 5 hours, cooling in the furnace to 250~300℃, and then air cooling to room temperature. The mass ratio of alumina to carbon black is 1:0.4.
[0029] Example 1 A method for preparing aluminum nitride powder includes the following steps: S1. Disperse 100 parts of the aluminum nitride semi-finished product prepared by carbothermal reduction method in 400 parts of solvent, add 2 parts of triethylamine and 3 parts of additives in sequence, and mix for 60 min to obtain a mixture; S2. After separation of the mixture, aluminum nitride slurry is obtained. After drying, aluminum nitride slurry is calcined and then cooled to obtain aluminum nitride powder. The solvent is acetone, and the auxiliary agent is o-methylbenzoyl chloride; The calcination process includes the following steps: the dried aluminum nitride slurry is heated to 650°C at a heating rate of 10°C / min, held at that temperature for 3 hours, and then cooled to obtain aluminum nitride powder.
[0030] Example 2 A method for preparing aluminum nitride powder includes the following steps: S1. Disperse 100 parts of the aluminum nitride semi-finished product prepared by carbothermal reduction in 400 parts of solvent, add 2.5 parts of triethylamine and 3.5 parts of additives in sequence, and mix for 60 min to obtain a mixture; S2. After separation of the mixture, aluminum nitride slurry is obtained. After drying, aluminum nitride slurry is calcined and then cooled to obtain aluminum nitride powder. The solvent is acetone, and the auxiliary agent is o-methylbenzoyl chloride; The calcination process includes the following steps: the dried aluminum nitride slurry is heated to 650°C at a heating rate of 10°C / min, held at that temperature for 3 hours, and then cooled to obtain aluminum nitride powder.
[0031] Example 3 A method for preparing aluminum nitride powder includes the following steps: S1. Disperse 100 parts of the aluminum nitride semi-finished product prepared by carbothermal reduction in 400 parts of solvent, add 3 parts of triethylamine and 4 parts of additives in sequence, and mix for 60 min to obtain a mixture; S2. After separation of the mixture, aluminum nitride slurry is obtained. After drying, aluminum nitride slurry is calcined and then cooled to obtain aluminum nitride powder. The solvent is acetone, and the auxiliary agent is o-methylbenzoyl chloride; The calcination process includes the following steps: the dried aluminum nitride slurry is heated to 650°C at a heating rate of 10°C / min, held at that temperature for 3 hours, and then cooled to obtain aluminum nitride powder.
[0032] Example 4 The difference between Example 4 and Example 1 is that o-methylbenzoyl chloride is replaced with an equal amount of m-methylbenzoyl chloride.
[0033] Example 5 The difference between Example 5 and Example 1 is that o-methylbenzoyl chloride is replaced with an equal amount of p-methylbenzoyl chloride.
[0034] Example 6 The difference between Example 6 and Example 5 is that the solvent consists of acetone and acetonitrile in a mass ratio of 20:7.
[0035] Example 7 The difference between Example 7 and Example 5 is that the solvent consists of acetone, acetonitrile and 18-crown-6 in a mass ratio of 20:7:1.
[0036] Example 8 The difference between Example 8 and Example 5 is that the solvent consists of acetone, acetonitrile and 18-crown-6 in a mass ratio of 20:7:2.
[0037] Example 9 Compared with Example 8, Example 9 differs in that the calcination includes the following steps: the dried aluminum nitride slurry is first heated to 250°C at a heating rate of 10°C / min, then heated to 650°C at a heating rate of 5°C / min and held at that temperature for 3 hours, and then cooled to obtain aluminum nitride powder.
[0038] Example 10 Compared with Example 8, the difference in Example 10 is that the calcination includes the following steps: the dried aluminum nitride slurry is first heated to 250°C at a heating rate of 5°C / min, then heated to 650°C at a heating rate of 10°C / min, held at that temperature for 3 hours, and then cooled to obtain aluminum nitride powder.
[0039] Example 11 Compared with Example 8, the difference in Example 11 is that the calcination includes the following steps: the dried aluminum nitride slurry is first heated to 250°C at a heating rate of 10°C / min, then heated to 450°C at a heating rate of 5°C / min, and finally heated to 650°C at a heating rate of 3°C / min, held at that temperature for 3 hours, and then cooled to obtain aluminum nitride powder.
[0040] Example 12 Compared with Example 8, Example 12 differs in that the calcination includes the following steps: the dried aluminum nitride slurry is first heated to 250°C at a heating rate of 3°C / min, then heated to 450°C at a heating rate of 5°C / min, and finally heated to 650°C at a heating rate of 10°C / min, held at that temperature for 3 hours, and then cooled to obtain aluminum nitride powder.
[0041] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that o-methylbenzoyl chloride was not added.
[0042] Experimental Example 1 The oxygen content of the aluminum nitride powders prepared in Examples 1-12 and Comparative Example 1 was tested.
[0043] The test results are shown in Table 1: Table 1 Performance test results of aluminum nitride powders prepared in Examples 1-12 and Comparative Example 1
[0044] As shown in Table 1, adding methyl benzoyl chloride as an additive during the preparation of aluminum nitride powder can reduce the oxygen content. When the solvent consists of acetone, acetonitrile, and 18-crown-6 in a mass ratio of 20:7:1~2, the oxygen content of aluminum nitride powder can be reduced. When calcination is carried out in three stages, and the heating rate of the first stage calcination is greater than that of the second stage calcination, which is greater than that of the third stage calcination, the oxygen content of aluminum nitride powder can be further reduced.
[0045] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing aluminum nitride powder, characterized in that, Includes the following steps: S1. Disperse the aluminum nitride semi-finished product prepared by carbothermal reduction in a solvent, add triethylamine and additives in sequence, and mix to obtain a mixture; S2. After separation, the mixture yields aluminum nitride slurry, which is then dried and calcined to obtain aluminum nitride powder. The auxiliary agent is a methylbenzoyl chloride compound.
2. The method for preparing aluminum nitride powder according to claim 1, characterized in that, The methylbenzoyl chloride compound includes one or more of o-methylbenzoyl chloride, m-methylbenzoyl chloride, and p-methylbenzoyl chloride.
3. The method for preparing aluminum nitride powder according to claim 1, characterized in that, In step S1, the mass ratio of triethylamine to the aluminum nitride semi-finished product is 2~3:
100.
4. The method for preparing aluminum nitride powder according to claim 1, characterized in that, The mass ratio of the additive to the aluminum nitride semi-finished product is 3~4:
100.
5. The method for preparing aluminum nitride powder according to claim 1, characterized in that, The solvent includes one or more of acetone, tetrahydrofuran, and acetonitrile.
6. The method for preparing aluminum nitride powder according to claim 5, characterized in that, The solvent also includes 18-crown-6, which is composed of acetone, acetonitrile and 18-crown-6 in a mass ratio of 20:7:1~2.
7. The method for preparing aluminum nitride powder according to claim 1, characterized in that, In step S2, the calcination heating process includes a first heating stage, a second heating stage, and a third heating stage, and the heating rates of the first heating stage, the second heating stage, and the third heating stage are different.
8. The method for preparing aluminum nitride powder according to claim 7, characterized in that, The heating rate of the first stage of heating is greater than the heating rate of the second stage of heating, which in turn is greater than the heating rate of the third stage of heating.
9. The method for preparing aluminum nitride powder according to claim 7, characterized in that, The heating rate of the first stage is 8~10℃ / min, the heating rate of the second stage is 4~6℃ / min, and the heating rate of the third stage is 1~3℃ / min.
10. A method for preparing aluminum nitride powder according to claim 7, characterized in that, The calcination process includes the following steps: the dried aluminum nitride slurry is heated to 200-250°C at a heating rate of 8-10°C / min, then heated to 400-450°C at a heating rate of 4-6°C / min, and then heated to 600-650°C at a heating rate of 1-3°C / min, and then held at that temperature for 2-3 hours. After cooling, aluminum nitride powder is obtained.