Preparation method of aluminum nitride nanopowder based on dual activation

Abstract

This disclosure relates to a method for preparing aluminum nitride nanopowder based on dual activation, and pertains to the field of aluminum nitride nanopowder preparation technology. The method includes: 1. Mixing an aluminum source, a carbon source, and an in-situ activator in a molar ratio of 1:(0-5):(0.1-5) to obtain a reaction precursor; the in-situ activator is melamine; 2. Placing the reaction precursor in a first crucible, which is then placed in the isothermal section of a tubular furnace; placing the non-in-situ activator melamine in a second crucible, which is then placed in the non-isothermal section of the tubular furnace near the gas inlet; the mass ratio of the reaction precursor to the non-in-situ activator is 1:(0.5-5); and undergoing a carbothermic reduction reaction at 1000-1500℃ under a nitrogen atmosphere to obtain a mixed powder; 3. Decarbonizing the mixed powder to obtain aluminum nitride nanopowder.

Description

Technical Field

[0001] This disclosure relates to the field of aluminum nitride nanoparticle preparation technology, and more specifically, to a method for preparing aluminum nitride nanoparticles based on dual activation. Background Technology

[0002] Aluminum nitride ceramics possess excellent comprehensive properties, including high thermal conductivity and a coefficient of linear expansion close to that of silicon, making them ideal heat dissipation substrate materials for next-generation large-scale integrated circuits, semiconductor module circuits, and high-power devices. Aluminum nitride has high added value, strong market demand, and a promising future. The performance of aluminum nitride ceramic products depends on the characteristics of the aluminum nitride powder. Aluminum nitride powder with low content of synthetic impurities (especially oxygen impurities) and high sintering activity is key to improving the thermal conductivity and mechanical properties of aluminum nitride ceramics. High sintering activity requires the powder to have a nano-sized particle size and uniform distribution. Currently, common methods for preparing aluminum nitride powder include: direct nitridation of aluminum powder, carbothermal reduction of alumina powder, self-propagating high-temperature synthesis, chemical vapor deposition, sol-gel method, and plasma method. Among these, carbothermal reduction is the most commonly used method for preparing high-performance aluminum nitride powder. However, this method involves high temperatures and long processing times, leading to the need for even higher temperatures for subsequent sintering into ceramics, resulting in high energy consumption and high costs. To address this, researchers have employed methods such as wet mixing, low-temperature combustion, and high-energy ball milling to improve the uniformity of raw material mixing (References: Ceram. Int. 2018, 44, 5774; J. Alloys Compd. 2012, 530, 144; Powder Technol. 2013, 247, 204). They have also improved reactivity by selecting raw materials with lower bond energies and using activators and sintering aids (References: J. Asian Ceram. Soc. 2018, 6, 63; ACS Omega 2019, 4, 14714; Ceram. Int. 2015, 41, 6715). In the decarburization stage, they have used more efficient microwave decarburization (refer to Chinese patent CN110577199A) to improve the performance of the prepared powder. While these methods have yielded good results, the preparation of aluminum nitride nanopowders remains challenging.

[0003] Methods for preparing nano-aluminum nitride powders have been reported. The "urea glass route" method for preparing nano-aluminum nitride powders has been widely reported (References: Appl. Surface Sci. 2013, 280, 42-49; Ceram. Int. 2018, 44, 5774-5779; Mater. Chem. Phys. 2022, 287, 126-280). This method uses the complex Al[(CON₂H₄)]₄. nCl3 is used as a precursor in the reaction, eliminating the need for additional carbon sources such as carbon black. This significantly improves the precursor's reactivity and lowers the reaction temperature. However, the prepared aluminum nitride exhibits low crystallinity and severe powder agglomeration. Chinese Patent CN103539088A discloses a method for preparing nano-aluminum nitride powder. Using aluminum nitrate nonahydrate and melamine as raw materials, a precursor is prepared through a complexation reaction in an aqueous solution. Then, a high-temperature carbothermic reduction reaction is performed under an ammonia atmosphere to prepare nano-aluminum nitride powder. During the subsequent heating process, the melamine is carbonized and serves as a carbon source, simultaneously releasing a highly reactive CN intermediate, which can also act as a nitrogen source, further enhancing the reactivity. However, this method requires 10–20 hours for precursor preparation, making the process relatively cumbersome and complex. Chinese patent CN104724685A discloses a method for preparing aluminum nitride powder using sol-gel. The method uses water-soluble inorganic aluminum salts aluminum chloride, aluminum nitrate, and aluminum sulfate as aluminum sources, water-soluble glucose, sucrose, and soluble starch as carbon sources, and ammonium nitrate, glycine, alanine, lysine, and citric acid as auxiliary agents. The method produces aluminum nitride powder with a particle size of less than 50 nm, which has good results. However, the method uses a variety of raw materials, the operation process is complicated, and the experimental cycle is long.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this disclosure is to overcome the shortcomings of the prior art and provide a method for preparing aluminum nitride nanopowder based on dual activation. By using the dual activation effect of in-situ and non-in-situ activators, the reaction temperature for preparing aluminum nitride nanopowder is reduced, thereby reducing the preparation cost and the difficulty of subsequent processing.

[0006] According to one aspect of this disclosure, a method for preparing aluminum nitride nanopowder based on dual activation includes the following steps:

[0007] S1. Obtain aluminum source, carbon source and in-situ activator, and mix aluminum source, carbon source and in-situ activator to obtain reaction precursor;

[0008] The molar ratio of aluminum source, carbon source and in-situ activator is 1:(0-5):(0.1-5); the in-situ activator is melamine.

[0009] S2. Place the reaction precursor in a first crucible and place the first crucible in the isothermal section of a tubular furnace; obtain a non-in-situ activator and place the non-in-situ activator in a second crucible, which is placed in the non-isothermal section of the tubular furnace near the gas inlet.

[0010] The mass ratio of the reaction precursor to the non-in-situ activator is 1:(0.5-5); the non-in-situ activator is melamine.

[0011] Nitrogen gas is continuously introduced into a tubular furnace, and the reaction precursor is reacted in a nitrogen atmosphere at a temperature of 1000-1500°C for 1-5 hours to obtain a mixed powder of carbon and aluminum nitride.

[0012] S3. Decarbonize the mixed powder of carbon and aluminum nitride obtained in step S2 in air at a temperature of 500-800°C for 1-4 hours to obtain aluminum nitride nanopowder.

[0013] In an exemplary embodiment of this disclosure, in step S1, the molar ratio of aluminum source, carbon source and in-situ activator is 1:(1-3):(0.25-4).

[0014] In one exemplary embodiment of this disclosure, in step S1, the molar ratio of aluminum source, carbon source and in-situ activator is 1:2:2.

[0015] In one exemplary embodiment of this disclosure, in step S2, the mass ratio of the reaction precursor to the non-in-situ activator is 1:1.5.

[0016] In one exemplary embodiment of this disclosure, in step S1, the aluminum source is aluminum oxide or aluminum hydroxide.

[0017] In one exemplary embodiment of this disclosure, in step S1, the aluminum source is at least one of aluminum hydroxide and γ-alumina.

[0018] In an exemplary embodiment of this disclosure, in step S1, the mixing of the aluminum source, carbon source and in-situ activator is carried out by one of mechanical stirring or ball milling.

[0019] In one exemplary embodiment of this disclosure, in step S1, the carbon source is carbon black.

[0020] In an exemplary embodiment of this disclosure, in step S2, the first crucible is a graphite crucible, and the second crucible is either a graphite crucible or a corundum crucible.

[0021] In one exemplary embodiment of this disclosure, in step S3, the particle size of the aluminum nitride nanoparticles is less than 100 nm.

[0022] This disclosure employs an in-situ activator, melamine, mixed with a carbon source and an aluminum source to obtain a reaction precursor. During the carbothermic reduction reaction in the isothermal zone of a tubular furnace, the in-situ activator melamine decomposes to produce products that increase the reactivity of the aluminum source, thereby enhancing the reactivity of the carbothermic reaction and lowering the reaction temperature. Simultaneously, a non-in-situ activator melamine is placed near the inlet of the tubular furnace. This allows the non-in-situ activator melamine to gradually heat up to its decomposition temperature from near the isothermal zone towards the inlet, ensuring a continuous activation effect of the decomposition products on the carbothermic reduction reaction. This results in higher reactivity throughout the carbothermic reduction process and lowers the reaction temperature for preparing aluminum nitride nanopowder.

[0023] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0024] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0025] Figure 1 This is the standard XRD characteristic map of aluminum nitride.

[0026] Figure 2 This is an XRD feature map of aluminum nitride nanopowder prepared in Example 1, according to one embodiment of this disclosure.

[0027] Figure 3 This is a SEM image of the mixed powder obtained by the carbothermal reduction reaction in Example 1, one embodiment of this disclosure.

[0028] Figure 4 This is a SEM image of aluminum nitride nanopowder obtained from the decarburization reaction in Example 1, in one embodiment of this disclosure, at two magnification ratios. Detailed Implementation

[0029] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. Furthermore, the drawings are merely illustrative of this disclosure and are not necessarily drawn to scale.

[0030] The terms “a,” “the,” “the,” and “at least one” are used to indicate the presence of one or more elements / components / etc.; the term “including” is used to indicate an open-ended inclusion and means that there may be other elements / components / etc. in addition to the listed elements / components / etc.; the terms “first,” “second,” etc. are used only as markers and are not a limitation on the number of objects.

[0031] This disclosure provides a method for preparing aluminum nitride nanopowder based on dual activation, comprising the following steps:

[0032] S1. Obtain an aluminum source, a carbon source, and an in-situ activator. Mix the aluminum source, carbon source, and in-situ activator to obtain a reaction precursor. The molar ratio of the aluminum source, carbon source, and in-situ activator is 1:(0-5):(0.1-5); the in-situ activator is melamine. Further, the molar ratio of the aluminum source, carbon source, and in-situ activator is 1:(1-3):(0.25-4). For example, the molar ratio of the aluminum source, carbon source, and in-situ activator can be: 1:2:2, 1:0:2, 1:0.1:3, 1:0.18:4, 1:2.5:0.25, 1:3:0.5, 1:2:0.1, 1:5:1, 1:1:4, 1:2:3, 1:3:1, 1:0.5:5, 1:5:1.5, or 1:4:2.5, etc.

[0033] In one example, the aluminum source can be aluminum oxide or aluminum hydroxide. Further, the aluminum source is a highly active aluminum oxide or aluminum hydroxide, for example, at least one of aluminum hydroxide and γ-alumina. In one example, the carbon source is carbon black. It is worth noting that the aluminum source (aluminum hydroxide, γ-alumina), carbon source (carbon black), in-situ activator, and non-in-situ activator (melamine) used in the embodiments of this disclosure are all readily available and inexpensive materials, effectively reducing the preparation cost of aluminum nitride nanopowder. In one example, the aluminum source, carbon source, and in-situ activator can be mixed by at least one of mechanical stirring and ball milling.

[0034] S2. The reaction precursor obtained in step S1 is placed in a first crucible, which is then placed in the isothermal section of a tubular furnace. A non-in-situ activator is obtained, and this non-in-situ activator is placed in a second crucible, which is then placed in the non-isothermal section of the tubular furnace near the gas inlet. Nitrogen gas is continuously introduced into the tubular furnace through the gas inlet, and the reaction precursor undergoes a carbothermic reduction reaction in a nitrogen atmosphere at a temperature of 1000–1500°C for 1–5 hours to obtain a mixed powder of carbon and aluminum nitride. For example, the conditions for a carbothermic reduction reaction can be: 1000℃ for 3 hours, or 1050℃ for 1 hour, or 1100℃ for 2 hours, or 1100℃ for 3 hours, or 1150℃ for 5 hours, or 1200℃ for 3 hours, or 1250℃ for 3 hours, or 1300℃ for 4 hours, or 1350℃ for 3 hours, or 1400℃ for 1 hour, or 1500℃ for 2 hours, etc.

[0035] In one embodiment of this disclosure, the mass ratio of the reaction precursor to the non-in-situ activator is 1:(0.5-5); the non-in-situ activator is melamine. For example, the mass ratio of the reaction precursor to the non-in-situ activator can be 1:0.5, or 1:0.75, or 1:1, or 1:1.33, or 1:1.5, or 1:2, or 1:2.5, or 1:3, or 1:3.5, or 1:4, or 1:4.5, or 1:5, etc.

[0036] It should be noted that the tubular furnace includes a constant-temperature section in the middle and non-constant-temperature sections at both ends. The constant-temperature section maintains a constant heating temperature; the non-constant-temperature sections consist of two parts: a non-constant-temperature section near the air inlet and a non-constant-temperature section near the air outlet. It can be understood that in the non-constant-temperature section near the air inlet, the temperature gradually decreases along the direction from the constant-temperature section to the air inlet.

[0037] The thermal decomposition temperature of melamine is around 350℃, while the carbothermic reaction temperature in the isothermal section is between 1000 and 1500℃. Therefore, when the reaction precursor formed by mixing the in-situ activator melamine with the aluminum and carbon sources is placed in the isothermal section, the melamine in the precursor quickly decomposes completely during heating, rendering it ineffective for activation. In this embodiment, the non-in-situ activator melamine is placed in the non-isothermal section near the air inlet. This allows the non-in-situ activator melamine near the isothermal section to preferentially rise to its thermal decomposition temperature. The decomposition products then enter the isothermal section with the nitrogen gas from the air inlet to participate in the high-temperature carbothermic reduction reaction. Simultaneously, the CN intermediate generated from the decomposition of the non-in-situ activator melamine reacts more readily with the aluminum source to form aluminum nitride, further enhancing the reactivity of the aluminum source and lowering the preparation temperature of the aluminum nitride powder. Based on the temperature gradient in the non-isothermal section, the non-in-situ activator melamine can gradually decompose, and the decomposition products are introduced into the isothermal section along with nitrogen gas through the inlet, where they participate as an activator in the high-temperature carbothermic reduction reaction. In this way, melamine can continuously act as an activator in the carbothermic reduction reaction, improving the reactivity of the aluminum source and reducing the preparation temperature of aluminum nitride powder. Currently, the reaction temperature of methods for preparing aluminum nitride using carbothermic reduction is generally greater than 1600℃. In step S2 of this embodiment, the temperature of the carbothermic reduction reaction is 1000–1500℃, significantly reducing the reaction temperature.

[0038] Furthermore, the reaction precursor is spread evenly in the first crucible to increase the contact area and reaction rate. The non-in-situ activator is spread evenly in the second crucible; for example, melamine can be spread evenly along the isothermal section towards the gas inlet, so that melamine at different locations is heated to the decomposition temperature at different times, thereby continuously generating decomposition products to activate the carbothermic reduction reaction and reduce the temperature of the nitriding reaction.

[0039] Furthermore, in step S2, the temperature of the carbothermic reduction reaction is relatively high, and the furnace tubes of the tubular heater can be made of corundum.

[0040] In one example, the first crucible is a graphite crucible, and the second crucible can be either a graphite crucible or a corundum crucible.

[0041] S3. The carbon and aluminum nitride mixed powder obtained in step S2 is subjected to a decarburization reaction in air at a temperature of 500-800°C for 1-4 hours to obtain aluminum nitride nanopowder. For example, the conditions for the decarburization reaction can be: reacting at 500°C for 1 hour, or reacting at 500°C for 3 hours, or reacting at 500°C for 4 hours, or reacting at 600°C for 2 hours, or reacting at 600°C for 3 hours, or reacting at 700°C for 3 hours, or reacting at 700°C for 5 hours, or reacting at 800°C for 1 hour, or reacting at 800°C for 3 hours, or reacting at 500°C for 1 hour followed by 2 hours at 700°C, or reacting at 600°C for 2 hours followed by 1 hour at 700°C, or reacting at 600°C for 1 hour followed by 2 hours at 800°C, or reacting at 700°C for 1 hour followed by 3 hours at 800°C, etc. The aluminum nitride nanoparticles prepared according to the above steps have a particle size of less than 100 nm and good dispersibility.

[0042] The following specific examples further illustrate the preparation process of aluminum nitride nanopowder based on dual activation and the characteristics of the prepared aluminum nitride nanopowder.

[0043] Example 1

[0044] 1. Preparation of precursor: Weigh 0.2 mol of aluminum hydroxide, 0.4 mol of carbon black and 0.4 mol of melamine (molar ratio of 1:2:2), and stir the above raw materials mechanically at 15000 rpm for 10 minutes to obtain a uniformly mixed reaction precursor.

[0045] 2. Carbothermic reduction reaction: Weigh 8g of the reaction precursor and spread it evenly in a graphite crucible. Place the graphite crucible containing the reaction precursor in the isothermal section of the corundum tube furnace. Separately weigh 6g of melamine and spread it evenly in a corundum crucible. Place the corundum crucible containing the melamine in the non-isothermal section of the corundum tube furnace near the gas inlet so that the melamine can decompose gradually.

[0046] A carbothermic reduction reaction was carried out at 1100℃ for 2 hours under a nitrogen atmosphere to obtain a mixed powder of carbon and aluminum nitride.

[0047] 3. Decarburization reaction: The mixed powder was decarburized in air at 700℃ for 3 hours to obtain grayish-white aluminum nitride nanopowder.

[0048] See Figure 1 and Figure 2 , Figure 2 The image shows the XRD pattern of the aluminum nitride nanopowder prepared in Example 1. Figure 1 This is the standard XRD characterization diagram of aluminum nitride. As can be seen from the figure, the aluminum nitride prepared according to the method provided in Example 1 has few impurities and high purity. See also... Figure 3 and Figure 4 , Figure 3 The image shows a scanning electron microscope (SEM) characterization of the mixed powder obtained after the carbothermic reduction reaction in Example 1. Impurities are clearly visible in the image. Figure 4 The scanning electron microscope (SEM) image shows the powder after the mixed powder has undergone a decarburization reaction. It can be seen that the obtained aluminum nitride nanoparticles are smaller than 100 nm in size and have good dispersibility.

[0049] Example 2

[0050] The difference from Example 1 is as follows:

[0051] The molar ratio of aluminum hydroxide, carbon black, and melamine used to prepare the precursor was 1:0:2.

[0052] The other steps are the same as in Example 1. Testing showed that the aluminum nitride nanopowder prepared in this example has the same properties as the aluminum nitride nanopowder prepared in Example 1.

[0053] Example 3

[0054] The difference from Example 1 is as follows:

[0055] The molar ratio of aluminum hydroxide, carbon black, and melamine used to prepare the precursor was 1:0:2.

[0056] The reaction temperature for the carbothermic reduction reaction is 1250℃.

[0057] The other steps are the same as in Example 1. Testing showed that the aluminum nitride nanopowder prepared in this example has the same properties as the aluminum nitride nanopowder prepared in Example 1.

[0058] Example 4

[0059] The difference from Example 1 is as follows:

[0060] The molar ratio of aluminum hydroxide, carbon black, and melamine used to prepare the precursor was 1:3:2.

[0061] In the carbothermic reduction reaction, 20g of the reaction precursor and 10g of the non-in-situ activator melamine were weighed out, and the reaction time was 3 hours.

[0062] The other steps are the same as in Example 1. Testing showed that the aluminum nitride nanopowder prepared in this example has the same properties as the aluminum nitride nanopowder prepared in Example 1.

[0063] Example 5

[0064] The difference from Example 1 is as follows:

[0065] The molar ratio of aluminum hydroxide, carbon black, and melamine used to prepare the precursor was 1:3:2.

[0066] In the carbothermic reduction reaction, 20g of the reaction precursor and 10g of the non-in-situ activator melamine were weighed out, and the reaction time was 3 hours.

[0067] The decarbonization reaction conditions were: decarbonization at 600℃ in air for 1 hour, followed by decarbonization at 700℃ in air for 3 hours.

[0068] The other steps are the same as in Example 1. Testing showed that the aluminum nitride nanopowder prepared in this example has the same properties as the aluminum nitride nanopowder prepared in Example 1.

[0069] Example 6

[0070] The difference from Example 1 is as follows:

[0071] The molar ratio of aluminum hydroxide, carbon black, and melamine used to prepare the precursor was 1:3:2.

[0072] In the carbothermic reduction reaction, 20g of the reaction precursor and 10g of the non-in-situ activator melamine were weighed out, and the reaction time was 3 hours.

[0073] The decarbonization reaction conditions were: decarbonization at 700℃ in air for 1 hour, followed by decarbonization at 800℃ in air for 2 hours.

[0074] The other steps are the same as in Example 1. Testing showed that the aluminum nitride nanopowder prepared in this example has the same properties as the aluminum nitride nanopowder prepared in Example 1.

[0075] Example 7

[0076] The difference from Example 1 is as follows:

[0077] The molar ratio of aluminum hydroxide, carbon black, and melamine used to prepare the precursor was 1:3:2.

[0078] In the carbothermic reduction reaction, 20g of the reaction precursor and 10g of the non-in-situ activator melamine were weighed out, and the reaction time was 3 hours.

[0079] The decarbonization reaction conditions were: decarbonization at 600℃ in air for 2 hours, followed by decarbonization at 800℃ in air for 1 hour.

[0080] The other steps are the same as in Example 1. Testing showed that the aluminum nitride nanopowder prepared in this example has the same properties as the aluminum nitride nanopowder prepared in Example 1.

[0081] Example 8

[0082] The difference from Example 1 is as follows:

[0083] The molar ratio of aluminum hydroxide, carbon black, and melamine used to prepare the precursor was 1:1:2.

[0084] In the carbothermic reduction reaction, 10g of the reaction precursor and 15g of the non-in-situ activator melamine were weighed out, the reaction temperature was 1200℃, and the reaction time was 3 hours.

[0085] The other steps are the same as in Example 1. Testing showed that the aluminum nitride nanopowder prepared in this example has the same properties as the aluminum nitride nanopowder prepared in Example 1.

[0086] Example 9

[0087] The difference from Example 1 is as follows:

[0088] The molar ratio of aluminum hydroxide, carbon black, and melamine used to prepare the precursor was 1:1:2.

[0089] In the carbothermic reduction reaction, 10g of the reaction precursor and 15g of the non-in-situ activator melamine were weighed out, the reaction temperature was 1300℃, and the reaction time was 3 hours.

[0090] The other steps are the same as in Example 1. Testing showed that the aluminum nitride nanopowder prepared in this example has the same properties as the aluminum nitride nanopowder prepared in Example 1.

[0091] Example 10

[0092] The difference from Example 1 is as follows:

[0093] The molar ratio of aluminum hydroxide, carbon black, and melamine used to prepare the precursor was 1:1:2.

[0094] In the carbothermic reduction reaction, 15g of the reaction precursor and 30g of the non-in-situ activator melamine were weighed out, the reaction temperature was 1300℃, and the reaction time was 3 hours.

[0095] The other steps are the same as in Example 1. Testing showed that the aluminum nitride nanopowder prepared in this example has the same properties as the aluminum nitride nanopowder prepared in Example 1.

[0096] Example 11

[0097] The difference from Example 1 is as follows:

[0098] The molar ratio of aluminum hydroxide, carbon black, and melamine used to prepare the precursor was 1:0.5:2.

[0099] In the carbothermic reduction reaction, 15g of the reaction precursor and 30g of the non-in-situ activator melamine were weighed out, the reaction temperature was 1300℃, and the reaction time was 3 hours.

[0100] The other steps are the same as in Example 1. Testing showed that the aluminum nitride nanopowder prepared in this example has the same properties as the aluminum nitride nanopowder prepared in Example 1.

[0101] Example 12

[0102] The difference from Example 1 is as follows:

[0103] The molar ratio of aluminum hydroxide, carbon black, and melamine used to prepare the precursor was 1:0.25:2.

[0104] In the carbothermic reduction reaction, 15g of the reaction precursor and 30g of the non-in-situ activator melamine were weighed out, the reaction temperature was 1300℃, and the reaction time was 3 hours.

[0105] The other steps are the same as in Example 1. Testing showed that the aluminum nitride nanopowder prepared in this example has the same properties as the aluminum nitride nanopowder prepared in Example 1.

[0106] Example 13

[0107] The difference from Example 1 is as follows:

[0108] The molar ratio of aluminum hydroxide, carbon black, and melamine used to prepare the precursor was 1:0.5:2.

[0109] In the carbothermic reduction reaction, 20g of the reaction precursor and 30g of the non-in-situ activator melamine were weighed out, the reaction temperature was 1300℃, and the reaction time was 3 hours.

[0110] The other steps are the same as in Example 1. Testing showed that the aluminum nitride nanopowder prepared in this example has the same properties as the aluminum nitride nanopowder prepared in Example 1.

[0111] Example 14

[0112] The difference from Example 1 is as follows:

[0113] The molar ratio of aluminum hydroxide, carbon black, and melamine used to prepare the precursor was 1:0.25:2.

[0114] In the carbothermic reduction reaction, 20g of the reaction precursor and 30g of the non-in-situ activator melamine were weighed out, the reaction temperature was 1300℃, and the reaction time was 3 hours.

[0115] The other steps are the same as in Example 1. Testing showed that the aluminum nitride nanopowder prepared in this example has the same properties as the aluminum nitride nanopowder prepared in Example 1.

[0116] Example 15

[0117] The difference from Example 1 is as follows:

[0118] The molar ratio of aluminum hydroxide, carbon black, and melamine used to prepare the precursor was 1:0.5:2.

[0119] In the carbothermic reduction reaction, 20g of the reaction precursor and 30g of the non-in-situ activator melamine were weighed out, the reaction temperature was 1350℃, and the reaction time was 3 hours.

[0120] The other steps are the same as in Example 1. Testing showed that the aluminum nitride nanopowder prepared in this example has the same properties as the aluminum nitride nanopowder prepared in Example 1.

[0121] Example 16

[0122] The difference from Example 1 is as follows:

[0123] The molar ratio of aluminum hydroxide, carbon black, and melamine used to prepare the precursor was 1:0.25:2.

[0124] In the carbothermic reduction reaction, 15g of the reaction precursor and 30g of the non-in-situ activator melamine were weighed out, the reaction temperature was 1350℃, and the reaction time was 3 hours.

[0125] The other steps are the same as in Example 1. Testing showed that the aluminum nitride nanopowder prepared in this example has the same properties as the aluminum nitride nanopowder prepared in Example 1.

[0126] Example 17

[0127] The difference from Example 1 is as follows:

[0128] The molar ratio of aluminum hydroxide, carbon black, and melamine used to prepare the precursor was 1:0.18:2.

[0129] In the carbothermic reduction reaction, 15g of the reaction precursor and 30g of the non-in-situ activator melamine were weighed out, the reaction temperature was 1350℃, and the reaction time was 3 hours.

[0130] The other steps are the same as in Example 1. Testing showed that the aluminum nitride nanopowder prepared in this example has the same properties as the aluminum nitride nanopowder prepared in Example 1.

[0131] Example 18

[0132] The difference from Example 1 is as follows:

[0133] The molar ratio of aluminum hydroxide, carbon black, and melamine used to prepare the precursor was 1:0.25:2.

[0134] In the carbothermic reduction reaction, 15g of the reaction precursor and 20g of the non-in-situ activator melamine were weighed out, the reaction temperature was 1500℃, and the reaction time was 3 hours.

[0135] The other steps are the same as in Example 1. Testing showed that the aluminum nitride nanopowder prepared in this example has the same properties as the aluminum nitride nanopowder prepared in Example 1.

[0136] Example 19

[0137] The difference from Example 1 is as follows:

[0138] The molar ratio of aluminum hydroxide, carbon black, and melamine used to prepare the precursor was 1:0.18:2.

[0139] In the carbothermic reduction reaction, 15g of the reaction precursor and 20g of the non-in-situ activator melamine were weighed out, the reaction temperature was 1500℃, and the reaction time was 3 hours.

[0140] The other steps are the same as in Example 1. Testing showed that the aluminum nitride nanopowder prepared in this example has the same properties as the aluminum nitride nanopowder prepared in Example 1.

[0141] Example 20

[0142] The difference from Example 1 is as follows:

[0143] The molar ratio of aluminum hydroxide, carbon black, and melamine used to prepare the precursor was 1:0.1:2.

[0144] In the carbothermic reduction reaction, 15g of the reaction precursor and 20g of the non-in-situ activator melamine were weighed out, the reaction temperature was 1500℃, and the reaction time was 3 hours.

[0145] The other steps are the same as in Example 1. Testing showed that the aluminum nitride nanopowder prepared in this example has the same properties as the aluminum nitride nanopowder prepared in Example 1.

[0146] It should be noted that although the above embodiments describe the steps of the preparation method of dual-activated aluminum nitride nanopowder in this disclosure in a specific order, this does not require or imply that these steps must be performed in that specific order, or that all the steps shown must be performed to achieve the desired result. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps, etc.

[0147] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

Claims

1. A method for preparing aluminum nitride nanopowder based on dual activation, characterized in that, Includes the following steps: S1. Obtain an aluminum source, a carbon source, and an in-situ activator; mix the aluminum source, carbon source, and in-situ activator to obtain a reaction precursor; wherein the aluminum source is at least one of aluminum hydroxide and γ-alumina; The molar ratio of aluminum source, carbon source and in-situ activator is 1:(0-5):(0.1-5); the in-situ activator is melamine. S2. Place the reaction precursor in a first crucible and place the first crucible in the isothermal section of a tubular furnace; obtain a non-in-situ activator and place the non-in-situ activator in a second crucible, which is placed in the non-isothermal section of the tubular furnace near the gas inlet. The temperature gradually decreases in the non-constant temperature section near the air inlet, along the direction from the constant temperature section to the air inlet. The non-in-situ activator is spread evenly in the second crucible along the direction from the constant temperature section to the air inlet, so that the non-in-situ activator at different positions is heated to the decomposition temperature at different times, so as to continuously generate decomposition products to activate the carbothermic reduction reaction. The mass ratio of the reaction precursor to the non-in-situ activator is 1:1.5; the non-in-situ activator is melamine. Nitrogen gas is continuously introduced into a tubular furnace, and the reaction precursor is reacted in a nitrogen atmosphere at a temperature of 1000-1500°C for 1-5 hours to obtain a mixed powder of carbon and aluminum nitride. S3. Decarbonize the mixed powder of carbon and aluminum nitride obtained in step S2 in air at a temperature of 500-800°C for 1-4 hours to obtain aluminum nitride nanopowder.

2. The method for preparing aluminum nitride nanopowder based on dual activation according to claim 1, characterized in that, In step S1, the molar ratio of aluminum source, carbon source and in-situ activator is 1:(1-3):(0.25-4).

3. The method for preparing aluminum nitride nanopowder based on dual activation according to claim 2, characterized in that, In step S1, the molar ratio of aluminum source, carbon source and in-situ activator is 1:2:

2.

4. The method for preparing aluminum nitride nanopowder based on dual activation according to claim 1, characterized in that, In step S1, the aluminum source, carbon source and in-situ activator are mixed by one of mechanical stirring or ball milling.

5. The method for preparing aluminum nitride nanopowder based on dual activation according to claim 4, characterized in that, In step S1, the carbon source is carbon black.

6. The method for preparing aluminum nitride nanopowder based on dual activation according to claim 5, characterized in that, In step S2, the first crucible is a graphite crucible, and the second crucible is either a graphite crucible or a corundum crucible.

7. The method for preparing aluminum nitride nanopowder based on dual activation according to claim 1, characterized in that, In step S3, the aluminum nitride nanoparticles have a particle size of less than 100 nm.

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