A method for synthesizing aluminum nitride using microgravity combustion

Abstract

Disclosed is a method for synthesizing aluminum nitride by microgravity combustion, which uses Mg4Al3 or Mg 17 Al 12 powder as raw material, and performs combustion in a microgravity and nitrogen atmosphere, and then purifies the combustion product using hydrochloric acid to obtain AlN powder. The method is applicable to both small particles (1 μm in diameter) and large particles (500 μm in diameter), and has a short synthesis time, high purity of the obtained aluminum nitride, and the heat generated by combustion can be used to maintain the temperature of the synthesis chamber, thereby reducing energy consumption.

Description

Technical Field

[0001] This invention belongs to the field of materials science and technology, and relates to a method for synthesizing aluminum nitride using microgravity combustion. Background Technology

[0002] In recent years, the synthesis and utilization of AlN have attracted increasing attention due to its superior properties. For example, AlN's high thermal conductivity, low dielectric constant, and high resistivity make it suitable as a packaging material for electronic devices; its piezoelectric properties have led to its application in radio frequency filters and its widespread use in mobile phones. Currently, there are two main methods for synthesizing AlN: carbothermal reduction and direct aluminum nitridation. In both methods, due to the high melting and boiling points of Al, nitridation experiments are conducted at high temperatures. Furthermore, the resulting AlN tends to agglomerate, requiring high pressure and long reaction times to obtain high-purity AlN. Therefore, developing a simple and economical method for preparing AlN is gaining increasing attention. In recent years, combustion synthesis has become one of the most effective and promising methods for preparing aluminum nitride. Compared to carbothermal reduction and direct nitridation, combustion synthesis can utilize the heat released by the self-diffusion combustion of the sample to produce high-purity AlN in a short time. However, current combustion synthesis methods still use elemental aluminum, aluminum salts, etc. as raw materials. During the synthesis process, the precipitation and agglomeration of AlN prevents N2 from penetrating into the Al particles, resulting in incomplete nitriding of the sample. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for synthesizing aluminum nitride using microgravity combustion. As a simple, economical and efficient method for synthesizing aluminum nitride, it can reduce the temperature required for aluminum nitride synthesis, shorten the synthesis time, reduce the emission of pollutants, and is easy to industrialize.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] A method for synthesizing aluminum nitride using microgravity combustion includes the following steps:

[0006] Step 1: Raise the temperature of the synthesis chamber to above 900°C and maintain it;

[0007] Step 2: Purge the synthesis chamber with nitrogen gas to remove the existing air.

[0008] Step 3: Adjust the pressure inside the synthesis chamber;

[0009] Step 4, add Mg 17 Al 12 The powder or Mg4Al3 powder is fed into the synthesis chamber from above, ignited, and then falls freely.

[0010] Step 5: Adjust the nitrogen mass flow rate;

[0011] Step 6: After the reaction is complete, begin cooling. Once the temperature reaches room temperature, remove the synthesized product.

[0012] Step 7: Dissolve the synthesized product obtained in step 6 in dilute hydrochloric acid;

[0013] Step 8: After no more bubbles are generated during the dissolution process in step 7, filter the mixture and wash the filter with distilled water 2-3 times.

[0014] Step 9: Place the product from step 8 into a drying oven and dry it. After drying, high-purity aluminum nitride powder is obtained.

[0015] The present invention also includes the following technical features:

[0016] Specifically, the synthesis chamber has a height of not less than 1m and a diameter of not less than 50cm.

[0017] Specifically, the Mg 17 Al 12 The powder and Mg4Al3 powder particles are nearly spherical, with a particle size of 1-500μm.

[0018] Specifically, in step 3, the pressure in the synthesis chamber is adjusted to 1-1.2 atmospheres.

[0019] Specifically, in step 5, the nitrogen mass flow rate is 0.6-2 times the powder mass flow rate.

[0020] Specifically, in step 7, each gram of Mg4Al3 requires no less than 1.67g of hydrochloric acid for dissolution.

[0021] Specifically, in step 7, each gram of Mg 17 Al 12 It requires at least 1.71g of hydrochloric acid to dissolve.

[0022] Specifically, in step 9, the temperature of the drying oven is 50-100℃.

[0023] Specifically, in step 9, the drying time is 1-3 hours.

[0024] Compared with the prior art, the present invention has the following technical effects:

[0025] This invention improves the aluminum nitride nitride rate and reduces the synthesis time by utilizing the gas-phase diffusion of magnesium in the raw materials to break the aluminum nitride shell. Furthermore, it utilizes the energy generated from the combustion of the raw materials to maintain the required synthesis temperature, thus reducing energy consumption. In addition, since no carbon or other substances are introduced, emissions of toxic gases such as CO are also reduced.

[0026] The preparation method of the present invention is simple, safe, produces good sample uniformity, has low process requirements, and is easy to achieve batch and automated preparation. Attached Figure Description

[0027] Figure 1 SEM image of the synthesized aluminum nitride;

[0028] Figure 2 XRD curve of synthesized aluminum nitride. Detailed Implementation

[0029] This invention provides a method for synthesizing aluminum nitride using microgravity combustion, the preparation principle of which is as follows:

[0030] 6Mg4Al3+17N2→8Mg3N2+18AlN;

[0031] 3Mg 17 Al 12 +29N2→17Mg3N2+24AlN;

[0032] Mg3N2 + 6HCl → 3MgCl2 + 2NH3;

[0033] Includes the following steps:

[0034] Step 1: Raise the temperature of the synthesis chamber to above 900℃ and maintain it; the height of the synthesis chamber should be no less than 1m and the diameter should be no less than 50cm. Theoretically, there is no restriction on its shape, and the longer the better. Specific requirements are determined according to the properties of the raw materials and the synthesis temperature.

[0035] Step 2: Purge the synthesis chamber with nitrogen gas to remove the existing air.

[0036] Step 3: Adjust the pressure inside the synthesis chamber; adjust the pressure inside the synthesis chamber to 1-1.2 atmospheres.

[0037] Step 4, add Mg 17 Al 12 The powder, or Mg4Al3 powder, is fed into the synthesis chamber from above, ignited, and then falls freely; Mg 17 Al 12 The powder and Mg4Al3 powder particles are nearly spherical, with a particle size of 1-500μm.

[0038] Step 5: Adjust the nitrogen mass flow rate; the nitrogen mass flow rate should be 0.6-2 times the powder mass flow rate.

[0039] Step 6: After the reaction is complete, begin cooling. Once the temperature reaches room temperature, remove the synthesized product.

[0040] Step 7: Dissolve the synthesized product obtained in Step 6 in dilute hydrochloric acid; each gram of Mg4Al3 requires no less than 1.67 g of hydrochloric acid for dissolution; each gram of Mg 17 Al 12 It requires at least 1.71g of hydrochloric acid to dissolve.

[0041] Step 8: After no more bubbles are generated during the dissolution process in step 7, filter the mixture and wash the filter with distilled water 2-3 times.

[0042] Step 9: Place the product from step 8 into a drying oven and dry it at a temperature of 50-100℃ for 1-3 hours. After drying, high-purity aluminum nitride powder is obtained.

[0043] During the synthesis process, the temperature of the synthesis chamber should be higher than 900℃, and theoretically the higher the better, but should not exceed 2000℃. The specific requirements need to be determined according to the size of the synthesis chamber and the properties of the sample.

[0044] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0045] Example 1:

[0046] This embodiment provides a method for synthesizing aluminum nitride using microgravity combustion, including the following steps:

[0047] (1) Raise the temperature of the synthesis chamber to 900℃ and maintain it. The synthesis chamber is 1m high and 50cm in diameter. A product collection tray is placed at the bottom.

[0048] (2) Nitrogen gas is introduced into the synthesis chamber to purge the original air in the synthesis chamber. The gas flow rate is 100 ml / s, and the purging time is 5 min.

[0049] (3) Adjust the pressure in the synthesis chamber to 1 atmosphere;

[0050] (4) 10g of Mg with an average particle size of 100μm 17 Al 12 The powder is fed into the synthesis chamber from above, allowing it to fall freely and be ignited.

[0051] (5) Adjust the nitrogen mass flow rate to twice the powder mass flow rate;

[0052] (6) After the reaction is complete, begin cooling. Once the temperature reaches room temperature, remove the synthesized product.

[0053] (7) Dissolve the synthetic product obtained in step (6) in 100g of 20% dilute hydrochloric acid;

[0054] (8) After no more bubbles are generated, filter the product obtained in step (7) and wash the filter with distilled water 2-3 times.

[0055] (9) Place the product obtained in step (8) into a drying oven and dry it at 100°C for 1 hour. After drying, high-purity aluminum nitride powder can be obtained, and its SEM image is as follows. Figure 1 As shown, XRD( Figure 2 The curve shows that only aluminum nitride diffraction peaks are present in the product, indicating that the aluminum nitride has high purity.

[0056] Example 2:

[0057] This embodiment provides a method for synthesizing aluminum nitride using microgravity combustion, including the following steps:

[0058] (1) Raise the temperature of the synthesis chamber to 900℃ and maintain it. The synthesis chamber is 1m high and 50cm in diameter. A product collection tray is placed at the bottom.

[0059] (2) Nitrogen gas is introduced into the synthesis chamber to purge the original air in the synthesis chamber. The gas flow rate is 100 ml / s, and the purging time is 5 min.

[0060] (3) Adjust the pressure in the synthesis chamber to 1.2 atmospheres.

[0061] (4) 10g of Mg4Al3 powder with an average particle size of 500μm is fed into the synthesis chamber from above, and is ignited after free fall.

[0062] (5) Adjust the nitrogen mass flow rate to be 0.6 times the powder mass flow rate;

[0063] (6) After the reaction is complete, begin cooling. Once the temperature reaches room temperature, remove the synthesized product.

[0064] (7) Dissolve the synthetic product obtained in step (6) in 100g of 20% dilute hydrochloric acid;

[0065] (8) After no more bubbles are generated, filter the product obtained in step (7) and wash the filter with distilled water 2-3 times.

[0066] (9) Place the product obtained in step (8) into a drying oven and dry it at a temperature of 100°C for 1 hour. After drying, high-purity aluminum nitride powder can be obtained.

Claims

1. A method for synthesizing aluminum nitride using microgravity combustion, characterized in that, Includes the following steps: Step 1: Raise the temperature of the synthesis chamber to above 900°C and maintain it; Step 2: Purge the synthesis chamber with nitrogen gas to remove the existing air. Step 3: Adjust the pressure inside the synthesis chamber; Step 4, add Mg 17 Al 12 The powder or Mg4Al3 powder is fed into the synthesis chamber from above, ignited, and then falls freely. Step 5: Adjust the nitrogen mass flow rate; Step 6: After the reaction is complete, begin cooling. Once the temperature reaches room temperature, remove the synthesized product. Step 7: Dissolve the synthesized product obtained in step 6 in dilute hydrochloric acid; Step 8: After no more bubbles are generated during the dissolution process in Step 7, filter the mixture and wash the filter with distilled water 2-3 times. Step 9: Place the product from step 8 into a drying oven and dry it. After drying, high-purity aluminum nitride powder is obtained.

2. The method for synthesizing aluminum nitride using microgravity combustion as described in claim 1, characterized in that, The synthesis chamber has a height of not less than 1m and a diameter of not less than 50cm.

3. The method for synthesizing aluminum nitride using microgravity combustion as described in claim 1, characterized in that, The Mg 17 Al 12 The powder and Mg4Al3 powder particles are nearly spherical, with a particle size of 1-500μm.

4. The method for synthesizing aluminum nitride using microgravity combustion as described in claim 1, characterized in that, In step 3, the pressure in the synthesis chamber is adjusted to 1-1.2 atmospheres.

5. The method for synthesizing aluminum nitride using microgravity combustion as described in claim 1, characterized in that, In step 5, the nitrogen mass flow rate is 0.6-2 times the powder mass flow rate.

6. The method for synthesizing aluminum nitride using microgravity combustion as described in claim 1, characterized in that, In step 7, each gram of Mg4Al3 requires at least 1.67g of hydrochloric acid for dissolution.

7. The method for synthesizing aluminum nitride using microgravity combustion as described in claim 1, characterized in that, In step 7, each gram of Mg 17 Al 12 It requires at least 1.71g of hydrochloric acid to dissolve.

8. The method for synthesizing aluminum nitride using microgravity combustion as described in claim 1, characterized in that, In step 9, the temperature of the drying oven is 50-100℃.

9. The method for synthesizing aluminum nitride using microgravity combustion as described in claim 1, characterized in that, In step 9, the drying time is 1-3 hours.

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