阅读说明：本技术 一种铝醇盐直接氮化制备氮化铝的方法 (Method for preparing aluminum nitride by directly nitriding aluminum alkoxide ) 是由 范光磊 卢胜波 于 2021-08-31 设计创作，主要内容包括：本发明公开了一种铝醇盐直接氮化制备氮化铝的方法,属于氮化铝制备技术领域,其包括S1,将铝醇盐放入窑炉中,在氮气气氛下将窑炉内温度升至200～500℃保温1～4h；S2,在氮气气氛下将窑炉内温度升至1100～1600℃,保温2～4h,制得含氮化铝的反应产物。本发明提供的铝醇盐直接氮化制备氮化铝的方法,利用铝醇盐在无氧高温条件下可热分解碳化的特点,在不引入其他碳源的情况下即可满足碳热反应的碳量,减少了污染因素的引入量,提高了氮化铝的纯度；铝醇盐自身热分解碳化过程能够使碳和铝直接充分接触,提高了反应面积；铝醇盐热分解碳化的过程中形成大量的孔洞和孔隙,有利于氮气的进入,使反应更加彻底。(The invention discloses a method for preparing aluminum nitride by directly nitriding aluminum alkoxide, which belongs to the technical field of aluminum nitride preparation and comprises the following steps of S1, putting the aluminum alkoxide into a kiln, heating the temperature in the kiln to 200-500 ℃ in a nitrogen atmosphere, and keeping the temperature for 1-4 h; s2, raising the temperature in the kiln to 1100-1600 ℃ in the nitrogen atmosphere, and preserving the heat for 2-4 h to obtain the reaction product containing the aluminum nitride. The method for preparing the aluminum nitride by directly nitriding the aluminum alkoxide provided by the invention utilizes the characteristic that the aluminum alkoxide can be thermally decomposed and carbonized under the oxygen-free high-temperature condition, can meet the carbon amount of carbothermic reaction under the condition of not introducing other carbon sources, reduces the introduction amount of pollution factors and improves the purity of the aluminum nitride; the self thermal decomposition and carbonization process of the aluminum alkoxide can ensure that carbon and aluminum are directly and fully contacted, thereby improving the reaction area; a large number of holes and pores are formed in the thermal decomposition and carbonization process of the aluminum alkoxide, which is beneficial to the entering of nitrogen and leads the reaction to be more thorough.)

1. A method for preparing aluminum nitride by directly nitriding aluminum alkoxide is characterized by comprising the following steps:

s1, putting aluminum alkoxide into a kiln, and heating the temperature in the kiln to 200-500 ℃ in a nitrogen atmosphere and preserving the heat for 1-4 h;

s2, raising the temperature in the kiln to 1100-1600 ℃ in the nitrogen atmosphere, and preserving the heat for 2-4 h to obtain the reaction product containing the aluminum nitride.

2. The method for preparing aluminum nitride by direct nitridation of aluminum alkoxide according to claim 1, further comprising the steps of:

and S3, naturally cooling the temperature in the kiln to 600-800 ℃, replacing nitrogen with compressed air, preserving the heat for 1-4h, and removing carbon in the reaction product to obtain the aluminum nitride powder.

3. The method for preparing aluminum nitride by direct nitridation of aluminum alkoxide according to claim 1, wherein the aluminum alkoxide in step S01 is selected from aluminum isopropoxide, aluminum n-butoxide, aluminum n-pentoxide, aluminum hexanoate and aluminum tert-butoxide.

4. The method for preparing aluminum nitride by directly nitriding aluminum alkoxide according to claim 1, wherein the flow rate of nitrogen in the kiln in step S1 is 2 to 5L/min; the temperature rise rate in the kiln is 3-5 ℃/min;

in the step S2, the flow rate of nitrogen in the kiln is 2-5L/min; the temperature rise rate in the kiln is 3-5 ℃/min.

5. The method for preparing aluminum nitride by directly nitriding aluminum alkoxide according to claim 1, wherein the flow rate of the compressed air in the kiln in step S3 is 2 to 5L/min.

6. The method for preparing aluminum nitride by directly nitriding aluminum alkoxide according to claim 1, wherein the method for preparing aluminum alkoxide in step S1 is:

s01, mixing aluminum, alcohol and a catalyst, heating to 120-210 ℃, and reacting completely to obtain a product solution;

s02, purifying the product solution to obtain high-purity aluminum alkoxide;

and S03, cooling the high-purity aluminum alkoxide at normal temperature to obtain solid platy aluminum alkoxide.

7. The method for preparing aluminum nitride by directly nitriding aluminum alkoxide according to claim 1, wherein the purity of the aluminum used in step S01 is greater than 99.99%, and the aluminum is aluminum particles, aluminum wires or aluminum scraps having a diameter of not greater than 2.5 mm; the alcohol is selected from isopropanol, n-butanol, n-pentanol, hexanol or tert-butanol.

8. The method for preparing aluminum nitride by directly nitriding aluminum alkoxide according to claim 1, wherein aluminum chloride or mercuric chloride is used as the catalyst, and the amount of the catalyst added is 0.04 to 0.07 wt% based on the total weight of the aluminum, the alcohol and the catalyst.

9. The method for preparing aluminum nitride by direct nitridation of aluminum alkoxide according to claim 1, wherein the purification method of the high purity aluminum alkoxide in step S02 is distillation purification under reduced pressure.

10. The method for preparing aluminum nitride by direct nitridation of aluminum alkoxide according to claim 1, wherein in step S03, the thickness of the solid plate-like aluminum alkoxide is 2 to 10 cm.

Technical Field

The invention relates to a method for preparing aluminum nitride by directly nitriding aluminum alkoxide, belonging to the technical field of aluminum nitride preparation.

Background

The aluminum nitride is a covalent bond compound with a hexagonal wurtzite structure, has the comprehensive advantages of high thermal conductivity, thermal expansion coefficient matched with silicon, excellent mechanical property, no toxicity and the like, becomes an ideal substrate material and packaging material of a high-power electronic device, and has wide application prospect in the fields of power electronic devices, photoelectronic devices, microwave power devices and the like. For example, when the content of impurities in the aluminum nitride powder is higher, the sintering performance of the aluminum nitride powder is poor, and it is difficult to obtain a dense aluminum nitride ceramic; and the aluminum nitride belongs to covalent compounds, the self-diffusion coefficient is low, and sintering densification is difficult if the particle size and the appearance are not uniform. Therefore, to prepare high-performance aluminum nitride ceramics, it is necessary to prepare aluminum nitride powder with high purity, narrow particle size distribution and stable performance.

At present, two main methods for synthesizing high-performance aluminum nitride powder are an aluminum direct nitriding method and a carbothermic reduction method. In contrast, the aluminum nitride powder prepared by the carbothermic method has high purity, stable performance, fine and uniform powder particle size, and good forming and sintering performance, so the carbothermic method becomes a main production method of the high-quality aluminum nitride powder. However, the method also has the problems of uneven mixing of raw materials, incomplete solid-gas reaction, high nitriding reaction temperature, long reaction time consumption, low loading capacity and the like, so that the purity of the synthesized aluminum nitride powder is not high. In the method of high purity ultrafine aluminum nitride powder provided in patent application with publication number CN109264680A, although the problem of difficult uniform mixing of alumina and amorphous carbon in the traditional carbothermic reduction method is improved by introducing nano amorphous carbon in the hydrolysis process of aluminum isopropoxide, the reaction steps are complicated, and the morphology, particle size distribution and purity of the obtained aluminum nitride still have a space for improvement.

The above description is included in the technical recognition scope of the inventors, and does not necessarily constitute the prior art.

Disclosure of Invention

The invention aims to solve the problems in the prior art and provides a method for preparing aluminum nitride by directly nitriding aluminum alkoxide, which utilizes the characteristic that the aluminum alkoxide can be thermally decomposed and carbonized under the oxygen-free high-temperature condition to ensure that carbon and aluminum are directly and fully contacted for reaction, and further improves the purity of the aluminum nitride without introducing other carbon sources.

The invention adopts the following technical scheme to realize the purpose:

a method for preparing aluminum nitride by directly nitriding aluminum alkoxide comprises the following steps:

s1, putting aluminum alkoxide into a kiln, and heating the temperature in the kiln to 200-500 ℃ in a nitrogen atmosphere and preserving the heat for 1-4 h;

s2, raising the temperature in the kiln to 1100-1600 ℃ in the nitrogen atmosphere, and preserving the heat for 2-4 h to obtain the reaction product containing the aluminum nitride.

Optionally, the method for preparing aluminum nitride by directly nitriding aluminum alkoxide further includes the steps of:

and S3, naturally cooling the temperature in the kiln to 600-800 ℃, replacing nitrogen with compressed air, preserving the heat for 1-4h, and removing carbon in the reaction product to obtain the aluminum nitride powder.

Optionally, the aluminum alkoxide in step S01 is selected from aluminum isopropoxide, aluminum n-butoxide, aluminum n-pentoxide, aluminum hexanoate, or aluminum tert-butoxide.

Optionally, in the step S1, the flow rate of nitrogen in the kiln is 2-5L/min; the temperature rise rate in the kiln is 3-5 ℃/min;

in the step S2, the flow rate of nitrogen in the kiln is 2-5L/min; the temperature rise rate in the kiln is 3-5 ℃/min.

Optionally, in the step S3, the flow rate of the compressed air in the kiln is 2-5L/min, and the pressure is 0.4-0.6 mpa.

Optionally, the preparation method of the aluminum alkoxide in step S1 includes:

s01, mixing aluminum, alcohol and a catalyst, heating to 120-210 ℃, and reacting completely to obtain a product solution;

s02, purifying the product solution to obtain high-purity aluminum alkoxide;

and S03, cooling the high-purity aluminum alkoxide at normal temperature to obtain solid platy aluminum alkoxide.

Optionally, the purity of the aluminum used in step S01 is greater than 99.99%, and the aluminum uses aluminum particles, aluminum wires or aluminum scraps with a diameter not greater than 2.5 mm; the alcohol is selected from isopropanol, n-butanol, n-pentanol, hexanol or tert-butanol.

Optionally, the catalyst is aluminum chloride or mercuric chloride, and the addition amount of the catalyst is 0.04-0.07 wt% of the total weight of the aluminum, the alcohol and the catalyst.

Optionally, in step S02, the purification method of the high-purity aluminum alkoxide is distillation purification under reduced pressure.

Optionally, in step S03, the thickness of the solid plate-like aluminum alkoxide is 2 to 10 cm.

The beneficial effects of the invention include but are not limited to:

the method for preparing the aluminum nitride by directly nitriding the aluminum alkoxide provided by the invention utilizes the characteristic that the aluminum alkoxide can be thermally decomposed and carbonized under the oxygen-free high-temperature condition, and can meet the carbon content of carbothermic reaction without introducing other carbon sources; other carbon sources are not additionally introduced in the reaction process, so that the introduction amount of pollution factors is reduced, and the purity of the aluminum nitride is improved; the self thermal decomposition and carbonization process of the aluminum alkoxide can ensure that carbon is directly and fully contacted with aluminum, thereby improving the reaction area, inhibiting the agglomeration and growth of particles and improving the particle size uniformity of aluminum nitride; a large number of holes and pores are formed in the thermal decomposition and carbonization process of the aluminum alkoxide, which is beneficial to the entering of nitrogen and leads the reaction to be more thorough.

The grain diameter of the high-purity superfine aluminum nitride powder prepared by the method for preparing the aluminum nitride by directly nitriding the aluminum alkoxide is 0.8-1.2 mu m, the purity is more than 99.9 percent, the impurity content Fe is less than 2ppm, the Si is less than 2ppm, the Na is less than 2ppm, and the oxygen content is less than 0.8 percent.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:

FIG. 1 is an SEM image of the aluminum nitride powder prepared in example 1 of the present invention;

FIG. 2 is an SEM image of the aluminum nitride powder prepared in comparative example 1, in which the particle diameter of the aluminum nitride particles is large and non-uniform.

Detailed Description

The present invention will be described in further detail in the following. It should be noted, however, that the following detailed description merely gives specific operation examples of the present invention by way of example, and the scope of the present invention is not limited thereto. The scope of the invention is limited only by the claims. It will be obvious to those skilled in the art that various other modifications and substitutions can be made to the described embodiments of the invention within the scope of the invention as defined by the claims and still achieve the same technical result and achieve the final technical object of the invention.

In the present invention, all proportions are by weight, all percentages are by weight, temperature is in units of degrees Celsius and pressure is in units of pascals. Room temperature refers to the normal ambient temperature in a room, varying with season and location, and is typically 25 ℃. In addition, all numerical ranges recited herein are inclusive of the endpoints and may include new numerical ranges that combine any of the upper and lower limits of the disclosed ranges with one another.

Unless otherwise specified, each raw material is commercially available in this specification.

Example 1:

the method for preparing aluminum nitride by directly nitriding aluminum alkoxide provided by the embodiment comprises the following steps:

s01, washing the surface of the high-purity aluminum ingot by deionized water, and then processing the high-purity aluminum ingot by a milling machine to prepare aluminum particles with the diameter of about 2 mm;

adding 200kg of isopropanol and 95g of aluminum chloride into 27kg of aluminum particles, uniformly mixing, heating to 120 ℃, reacting completely to obtain a product solution, and continuously stirring in the reaction process;

s02, heating the product solution to 190 ℃, and distilling for 4 hours under reduced pressure under the vacuum degree of 12mm mercury column to obtain high-purity aluminum isopropoxide;

s03, pouring high-purity aluminum isopropoxide into the mold, and cooling to be a solid plate with the thickness of 2cm at normal temperature;

s1, placing solid plate-shaped high-purity aluminum isopropoxide into an aluminum nitride sagger, placing the aluminum nitride sagger in a furnace kiln, maintaining the nitrogen flow rate in the furnace kiln at 2L/min, raising the temperature in the furnace kiln to 500 ℃ at the heating rate of 3 ℃/min, and preserving the temperature for 3 h;

s2, maintaining the flow rate of nitrogen in the kiln at 3.5L/min, raising the temperature in the kiln to 1400 ℃ at the heating rate of 3 ℃/min, and preserving the temperature for 4h to obtain a reaction product containing aluminum nitride;

and S3, naturally cooling the temperature in the kiln to 700 ℃, replacing the nitrogen with 0.6mpa compressed air, maintaining the flow rate of the compressed air at 3L/min, preserving the heat for 3h, and removing carbon in the reaction product to obtain the aluminum nitride powder.

FIG. 1 is an SEM image of the aluminum nitride powder prepared in example 1 of the present invention, wherein the aluminum nitride has a small particle size and a uniform size.

Example 2:

the method for preparing aluminum nitride by directly nitriding aluminum alkoxide provided by the embodiment comprises the following steps:

s01, cleaning the surface of the high-purity aluminum ingot by deionized water, and then processing the high-purity aluminum ingot by a milling machine to prepare an aluminum wire with the diameter of about 2 mm;

292kg of n-butanol and 146g of aluminum chloride are added into 27kg of aluminum particles to be uniformly mixed, the mixture is heated to 210 ℃ to be completely reacted to obtain a product solution, and the product solution is continuously stirred in the reaction process;

s02, heating the product solution to 150 ℃, and distilling for 4 hours under reduced pressure under the vacuum degree of 12mm mercury column to obtain high-purity aluminum isopropoxide;

s03, pouring high-purity aluminum isopropoxide into the mold, and cooling to be a solid plate with the thickness of 3cm at normal temperature;

s1, placing solid plate-shaped high-purity aluminum isopropoxide into an aluminum nitride sagger, placing the aluminum nitride sagger in a furnace kiln, maintaining the nitrogen flow rate in the furnace kiln at 3L/min, raising the temperature in the furnace kiln to 500 ℃ at the heating rate of 3 ℃/min, and preserving the temperature for 3 h;

s2, maintaining the flow rate of nitrogen in the kiln at 4L/min, raising the temperature in the kiln to 1100 ℃ at the temperature raising rate of 5 ℃/min, and preserving the temperature for 3h to obtain a reaction product containing aluminum nitride;

and S3, naturally cooling the temperature in the kiln to 600 ℃, replacing the nitrogen with 0.4mpa compressed air, maintaining the flow rate of the compressed air at 2L/min, preserving the heat for 4h, and removing carbon in the reaction product to obtain the aluminum nitride powder.

Example 3:

the method for preparing aluminum nitride by directly nitriding aluminum alkoxide provided by the embodiment comprises the following steps:

s01, washing the surface of the high-purity aluminum ingot by deionized water, and then processing the high-purity aluminum ingot by a milling machine to prepare aluminum scraps with the diameter of about 2 mm;

adding 260kg of n-amyl alcohol and 175kg of mercuric chloride into 27kg of aluminum particles, uniformly mixing, heating to 180 ℃, reacting completely to obtain a product solution, and continuously stirring in the reaction process;

s02, heating the product solution to 210 ℃, and distilling for 4 hours under reduced pressure under the vacuum degree of 12mm mercury to prepare high-purity aluminum isopropoxide;

s03, pouring high-purity aluminum isopropoxide into the mold, and cooling to a solid plate shape with the thickness of 5cm at normal temperature;

s1, placing solid plate-shaped high-purity aluminum isopropoxide into an aluminum nitride sagger, placing the aluminum nitride sagger in a furnace kiln, maintaining the nitrogen flow rate in the furnace kiln at 3L/min, raising the temperature in the furnace kiln to 500 ℃ at the temperature rise rate of 4 ℃/min, and preserving the temperature for 4 hours;

s2, maintaining the flow rate of nitrogen in the kiln at 4.5L/min, raising the temperature in the kiln to 1600 ℃ at the heating rate of 4 ℃/min, and preserving the temperature for 4h to obtain a reaction product containing aluminum nitride;

and S3, naturally cooling the temperature in the kiln to 800 ℃, replacing the nitrogen with 0.8mpa compressed air, maintaining the flow rate of the compressed air at 5L/min, preserving the heat for 3h, and removing carbon in the reaction product to obtain the aluminum nitride powder.

Through detection, the content of impurities in the aluminum nitride powder prepared by the method is extremely low, wherein Fe is less than 2ppm, Si is less than 2ppm, Na is less than 2ppm, and the oxygen content is less than 0.8%; the average grain diameter of the aluminum nitride is 0.8-1.2 μm, and the D10 is 0.7-0.8 μm; d50 ═ 1.0 to 1.2 μm; d90 is 1.5-1.8 μm, and has narrow particle size distribution and uniform particle size.

Comparative example 1:

the method for preparing aluminum nitride by directly nitriding aluminum alkoxide provided by the comparative example comprises the following steps:

cleaning the surface of a high-purity aluminum ingot by using deionized water, and then processing the high-purity aluminum ingot by using a milling machine to prepare aluminum particles with the diameter of about 2 mm;

adding 200kg of isopropanol and 95g of aluminum chloride into 27kg of aluminum particles, uniformly mixing, heating to 120-210 ℃, reacting completely to obtain a product solution, and continuously stirring in the reaction process;

carrying out reduced pressure distillation and purification on the product solution to obtain high-purity aluminum isopropoxide;

adding pure water into high-purity aluminum isopropoxide, uniformly mixing, and carrying out hydrolysis reaction at 80 ℃ to obtain slurry containing high-purity aluminum hydroxide;

mixing 21.5kg of carbon black into the slurry containing high-purity aluminum hydroxide, uniformly stirring and drying the mixture, then filling the mixture into an aluminum nitride sagger and putting the sagger into a furnace;

maintaining the flow rate of nitrogen in the kiln at 2L/min, and heating the temperature in the kiln to 500 ℃ and preserving the temperature for 3 h; maintaining the nitrogen flow rate in the kiln at 3.5L/min, and raising the temperature in the kiln to 1400 ℃ and preserving the temperature for 4 h; and naturally cooling the temperature in the kiln to 700 ℃, replacing nitrogen with 0.6mpa compressed air, keeping the temperature for 3 hours, and obtaining the aluminum nitride powder, wherein the flow of the compressed air is 2L/min.

FIG. 2 is an SEM image of the aluminum nitride powder prepared in comparative example 1, in which the particle diameter of the aluminum nitride particles is large and non-uniform.

The above-described embodiments should not be construed as limiting the scope of the invention, and any alternative modifications or alterations to the embodiments of the present invention will be apparent to those skilled in the art.

The present invention is not described in detail, but is known to those skilled in the art.