阅读说明：本技术 一种高活性氮化铝粉体前驱物及其制备方法和应用 (High-activity aluminum nitride powder precursor and preparation method and application thereof ) 是由 韩耀 王华栋 吕毅 张剑 张天翔 赵英民 于 2019-11-18 设计创作，主要内容包括：本发明涉及一种高活性氮化铝粉体前驱物的制备方法,所述制备方法包括如下步骤：(1)将碳源加热溶解成液体；(2)将铝源加入所述液体中并混合,然后球磨,获得混合浆料；(3)将混合浆料干燥,研磨,得到高活性氮化铝粉体前驱物。本发明制备工艺流程简单,操作简便易于掌握,对设备无苛刻要求。本发明方法工艺流程简单,操作简便易于掌握,对设备无苛刻要求。所制得的氮化铝粉体前驱物分散均匀,反应活性高,有效地促进了氮化铝粉体的后续烧结合成,提高了高纯氮化铝粉体大批量稳定性生产的可行性,并最终有效提高氮化铝陶瓷产品的热导率等性能。(The invention relates to a preparation method of a high-activity aluminum nitride powder precursor, which comprises the following steps: (1) heating and dissolving a carbon source into liquid; (2) adding an aluminum source into the liquid, mixing, and then carrying out ball milling to obtain mixed slurry; (3) and drying and grinding the mixed slurry to obtain the high-activity aluminum nitride powder precursor. The preparation process has the advantages of simple flow, simple and convenient operation, easy mastering and no harsh requirements on equipment. The method has simple process flow, simple and convenient operation, easy mastering and no strict requirement on equipment. The prepared aluminum nitride powder precursor is uniformly dispersed and has high reaction activity, the subsequent sintering synthesis of the aluminum nitride powder is effectively promoted, the feasibility of large-scale stable production of high-purity aluminum nitride powder is improved, and the heat conductivity and other properties of the aluminum nitride ceramic product are finally effectively improved.)

1. A preparation method of a high-activity aluminum nitride powder precursor comprises the following steps:

(1) heating and dissolving a carbon source into liquid;

(2) adding an aluminum source into the liquid, mixing, and then carrying out ball milling to obtain mixed slurry;

(3) and drying and grinding the formed slurry to obtain the high-activity aluminum nitride powder precursor.

2. The method of claim 1, wherein:

the aluminum source is selected from the group consisting of alumina powder, gibbsite, and boehmite, and the aluminum source is in a crystalline state; preferably, the particle size of the aluminum source is 100nm to 500 nm; and/or

The carbon source is a soluble sugar, preferably selected from the group consisting of glucose, fructose and sucrose, more preferably the purity of the carbon source is analytically pure;

in addition, the molar ratio of the aluminum source to the carbon source is preferably 1 (3-6), and preferably 1: (3-4).

3. The method according to claim 1 or 2, wherein in the step (1), the heating temperature is 60 to 100 ℃, preferably 70 to 90 ℃; the dissolution time is based on the complete conversion of the carbon source from a solid state to a liquid state.

4. The production method according to any one of claims 1 to 3, characterized in that:

in the step (2), after the carbon source and the aluminum source are mixed, the mixture is put into a magnetic stirrer to be stirred and mixed, so that a mixture containing the carbon source and the aluminum source is obtained, and the mixture is put into a roller ball mill or a planetary ball mill to be ball-milled and dispersed, so that the mixed slurry is obtained.

5. The method of claim 4, wherein:

the magnetic stirrer stirs and mixes the mixture containing the carbon source and the aluminum source at a rotor speed of 50-80 rpm, and the preferred stirring time is 30-60 minutes; and/or

The ball milling is carried out by adopting a roller ball mill, in the ball milling process, the roller ball mill disperses the mixture containing the carbon source and the aluminum source at the rotating speed of 100-200 r/min, and the ball milling time is preferably 18-20 hours; or, the ball milling is carried out by adopting a planetary ball mill, and in the ball milling process, the planetary ball mill stirs the mixture containing the carbon source and the aluminum source at the rotating speed of 600-800 r/min, and the ball milling time is preferably 3-4 hours.

6. The production method according to any one of claims 1 to 5, characterized in that:

the ball milling medium adopted by the ball milling is selected from the group consisting of alumina balls, nylon balls and nylon-coated steel balls; preferably, the ball/material mass ratio is 3: 1.

7. The production method according to any one of claims 1 to 6, characterized in that:

in the step (3), drying the formed slurry, wherein the drying temperature is 20-50 ℃, and preferably 30-40 ℃; the drying time is preferably 6-8 hours; and/or

In the step (3), the grinding is carried out by adopting an agate mortar, and the grinding time is more than 1 hour; preferably, the grinding is carried out until the coarse grainy feel of the mixture disappears.

8. The highly active aluminum nitride powder precursor prepared by the preparation method according to any one of claims 1 to 7.

9. The use of the highly active aluminum nitride powder precursor according to claim 8 in the preparation of aluminum nitride powder.

10. Use according to claim 9, wherein the aluminum nitride powder is used for the manufacture of aluminum nitride ceramics; preferably, the aluminum nitride ceramic is used for manufacturing an integrated circuit substrate.

Technical Field

The invention relates to the technical field of aluminum nitride ceramic materials, in particular to a high-activity aluminum nitride powder precursor and a preparation method thereof.

Background

In the integrated circuit substrate industry, substrate materials used in the past are mainly alumina, beryllia, diamond, silicon carbide, and the like. However, with the development of high and new technology fields such as modern electronics and microelectronics, the thermal conductivity of the aluminum oxide is only about 40W/m/K, and the requirement of the current large-scale integrated circuit can not be met; the toxicity of beryllium oxide powder limits the industrial application; although the heat-conducting property of diamond is good, the price is too high; the silicon carbide material is not suitable for industrial production due to large dielectric constant and low resistivity. Aluminum nitride ceramics have attracted much attention due to their high theoretical thermal conductivity (319W/m · K), low dielectric constant, thermal expansion coefficient similar to that of silicon materials, excellent electrical insulation, high mechanical strength, nontoxicity, corrosion resistance, etc., and are becoming the first choice materials for large-scale integrated circuit substrates and heat dissipation substrates for high-density packaging. However, aluminum nitride belongs to a compound bonded by covalent bonds, has a small self-diffusion coefficient, is difficult to sinter and densify, and is difficult to obtain high-density aluminum nitride ceramic, so that the thermal conductivity of a product is influenced, and the application of the aluminum nitride ceramic in the fields of substrate materials and the like is limited.

Aiming at the sintering preparation of the aluminum nitride ceramic, the particle size, purity and other characteristics of the aluminum nitride powder greatly influence the subsequent molding and sintering. As a sintering process based on the diffusion mass transfer theory as a leading factor, the growth rate of the neck part in the early sintering stage of the aluminum nitride ceramic is inversely proportional to the 3/5 th power of the grain size. Therefore, the powder with small particle size, high specific surface area, high activity and high purity is used as the raw material, so that the diffusion distance of atoms in the sintering process can be obviously shortened, the mass transfer rate is accelerated, the ceramic sintering driving force is increased, the sintering densification of the aluminum nitride ceramic is accelerated, and finally the performances such as the thermal conductivity of the aluminum nitride ceramic product are effectively improved.

At present, the synthesis methods of aluminum nitride powder mainly include methods such as direct aluminum powder nitriding method, carbothermic alumina reduction method, self-propagating high-temperature synthesis method, chemical vapor deposition method and the like. The latter two methods are mainly applied in laboratories and have a smaller production scale; the aluminum powder direct nitriding method is to directly heat and nitride metal aluminum powder and nitrogen to synthesize aluminum nitride powder, wherein the aluminum powder is easy to agglomerate or form molten aluminum in the high-temperature reaction process, so that incomplete reaction is caused, and the purity of the aluminum nitride is influenced; the AlN powder synthesized by the carbothermic method has high purity and excellent molding and sintering performance, and is the method with the widest industrial production application at present.

The carbothermic reduction reaction is essentially carried out in two steps, namely, firstly, carbon is reduced to alumina to generate a gas-phase intermediate product, and then nitridation is carried out to generate aluminum nitride powder. In the current mature preparation process, alumina matrix powder and solid activated carbon material are still used as the preferred materials of an aluminum source and a carbon source in the carbothermic reduction reaction respectively. The process has the advantages of wide raw material source, low cost, insensitivity to process conditions, good stability, and suitability for large-scale production. However, in the process, the aluminum source and the carbon source initial powder are not easy to mix uniformly and are often agglomerated, so that incomplete reaction is caused, the subsequent product conversion rate is affected, and the energy consumption is often too high due to too high reaction temperature. Researchers at home and abroad make many improvements on the carbothermic reduction method, but the improved methods still have the phenomenon that a solid precursor consisting of an aluminum source and a carbon source is incompletely reacted with nitrogen, the initial aluminum source and the initial carbon source only exist in an atmosphere furnace in a simple powder stacking mode, and the nitrogen introduced into the atmosphere furnace cannot completely enter the gathered powder, so that the phenomenon of inconsistent reaction degrees on the surface and inside of the powder stacking body is caused, the sintering synthesis of aluminum nitride powder is influenced, and the mass production with stability cannot be formed.

Disclosure of Invention

Technical problem to be solved

The technical problem to be solved by the invention is as follows: the method for preparing the aluminum nitride ceramic material by using the carbothermic reduction reaction method has one or more of the following technical problems:

(1) because the aluminum source and the carbon source initial powder are not easy to be mixed uniformly and are easy to agglomerate, incomplete reaction can be caused, the conversion rate of subsequent products is influenced, and the energy consumption is overlarge due to the overhigh reaction temperature.

(2) The precursor consisting of the aluminum source and the carbon source does not react completely with the nitrogen.

(II) technical scheme

In order to solve the above technical problems, the present invention provides, in a first aspect, a method for preparing a high-activity aluminum nitride powder precursor, the method comprising the steps of:

(1) heating and dissolving a carbon source into liquid;

(2) adding an aluminum source into the liquid, mixing, and then carrying out ball milling to obtain a molding slurry;

(3) and drying and grinding the formed slurry to obtain the high-activity aluminum nitride powder precursor.

The invention provides, in a second aspect, a highly active aluminum nitride powder precursor prepared by the preparation method according to the first aspect of the invention.

In a third aspect, the invention provides an application of the high-activity aluminum nitride powder precursor of the second aspect in preparing aluminum nitride powder.

(III) advantageous effects

The technical scheme of the invention has the following advantages:

the aluminum nitride powder precursor is prepared by mixing a solid carbon source and a liquid aluminum source, and is obtained by optimally combining the factors such as the raw material ratio, the carbon source dissolving temperature, the ball-milling stirring mixing mode, the stirring speed, the mixing time, the drying temperature and the like. The precursor is uniformly dispersed and high in reaction activity, a liquid phase in a mixture is only a liquid carbon source, the high-fluidity liquid carbon source can be fully mixed with solid aluminum source powder, the preparation process is different from that of the traditional aluminum nitride powder precursor, and other liquid solvents such as water, alcohol and the like are not contained in the mixing process of the carbon source and the aluminum source. When the high-activity aluminum nitride powder precursor is adopted to carry out subsequent nitrogen nitridation reduction reaction, nitrogen can be fully contacted with the precursor containing a carbon source and an aluminum source, so that the internal reaction degree of the powder is consistent when the precursor is nitrided, the nitridation efficiency of solid-gas reaction is greatly increased, and the phenomenon of incomplete nitridation reaction of the traditional solid precursor and nitrogen is effectively improved.

Meanwhile, the preparation process flow of the precursor is simple, the operation is simple and convenient and is easy to master, and the high-activity aluminum nitride powder precursor prepared by the carbothermic method has no strict requirements on equipment.

Drawings

Fig. 1 is a microstructure diagram of an aluminum nitride powder precursor prepared in example 1 of the present invention.

FIG. 2 is a phase analysis diagram of the aluminum nitride powder obtained in example 1 of the present invention.

FIG. 3 is a phase diagram of the aluminum nitride powder obtained in example 2 of the present invention.

FIG. 4 is a phase analysis diagram of the aluminum nitride powder obtained in example 3 of the present invention.

FIG. 5 is a phase diagram of the aluminum nitride powder obtained in example 4 of the present invention

FIG. 6 is a phase analysis chart of the aluminum nitride powder obtained in comparative example 1 of the present invention.

FIG. 7 is a phase analysis chart of the aluminum nitride powder obtained in comparative example 2 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

As described above, the present invention provides, in a first aspect, a method for preparing a highly active aluminum nitride powder precursor, the method comprising the steps of:

(1) heating and dissolving a carbon source into liquid;

(2) adding an aluminum source into the liquid, mixing, and then carrying out ball milling to obtain mixed slurry;

(3) and drying and grinding the formed slurry to obtain the high-activity aluminum nitride powder precursor.

In some more specific embodiments, the carbon source may be heated to dissolve into a liquid, placed into a vessel such as a beaker; adding the weighed aluminum source into the fully dissolved carbon source, stirring and mixing, and fully ball-milling to obtain molding slurry; and then drying and grinding the uniformly mixed slurry to obtain the high-activity aluminum nitride powder precursor.

In some preferred embodiments, the aluminum source is selected from the group consisting of alumina powder, gibbsite, and boehmite, and the aluminum source is crystalline. In other words, the aluminum source may be selected from any one or more of crystalline alumina powder, gibbsite, and boehmite, and for example, crystalline alumina powder such as α -alumina, γ -alumina, θ -alumina, η -alumina, κ -alumina, and χ -alumina may be used. Gibbsite, such as alpha-gibbsite, may be selected; it is also possible to use boehmite (also known as boehmite) and also any two or three of the above-mentioned components, the invention not being described in more detail in the context of possible combinations. Preferably, the aluminum source has a particle size of 100nm to 500 nm. The particle size may be all values or any subrange within this range, for example, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, or 500 nm. The sub-range may be 100-200 nm, 150-300 nm, 200-400 nm or 350-500 nm. The carbon source preferably has a particle size of 10 to 50nm, and may be any value or any subrange within this range, for example, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, or 50 nm. The sub-range may be 10-20 nm, 25-40 nm or 35-50 nm.

In other preferred embodiments, the carbon source is a soluble sugar. More preferably selected from the group consisting of glucose, fructose and sucrose. That is, the carbon source is selected from any one or more of three soluble sugars, glucose, fructose, and sucrose. For example, glucose may be selected, fructose may be selected, sucrose may be selected, any two or all of the three preferred components may be selected, and the invention is not described in detail herein with respect to possible combinations thereof. It is further preferred that the purity of the carbon source is analytically pure.

The dosage of the selected carbon source can be calculated according to the molar ratio of the subsequent carbon source addition, preferably, the molar ratio of the carbon source to the aluminum source is (3-6): 1, preferably (3-4): 1; the molar ratio can be all values or subranges within the range. For example, the number of moles of C atoms in the carbon source may be 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0 times the number of moles of aluminum atoms in the aluminum salt; the sub-range may be 3.0 to 3.5 times or 3.5 to 4.0 times. For example, in other preferred embodiments, the molar ratio of the aluminum source to the carbon source is 1 (3-6), preferably 1: (3-4).

In other preferred embodiments, in step (1), the heating temperature is 60 to 100 ℃, preferably 70 to 90 ℃. The temperature may be all values or subranges within this range, for example, 70 ℃, 71 ℃, 72 ℃, 73 ℃, 74 ℃, 75 ℃, 76 ℃, 77 ℃, 78 ℃, 79 ℃, 80 ℃, 81 ℃, 82 ℃, 83 ℃, 84 ℃, 85 ℃, 86 ℃, 87 ℃, 88 ℃, 89 ℃, 90 ℃, specifically, the subranges may be 70-75 ℃, 75-80 ℃, 80-85 ℃, or 85-90 ℃. The dissolution time is based on the complete conversion of the carbon source from a solid state to a liquid state. The heating and dissolving time is subject to the condition that the carbon source powder state is completely converted from a solid state into a liquid state. When glucose is used as a carbon source, the heating time is preferably 2 hours; when fructose is used as a carbon source, the heating time is preferably 1 hour; the heating time is preferably 0.5 hour using the sucrose as a carbon source.

In other preferred embodiments, in step (2), after the carbon source and the aluminum source are mixed, the mixture is placed into a magnetic stirrer to be stirred and mixed, so as to obtain a mixture containing the carbon source and the aluminum source, and the mixture is placed into a roller ball mill or a planetary ball mill to be ball-milled and dispersed, so as to obtain a mixed slurry.

In other preferred embodiments, the magnetic stirrer stirs and mixes the mixture containing the carbon source and the aluminum source at a rotor speed of 50 to 80 rpm, the stirring time is preferably 30 to 60 minutes, and the stirring medium is a rotor. In some optional embodiments, the ball milling is performed by using a roller ball mill, and during the ball milling, the roller ball mill disperses the mixture containing the carbon source and the aluminum source at a rotation speed of 100 to 200 rpm, and the ball milling time is preferably 18 to 20 hours. In other alternative embodiments, the ball milling is performed by using a planetary ball mill, and during the ball milling, the planetary ball mill stirs the mixture containing the carbon source and the aluminum source at a rotation speed of 600 to 800 rpm, and the ball milling time is preferably 3 to 4 hours.

In other preferred embodiments, the ball milling is carried out using a milling medium selected from the group consisting of alumina balls, nylon balls, and nylon coated steel balls; preferably, the ball/material mass ratio is 3: 1.

In other preferred embodiments, in step (3), the shaped slurry is dried. The drying temperature is 20 to 50 ℃, preferably 30 to 40 ℃, and the temperature can be all values or subranges within this range, for example, the drying can be performed at 30 ℃, 31 ℃, 32 ℃, 33 ℃, 34 ℃, 35 ℃, 36 ℃, 37 ℃, 38 ℃, 39 ℃ or 40 ℃. The drying time is preferably 6 to 8 hours, and for example, may be 6 hours, 7 hours, or 8 hours.

In other preferred embodiments, in step (3), the dried mixture is collected and ground, and the grinding is performed in an agate mortar for more than 1 hour; preferably, the grinding is carried out until the coarse grainy feel of the mixture disappears. In other words, the grinding effect may be based on the disappearance of the coarse granular feel of the mixture.

The invention provides, in a second aspect, a highly active aluminum nitride powder precursor prepared by the preparation method according to the first aspect of the invention. The precursor is uniformly dispersed and high in reaction activity, a liquid phase in a mixture is only a liquid carbon source, the high-fluidity liquid carbon source can be fully mixed with solid aluminum source powder, the preparation process is different from that of the traditional aluminum nitride powder precursor, and other liquid solvents such as water, alcohol and the like are not contained in the mixing process of the carbon source and the aluminum source. When the high-activity aluminum nitride powder precursor is adopted to carry out subsequent nitrogen nitridation reduction reaction, nitrogen can be fully contacted with the precursor containing a carbon source and an aluminum source, so that the internal reaction degree of the powder is consistent when the precursor is nitrided, the nitridation efficiency of solid-gas reaction is greatly increased, and the phenomenon of incomplete nitridation reaction of the traditional solid precursor and nitrogen is effectively improved.

In a third aspect, the invention provides an application of the high-activity aluminum nitride powder precursor of the second aspect in preparing aluminum nitride powder. Preferably, the aluminum nitride powder is used for manufacturing aluminum nitride ceramics. Further preferably, the aluminum nitride ceramic is used for manufacturing an integrated circuit substrate.