阅读说明：本技术 一种高纯度氮化铝粉体及其制备方法 (high-purity aluminum nitride powder and preparation method thereof ) 是由 刘荣辉 刘元红 蒋周青 李楠 江泽 于 2019-06-06 设计创作，主要内容包括：本发明属于粉体材料加工技术领域,具体涉及一种高纯度氮化铝粉体,并进一步公开其制备方法。本发明所述高纯度氮化铝粉体的制备方法,以氧化铝为原料,并通过第一次与纳米级碳粉混合、第二次与微米级碳粉混合的分级混合方式,能够在反应物中形成更多的间隙,有效促进高温反应产物一氧化碳的排出和反应气体氮气与固相原料的交换,有助于提高原料的氮化率,从而得到高纯度的氮化铝粉体。制得的氮化铝粉体性能优良,有利于烧结得到致密的氮化铝陶瓷基板,提高基板的热导率,并作为大功率电子器件的散热基片广泛使用。(the invention belongs to the technical field of powder material processing, and particularly relates to high-purity aluminum nitride powder and a preparation method thereof. The preparation method of the high-purity aluminum nitride powder takes the aluminum oxide as the raw material, and can form more gaps in reactants through a grading mixing mode of mixing with the nanoscale carbon powder for the first time and mixing with the micron-sized carbon powder for the second time, effectively promote the discharge of high-temperature reaction products, namely carbon monoxide, and exchange of reaction gas, namely nitrogen and solid-phase raw materials, and contribute to improving the nitridation rate of the raw materials, so that the high-purity aluminum nitride powder is obtained. The prepared aluminum nitride powder has excellent performance, is beneficial to obtaining a compact aluminum nitride ceramic substrate by sintering, improves the thermal conductivity of the substrate, and is widely used as a heat dissipation substrate of a high-power electronic device.)

1. A method for preparing high-purity aluminum nitride powder is characterized by comprising the following steps:

(1) taking aluminum oxide powder and a nano carbon source, adding grinding balls, fully mixing, and sieving to obtain a first mixture;

(2) adding a micron carbon source into the first mixture, fully mixing, and sieving to obtain a second mixture;

(3) Roasting the second mixture at 1550-;

(4) And (4) carrying out heat preservation reaction on the roasting product obtained in the step (3) at the temperature of 600-800 ℃ in the air atmosphere, and carrying out decarbonization treatment to obtain the high-purity aluminum nitride powder.

2. the method according to claim 1, wherein in the step (1), the alumina powder has a median particle diameter D50 of 0.2-0.4 μm.

3. The method for preparing high-purity aluminum nitride powder according to claim 1 or 2, wherein in the step (1), the nano-carbon source has a median particle diameter D50 of 10-50 nm.

4. The method for preparing high-purity aluminum nitride powder according to any one of claims 1 to 3, wherein in the step (1), the mass ratio of the aluminum oxide powder to the nano carbon source is 2: 0.6-1.0.

5. The method for preparing high-purity aluminum nitride powder according to any one of claims 1 to 4, wherein in the step (1), the grinding balls are alumina balls or aluminum nitride balls with the diameter of 5-20 mm.

6. The method for preparing high-purity aluminum nitride powder according to any one of claims 1 to 5, wherein in the step (1), the mass ratio of the grinding balls to the mixture of the aluminum oxide powder and the nano carbon source is 2: 0.5-1.5.

7. The method for preparing high-purity aluminum nitride powder according to any one of claims 1 to 6, wherein in the step (2), the micron carbon source has a median particle diameter D50 of 0.5 to 5 μm.

8. the method for preparing high-purity aluminum nitride powder according to any one of claims 1 to 7, wherein in the step (2), the mass ratio of the first mixture material to the micron carbon source is 2: 0.1-0.3.

9. The method for preparing high-purity aluminum nitride powder according to any one of claims 1 to 8, wherein in the step (3), the time of the roasting step is 8 to 15 hours.

10. The method for producing a high-purity aluminum nitride powder according to any one of claims 1 to 9, characterized in that: in the step (4), the time of the heat preservation reaction is 3-5 h.

Technical Field

The invention belongs to the technical field of powder material processing, and particularly relates to high-purity aluminum nitride powder and a preparation method thereof.

background

With the rapid development of modern electronic technology, the electronic devices are developed in the direction of miniaturization, light weight, high integration, high density, high power and high reliability. Moreover, as the structure of the electronic device is more and more complex, the size of the substrate is increased and the integration level is improved, so that the dissipation power of the substrate is further increased. Therefore, higher demands are made on the heat dissipation performance of electronic devices, particularly substrates.

Because the thermal conductivity coefficient of the aluminum nitride ceramic is 8-10 times higher than that of the aluminum oxide ceramic, and the electrical properties such as volume resistivity, breakdown field strength, dielectric loss and the like can be compared favorably with those of the aluminum oxide ceramic, the aluminum nitride ceramic has the advantages of low dielectric constant, high mechanical strength, thermal expansion coefficient close to that of silicon, and capability of carrying out multilayer wiring, can meet the heat dissipation requirement of a high-power device, and is considered as a new generation of excellent insulating heat dissipation substrate material with good development prospect. Therefore, the LED power generation system is widely applied to the fields of high-speed rails, new energy automobiles, smart power grids, wind power generation, high-power LEDs and the like.

the aluminum nitride powder is a core material for forming the aluminum nitride ceramic substrate and has decisive influence on the performance of the substrate. Therefore, high-performance AlN powder is the key for preparing the high-thermal-conductivity aluminum nitride ceramic. The method for preparing aluminum nitride powder in the prior art mainly comprises an aluminum powder direct nitriding method, a carbothermic reduction method, a chemical vapor deposition method, a self-propagating combustion synthesis method, a microwave synthesis method and the like. Among them, the direct nitriding method and carbothermic reduction method of aluminum powder realize the industrialized production, and the carbothermic reduction method is most widely applied.

The carbothermic reduction method is that the mixed material of alumina and carbon is reacted for 4 to 10 hours in nitrogen flow at the temperature of 1600-1800 ℃ to obtain aluminum nitride powder containing excessive carbon, then the heat preservation is carried out for 10 to 16 hours at the temperature of 600-900 ℃ and the aluminum nitride powder is obtained after decarburization. The carbothermic method has the characteristics of wide raw material source, low price, simple process and suitability for large-scale production, and the synthesized aluminum nitride powder is nearly spherical, has fine granularity and good dispersibility, has great advantages in the aspects of purity, granularity, stability and the like, and is beneficial to the densification of a sintered substrate.

However, in the carbothermic process, after the alumina and the carbon powder are mixed, the powder is accumulated in the reaction equipment and is roasted in a high-temperature nitrogen atmosphere, and the gaps among the raw materials are small, so that the discharge of the generated product carbon monoxide gas and the material exchange of nitrogen, alumina and carbon powder are not facilitated, and the nitridation reaction is often incomplete. In order to solve the above problems, for example, chinese patent CN106882773A discloses a method of reacting and grinding alumina and carbon powder under high temperature vacuum condition, and performing high temperature nitridation under nitrogen atmosphere; however, this method still has a problem that the nitriding is not complete because of a small gap between the reactants. As in the scheme of chinese patent CN105836717A, in order to increase the nitridation rate of the reactant, the method adds aluminum powder into the mixture of alumina and carbon powder to promote the nitridation rate; however, the aluminum nitride powder is not suitable for preparing a substrate because the aluminum powder is melted at about 660 ℃ and the generated aluminum nitride is seriously agglomerated. Therefore, the development of a method for efficiently preparing high-purity aluminum nitride powder has positive significance.

Disclosure of Invention

Therefore, the technical problem to be solved by the present invention is to provide a method for preparing high purity aluminum nitride powder, so as to solve the problem that the purity of the aluminum nitride powder prepared by the conventional carbothermic method in the prior art is slightly low.

In order to solve the technical problems, the method for preparing the high-purity aluminum nitride powder comprises the following steps:

(1) taking aluminum oxide powder and a nano carbon source, adding grinding balls, fully mixing, and sieving to obtain a first mixture;

(2) adding a micron carbon source into the first mixture, fully mixing, and sieving to obtain a second mixture;

(3) Roasting the second mixture at 1550-;

(4) and (4) carrying out heat preservation reaction on the roasting product obtained in the step (3) at the temperature of 600-800 ℃ in the air atmosphere, and carrying out decarbonization treatment to obtain the high-purity aluminum nitride powder.

In the step (1), the median particle diameter D50 of the alumina powder is 0.2-0.4 μm.

In the step (1), the median particle size D50 of the nano carbon source is 10-50 nm.

In the step (1), the mass ratio of the alumina powder to the nano carbon source is 2: 0.6-1.0.

In the step (1), the grinding balls are alumina balls or aluminum nitride balls with the diameter of 5-20 mm.

In the step (1), the mass ratio of the grinding balls to the mixture of the alumina split body and the nano carbon source is 2: 0.5-1.5.

In the step (2), the median particle size D50 of the micron carbon source is 0.5-5 μm.

In the step (2), the mass ratio of the first mixture to the micron carbon source is 2: 0.1-0.3.

In the step (3), the roasting step is carried out for 8-15 h;

In the step (4), the time of the heat preservation reaction is 3-5 h.

The preparation method of the high-purity aluminum nitride split body takes the aluminum oxide as the raw material, and can form more gaps in reactants through a grading mixing mode of mixing with the nano-scale carbon powder for the first time and mixing with the micron-scale carbon powder for the second time, effectively promotes the discharge of high-temperature reaction products of carbon monoxide and the exchange of reaction gas nitrogen and solid-phase raw materials, is beneficial to improving the nitridation rate of the raw materials, and thus the high-purity aluminum nitride powder is obtained. The prepared aluminum nitride powder has excellent performance, is beneficial to obtaining a compact aluminum nitride ceramic substrate by sintering, improves the thermal conductivity of the substrate, and is widely used as a heat dissipation substrate of a high-power electronic device.

The method for preparing the aluminum nitride powder has the advantages of simple process, low requirement on equipment, low raw material cost and low energy consumption, and is more suitable for large-scale industrial production.

drawings

in order that the present disclosure may be more readily and clearly understood, the following detailed description of the present disclosure is provided in connection with specific embodiments thereof and the accompanying drawings, in which,

FIG. 1 is an XRD diffraction pattern of the aluminum nitride powder obtained in example 1;

FIG. 2 is a microscopic morphology of the aluminum nitride powder prepared in example 1.

Detailed Description