阅读说明：本技术 一种氮化铝粉体的纯化方法、该方法制得的氮化铝粉体及其应用 (Purification method of aluminum nitride powder, aluminum nitride powder prepared by method and application of aluminum nitride powder ) 是由 韩耀 王华栋 吕毅 赵英民 张昊 张天翔 于 2019-11-20 设计创作，主要内容包括：本发明涉及一种氮化铝粉体的纯化方法,包括：(1)将含有碳杂质的氮化铝粉体原料放入容器中,并容器置于烧结炉中,然后通过抽真空排出炉内杂质气体；(2)向烧结炉中通入二氧化碳气体,然后进行烧结处理,从而获得所述氮化铝粉体。本发明还涉及由所述方法制得的氮化铝粉体以及所述氮化铝粉体在氮化铝陶瓷制备中的应用。本发明方法突破传统排碳工艺的局限性,在不引入新的氧元素杂质条件下,除去氮化反应中未反应完全的碳杂质,获得高纯度的氮化铝粉体,其能够有效促进氮化铝陶瓷的烧结合成,最终有效提高氮化铝陶瓷产品的热导率等性能,因此在制造散热基片和电路基板尤其是大规模集成电路基板领域具有广阔的应用前景。(The invention relates to a method for purifying aluminum nitride powder, which comprises the following steps: (1) putting the aluminum nitride powder raw material containing carbon impurities into a container, putting the container into a sintering furnace, and then vacuumizing to discharge impurity gas in the furnace; (2) and introducing carbon dioxide gas into the sintering furnace, and then performing sintering treatment to obtain the aluminum nitride powder. The invention also relates to the aluminum nitride powder prepared by the method and application of the aluminum nitride powder in preparation of aluminum nitride ceramics. The method breaks through the limitation of the traditional carbon removal process, removes carbon impurities which are not completely reacted in the nitridation reaction under the condition of not introducing new oxygen element impurities, obtains high-purity aluminum nitride powder, can effectively promote the sintering synthesis of aluminum nitride ceramics, and finally effectively improves the performances of the thermal conductivity and the like of the aluminum nitride ceramics, so the method has wide application prospect in the field of manufacturing heat dissipation substrates and circuit substrates, especially large-scale integrated circuit substrates.)

1. A method for purifying aluminum nitride powder is characterized by comprising the following steps:

(1) putting the aluminum nitride powder raw material containing carbon impurities into a container, putting the container into a sintering furnace, and then vacuumizing to discharge impurity gas in the furnace;

(2) and introducing carbon dioxide gas into the sintering furnace, and then performing sintering treatment to obtain the aluminum nitride powder.

2. The purification process according to claim 1, characterized in that:

in the step (1), the container is a boron nitride crucible or a corundum crucible.

3. The purification process according to claim 1 or 2, characterized in that:

the sintering furnace is a tubular sintering furnace.

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

the gas flow range when the carbon dioxide gas is introduced is 100-400 ml/min.

5. The purification method according to claim 4, characterized in that:

the gas flow range when the carbon dioxide gas is introduced is 100-200 ml/min.

6. Purification process according to any one of claims 1 to 5, characterized in that:

the sintering temperature of the sintering treatment is 700-1100 ℃; the heat preservation time of the sintering treatment is 1-6 hours.

7. Purification process according to any one of claims 1 to 6, characterized in that:

the sintering temperature of the sintering treatment is 700-1000 ℃; the heat preservation time of the sintering treatment is 3-4 hours.

8. Purification process according to any one of claims 1 to 7, characterized in that:

the aluminum nitride powder raw material containing carbon impurities is prepared by a carbothermic reduction process;

preferably, the carbon impurity-containing aluminum nitride powder raw material has a carbon impurity content of not less than 1% by weight, preferably not less than 2% by weight, more preferably not less than 3.5% by weight, and still more preferably 3.5% by weight to 6.0% by weight, based on the total weight of the aluminum nitride powder raw material containing carbon impurities.

9. The aluminum nitride powder according to any one of claims 1 to 8;

preferably, the aluminum nitride powder has an oxygen content of less than 1.00 wt%, more preferably less than 0.80 wt%;

more preferably, the carbon impurity content of the aluminum nitride powder is less than 0.50 wt%, and more preferably less than 0.40 wt%.

10. The application of the aluminum nitride powder of claim 9 in the preparation of aluminum nitride ceramics; preferably, the aluminum nitride ceramics are used for manufacturing heat-dissipating substrates and circuit substrates, particularly integrated circuit substrates.

Technical Field

The invention relates to the technical field of materials, in particular to a method for purifying aluminum nitride powder, the aluminum nitride powder prepared by the method and application of the aluminum nitride powder.

Background

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 and other properties, and are becoming the first choice materials for LSI substrates and heat dissipation substrates for high density packaging. Aiming at the sintering preparation of the aluminum nitride ceramic, the aluminum nitride ceramic is taken as the most key raw material, the characteristics of the aluminum nitride powder such as purity greatly influence the subsequent molding and sintering, and the powder with high purity is taken as the raw material, so that the performances of the aluminum nitride ceramic such as heat conductivity and the like can be effectively improved, and the application of the aluminum nitride ceramic in the fields of substrate materials and the like is promoted.

At present, in the synthesis process of aluminum nitride powder, AlN powder synthesized by a carbothermic method has high purity and excellent molding and sintering performances, and is the method with the widest industrial production application at present. Due to the limitation of the preparation process, an excessive carbon source needs to be added in the carbothermic reduction process, so that the smooth proceeding of the nitridation reaction is promoted, carbon impurities are inevitably introduced into the prepared aluminum nitride powder, the existence of the carbon impurities in the powder can influence the purity and the subsequent sintering process of the ceramic, and finally the thermal conductivity of the product is influenced.

Currently, for carbon impurities remaining in powder, a common treatment method is to calcine the powder in an air atmosphere, for example, in the invention patent "a method for preparing gamma-AlON ceramic powder based on carbothermic reduction nitridation" (application No. 200910061558.X), carbon-containing AlON powder is placed in air and calcined at 500-650 ℃ for 12 hours to remove the remaining carbon in the mixed powder, so as to achieve a purification effect; the invention discloses a purification method of superfine and high-purity gamma-AlON ceramic powder (application No. 201010190470.0), which is characterized in that the obtained product powder is subjected to heat preservation for 2-24 hours at 650-700 ℃ in the air to remove residual carbon. The simple carbon removal purification process can remove redundant carbon contained in the powder in a certain range, but in the air atmosphere, the aluminum nitride powder can react with oxygen to a certain extent, so that oxygen impurities are introduced into the carbon-removed powder, and the thermal conductivity of the aluminum oxide is generally 30-40W/m/K and is far lower than the theoretical thermal conductivity (319W/m/K) of the aluminum nitride ceramic, so that the thermal conductivity of the aluminum nitride ceramic product can be greatly reduced due to the existence of the oxygen impurities, and the purification method of the aluminum nitride powder is not beneficial to the production and popularization of the powder. Therefore, there is an urgent need to provide a method for preparing aluminum nitride powder that can effectively remove residual carbon without introducing oxygen impurities.

Disclosure of Invention

In order to solve one or more of the above technical problems, the present invention provides, in a first aspect, a method for purifying aluminum nitride powder, the method comprising the steps of:

(1) putting the aluminum nitride powder raw material containing carbon impurities into a container, putting the container into a sintering furnace, and then vacuumizing to discharge impurity gas in the furnace;

(2) and introducing carbon dioxide gas into the sintering furnace, and then performing sintering treatment to obtain the aluminum nitride powder.

In a second aspect, the present invention provides an aluminum nitride powder prepared by the method of the first aspect of the present invention.

In a third aspect, the invention provides an application of the aluminum nitride powder in the second aspect of the invention in the preparation of aluminum nitride ceramics; preferably, the aluminum nitride ceramics are used for manufacturing heat-dissipating substrates and circuit substrates, particularly integrated circuit substrates.

Compared with the existing purification process for preparing the aluminum nitride powder by the carbothermic method, the purification method for the aluminum nitride powder can break through the limitation of the traditional carbon removal process, remove carbon impurities which are not completely reacted in the nitridation reaction under the condition of not introducing new oxygen element impurities, obtain high-purity aluminum nitride powder, and effectively promote the sintering synthesis of aluminum nitride ceramics by the high-purity aluminum nitride powder, so that the heat conductivity and other properties of the aluminum nitride ceramic product are effectively improved finally.

Description of the drawings:

FIG. 1 is a microstructure diagram of the aluminum nitride powder of example 1 before high-purity treatment.

FIG. 2 is a microstructure diagram of the highly purified aluminum nitride powder in example 1.

FIG. 3 is a phase analysis diagram of the aluminum nitride powder after the high-purification treatment in example 1.

FIG. 4 is a microstructure diagram of an aluminum nitride powder after the air atmosphere treatment in comparative example 1.

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.

The invention provides a method for purifying aluminum nitride powder in a first aspect, which comprises the following steps:

(1) putting the aluminum nitride powder raw material containing carbon impurities into a container, putting the container into a sintering furnace, and then vacuumizing to discharge impurity gas in the furnace;

(2) and introducing carbon dioxide gas into the sintering furnace, and then performing sintering treatment to obtain the aluminum nitride powder.

The method can remove carbon impurities in the aluminum nitride powder without introducing oxygen impurities, thereby obtaining high-purity aluminum nitride powder. According to the invention, the aluminum nitride powder prepared by carbothermic reduction is purified by adopting a carbon dioxide reduction process, carbon dioxide and carbon can generate an oxidation reduction reaction to generate carbon monoxide, the reaction is a reversible endothermic reaction, carbon impurities and carbon dioxide are gradually converted into carbon monoxide along with the increase of temperature, and the reaction balance moves to the right. When the reaction temperature is higher than 700 ℃, the reaction speed is accelerated, and the reaction is favorably carried out in the direction of generating carbon monoxide.

The present invention does not specifically limit the vessel described in step (1), so long as it can withstand the sintering temperature employed in the method of the present invention. However, in some preferred embodiments, in step (1), the container is a boron nitride crucible or a corundum crucible.

The present invention does not particularly limit the sintering furnace described in step (1) as long as it can be used for the sintering treatment described in the examples. However, in other preferred embodiments, the sintering furnace is a tubular sintering furnace.

In other preferred embodiments, the gas flow rate when the carbon dioxide gas is introduced is in the range of 100 to 400ml/min, for example, 200ml/min or 300 ml/min. Preferably, the gas flow rate when the carbon dioxide gas is introduced is in the range of 100 to 200 ml/min.

In other preferred embodiments, the sintering temperature of the sintering treatment is 700 to 1100 ℃, and may be, for example, 800 ℃, 900 ℃, or 1000 ℃. The heat preservation time of the sintering treatment is 1 to 6 hours, and for example, may be 2, 3, 4, or 5 hours. In other preferred embodiments, the sintering temperature of the sintering treatment is 700-1000 ℃; the heat preservation time of the sintering treatment is 3-4 hours.

In other preferred embodiments, the aluminum nitride powder raw material containing carbon impurities is an aluminum nitride powder raw material prepared by a carbothermic reduction process. The aluminum nitride powder raw material prepared by the carbothermic reduction process has smaller residual carbon impurity granularity of less than 10 mu m and higher reaction activity, a resistance tube furnace is selected as powder purification equipment, carbon dioxide reaction gas is introduced, and sintering treatment can be carried out under normal pressure operation pressure.

In other preferred embodiments, the carbon impurity content of the aluminum nitride powder raw material containing carbon impurities is not less than 1 wt%, preferably not less than 2 wt%, further preferably not less than 3.5 wt%, and still further preferably 3.5 wt% to 6.0 wt%, based on the total weight of the aluminum nitride powder raw material containing carbon impurities.

Preferably, the aluminum nitride powder has an oxygen content of less than 1.00 wt%, more preferably less than 0.80 wt%. More preferably, the carbon impurity content of the aluminum nitride powder is less than 0.50 wt%, and more preferably less than 0.40 wt%.

In some embodiments, step (1) of the purification process may be performed by: putting the aluminum nitride powder raw material containing carbon impurities prepared by the carbothermic reduction process into a boron nitride crucible, putting the boron nitride crucible into a tubular sintering furnace, vacuumizing, and discharging the redundant gas impurities in the furnace. It is also preferable that the step (2) of the purification method may be performed by: and (3) introducing carbon dioxide gas into the tubular sintering furnace with the flow range of 100-400 ml/min, heating to 700-1100 ℃, and preserving the heat for 1-6 hours within the temperature range, thereby obtaining the high-purity aluminum nitride powder product.

In a second aspect, the present invention provides an aluminum nitride powder prepared by the method of the first aspect of the present invention.

In a third aspect, the invention provides an application of the aluminum nitride powder in the second aspect of the invention in the preparation of aluminum nitride ceramics; preferably, the aluminum nitride ceramics are used for manufacturing heat-dissipating substrates and circuit substrates, particularly integrated circuit substrates.