JP7401330B2 - Aluminum nitride powder manufacturing method and manufacturing equipment - Google Patents

Description

The present invention relates to a novel method and apparatus for producing aluminum nitride powder, which is suitably used as a material for insulating and highly thermally conductive members.

Aluminum nitride has excellent properties such as high electrical insulation, high plasma resistance, and high thermal conductivity, and is therefore widely used for insulating heat dissipation substrates, semiconductor manufacturing equipment materials, and the like. These are manufactured by adding a sintering aid to aluminum nitride powder, if necessary, and sintering it under normal pressure or pressure. When yttrium oxide, which is a typical sintering aid, is used, high thermal conductivity is achieved by trapping impurity oxygen in aluminum nitride.

By the way, as a general method for producing aluminum nitride powder, a reduction nitriding method is known in which a mixed raw material of aluminum oxide powder and carbon powder is heated in a nitriding reaction chamber controlled to have a nitrogen atmosphere. The aluminum nitride powder obtained by this reduction nitriding method has few coarse particles with a particle size exceeding 10 μm, and the particle shape is close to a sphere and has high purity, so it has excellent formability and sinterability, and it can be made into a sintered body. It has the characteristic that it is easy to obtain high thermal conductivity when Therefore, aluminum nitride powder produced by the reduction nitriding method is suitable as a raw material for highly thermally conductive ceramic members, particularly for semiconductor manufacturing equipment members that require high purity.
The present applicant has also proposed a graphite firing container suitable for such a reductive nitriding method in Patent Document 1.

Special Publication No. 5-013909

However, after several months had passed since the start of operation of the aluminum nitride manufacturing plant using the reductive nitriding method, an inspection of the nitriding reaction chamber revealed a problem in that the members and firing vessel inside the chamber had deteriorated significantly. As a result of the investigation, it was determined that the cause was the oxidation and consumption of the graphite used in the furnace material and firing container due to the moisture brought into the raw material powder (mixed powder of alumina and carbon).

The heating loss of raw material alumina is 1% by mass or less, but bound water (adsorbed water) is present in 0.2 to 0.3% by mass. Since the drying temperature of a normal dryer is limited to 200° C., bound water is directly carried into the reduction nitriding furnace. On the other hand, a high temperature of 650° C. or higher is required to complete the desorption of bound water from alumina. Furthermore, the graphite in the firing container also adsorbs moisture when it comes into contact with the atmosphere.
Therefore, the present inventors provided a heat treatment step before supplying the firing container filled with the mixed raw materials to the nitriding reaction chamber (reduction nitriding furnace), and by adjusting the moisture brought into the reducing nitriding furnace, The inventors have discovered that the above problems can be solved, and have completed the present invention.

The method for producing aluminum nitride powder of the present invention includes:
A method for producing aluminum nitride powder by filling a firing container with a mixed raw material consisting of aluminum oxide powder and carbon and supplying the mixture to a nitriding reaction chamber heated to 1450 to 1800°C in a nitrogen atmosphere, the method comprising:
As a pretreatment for nitriding aluminum oxide, the mixed raw material and the firing container are heat-treated at a temperature of 650° C. or more and less than 1250° C. for 30 minutes or more under nitrogen flow, and then the heated mixed raw material and It is characterized by supplying the nitriding reaction chamber to the nitriding reaction chamber without bringing the firing container into contact with outside air.
In the pretreatment, the firing container is filled with the mixed raw material, and the heating loss at 1000 ° C. (the loss when heated until there is no loss) is 5% by mass or less based on the total weight of the firing container and the mixed raw material. It is preferable to carry out a heat treatment.

Furthermore, the aluminum nitride powder manufacturing apparatus according to the present invention includes:
Equipped with a nitrogen purge chamber that replaces the mixed raw material of aluminum oxide powder and carbon filled in a firing container with nitrogen, a heat treatment chamber, and a nitriding reaction chamber,
Each chamber is equipped with a gas inlet and a gas outlet, and is also provided with a transfer means for moving the firing container and an opening/closing means for opening and closing the partition between the chambers in accordance with the movement of the firing container. .

Further, it is preferable that at least a part of the interior lining material in the heat treatment chamber that comes into contact with the gas is made of aluminum oxide, and in the nitriding reaction chamber, at least a part of the interior wall material that comes in contact with the gas is made of a carbon material.
Furthermore, it is preferable to include an oxidation treatment chamber for oxidizing residual carbon discharged from the nitridation reaction chamber and existing together with the obtained aluminum nitride powder in the firing container by heating it in the presence of an oxygen-containing gas.

By adopting the manufacturing method and manufacturing apparatus of the present invention, it is possible to manufacture aluminum nitride powder of excellent quality while preventing corrosion of the inner wall of the nitriding reaction chamber and the firing container due to moisture brought in from the mixed raw materials and the firing container. can. Additionally, this dramatically extends the service life of the device and enables long-term continuous operation.

FIG. 1 is a plan view showing a schematic diagram of a manufacturing apparatus of the present invention. 1 is a perspective view of a typical embodiment of a firing container used in the present invention. FIG. 3 is a perspective view of another typical embodiment of a firing container used in the present invention.

Embodiments of the present invention will be described below.

[Mixed raw materials]
alumina powder
As the alumina powder used as a starting material for the aluminum nitride powder of the present invention, alumina or a hydrate thereof can be used without particular limitation. Alumina powder is alumina with a crystal structure of α, γ, θ, δ, η, κ, χ, etc., as well as boehmite, diaspore, gibbsite, bayerite, todite, etc. Dehydration transition occurs when heated, and eventually all or part of it is All alumina hydrates that convert to α-alumina are available.

These may be used alone or in a mixture of different types, but α-alumina, γ-alumina, and boehmite are particularly preferably used because they have high reaction activity and are easy to control.

In addition, it is preferable to use raw material aluminum oxide with as high a purity as possible. Specifically, the total content of Fe, Ca, Si, Ti, V, Cr, and Ni is 500 mass ppm or less, particularly 400 mass ppm or less. It is preferable to use one with a content of ppm or less.
The method for producing aluminum oxide powder is not limited either, and includes alumina produced by the so-called Bayer method using bauxite as a starting material, a thermal decomposition method of ammonium alum, a method of thermal decomposition of ammonium aluminum carbonate, and a method of hydrolysis of aluminum alkoxide. High-purity alumina produced by synthesis can be used. When strictly controlling the concentration of metal components in the resulting aluminum nitride powder, it is preferable to use synthetically produced high-purity alumina as a raw material.

The specific surface area and average particle size of the aluminum oxide powder used in the present invention are not limited in any way, but those with a BET specific surface area of 2 to 20 m ² /g and an average particle size of 0.1 to 10 μm are preferably used. .

When carbon powder aluminum oxide is nitrided in a nitrogen atmosphere, carbon powder is usually used for reduction.

As the raw material carbon powder, carbon black or graphite powder can be used. As the above-mentioned carbon black, furnace method carbon black, channel method carbon black, and acetylene black are preferably used.

Although the specific surface area of these carbon powders is arbitrary, it is preferable to use one having a specific surface area of 0.01 m ² /g to 500 m ² /g.

In addition, it is preferable to use raw carbon powder with as high a purity as possible, and specifically, for example, if the total content of Na, Fe, Ca, Si, Ti, V, Cr, and Ni is 100 mass ppm or less, especially It is preferable to use one having a content of 70 mass ppm or less.

In addition, synthetic resin condensates such as phenol resins, melamine resins, epoxy resins, and furanphenol resins, hydrocarbon compounds such as pitch and tar, cellulose, sucrose, polyvinylidene chloride, A carbon source such as an organic compound such as polyphenylene can also be used in combination as a raw material.

Mixing of raw materials In the method for producing aluminum nitride powder of the present invention, any method of mixing the raw materials, whether wet or dry, may be used as long as the aluminum oxide powder and carbon powder are present in a uniform composition. However, mixing using a blender, mixer, or ball mill is preferred.

The amount of carbon powder used may be 40 to 60 parts by mass per 100 parts by mass of aluminum oxide powder.

Nitrogen In the present invention, as the nitrogen gas used for nitriding, any nitrogen gas equivalent to that used in a known reduction nitriding reaction can be used without particular limitation. It is also possible to use reducing gases such as hydrogen, carbon monoxide, and ammonia.

[Raw material filling]
A mixed raw material consisting of aluminum oxide powder and carbon is filled into a firing container.
Although the firing container is not particularly limited, it is preferable to use the firing container described in Japanese Patent Publication No. 5-13909 from the viewpoint of nitrogen gas replacement efficiency and nitrogen gas flowability. Typically, the firing vessel is constructed from a carbon material such as graphite.

For example, it is possible to use a firing container as shown in FIG. 2, which has a raw material chamber filled with a mixed raw material to be fired and a gas discharge chamber. FIG. 2 is a perspective view of a firing vessel used in the method of the invention. A mixed raw material 1 of the object to be fired is placed in a firing container 2 having a shallow bottom and a large opening area. The firing container 2 has a raw material chamber 3 filled with mixed raw materials 1 and a gas discharge chamber 5 separated from the raw material chamber 3 by a partition wall 4 .

The firing containers 2 can be stacked in multiple stages to improve productivity.
A gas inlet 6 is provided in the raw material chamber 3 to allow gas to flow into the firing containers when the firing containers are stacked in multiple stages. The position where the gas inlet 6 is provided is preferably on the side wall of the raw material chamber 3, but is not particularly limited.
A gas exhaust port 7 is provided in the gas exhaust chamber 5 of the firing container 2 . The gas discharge chamber 5 is for collecting the gas that has passed through the raw material chamber 3 of each firing container 2 in order to discharge the gas to the outside of the firing furnace. Therefore, it is preferable that the gas discharge chamber 5 communicates with the firing containers 2 stacked in multiple stages from the uppermost stage to the lowermost stage. For this reason, the gas exhaust port 7 is usually provided on the bottom surface of the gas exhaust chamber 5.

In order to allow gas to flow between the raw material chamber 3 and the gas discharge chamber 5 of the firing container 2 described above, a gas passage hole 8 is provided in the partition wall 4 that separates the raw material chamber 3 and the gas discharge chamber 5. In this way, the gas introduced into the firing furnace passes through the gas inlet 6 provided in the raw material chamber 3 and is led to the raw material chamber 3, and then passes through the gas passage hole 8 and reaches the gas discharge chamber 5. , and is discharged through the gas outlet 7.

Although the above-mentioned firing container has one raw material chamber and one gas discharge chamber, it may also have two raw material chambers with a gas discharge chamber in between, as shown in FIG.
2 and 3 are drawn so that the inside of the uppermost firing container can be seen, but in order to equalize the amount of gas flowing into each firing container during firing, the uppermost firing container It is preferable to cover it with a lid.

[Heat treatment]
In the present invention, as a pretreatment for nitriding aluminum oxide, a firing container filled with the mixed raw materials is heated under nitrogen flow at a temperature of 650°C or more and less than 1250°C, preferably 800 to 1000°C for 30 minutes or more. Heat treatment. At the above temperature, the nitriding reaction of aluminum oxide does not occur, and the moisture attached in the aluminum oxide is removed. If the heating temperature is low, moisture will not be removed and it will be difficult to prevent furnace erosion. Furthermore, if the heating temperature is high, sintering of aluminum oxide begins, which may affect the production of aluminum nitride and the physical properties of the final powder.

The heat treatment is performed for 30 minutes or more, preferably 200 minutes or more. Thereafter, the heat-treated mixed raw material and the firing container are transferred to a nitriding reaction chamber without contacting with outside air.
In the above heat treatment, it is preferable that the nitrogen gas to be passed has a lower dew point, and in general, nitrogen gas of −70° C. or lower, preferably −75° C. or lower under atmospheric pressure is suitably used. Further, the flow rate of nitrogen gas may be appropriately determined so as to ensure a flow rate that can remove moisture.
In addition, in the heat treatment chamber in which the heat treatment is performed, the material of the gas contact portion is preferably made of alumina. Usually, the heat treatment is performed in a drying oven or a nitrogen purging room. For this reason, it is preferable that the lining portion that comes into contact with the gas be made of alumina brick.

In the heat treatment, it is preferable that the firing container is filled with the mixed raw materials and heat-treated so that the heating loss at 1000° C. is 5% by mass or less based on the total weight of the firing container and the mixed raw materials.
Incidentally, although the heating loss of raw alumina is 1% by mass or less, bound water including adsorbed water is present in 0.2 to 0.3% by mass. By this heat treatment, the amount of bound water is removed to 0.1% by mass or less.

In addition, in the mixed raw material filled in the firing container, gases other than nitrogen contained in the firing container and the raw materials are replaced with nitrogen gas. Such nitrogen substitution may be performed during the heat treatment, but it can also be performed separately before being subjected to the heat treatment. Such nitrogen substitution is generally performed by first evacuating the gas in the chamber housing the firing container filled with the mixed raw materials, and then introducing nitrogen gas.

[Nitriding reaction treatment]
The firing container filled with the mixed raw material after heat treatment is supplied to the nitriding reaction chamber under a nitrogen atmosphere without contacting the mixed raw material and the firing container with outside air, and heated to 1450 to 1800°C, preferably 1500 to 1700°C. The aluminum oxide is supplied to a nitriding reaction chamber that is heated to a temperature of 2,000 yen, and is reduced by nitriding to produce aluminum nitride powder.
The supplied nitrogen gas passes through the above-described firing vessel, contacts the mixed raw materials, and undergoes a reduction-nitridation reaction.
In the nitriding reaction treatment, the following reductive nitriding reaction proceeds to produce aluminum nitride.
Al ₂ O ₃ + 3C + N ₂ → AlN + 3CO
This reaction is an endothermic reaction (27 kJ/AlN·mol, 1800° C.), the reaction can be easily controlled, and high purity aluminum nitride powder with uniform particle size can be obtained.

If the firing temperature is lower than the above-mentioned lower limit temperature, the nitriding reaction will not proceed sufficiently, and if the firing temperature is higher than the above-mentioned upper limit temperature, the nitriding reaction will proceed sufficiently, but the agglomeration of the aluminum nitride powder will become significant. There is.

During the firing, it is preferable to take care to ensure that the materials of the firing furnace and the firing boat do not cause impurities. In addition, the nitrogen atmosphere is preferably a high-purity nitrogen gas flow or a gas containing ammonia gas, etc., and these reaction gases are normally supplied continuously or intermittently in an amount sufficient for the nitriding reaction to proceed. It is best to bake it while supplying it. In addition, in the nitriding reaction treatment, it is preferable that at least a part of the interior lining material that comes into contact with the gas is made of a carbon material.

Further, in the reductive nitriding reaction, the rate of temperature rise to the reaction temperature for reductive nitriding may be any rate, but is generally preferably 5 to 20° C./min.
Further, the time for performing the reductive nitriding at the reductive nitriding temperature may be appropriately determined by the time required to complete the nitriding of the aluminum oxide powder. Generally, such time will be 2 hours or more, preferably 5 to 50 hours.

In addition, the nitriding reaction treatment consists of a first nitriding reaction treatment in which the reaction proceeds until a conversion rate of at least 60% is reached, and a second nitriding reaction treatment in which the reaction is heated at a higher temperature than the first treatment. The first nitriding reaction may be performed at a temperature of 1,450°C or more and 1,600°C or less, and the second nitriding reaction may be performed at a temperature of more than 1,600°C and 1,800°C or less.
The obtained aluminum nitride powder is recovered from the firing vessel.

[Oxidation treatment]
Since the recovered aluminum nitride powder contains free excess carbon powder, it is preferable to perform an oxidation treatment to remove this. Oxidation treatment is generally performed by burning excess carbon powder using oxidizing gas at high temperatures.

As the oxidizing gas for performing the oxidation treatment, any gas that can oxidize carbon, such as air or oxygen, can be used without restriction, but air is preferred in consideration of economic efficiency and the oxygen concentration of the resulting aluminum nitride. It is. In addition, when performing oxidation treatment in an air atmosphere at normal pressure, rapid oxidation of aluminum nitride occurs from around 1200°C, so the treatment temperature is preferably 500 to 1100°C, which reduces oxidation efficiency and excessive oxidation of the aluminum nitride surface. Considering this, 600 to 900°C is more preferable.

The time for the oxidation treatment may be set as appropriate depending on the degree of carbon reduction, but for example, if the oxidation treatment is carried out at 600 to 900°C, it can be carried out for 1 to 6 hours.
For the oxidation treatment, an oxidation furnace is used, but its type is not particularly limited, and a stationary oxidation furnace, an oxidation furnace with a stirring function, or the like can be used. Specifically, examples include a muffle furnace, a box furnace, a box furnace, a rotary kiln, a box furnace equipped with a powder stirring mechanism such as a stirring blade, and the like. Among these, rotary kilns are suitable for continuous processing and are preferably used. Further, it is preferable that the above-mentioned stirring type oxidation furnace is equipped with a heating means in order to maintain the temperature within a predetermined range. In particular, a rotary kiln equipped with heating means on its outer periphery is suitable.

After the oxidation treatment, the aluminum nitride powder is made uniform in quality using a mixer, etc., and then filled into various packaging bags and canned goods and shipped as products.
The aluminum nitride powder obtained by the production method of the present invention has an average circularity of primary particles of 80% or more. In many cases it is 90% or more. Since it has a high circularity, it has good formability when obtaining a sintered body using aluminum nitride powder as a raw material. Such a high degree of circularity can be achieved by manufacturing aluminum nitride powder using the reduction nitriding method, whereas the direct nitriding method requires processing such as pulverization, resulting in an extremely low degree of circularity. .

[Aluminum nitride powder production equipment]
As shown in FIG. 1, the manufacturing apparatus of the present invention includes a nitrogen purge chamber 10 for purging a firing container 2 filled with a mixed raw material made of aluminum oxide powder and carbon with nitrogen, a heat treatment chamber 11, and a nitriding reaction chamber. 12.
Each chamber is provided with a gas inlet and a gas outlet, and is also provided with transfer means for moving the firing container to each chamber, and means for opening and closing a partition wall that partitions each chamber in accordance with the movement of the firing container 2. For these devices, devices having a known structure can be used without any particular restrictions.

-Nitrogen substitution chamber In the nitrogen substitution chamber 10, the partition wall on the inlet side is opened, and the firing container 2 filled with raw material powder consisting of aluminum oxide powder and carbon powder is supplied.

In the nitrogen substitution chamber 10, the gas mixed in the raw materials and the firing container 2 is replaced with nitrogen gas. Such a nitrogen substitution method may be performed by replacing the gas other than nitrogen in the nitrogen substitution chamber 10 with nitrogen gas, for example, by first evacuating the nitrogen substitution chamber 10 with a vacuum pump, and then introducing nitrogen. The method is reliable and is generally preferred. Of course, a replacement method in which nitrogen gas continues to flow into the nitrogen replacement chamber 10 can also be adopted.

The partition wall at the entrance of the nitrogen substitution chamber 10 and the partition wall between it and the heat treatment chamber 11 are composed of shutters, valves, etc. After opening the partition wall at the entrance and charging the firing container 2, the partition wall is closed and the partition wall is replaced with nitrogen. Thereafter, the partition wall between the heat treatment chamber 11 and the heat treatment chamber 11 is opened, and the fired vessel 2 after the treatment is transferred to the nitriding reaction chamber 12. An example of a transfer means is, for example, a push-type transfer mechanism, in which the entire container is pushed and moved on a transfer path provided with a conveyor, rollers, or the like.

- Heat treatment chamber The heat treatment chamber 11 heats the mixed raw material that has been nitrogen-substituted in the nitrogen substitution chamber 10 and the firing container 2 at a predetermined temperature while flowing nitrogen gas by introducing and discharging nitrogen gas. , reduce the water content so that it is below a predetermined amount. It is preferable that at least a part of the interior lining material of the heat treatment chamber 11 that comes into contact with the gas is made of aluminum oxide. When made of carbon material, the interior lining material may be eroded by moisture removed during heat treatment.
The heat treatment chamber 11 is provided with a heating means for heating to a predetermined temperature, and the heating means may be provided inside the heat treatment chamber 11 or may be provided outside so as to heat the inside. .
In the present invention, the heat treatment chamber 11 can also serve as the nitrogen substitution chamber 10. That is, it is also possible to perform the heat treatment after nitrogen substitution in the heat treatment chamber 11, and in this case, there is no need to separately provide the nitrogen substitution chamber 10.

-Nitriding Reaction Chamber In the nitriding reaction chamber 12, nitrogen gas is passed through the firing container 2 to nitride the aluminum oxide powder. In the nitriding reaction chamber 12, from the viewpoint of thermal conductivity, it is preferable that at least a part of the interior lining material that comes into contact with the gas is made of a carbon material.
The nitriding reaction chamber 12 is provided with a heating means for heating to a predetermined temperature, and the heating means may be provided inside the heat treatment chamber 11 or may be provided outside so as to heat the inside. .
Nitrogen gas is introduced into the heat treatment chamber 11 and the nitriding reaction chamber 12 so as to pass through the firing container 2 . Furthermore, nitrogen from the heat treatment chamber 11 is allowed to enter the nitrogen substitution chamber 10 without directly passing nitrogen gas therethrough.

- Oxidation treatment chamber Furthermore, an oxidation treatment chamber (oxidation furnace) may be provided for oxidizing residual carbon present together with the aluminum nitride powder discharged from the nitridation reaction chamber 12 by heating it in the presence of an oxygen-containing gas. preferable. For this reason, the manufacturing apparatus of the present invention may be provided with a recovery means for recovering the aluminum nitride powder and residual carbon discharged from the nitriding reaction chamber 12. Specifically, an industrial robot or the like may One example is an automatic collection method.
As the oxidation furnace, a stationary oxidation furnace as described above, an oxidation furnace with a stirring function, or the like can be used. Specifically, examples include a muffle furnace, a box furnace, a box furnace, a rotary kiln, and a box furnace equipped with a powder stirring mechanism such as a stirring blade.

The aluminum nitride powder obtained by the production method of the present invention has an appropriate particle size, has few coarse particles, is spherical, and has extremely few impurities, so it can be suitably used for various applications such as raw materials for sintered bodies and filler applications. When used as a raw material for a sintered body, the aluminum nitride powder of the present invention is molded by a known method such as tape molding or press molding, and sintered under normal pressure or pressure. Specific uses include heat dissipation substrates for LEDs, power modules, etc., heaters for semiconductor manufacturing equipment, electrostatic chucks, and the like.

The present invention will be explained in more detail below, but the present invention is not limited to these Examples. Various physical properties and related numerical values in Examples and Comparative Examples were measured by the following methods.

(1) 50% particle size based on volume (D ₅₀ )
The average particle diameter (D ₅₀ ) of aluminum oxide powder, aluminum nitride powder, and mixed powder of aluminum nitride and unreacted raw material aluminum oxide was determined by dispersing the sample in a sodium pyrophosphate aqueous solution using a homogenizer, and using MICROTRAC HRA manufactured by Nikkiso Co., Ltd. The measurement was performed using a laser diffraction method.

(2) Specific surface area The specific surface area of aluminum oxide powder, carbon powder, aluminum nitride powder, and mixed powder of aluminum nitride and unreacted raw material aluminum oxide was determined by the BET method using a flow-type surface area automatic measuring device Flowsorb 2300 manufactured by Shimadzu Corporation. It was measured.

[Example 1]
100 parts by mass of α-alumina with a D ₅₀ of 0.8 μm and a specific surface area of 6.5 m ² /g and 50 parts by mass of carbon black with a specific surface area of 3.4 m ² /g were mixed in a vibrating ball mill. It was filled into the graphite firing container shown. After the firing container was purged with nitrogen in a nitrogen purging chamber, it was sent to a heat treatment chamber, and while being heated to 1000° C., nitrogen gas having a dew point of -70° C. or lower was passed through, and heat treatment was performed for 3 hours. As a result of the above heat treatment, the heating loss at 1000° C. of the firing container and mixed raw materials was 2% by mass.
After the above treatment, the firing container was sent to a nitriding reaction chamber, and a nitriding reaction treatment was performed at 1600° C. for 20 hours in a nitrogen atmosphere.

The obtained reaction mixture powder was oxidized (decarburized) at 630° C. for 8 hours in an air atmosphere, and then crushed to obtain aluminum nitride powder.
After the above series of treatments had been carried out continuously for one year, the inner wall (graphite) of the nitriding reaction chamber and the repeatedly used firing vessel were observed, and no corrosion spots were found at all.

[Comparative example 1]
Aluminum nitride powder was produced in the same manner as in Example 1, except that the nitriding reaction treatment was performed by directly supplying a firing container filled with mixed raw materials to the nitriding reaction chamber without performing the heat treatment.
When the firing vessel and the walls of the nitriding reaction chamber were observed one month after the start of the above series of treatments, severe erosion had occurred in the firing vessel and the walls of the reaction chamber.

1... Mixed raw materials 2... Firing container 3... Raw material chamber 4... Partition wall 5... Gas discharge chamber 6... Gas inlet 7... Gas outlet 8... Gas passage Hole 10...Nitrogen substitution chamber 11...Heat treatment chamber 12...Nitriding reaction chamber

Claims (5)

A method for producing aluminum nitride powder by filling a firing container with a mixed raw material consisting of aluminum oxide powder and carbon and supplying the mixture to a nitriding reaction chamber heated to 1450 to 1800°C in a nitrogen atmosphere, the method comprising:
As a pretreatment for nitriding aluminum oxide, the mixed raw material and the firing container are heat-treated at a temperature of 650° C. or higher and lower than 1250° C. for 30 minutes or more under nitrogen flow, and then the heated mixed raw material and A method for producing aluminum nitride powder, characterized in that the aluminum nitride powder is supplied to a nitriding reaction chamber without bringing the firing container into contact with outside air. Claim characterized in that, in the pretreatment, a firing container is filled with the mixed raw material, and heat-treated so that the heating loss at 1000° C. is 5% by mass or less based on the total weight of the firing container and the mixed raw material. 1. The method for producing aluminum nitride powder according to 1. a nitrogen purge chamber that purges the mixed raw material of aluminum oxide powder and carbon filled in the firing container with nitrogen ;
a heat treatment chamber in which the nitrogen-substituted mixed raw material and the firing container are heat-treated at a temperature of 650° C. or more and less than 1250° C. for 30 minutes or more under nitrogen flow to reduce the moisture content ;
Equipped with a nitriding reaction chamber for nitriding heat-treated aluminum oxide powder under nitrogen flow ,
Each chamber is equipped with a gas inlet and a gas outlet, and includes a transfer means for moving the firing container, an opening/closing means for opening and closing partition walls between the chambers in accordance with the movement of the firing container , and a mixed raw material after heat treatment. An apparatus for producing aluminum nitride powder, comprising a transfer mechanism capable of supplying the powder and the firing container to a nitriding reaction chamber without contacting the outside air . According to claim 3, in the heat treatment chamber, at least a part of the interior wall material that comes into contact with the gas is made of aluminum oxide, and in the nitriding reaction chamber, at least a part of the interior wall material that comes in contact with the gas is made of a carbon material. production equipment for aluminum nitride powder. Furthermore, the present invention is characterized by comprising an oxidation treatment chamber for oxidizing residual carbon discharged from the nitridation reaction chamber and existing together with the obtained aluminum nitride powder in the firing container by heating it in the presence of an oxygen-containing gas. The apparatus for producing aluminum nitride powder according to claim 3 or 4.

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