JP5804910B2 - Aluminum nitride powder and method for producing aluminum nitride powder - Google Patents

Description

The present invention relates to a novel production method for obtaining aluminum nitride powder by a reduction nitriding method. Specifically, the present invention provides a method for producing aluminum nitride powder by a reductive nitriding method, which can obtain a sintered body having a low content of carbon in grain boundaries, excellent sinterability, and higher thermal conductivity. is there.

  Since aluminum nitride is excellent in electrical insulation and has high thermal conductivity, the sintered body is expected as a heat radiating member having high thermal conductivity. Since the thermal conductivity of the aluminum nitride sintered body is greatly influenced by the purity of the aluminum nitride powder as a raw material, the aluminum nitride powder is required to have a small amount of impurities.

  In general, as a method for producing an aluminum nitride powder, a reduction nitriding method in which a mixture of an alumina raw material made of alumina powder and a carbon powder is heated in nitrogen, and a direct nitriding method in which metal aluminum and nitrogen are reacted at a high temperature are known. Since the aluminum nitride powder obtained by the direct nitriding method is manufactured by pulverization and classification, it easily contains metal impurities. On the other hand, the aluminum nitride powder obtained by the reduction nitriding method generally has a smaller amount of metal impurities than the aluminum nitride powder obtained by the direct nitriding method. However, since carbon is used as a raw material, Has a problem of containing a large amount of carbon. Therefore, in the manufacturing method of the aluminum nitride powder by the reduction nitriding method, it is strongly required to reduce the carbon content in the obtained aluminum nitride powder.

  In the reductive nitriding method, carbon that is free after the aluminum nitride powder is produced can be easily decomposed and removed by the subsequent oxidation treatment. However, in the aluminum nitride powder obtained by the reductive nitriding method, the carbon (hereinafter also referred to as “intragranular carbon”) that is incorporated into the grain boundaries of the aluminum nitride crystal particles constituting the powder is the oxidation treatment. However, it cannot be sufficiently removed and remains as an impurity in the obtained aluminum nitride powder.

  Conventionally, as a method for reducing the amount of carbon in grain boundaries of aluminum nitride powder obtained by the reduction nitriding method, after the reduction nitriding is completed, the state at the time of the reduction nitriding reaction is further maintained and maintained for a certain period of time. A method is known in which the amount of carbon is reduced by reacting the internal oxygen and carbon in the grain boundaries.

  However, in order to sufficiently reduce the amount of carbon in the grain boundary by the above method, it is necessary to maintain the state during the reductive nitridation reaction for a long time, so a large amount of reducing gas and a large amount of power are required during that time. It's not a productive method.

JP-A-2-160611

  The objective of this invention is providing the manufacturing method of the aluminum nitride powder which can obtain efficiently the aluminum nitride powder with little carbon content by the reductive nitriding method.

  As a result of diligent research to solve the above problems, the present inventors have used together an alumina powder and a carbon powder, an alkaline earth metal compound or a rare earth metal compound that can be co-melted with alumina at a specific temperature, and a sodium compound. Then, by reducing and nitriding, the carbon in the grain boundary between the obtained aluminum nitride powders can be effectively reduced, and the sodium compound is volatilized and removed after the aluminum nitride powder is produced. The inventors have found that the content of metal impurities can be kept low and that the desired aluminum nitride powder can be obtained with high productivity, and the present invention has been completed.

That is, the present invention provides (a) alumina powder, (b) carbon powder, (c) sodium compound, and (d) coexisting with alumina under the above-described reducing nitriding temperature when producing aluminum nitride powder by the reductive nitriding method. An alkaline earth metal compound or a rare earth metal compound that can be melted, and 0.02 to 3 parts by mass of the sodium compound in terms of oxide (Na ₂ O) with respect to 100 parts by mass of the alumina powder, the alkali the earth metal compound or a rare earth metal compound containing 50 parts by 3 parts by weight in terms of oxide composition, the method of manufacturing a powder of aluminum nitride powder which comprises reducing nitriding at a temperature of 1300 ° C. 1750 ° C. It is to provide.

  According to the production method of the present invention, it is possible to obtain an aluminum nitride powder with a low content of carbon contained as intergranular carbon with high productivity. And in the aluminum nitride sintered compact manufactured from this aluminum nitride powder, it is possible to implement | achieve high thermal conductivity.

As an action mechanism by which the aluminum nitride powder having the above-described characteristics can be obtained by the production method of the present invention, the present inventors presume as follows.
In the method of the present invention, a sodium compound is used together with an alumina powder and a carbon powder that are subjected to a reductive nitriding reaction. At that time, the sodium compound acts catalytically on the surface of the carbon powder to promote oxidative decomposition of carbon and reductive nitridation of alumina. In addition, the sodium compound effectively acts on carbon existing in the powder in a liquid phase in which alumina and an alkaline earth metal compound or a rare earth metal compound are co-melted, and immediately in a high temperature atmosphere of reductive nitriding. Does not volatilize and exists in the liquid phase for an effective time at the firing temperature, so that the carbon oxidative decomposition effect of the sodium compound can be sufficiently exhibited even in a high-temperature atmosphere in reduction nitridation.

  In addition, in the manufacturing method of the aluminum nitride powder by the reductive nitriding method, the mixed powder of the alumina raw material and the carbon powder is about 1500 ° C. to about 1500 ° C. in the presence of a sodium compound in a nitrogen atmosphere for the purpose of suppressing the formation of aggregate particles. A method of producing aluminum nitride powder by firing at a temperature of about 1700 ° C. and performing reductive nitriding of an alumina raw material is disclosed (see Patent Document 1). However, in such a method, although the formation of powder agglomerates is suppressed, the reaction temperature is high, so that the sodium compound is scattered in a short time, and the carbon reduction effect by the sodium compound is expected. I can't.

[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 is used without particular limitation. Alumina powder is dehydrated and transitioned by heating such as alumina, boehmite, diaspore, gibbsite, bayerite, and todite with crystal structures such as α, γ, θ, δ, η, κ, χ, etc. Any alumina hydrate that transforms to α-alumina is available.

  These may be used alone or in a mixed state, but α-alumina, γ-alumina, and boehmite, which have high reaction activity and are easy to control, are preferably used.

  In the present invention, the particle diameter of the alumina powder is not particularly limited, but those having a particle diameter of 2 μm or less are particularly preferable.

[Carbon powder]
Carbon black and graphite powder can be used as the carbon powder used in the present invention. As said carbon black, carbon black, such as a furnace method and a channel method, and acetylene black can be 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, within the range not impairing the effects of the present invention, synthetic resin condensates such as phenol resin, melamine resin, epoxy resin, furan phenol resin, hydrocarbon compounds such as pitch and tar, cellulose, sucrose, polyvinylidene chloride, A carbon source such as an organic compound such as polyphenylene and a reducing gas such as hydrogen, carbon monoxide, and ammonia can be used in combination.

[Sodium compound]
In the present invention, the sodium compound is a liquid formed by a co-melting agent, which will be described later, with respect to the carbon that exists between the alumina powder particles in the reductive nitriding reaction and remains as intergranular carbon in the produced aluminum nitride powder. By the action in the phase, oxidative decomposition by oxygen existing at the grain boundaries of alumina or produced aluminum nitride is promoted, and the content of carbon in the grain boundaries of the obtained aluminum nitride powder is reduced.

  As the sodium compound, a known sodium compound is used without particular limitation as long as it does not adversely affect the reductive nitridation reaction. For example, sodium oxide, sodium bicarbonate, sodium carbonate, sodium nitrate, sodium aluminate, sodium hydroxide, sodium stearate, sodium fluoride, sodium acetate and the like. Although the said sodium compound may use a single compound, it can also be used in combination of multiple types of compound. The sodium compounds include those that produce the exemplified sodium compounds during reductive nitriding.

  In the present invention, the sodium compound is not particularly limited in its origin as long as it exists in the reductive nitriding reaction. The most typical embodiment is a method in which a sodium compound is mixed and present together with the alumina powder, the carbon powder, and the co-melting agent, but part or all of the amount used is an alumina powder, a carbon powder, You may use for a reductive nitriding reaction in the state contained in the co-melting agent. Specifically, alumina powder containing a predetermined amount of sodium compound may be used, or carbon powder containing a predetermined amount of sodium compound or a co-melting agent is used to convert the sodium compound into a reaction system. May exist.

  When the sodium compound is mixed and used, the particle diameter is not particularly limited, but is preferably 0.01 μm to 100 μm, and more preferably 0.1 μm to 30 μm.

In the present invention, sodium compounds, alumina powder 100 parts by weight with respect to (alumina basis), with oxide _(Na 2 O) in terms of, 0.02 to 3 parts by weight, preferably, 0.05 to 1 parts by weight Present in proportion. That is, when the proportion of the sodium compound is less than 0.02 parts by mass, the effect of reducing the amount of carbon in the grain boundaries of the obtained aluminum nitride powder cannot be obtained, and the content of the sodium compound is more than 3 parts by mass. In this case, not only the effect of further reducing the amount of carbon in the grain boundaries cannot be obtained, but also contamination of the apparatus with sodium volatilized during the reaction may be a problem.

[Alkaline earth metal compound or rare earth metal compound (co-melting agent)]
In the reductive nitriding reaction, the co-melting agent used in the present invention is co-melted with a part or all of the alumina powder, promotes the reductive nitriding reaction, and extends the time for the sodium compound compatible with this to evaporate, This is for sufficiently expressing the carbon oxidative decomposition effect of the sodium compound even in a high temperature atmosphere in the reduction nitriding.

  Examples of the alkaline earth metal compound or rare earth metal compound as the co-melting agent include oxides, carbonates, hydroxides, acetates, carbides, and fluorides of alkaline earth metals or rare earth metals.

  Examples of the alkaline earth metal include calcium, strontium, barium, and magnesium. Examples of the rare earth metal include yttrium, lanthanum, cerium, praseodymium, and terbium. Typical oxides are calcium oxide, strontium oxide, yttrium oxide, lanthanum oxide, and the fluoride is typically calcium fluoride. A single compound may be used as the alkaline earth metal compound or the rare earth metal compound, but a plurality of types of compounds may be used in combination.

  The alkaline earth metal compound or the rare earth metal compound includes those that produce the exemplified alkaline earth metal compound or rare earth metal compound during the reductive nitriding.

  In the present invention, the co-melting agent is an alkaline earth metal in which the obtained aluminum nitride powder has a low carbon content and the thermal conductivity of a sintered body produced from the obtained aluminum nitride powder tends to be high. Compounds are particularly preferred.

In the present invention, the particle diameter of the alkaline earth metal compound or rare earth metal compound is not particularly limited, but is preferably 0.01 μm to 100 μm, and more preferably 0.1 μm to 30 μm. The specific surface area of the alkaline earth metal compound or a rare earth metal compound is not particularly limited, particularly ^{preferably 0.01m 2 /g~500.0m 2 / g, 0.1m} 2 /g~100.0m 2 / G is more preferable.

  What is necessary is just to select and use the said co-melting agent from the above which can produce | generate a co-melt at the temperature employ | adopted by the reductive nitriding reaction mentioned later.

In this invention, the usage-amount of the said co-melting agent is 3 mass parts-50 mass parts in conversion of an oxide with respect to 100 mass parts (alumina conversion) of an alumina powder, Preferably 3 mass parts-25 mass parts, Furthermore, preferably, a 3 parts by weight to 10 parts by weight. When the proportion of the co-melting agent is lower than the above range, the effect of trapping the sodium compound is small, and an aluminum nitride powder with a small amount of carbon in the grain boundary cannot be obtained. Moreover, even if the ratio of a co-melting agent is made larger than the said range, a further effect will not be acquired and it is not economical.

[Ingredient mixing]
In the present invention, the raw material mixing method may be any method, whether wet or dry, as long as the alumina powder, carbon powder, sodium compound, and co-melting agent are present in a uniform composition. Mixing with a blender, a mixer or a ball mill is preferred.

[Reduction nitriding]
In the method for producing an aluminum nitride powder of the present invention, the reduction nitridation is carried out at 1300 to 1750 ° C. in the presence of carbon and a reducing gas in the presence of carbon and a reducing compound such as alumina powder, sodium compound, alkaline earth metal compound or rare earth metal compound. Preferably it implements at the temperature of 1400 degreeC-1730 degreeC, More preferably, it is 1550 degreeC-1700 degreeC. In this case, the rate of temperature increase may be any rate, and any holding time may be taken during the temperature increase, but generally 5 to 20 ° C./min is preferable.

  When the firing temperature is less than 1300 ° C., the reductive nitriding reaction hardly occurs. On the other hand, when the calcination temperature exceeds 1750 ° C., the volatilization of the sodium compound is severe and the oxidative decomposition effect of carbon cannot be obtained sufficiently, making it difficult to obtain an aluminum nitride powder with a small amount of carbon in the grain boundary. Further, at a temperature exceeding 1800 ° C., an oxynitride having a low thermal conductivity is generated.

  The reduction nitriding time is preferably 0.1 to 50 hours, preferably 0.3 to 20 hours, more preferably 0.5 to 10 hours, and firing at the above temperature. When the reduction nitridation time is less than 0.1 hour, the reaction is not sufficiently completed. On the other hand, when the reduction nitridation time exceeds 50 hours, the aluminum nitride particles are aggregated to easily generate coarse particles. Coarse grains tend to inhibit sintering during the production of the sintered body.

In the present invention, as the method for performing the reductive nitridation, a known method can be employed without any limitation as long as nitrogen is sufficiently diffused into contact with the raw material. For example, there are a method in which the mixed powder is filled in a carbon setter or the like and nitrogen is circulated, a method using a rotary kiln, a method using a fluidized bed, and a method using a vertical tube furnace. Of these, a method of filling a carbon setter or the like and circulating nitrogen is preferable.
Moreover, in order to distribute | circulate nitrogen efficiently in mixed powder, you may granulate a raw material. In that case, the granulated body can be produced by employing any known granulation method without any limitation, such as compression granulation, extrusion granulation, rolling granulation, spray granulation and the like. The particle size of the granulated body is not particularly limited, but is preferably 0.01 mm to 50 mm, and more preferably 0.1 mm to 10 mm.
As the surfactant and the binder used as necessary at the time of granulation production, known ones are used without any limitation as long as the effects of the present invention are not hindered. For example, as a surfactant, fatty acid salt, sulfate ester salt, sulfonate salt, phosphate ester salt, quaternary ammonium salt, alkyl betaine, alkyl amide betaine, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenol ether, polyoxy Examples include ethylene alkylamino ether, polyethylene glycol fatty acid ester, pentaerythritol fatty acid ester, sorbitan fatty acid ester, polyoxoethylene sorbitan fatty acid ester, fatty acid alkanolamide, and binders include polyvinyl alcohol, alginate, sugar, cellulose ether, Examples include dextrin, starch, molasses, and polyvinyl pioridone.

[Oxidation treatment]
In the present invention, since the aluminum nitride powder after the reduction reaction contains free surplus carbon powder, it is preferable to perform a decarbonization treatment. The decarbonization treatment is generally performed at a high temperature by burning excess carbon powder using an oxidizing gas. As the oxidizing gas for performing the decarbonization treatment, any gas that can remove carbon such as air, oxygen, etc. can be used without any limitation. However, in consideration of economy and the oxygen concentration of the obtained aluminum nitride, air is preferable. It is. The treatment temperature is generally 500 to 900 ° C., and 600 to 750 ° C. is preferable in consideration of the efficiency of decarbonization and excessive oxidation of the aluminum nitride surface.

  If the oxidation temperature is too high, the surface of the aluminum nitride powder is excessively oxidized, and it is difficult to obtain the target powder. Therefore, it is preferable to select an appropriate oxidation temperature and time.

By adopting the method of the present invention, it is possible to obtain an aluminum nitride powder that has a low carbon content, is excellent in sinterability, and can obtain a sintered body having a higher thermal conductivity.
[Post-processing]
In the present invention, the oxidized aluminum nitride powder can be pulverized and classified as necessary.
Furthermore, the aluminum nitride powder of the present invention is then molded and then fired to obtain an aluminum nitride sintered body. For this purpose, a known method is employed without any particular limitation. To give specific examples, a sintering aid powder is added in the range of 1 to 10 parts by weight to the raw material aluminum nitride powder, and further required. Add organic binders, plasticizers, dispersants, solvents, etc., depending on the planetary ball etc., mixed by dry or wet with a mixer, for example, doctor blade method, press molding method, extrusion molding method, injection molding It is preferable to mold by a method or the like. In this invention, when shape | molded with the said organic binder, it is common that the molded object performs a degreasing process prior to baking. As the degreasing treatment, known conditions can be used without particular limitation. For example, a method of treating at a temperature of 300 to 1000 ° C. for 1 to 10 hours in an oxidizing atmosphere or a non-oxidizing atmosphere is common. is there. For the firing, known firing conditions are not particularly limited. For example, the degreased body is subjected to a temperature of 1600 to 1900 ° C., preferably 1650 to 1850 ° C., more preferably 1680 to 1600 in a non-oxidizing atmosphere such as nitrogen. Firing is preferably performed at 1820 ° C. for 1 to 100 hours, preferably 2 to 50 hours, and more preferably 2 to 30 hours.

  Hereinafter, the present invention will be described more specifically, but the present invention is not limited to these examples. Various physical properties in Examples and Comparative Examples were measured by the following methods.

(1) Average particle diameter The average particle diameter of alumina powder, carbon powder, sodium compound, alkaline earth metal compound or rare earth metal compound was determined by dispersing the sample in an aqueous solution of sodium pyrophosphate using a homogenizer. Measurement was performed with MICROTRAC HRA manufactured by Nikkiso Co., Ltd.

(2) Specific surface area The specific surface area of alumina powder, carbon powder, sodium compound, alkaline earth metal compound, or rare earth metal compound is determined by the BET method using N ₂ adsorption using a flow type surface area measuring apparatus Flowsorb 2300 manufactured by Shimadzu Corporation. Asked.

(3) Raw material sodium content The sodium content of alumina powder, carbon powder, alkaline earth metal compound or rare earth metal compound is thermally decomposed by adding an acid to the sample (in the case of carbon powder, it is thermally decomposed by acid after oxidative decomposition) ), Measured by ICP emission spectroscopy using ICPS-1000-II manufactured by Shimadzu Corporation.

(4) Yttria concentration in aluminum nitride powder The yttria concentration in the aluminum nitride powder was measured by fluorescent X-rays (XRF).

(5) Carbon content in the aluminum nitride powder The carbon content in the aluminum nitride powder was generated by burning the powder in an oxygen stream using a metal-in-carbon analyzer “EMIA-110” manufactured by HORIBA, Ltd. It quantified from the amount of CO and CO ₂ gas.

(6) Thermal conductivity of aluminum nitride sintered body Thermal conductivity was measured by a laser flash method using LFA-502 manufactured by Kyoto Electronics Industry.

Example 1
100 parts by mass of α-alumina having an average particle size of 0.9 μm, a specific surface area of 6.7 m ² / g, and a Na ₂ O content of 0.005 parts by mass with respect to 100 parts by mass of alumina (including the contained sodium compound) 1000.005 parts by mass), 50 parts by mass of carbon black having a specific surface area of 125 m ² / g, 1 part by mass of sodium hydroxide having an average particle diameter of 1.2 μm, an average particle diameter of 1.0 μm, and a specific surface area of 11.7 m ² / g. After mixing 3.0 parts by mass of calcium oxide, the graphite setter was filled. Next, after nitriding under a condition of a firing temperature of 1650 ° C. and a firing time of 2 hours in a nitrogen atmosphere, an oxidation treatment was performed at 700 ° C. for 12 hours in an air atmosphere to obtain an aluminum nitride powder. The carbon content of the obtained aluminum nitride powder was measured by the method described above. The results are shown in Table 1.

  To 100 parts by mass of the obtained aluminum nitride powder, yttrium oxide was added so as to be 5 parts by mass, and a dispersant and a solvent were further added to the above composition and mixed for 14 hours. Thereafter, polyvinyl butyral and a plasticizer were added as binders and mixed for 18 hours to obtain an aluminum nitride slurry. The aluminum nitride slurry was defoamed and then adjusted to a viscosity of 20,000 cps, and a molded body having a thickness of 0.75 mm was prepared by a doctor blade method. The obtained molded body was degreased in an air atmosphere at 500 ° C. for 4 hours, and fired in a nitrogen atmosphere at 1740 ° C. for 5 hours to obtain an aluminum nitride sintered body. Table 1 also shows the thermal conductivity of the sintered body.

Example 2
α alumina has an average particle diameter of 1.0 μm, a specific surface area of 12.7 m ² / g, and Na ₂ O content is 0.005 parts by mass with respect to 100 parts by mass of alumina, and γ-alumina has an average particle size of sodium hydroxide. Sodium carbonate having a diameter of 0.9 μm, 0.333 parts by mass of sodium carbonate with respect to 100 parts by mass of alumina, and calcium oxide having an average particle size of 2.0 μm and a specific surface area of 3.7 m ² / g, An aluminum nitride powder was produced in the same manner as in Example 1 except that 5 parts by mass of the calcium carbonate was added to 100 parts by mass of alumina. The carbon content of the obtained aluminum nitride powder was measured. The results are shown in Table 1.

  Furthermore, the obtained aluminum nitride powder produced the sintered compact similarly to Example 1, and measured thermal conductivity. The results are shown in Table 1.

Example 3
Sodium hydroxide is used as sodium carbonate with an average particle size of 0.9 μm, 0.162 parts by mass of sodium carbonate is added to 100 parts by mass of alumina, and calcium oxide has an average particle size of 1.0 μm and a specific surface area of 2.2 m ² / An aluminum nitride powder was prepared in the same manner as in Example 1 except that 3 parts by mass of yttrium oxide was added to 100 parts by mass of alumina. The carbon content of the obtained aluminum nitride powder was measured. The results are shown in Table 1.

  Furthermore, the obtained aluminum nitride powder produced the sintered compact similarly to Example 1, and measured thermal conductivity. The results are shown in Table 1.

Example 4
1.045 parts by mass of sodium hydroxide is added to 100 parts by mass of alumina, calcium oxide is yttrium oxide having an average particle diameter of 1.0 μm and a specific surface area of 2.2 m ² / g, and the yttrium oxide is added to 100 parts by mass of alumina. On the other hand, an aluminum nitride powder was produced in the same manner as in Example 1 except that 5 parts by mass was added. The carbon content of the obtained aluminum nitride powder was measured. The results are shown in Table 1.

  Furthermore, the obtained aluminum nitride powder produced the sintered compact similarly to Example 1, and measured thermal conductivity. The results are shown in Table 1.

Example 5
α-alumina having an average particle diameter of 0.7 μm, a specific surface area of 6.4 m ² / g, and an Na ₂ O content of 0.25 parts by mass with respect to 100 parts by mass of alumina (including the contained sodium compound) 100.25 parts by mass), and an aluminum nitride powder was produced in the same manner as in Example 1 except that the sodium compound was not added. The carbon content of the obtained aluminum nitride powder was measured. The results are shown in Table 1.

  Furthermore, the obtained aluminum nitride powder produced the sintered compact similarly to Example 1, and measured thermal conductivity. The results are shown in Table 1.

Example 6
An aluminum nitride powder was produced in the same manner as in Example 1 except that the firing temperature was 1400 ° C. The carbon content of the obtained aluminum nitride powder was measured. The results are shown in Table 1.

  Furthermore, the obtained aluminum nitride powder produced the sintered compact similarly to Example 1, and measured thermal conductivity. The results are shown in Table 1.

Example 7
Aluminum nitride was prepared in the same manner as in Example 1 except that calcium oxide was changed to yttrium oxide having an average particle diameter of 1.0 μm and a specific surface area of 2.2 m ² / g, and 3 parts by mass of the yttrium oxide was added to 100 parts by mass of alumina. A powder was prepared. The carbon content of the obtained aluminum nitride powder was measured. The results are shown in Table 1.

  Furthermore, the obtained aluminum nitride powder produced the sintered compact similarly to Example 1, and measured thermal conductivity. The results are shown in Table 1.

Comparative Example 1
Aluminum nitride powder was produced in the same manner as in Example 1 except that calcium oxide was not added. The carbon content of the obtained aluminum nitride powder was measured. The results are shown in Table 1.

  Furthermore, the obtained aluminum nitride powder produced the sintered compact similarly to Example 1, and measured thermal conductivity. The results are shown in Table 1.

Comparative Example 2
An aluminum nitride powder was produced in the same manner as in Example 1 except that no sodium compound was added. The carbon content of the obtained aluminum nitride powder was measured. The results are shown in Table 1.

  Furthermore, the obtained aluminum nitride powder produced the sintered compact similarly to Example 1, and measured thermal conductivity. The results are shown in Table 1.

Comparative Example 3
Except for adding calcium oxide to yttrium oxide having an average particle size of 1.0 μm and a specific surface area of 2.2 m ² / g, and adding 0.1 part by mass of the yttrium oxide to 100 parts by mass of alumina, the same as in Example 1. Aluminum nitride powder was produced. The carbon content of the obtained aluminum nitride powder was measured. The results are shown in Table 1.

  Furthermore, the obtained aluminum nitride powder produced the sintered compact similarly to Example 1, and measured thermal conductivity. The results are shown in Table 1.

Comparative Example 4
An aluminum nitride powder was produced in the same manner as in Example 1 except that the firing temperature was 1850 ° C. The carbon content of the obtained aluminum nitride powder was measured. The results are shown in Table 1.

  Furthermore, the obtained aluminum nitride powder produced the sintered compact similarly to Example 1, and measured thermal conductivity. The results are shown in Table 1.

Claims (1)

(A) Alumina powder, (b) Carbon powder, (c) Sodium compound, and (d) Alkaline earth that can be co-melted with alumina at the above-mentioned reduction nitriding temperature when producing aluminum nitride powder by the reductive nitriding method A metal compound or a rare earth metal compound is included, and 0.02 to 3 parts by mass of the sodium compound in terms of oxide (Na ₂ O), 100% by mass of the alumina powder, the alkaline earth metal compound or the rare earth the metal compound oxide 3 parts by mass to 50 parts by mass containing compositions in terms of the production method of the fine aluminum nitride powder which comprises reducing nitriding at a temperature of 1300 ° C. 1750 ° C..