JPH0376820A - Production of aluminum nitride fiber - Google Patents

Abstract

PURPOSE:To obtain the title fiber useful for SAN elements, electrical insulating films for semiconductor devices, optical elements, etc., by mixing an Al-contg. compound with an organic polymer rich in drawability and forming into a filamentous form, which is then baked in a nitrogen-contg. non-oxidative atmosphere. CONSTITUTION:A mixture comprising (A) an Al-contg. compound (pref. aluminum polynuclear complex or aluminum alkoxide), (B) an organic polymer rich in drawability (e.g. methyl cellulose, polyethylene oxide, PVA), and, if needed, (C) a carbon contg. compound and/or a carbon-nitrogen-contg. compound (e.g. glucose, urea) is formed into a filamentous form, which is then baked in a nitrogen-contg. non-oxidative atmosphere, thus obtaining the objective fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to a method for producing aluminum nitride fibers.

[Conventional technology]

Aluminum nitride has electrical insulation properties and high thermal conductivity, and its coefficient of thermal expansion is close to that of silicon.
It is used as a high heat dissipation substrate that supports higher integration and higher output ICs.

In addition, aluminum nitride has excellent propagation speed, corrosion resistance against molten metal, chemical stability, etc.
Application to elements, use as insulating film for semiconductor devices,
There are great expectations for this material as it has the potential to be widely used in applications such as optical devices.

[Problem to be solved by the invention]

However, the aluminum nitride conventionally used is in powder form. In order to effectively utilize aluminum nitride, fibrous materials are strongly desired.

However, conventional methods for producing aluminum powder, such as the reduction nitriding method of alumina using carbon black and the direct nitriding method of metallic aluminum powder, are not suitable for producing aluminum nitride fibers. On the other hand, the melting method, flux method, and hydrothermal method, which are conventionally known methods for producing ceramic/resin fibers, are not effective for producing aluminum nitride fibers.

In view of the above circumstances, it is an object of the present invention to provide a method for easily producing aluminum nitride fibers.

[Means to solve the problem]

In order to solve the above problems, the method for manufacturing aluminum nitride fibers according to the present invention has the following configuration.

In the method for producing aluminum nitride fibers according to claims 1 to 6, a fibrous material comprising an aluminum-containing compound, an organic polymer compound with high stretchability, and a carbon-containing compound and/or a carbon/nitrogen-containing compound added as necessary. The molded mixture is fired in a non-oxidizing atmosphere containing nitrogen.

In the manufacturing method of the present invention, it is preferable that the aluminum-containing compound, the highly stretchable organic polymer compound, the carbon-containing compound, and/or the carbon/nitrogen-containing compound are water-soluble.

Examples of water-soluble aluminum-containing compounds include aluminum polynuclear complexes. In addition, as a water-soluble aluminum-containing compound, claim 4
Aluminum alkoxides can also be mentioned, such as
In this case, it is desirable to add tetraalkylammonium hydroxide when mixing each compound.

Each compound in the fibrous mixture is heated to 90% by heating the fibrous mixture under a non-oxidizing atmosphere containing nitrogen.
The ClA1 molar ratio after baking at 0°C for 1 hour is 0.
It is preferable that the content is in the range of 4 to 1.6.

When firing the mixture, carbon and/or a carbon-containing compound is added to and mixed with the fibrous mixture, or the fibrous mixture is mixed during the reaction. When the former carbon and/or carbon-containing compound is added, the fibrous mixture is added and mixed with nitrogen. Under a non-oxidizing atmosphere containing 9
It is preferable to mix so that the C/Art molar ratio after baking at 0° C. for 1 hour is 1.65 or more.

This invention will be explained in more detail below.

The fibrous mixture (aluminum nitride fiber precursor) used in the production method of the present invention can be easily obtained by molding and drying in a conventional manner using a solution containing each of the above compounds. If each compound is water-soluble, water can be used as a solvent, and each compound can be mixed on a molecular order, which is convenient. The diameter of the fibrous mixture can be adjusted as appropriate depending on the molding conditions, and the length can also be adjusted as appropriate by cutting treatment after drying.

Examples of the aluminum-containing compound in this invention include aluminum polynuclear complexes and aluminum alkoxides. Examples of aluminum polynuclear complexes include basic aluminum chloride, basic aluminum lactate, basic aluminum nitrate, basic aluminum sulfate, and basic aluminum acetate. Examples of alkium alkoxides include:
Examples include aliphatic alkoxides having 10 or less carbon atoms, such as aluminum methoxide, aluminum ethoxide, aluminum propoxide, and aluminum butoxide.

Furthermore, in addition to the above, other aluminum-containing compounds such as aluminum chloride, aluminum sulfate, aluminum acetate, aluminum nitrate, aluminum hydroxide, and alumina may also be used.

Examples of highly stretchable organic polymer compounds include methylcellulose, polyethylene oxide, and polyvinyl alcohol.A fibrous mixture is obtained by using an organic polymer with a high molecular weight as a binder.

The carbon-containing compounds or carbon-nitrogen-containing compounds in the mixture perform a reducing action. Examples of carbon-containing compounds include various sugars, glucose, sorbitol, pentaerythritol, and the like, and examples of carbon- and nitrogen-containing compounds include urea, glycine, alanine, caprolactam, and guanidine salts.

Examples of the tetraalkylammonium hydroxide include the following water-soluble ones, such as tetramethylammonium hydroxide, tetraethylammonium hydroxide,
Preferred are aliphatic compounds having 4 or less carbon atoms, such as tetraisopropylammonium hydroxide and tetrabutylammonium hydroxide.

This tetraalkylammonium hydroxide is added when each compound used in the mixture is mixed in an aqueous solution state,
It works to prevent aluminum-containing components from forming a precipitate and to ensure that a suitable mixing state is obtained.

Each compound has a C/Al molar ratio of 0.4 to 1 after firing a fibrous mixture at 900°C for 1 hour in a non-oxidizing atmosphere containing N□ (for example, in NI). It is usually blended so that it falls within the range of 6. If the C/AA molar ratio is less than 0.4, the nitriding reaction will be difficult to proceed during firing;
When the molar ratio exceeds 1.6, the fiber tends to become powdery after firing, making it difficult to maintain the fiber shape.

By adding a compound containing a rare earth element such as yttrium or a lanthanide group element or a compound containing an alkaline earth element to the mixture, which acts as a sintering aid, an aluminum nitride fiber with higher thermal conductivity and higher strength can be obtained. be able to.

Examples of rare earth element-containing compounds include yttrium oxide, yttrium chloride, yttrium nitrate, and basic indolium acetate. Examples of alkaline earth element-containing compounds include calcium oxide, calcium carbide, calcium chloride, and calcium nitrate. .

The fibrous mixture may be subjected to main firing as it is, but may be pre-calcined before that. The pre-firing is a process performed in a non-oxidizing atmosphere containing nitrogen, for example, at a temperature of 800 to 1000° C. for about one time. Calcining also removes unnecessary elements in the mixture.

Subsequently, the uncalcined or calcined fibrous mixture is
It is fired as it is or after adding and mixing carbon or a carbon-containing compound in a non-oxidizing atmosphere containing nitrogen.

Examples of the non-oxidizing atmosphere containing nitrogen include an atmosphere consisting only of nitrogen, an argon atmosphere containing nitrogen, a carbon monoxide atmosphere containing nitrogen, an ammonia atmosphere, and the like. The firing temperature is usually in the range of about 1400 to 1900°C.

In addition, carbon or a carbon-containing compound is obtained by adding and mixing an uncalcined (or pre-calcined) fibrous mixture to these,
Under a non-oxidizing atmosphere containing nitrogen (e.g. N, medium), 90
The C/Al molar ratio after baking at 0°C for 1 hour is 1.
It is added so that it becomes 65 or more, 1.65 to 6, or about 1.65 to 4.

When the C/A It molar ratio is less than 1.65, the effect of adding a carbon source will not be sufficiently exhibited, making it difficult to obtain aluminum nitride fibers with high purity. If the above C/Al molar ratio is too high,
It takes time and effort to remove carbon remaining in the obtained alkenium nitride fibers.

In this invention, the C/Al1 molar ratio is precisely related to the amount that participates in the reaction after baking at 900 ° C. for 1 hour in a non-oxidizing atmosphere containing nitrogen and removing those that do not participate in the reaction. We try to specify it using valid numerical values.

Of course, it goes without saying that in actual production, it is not necessarily necessary to undergo firing under these conditions.

Note that instead of adding carbon or a carbon-containing compound as described above, firing may be performed by further including carbon vapor in a non-oxidizing atmosphere containing nitrogen. Specifically, a method such as firing a fibrous mixture in a graphite reaction vessel to which carbon vapor can be supplied during the reaction is exemplified.

If you want to remove residual carbon after firing, 600~
Heat treatment (baking) may be performed in an oxidizing atmosphere at 750°C.

The aluminum nitride fiber finally obtained is, for example, 1
Examples include those with a diameter of about 00μ or less to 1fi or less, and a length of about 0°1fl or less to 10C11 or less.

It goes without saying that the compounds, processing conditions, etc. used in this invention are not limited to those exemplified above.

[For production]

With the manufacturing method of the present invention, aluminum nitride fibers can be easily manufactured. For example, a fibrous mixture can be easily formed by forming and drying a solution containing an aluminum-containing compound, a highly stretchable organic polymer compound, a carbon-containing compound, and/or a compound for a mixture of carbon and nitrogen-containing compounds. is obtained, and then firing can be performed in a non-oxidizing atmosphere containing nitrogen.

When each compound is water-soluble, water can be used as a solvent and the compounds are mixed on a molecular order, making it easy to obtain homogeneous and excellent aluminum nitride fibers with a high nitridation rate.

When a carbon/nitrogen-containing compound is included, since there is also a nitrogen source in the mixture, a reducing atmosphere is locally formed and nitridation tends to proceed.

The carbon or carbon-containing compound added to the fibrous mixture serves to prevent adhesion between fibers and to increase the nitridation rate.

〔Example〕

Examples of the present invention will be described below.

Note that the aluminum-containing compounds include aluminum polynuclear complexes (Examples 1 to 6) and aluminum sulfate (Examples A to C).
), aluminum alkoxide (Examples I to E).

Example 1 - Dissolving basic aluminum chloride and glucose in a 1% by weight aqueous solution of polyethylene oxide (C/Al molar ratio 1.5)
) L was formed into a fibrous form and dried to obtain a fibrous mixture.

The basic aluminum chloride used had an alenium content of 50% by weight in terms of ANsOs and a basicity of 84%.

Next, the obtained fibrous mixture was heated at 900°C in N8 for 1
It was pre-baked for an hour. The C/A 1 molar ratio after calcining is 1.
It was 1. After the preliminary firing, 26 parts by weight of carbon black was added and mixed, and the mixture was fired at 1700° C. for 6 hours in N8.

After firing, heat treatment was further performed at 650° C. for 2 hours to remove residual carbon to obtain aluminum nitride fibers. The AIN purity of this fiber was 98.0%.

Example 2 The basic aluminum chloride and glucose used in Example 1 were dissolved in a 1% by weight aqueous solution of polyethylene oxide (C/
Affi molar ratio 1.2) L, 1.5 parts by weight of yttrium chloride was added to basic aluminum chloride in terms of oxide, and a fibrous mixture was obtained by forming and drying into a fibrous form ( , this fibrous mixture is N, medium, 9
It was separately investigated that the C/AJ molar ratio after baking at 00°C for 1 hour was 0.8).

After that, similar to Example 1, after pre-calcining, 28 parts by weight of carbon blank was added and mixed, and the mixture was heated in Nt at 1800°C for 30 minutes.
Baked for an hour. After firing, heat treatment was further performed at 650° C. for 2 hours to remove residual carbon to obtain aluminum nitride fibers. The AtN purity of this fiber is 97.5%,
The amount of oxygen impurities was as low as 1.0% by weight or less.

Example 3 - Basic aluminum chloride and sorbitol used in Example 1 were dissolved in a 1% by weight aqueous solution of polyethylene oxide (C
/Al molar ratio 1.8)L, it is desired to obtain a fibrous mixture by forming and drying it into a fibrous form.
It was separately investigated that the C/Al molar ratio after baking at 900"C for 11 hours was 1.0).

This fibrous mixture was pre-calcined in Nz at 800°C for 1 hour, then 25 parts by weight of carbon black was added and mixed, and fired in N2 at 1700°C for 2 hours. After firing, heat treatment was further performed at 700° C. for 1 hour to remove residual carbon to obtain aluminum nitride fibers. AfN of this fiber
Purity was 97.5%.

Example 4 - Dissolving basic aluminum lactate and glucose in a 1% by weight aqueous solution of polyethylene oxide (C/A4 molar ratio 3.6
) L was formed into a fibrous form and dried to obtain a fibrous mixture.

In addition, the aluminum content of basic aluminum lactate is 37% by weight in terms of Al1xOx, and the lactic acid content is 56%.
I used the one from

Next, the obtained fibrous mixture was heated in N, medium, 900°C, 1
It was pre-baked for an hour. The ClA 1 molar ratio after calcining is 1.
It was 2. After the preliminary firing, 25 parts by weight of carbon blank was added and mixed, and the mixture was fired at 1900° C. for 6 hours in N2.

After firing, heat treatment was further performed at 650° C. for 2 hours to remove residual carbon to obtain aluminum nitride fibers. The AIN purity of this fiber was 98.2%.

Example 5 - Dissolve the basic aluminum lactate and glucose used in Example 4 in a 1% by weight aqueous solution of polyethylene oxide (C/
The aluminum molar ratio was 3.6)L, and the mixture was molded into a fibrous form and dried to obtain a fibrous mixture.

Next, 25% of carbon black was added to the obtained fibrous mixture.
Parts by weight were added and mixed, and baked in N3 at 1800° C. for 6 hours. After firing, heat treatment was further performed at 650° C. for 2 hours to remove residual carbon to obtain aluminum nitride fibers.

The AIN purity of this fiber was 98.0%.

Example 6 - Dissolve the basic aluminum lactate and glucose used in Example 4 in a 1% by weight aqueous solution of polyethylene oxide (C/
The aluminum molar ratio was 3.9)L, and the mixture was molded into a fibrous form and dried to obtain a fibrous mixture.

The obtained fibrous mixture was calcined in N8 at 900° C. for 1 hour. The C/Al molar ratio after calcining was 1.4. This was placed in a graphite reaction vessel and heated to 1900 mL in Nz.
C. for 6 hours to obtain aluminum nitride fibers. The AfN purity of this fiber was 95.0%. This graphite reaction vessel (case) functions to provide a reducing atmosphere containing carbon vapor.

Example A - Dissolving aluminum sulfate and glucose in a 1% by weight aqueous solution of polyethylene oxide (C/Al molar ratio 1.5) L,
A fibrous mixture was obtained by molding and drying the mixture into a fibrous form.

Next, the obtained fibrous mixture was heated in N, medium, 900°C, 1
It was pre-baked for an hour. ClA1 molar ratio after calcining is 1.1
Met. After the preliminary firing, 26 parts by weight of carbon black was added and mixed, and the mixture was fired at 1600° C. for 6 hours in N. After firing, a heat treatment was further performed at 650'C for 12 hours to remove residual carbon to obtain aluminum nitride fibers. The IN purity of this fiber was 97.5%.

Example B - Dissolving aluminum sulfate and glucose in a 1% by weight solution of polyethylene oxide (C/Aj2 molar ratio 1.2) L,
Yttrium chloride was added in an amount of 1.2 parts by weight based on arenium sulfate, and the mixture was formed into a fiber and dried to obtain a fibrous mixture. C/AJ after baking at 900℃ for 1 hour
It was separately investigated that the molar ratio was 0.8).

After that, similar to Example A, after pre-calcining, 28ffi parts of carbon black was added and mixed, and heated to 1600°C in N.
, and baked for 3 hours. After firing, heat treatment was further performed at 650° C. for 2 hours to remove residual carbon to obtain aluminum nitride fibers. The Al1N purity of this fiber was 97.5%, and the amount of oxygen impurities was as low as 1.0% by weight or less.

Example C - Dissolving aluminum sulfate and sorbitol in a 1% by weight aqueous solution of polyethylene oxide (C/A2 molar ratio 1.8) L
A fibrous mixture was obtained by molding and drying it into a fibrous form (this fibrous mixture was heated in N8 at 900°C for 1 hour,
It was separately investigated that the C/Al molar ratio after baking was 1.0).

This fibrous mixture was pre-calcined at 800° C. for 1 hour in Nt, then 25 parts by weight of carbon black was added and mixed, and fired at 1700° C. for 2 hours in Nt. After firing, heat treatment was further performed at 700° C. for 1 hour to remove residual carbon to obtain aluminum nitride fibers. AlN of this fiber
Purity was 97.5%.

Example 1 Aluminum isopropoxide, D-glucose, and tetramethylammonium hydroxide were added to a 1% aqueous solution of polyethylene oxide in a molar ratio of 4:1:4, and the mixture was formed into a fibrous form and dried. A mixture of was obtained.

Next, the obtained fibrous mixture was heated at 900°C in Nt for 1
It was pre-baked for an hour. The C/A 1 molar ratio after calcining is 1.
It was 1. After the preliminary firing, 26 parts by weight of carbon black was added and mixed, and the mixture was fired at 1700° C. for 6 hours in N8.

After firing, heat treatment was further performed at 650° C. for 2 hours to remove residual carbon to obtain aluminum nitride fibers. The AlN purity of this fiber was 97.5%.

Example 1 Aluminum isopropoxide, D-glucose, and tetramethylammonium hydroxide were added to a 411M% aqueous solution of polyethylene oxa in a molar ratio of 5:1:5, and yttrium chloride was added to aluminum in terms of oxide. A fibrous mixture was obtained by adding 160 parts by weight to isopropoxide, forming it into a fibrous form and drying it.
It was separately investigated that the C/Al molar ratio after pre-calcining at ℃ for 1 hour was 0.8).

After that, in the same manner as in Example A, after pre-calcining, 28 parts by weight of carbon blank was added and mixed, and the mixture was heated in N, medium, 1800°C, 3
Baked for an hour. After firing, heat treatment was further performed at 650° C. for 2 hours to remove residual carbon to obtain aluminium nitride fibers. The AlN purity of this fiber is 98.0%,
The amount of oxygen impurities was as low as 1.0% by weight or less.

One Example: Aluminum isopropoxide, D-sorbitol, and tetramethylammonium hydroxide were added to a 1% by weight aqueous solution of polyethylene oxide in a molar ratio of 10:3:10, respectively.
The fibrous mixture was formed into a fibrous form and dried to obtain a fibrous mixture (this fibrous mixture contained N, medium, 9
After pre-calcining at 00°C for 1 hour, the C/Al molar ratio was 1.
We separately investigated that it was 0).

This fibrous mixture was pre-fired at 800° C. for 1 hour in N3, then 25 parts by weight of carbon blank was added and mixed, and fired at 1700° C. for 2 hours in N3. After firing, heat treatment was further performed at 700° C. for 1 hour to remove residual carbon to obtain aluminum nitride fibers. /IN of this fiber
Purity was 97.5%.

Example 1 Aluminum butoxide, D-glucose, and tetramethylammonium hydroxide were added to a 1% aqueous solution of polyethylene oxide in a molar ratio of 4:1:4, and the mixture was formed into a fibrous form and dried. A mixture of was obtained.

Next, the obtained fibrous mixture was heated at 900°C in N8 for 1
It was pre-baked for an hour. C//1 molar ratio after calcining is 1.2
Met. After the preliminary firing, 25 parts by weight of carbon black was added and mixed, and the mixture was fired at 1900° C. for 6 hours in N. After firing, heat treatment was further performed at 650° C. for 2 hours to remove residual carbon to obtain aluminum nitride fibers. The A/N purity of this fiber was 97.8%.

One Example: Aluminum isopropoxide, D-glucose, and tetraethylammonium hydroxide were added to a 1% by weight aqueous solution of polyethylene oxide in a molar ratio of 4:1:4, and the mixture was formed into a fibrous form and dried. A mixture was obtained.

Next, 25% carbon blank was added to the obtained fibrous mixture.
Parts by weight were added and mixed, and baked in N3 at 1800° C. for 6 hours. After firing, heat treatment was further performed at 650° C. for 2 hours to remove residual carbon to obtain aluminum nitride fibers.

The AIN purity of this fiber was 98.2%.

In addition, the polyethylene oxide (Alcox E-160 manufactured by Meikai Kagaku Kogyo@) in each of the above examples had an average molecular weight of 40.
It is more than 0,000. In addition, in each example, the additive mixture A ton N after adding the carbon blank was
It was also separately confirmed that the C/Al molar ratio after baking under the conditions of 1 hour at ℃ was 1.65 or more.

〔Effect of the invention〕

As described above, according to the method for producing aluminum nitride fibers according to claims 1 to 6, fibers with a sufficient nitridation rate can be easily obtained.

In addition, in the method for producing aluminum nitride fibers according to claims 2 to 4, water can be used as a solvent, and homogeneous fibers with a sufficient nitridation rate can be easily obtained.

In the method for producing aluminum nitride fiber according to claim 5,
In addition, fibers with a sufficient nitridation rate and whose fiber shape is firmly maintained can be easily obtained.

In the method for producing aluminum nitride fiber according to claim 6,
In addition, aluminum nitride fibers with a more sufficient nitriding rate can be obtained.

Claims (1)

[Scope of Claims] 1. A mixture formed into a fibrous shape consisting of an aluminum-containing compound, an organic polymer compound with high stretchability, and a carbon-containing compound and/or a carbon/nitrogen-containing compound added as necessary, A method for producing aluminum nitride fibers in which the fibers are fired in a non-oxidizing atmosphere containing nitrogen. 2. The method for producing aluminum nitride fibers according to claim 1, wherein the aluminum-containing compound, the highly stretchable organic polymer compound, the carbon-containing compound, and/or the carbon/nitrogen-containing compound are water-soluble. 3. The method for producing aluminum nitride fibers according to claim 1 or 2, wherein the aluminum-containing compound is an aluminum polynuclear complex. 4. The method for producing aluminum nitride fibers according to claim 1 or 2, wherein the aluminum-containing compound is an aluminum alkoxide, and tetraalkylammonium hydroxide is added at the time of mixing each compound. 5 Each compound is C/
The method for producing aluminum nitride fibers according to any one of claims 1 to 4, wherein the aluminum nitride fibers are blended so that the Al molar ratio is in the range of 0.4 to 1.6. 6 Carbon and/or carbon-containing compounds are added and mixed to the fibrous mixture and then fired, or the fibrous mixture is fired in a graphite reaction vessel that can supply carbon vapor during the reaction. When adding the carbon and/or carbon-containing compound, the fibrous mixture was added and mixed and baked at 900°C for 1 hour in a non-oxidizing atmosphere containing nitrogen. The method for producing aluminum nitride fibers according to claim 5, wherein the aluminum nitride fibers are blended so that the subsequent C/Al molar ratio is 1.65 or more.