JPH0458404B2 - - Google Patents
Info
- Publication number
- JPH0458404B2 JPH0458404B2 JP1266885A JP1266885A JPH0458404B2 JP H0458404 B2 JPH0458404 B2 JP H0458404B2 JP 1266885 A JP1266885 A JP 1266885A JP 1266885 A JP1266885 A JP 1266885A JP H0458404 B2 JPH0458404 B2 JP H0458404B2
- Authority
- JP
- Japan
- Prior art keywords
- aluminum
- nitrogen
- aluminum nitride
- hydrogen
- gas
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 53
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims description 28
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 27
- 229910052782 aluminium Inorganic materials 0.000 claims description 25
- 229910052757 nitrogen Inorganic materials 0.000 claims description 25
- 239000001257 hydrogen Substances 0.000 claims description 20
- 229910052739 hydrogen Inorganic materials 0.000 claims description 20
- 239000002245 particle Substances 0.000 claims description 16
- 229910052751 metal Inorganic materials 0.000 claims description 13
- 239000002184 metal Substances 0.000 claims description 13
- 239000011882 ultra-fine particle Substances 0.000 claims description 13
- 150000001875 compounds Chemical class 0.000 claims description 9
- 239000011261 inert gas Substances 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 8
- 238000001704 evaporation Methods 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 6
- 230000008020 evaporation Effects 0.000 claims description 5
- 210000001787 dendrite Anatomy 0.000 claims description 3
- 239000000155 melt Substances 0.000 claims description 3
- 125000004435 hydrogen atom Chemical class [H]* 0.000 claims 2
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical group [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 claims 1
- 239000007789 gas Substances 0.000 description 25
- 238000000034 method Methods 0.000 description 16
- 239000000047 product Substances 0.000 description 15
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 12
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 11
- 150000002431 hydrogen Chemical class 0.000 description 7
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 230000006698 induction Effects 0.000 description 6
- 238000001816 cooling Methods 0.000 description 5
- 229910021529 ammonia Inorganic materials 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 229910052786 argon Inorganic materials 0.000 description 3
- 229910001873 dinitrogen Inorganic materials 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 238000005121 nitriding Methods 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000011835 investigation Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- IWBUYGUPYWKAMK-UHFFFAOYSA-N [AlH3].[N] Chemical compound [AlH3].[N] IWBUYGUPYWKAMK-UHFFFAOYSA-N 0.000 description 1
- -1 aluminum halide Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000012809 cooling fluid Substances 0.000 description 1
- 239000000112 cooling gas Substances 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 239000012776 electronic material Substances 0.000 description 1
- 238000010574 gas phase reaction Methods 0.000 description 1
- 239000003779 heat-resistant material Substances 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 150000002829 nitrogen Chemical class 0.000 description 1
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229910052724 xenon Inorganic materials 0.000 description 1
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B21/00—Nitrogen; Compounds thereof
- C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
- C01B21/072—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with aluminium
- C01B21/0722—Preparation by direct nitridation of aluminium
- C01B21/0724—Preparation by direct nitridation of aluminium using a plasma
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
Description
（産業上の利用分野）
本発明は、例えば電子材料や光学材料の焼結用
粉末等の素材としてその優れた特性が利用され
る、直径1μｍ以下の窒化アルミニウム超微粒子
を製造する方法に関する。
（従来の技術）
従来、窒化アルミニウムの超微粒子を製造する
方法として主流となつているのは、アルミニウム
のハロゲン化物をアンモニアまたは窒素ガスと反
応させる所謂気相反応法、アルミニウム金属粉末
を直接窒素ガスと反応させる方法、アルミニウム
の酸化物を還元後窒素ガスと反応させる方法等で
ある。
また、近時、アークまたはプラズマジエツトに
より窒素を主成分とする高温活性ガスを発生さ
せ、当該高温活性ガスによつて金属アルミニウム
を溶融・蒸発させて窒化反応により窒化アルミニ
ウムの超微粒子を得る方法が開発され、注目され
つつある。
（従来技術に存する問題点）
上記の主流とされている方法には、何れも副生
成物の伴出や、未反応物の残留等の問題点があつ
た。
また、近時開発されたアークまたはプラズマジ
エツトを利用する方法は電極等が溶損・蒸発して
製品中に不純物として混入したり、生成速度が遅
いという欠点があり、生成速度が遅いということ
は製品の価格を高騰させているという問題点もあ
つた。
（発明の目的）
本発明は窒化アルミニウムの超微粒子を製造す
る従来方法に存する上述した問題点を解決するた
めになされたもので、高能率で高純度の窒化アル
ミニウム超微粒子を容易かつ安価に製造可能な方
法を提供することを目的とする。
（発明の構成）
本発明の構成は、
窒素を主成分とする雰囲気中で高周波エネルギ
ーによる高温プラズマを発生させ、発生した高温
プラズマフレームで金属アルミニウムを溶融・蒸
発させて窒化アルミニウムの超微粒子を得る場合
において、上記雰囲気および高温プラズマの成分
を窒素、水素または窒素と水素との化合物および
必要に応じて添加される不活性ガスとし、発生さ
せた高温プラズマフレームの尾炎部に水冷ハース
台上の金属アルミニウムを位置せしめ、雰囲気お
よび高周波エネルギーを所定の如く制御すること
により溶融・蒸発するアルミニウムが溶融面上に
樹枝状物を形成するように設定し、当該樹枝状物
表面から蒸発する粒子が高温反応性プラズマ中に
通過するようにした
ことを特徴とする窒化アルミニウム超微粒子の製
造方法にある。
（発明の作用）
本発明は雰囲気および高温プラズマの成分が窒
素、水素または窒素と水素との化合物および必要
に応じて添加される不活性ガスとし、これらのガ
スを高周波エネルギーにより高温プラズマ化して
大形のプラズマフレームを形成し、当該プラズマ
フレーム中では温度が2500〜3000Kと比較的低温
の尾炎部に水冷ハース台上の金属アルミニウムを
位置させて溶融・蒸発させ、アルミニウム蒸気は
プラズマ中の活性基の窒素種と反応して窒化アル
ミニウム核となつて窒素、水素または窒素と水素
との化合物および必要に応じて添加される不活性
ガスからなる雰囲気中に拡散する過程で、一部は
窒化アルミニウム超微粒子となつて飛散し、一部
は飛散せずに溶融状態のアルミニウム表面に沈降
して樹枝状の生成物を形成するようにさせ、当該
樹枝状生成物の形成により水冷ハース台の冷却作
用からの蒸発速度の低下から免れるようにすると
ともに、樹枝状生成物の極端に面積の広い表面が
略3000〜5000Kに達する中心部に近接したフレー
ム内に位置せしめるようにして、高率的に窒化ア
ルミニウム超微粒子を生成させる作用を発揮す
る。
この場合の不活性ガスはプラズマの安定化、水
素主として上記樹枝状生成物の成長に介在し、ま
た添加もしくは反応によつて化合生成した窒素と
水素との化合物は窒化反応を促進するもののよう
である。
（実施例）
本発明方法を実施例に従つて以下に詳述する。
第１図は本発明方法を実施するための装置の一
例であつて、Chはチヤンバ、１０はチヤンバCh
の上部に配置された高周波誘導高温プラズマ発生
装置である。
上記高周波誘導高温プラズマ発生装置１０は耐
熱材製トーチ１１、高周波電源Ｅおよび当該高周
波電源Ｅに接続される誘導コイルＣとからなり、
上記トーチ１１は外管１１１および内管１１２と
して示す二重管で、外管１１１の一方端面が上記
チヤンバChの上部に開口し、閉端面となつた他
方端面を内管１１２が貫通して所定位置に開口す
る。上記誘導コイルＣは外管１１１の一重となつ
ているチヤンバChに近接した外周に巻回されて
いる。上記トーチ１１には、内管１１２の外管１
１１外とされている部分の例えば端面に近接して
開口する導管１２から高温プラズマ発生用ガス…
（以下コアガスという）として窒素または窒素と
不活性ガスである例えばアルゴンとの混合ガスＧ
１が、また外管１１１の閉端面近傍に開口する導
管１３から当該外管１１１の管壁冷却用と上記チ
ヤンバCh内の雰囲気形成用とを兼ねる冷却用ガ
スＧ２として窒素と水素との混合ガスＧ２が、さ
らに外管１１１とチヤンバChとの接続部に介挿
した１４として示す環状ジヤケツトのスリツトか
らチヤンバCh内の雰囲気形成用として窒素と水
素との化合物であるアンモニアガスＧ３がそれぞ
れ導入可能に構成されている。
上記チヤンバChには、前記外管１１１の開口
部に対向する底面を摺動可能に貫通して内部所定
位置まで上昇または下降する構成からなるハース
台Ｈが備えられ、また所定位置には排ガス用導管
２が開口している。上記ハース台Ｈは、内部に冷
却流体が循環する冷却構造とされ、また外管１１
１の開口部に対向する端面に金属アルミニウムの
バルク１を載置可能な如く、例えば窪みが形成さ
れている。上記排ガス用導管２は３１として示す
フイルタを備えた捕集器３を介して図示しないガ
ス吸引装置に接続されている。
以上の構成からなる装置を用いて、ハース台Ｈ
に載置した金属アルミニウムのバルク１から窒化
アルミニウムの超微粒子を製造する場合を以下に
述べる。
ハース台Ｈを下方変位状態とし、チヤンバCh
内の空気を排出して代わりにジヤケツト１４から
Ｇ３を流入してチヤンバCh内に所定の雰囲気を
形成したうえ、コアガスＧ１を導管１２から流出
させたのち高周波電源Ｅを投入して誘導コイルＣ
に通電する。コアガスＧ１は誘導コイルＣが外周
に巻回されている外管１１１内の高周波エネルギ
ー付与領域において点火され、高温プラズマ化す
る。同時にガスＧ２を導管１３から導入して外管
１１１の管壁の冷却およびチヤンバCh内の雰囲
気調整をする。ついでコアガスＧ１の供給量を順
次所定量まで増加して高温プラズマフレームＰが
チヤンバCh内にまで達するように調整する。
この状態において、高温プラズマフレームＰの
中心部の温度は略10000Kに達し、Peとして示す
先端部分＝尾炎部は最先端が2500〜3000K、上記
中心部近接位置では5000K程度なつており、フレ
ームＰ内の5000K以上ある領域内では、窒素成分
は高いエンタルピーを有する活性状態にある。ま
たフレームＰの周縁部に接す窒素と水素との混合
ガスＧ２およびアンモニアガスＧ３からなる雰囲
気ガスも高温により活性化している。
この時点でハース台Ｈを上方変位させ、当該ハ
ース台Ｈの端面上の金属アルミニウムバルク１を
高温プラズマフレームＰの尾炎部Pe内に位置せ
しめる。
金属アルミニウムバルク１は表面から溶解し、
次いで溶融アルミニウムは蒸発する。蒸発したア
ルミニウム蒸気の一部は高い活性状態にある窒素
と反応して窒化アルミニウム核となつてプラズマ
フレームＰ外の雰囲気ガスＧ３内へとに拡散する
過程で窒化アルミニウム超微粒子となつて飛散す
る。また蒸発したアルミニウム蒸気の一部は尾炎
部Pe内で活性化された窒素と反応したうえ下降
し、あるいは反応せずに下降して溶融表面上に図
示Ｂの如き樹枝状の生成物を次第に形成する。当
該樹枝状生成物は、上気反応操作時には高温プラ
ズマフレームＰ中にあつて組成確認をし難いが、
反応操作停止後に行つた組成確認で窒化アルミニ
ウムの結晶と固化したアルミニウムとが混在して
いることが判明している。樹枝状生成物はバルク
１の表面積に比べると極めて大きな表面積をも
ち、かつ冷却されているハース台Ｈからフレーム
Ｐの中心方向へ伸びているので、殆ど冷却作用を
受けず、3000〜5000Kの高温に曝される広大な表
面から窒化アルミニウム（結晶）の分解・蒸発お
よびアルミニウムの溶融・蒸発が活発におこなわ
れ、蒸発量が大である。
上記状態時の溶融アルミニウムおよび樹枝状生
成物はプラズマフレームＰに完全に囲繞されてお
り、従つて蒸気が高い活性状態にある窒素と遭遇
する確率は極めて大きい。
このようなプラズマフレームＰ内での現象によ
り生成した窒化アルミニウム核は、雰囲気ガスＧ
３内へ拡散し浮遊する間に冷却され、かつ集合し
て1μｍ以下の超微粒子となり、チヤンバCh内に
開口する排ガス用導管２から排ガスとともにチヤ
ンバCh外へ排出され、捕集器３のフイルタ３１
により排ガスと分離されて捕集される。
一方、バルク１は表面から順次溶解されてゆく
ので、上記現象の繰り返しにより樹枝状生成物か
らの蒸発・減少分が補充され、バルク１は次第に
小となり冷却されているハース台Ｈに接して冷却
効果をまともに受ける底面を残す迄減少すると補
給が止まり、窒化アルミニウム超微粒子の生成も
終了する。
上記樹枝状生成物の大きさは、大き過ぎるとハ
ース台Ｈ上に大きな窒化アルミニウムの残留物を
残すこととなり、また小さ過ぎると窒化アルミニ
ウム超微粒子の生成速度が低下するので、その大
きさを制御するのが好ましい。当該大きさの制御
は、例えば反応に介在する水素の量の調節、高周
波エネルギーによるプラズマ温度の調節等により
可能である。例えばプラズマ温度を高くすれば水
素の量は少、プラズマ温度が低いときは水素の量
を多くして制御する。尚、樹枝状生成物の適正大
きさは形成しうるプラズマフレームＰの大きさに
関係するので、保有している個々の設備・装置に
応じてそれぞれ決定される。
また、チヤンバCh内の雰囲気ガスＧ３のガス
圧は、必要な温度のプラズマフレームＰが安定し
て得られる圧力とされればよく、例えば常圧、下
限は通常100Torr程度である。
（実験例）
本発明者が行つた多数の実験のなかから数例を
次ぎに示す。
☆使用装置；第１図に示す装置を使用した。
☆電源；周波数…13.56MHz
出力…5KW
☆原材料；金属アルミニウム
純度…99.99％
☆実験方法；上記設備および装置を使用し、ガス
Ｇ１，Ｇ２，Ｇ３それぞれに含まれる窒素囲
N2、アルゴン：Ar、水素：H2およびアンモ
ニア：NH3の流量を調節して窒化アルミニウ
ム超微粒子を生成し、その生成速度および収率
ならびに粒度を調査した。
各条件ごとの生成操作は、１回の操作で原材
料から窒化アルミニウム超微粒子の生成が停ま
ると、ハース台Ｈ上の残留物を除去し、新たな
原材料を載置のうえ生成操作を複数回繰り返し
行い、その結果をまとめた均により上記の調査
を行つた。
☆実験結果；別表に示すとおりであつた。
また、各条件にそれぞれ従つて実験のいづれ
においても高純度の窒化アルミニウム超微粒子
が得られた。得られた超微粒子のSEM顕微鏡
写真（×50000）を第２図に、またＸ線回折線
図を第３図にそれぞれ示す。
(Field of Industrial Application) The present invention relates to a method for producing ultrafine aluminum nitride particles with a diameter of 1 μm or less, whose excellent properties are utilized as a material for, for example, sintering powders for electronic materials and optical materials. (Prior art) Conventionally, the mainstream methods for producing ultrafine particles of aluminum nitride are the so-called gas phase reaction method in which aluminum halide is reacted with ammonia or nitrogen gas, and the method in which aluminum metal powder is directly reacted with nitrogen gas. A method in which aluminum oxide is reduced and then reacted with nitrogen gas, etc. Recently, a method has been developed in which a high-temperature active gas containing nitrogen as a main component is generated using an arc or a plasma jet, and metal aluminum is melted and vaporized by the high-temperature active gas to obtain ultrafine particles of aluminum nitride through a nitriding reaction. has been developed and is attracting attention. (Problems in the Prior Art) The mainstream methods described above all have problems such as by-products being entrained and unreacted substances remaining. In addition, recently developed methods that use arc or plasma jets have the drawbacks of melting and evaporating the electrodes and contaminating the product as impurities, and of slow production speed. There was also the problem that the price of the product was soaring. (Objective of the Invention) The present invention has been made to solve the above-mentioned problems in the conventional method for producing ultrafine particles of aluminum nitride. The purpose is to provide a possible method. (Structure of the Invention) The structure of the present invention is to generate high-temperature plasma using high-frequency energy in an atmosphere containing nitrogen as a main component, and to obtain ultrafine particles of aluminum nitride by melting and vaporizing metal aluminum in the generated high-temperature plasma flame. In this case, the atmosphere and high-temperature plasma components are nitrogen, hydrogen, or a compound of nitrogen and hydrogen, and an inert gas added as necessary, and the tail flame of the generated high-temperature plasma flame is placed on a water-cooled hearth stand. By positioning metal aluminum and controlling the atmosphere and high-frequency energy in a predetermined manner, the melting and evaporating aluminum is set to form dendrites on the molten surface, and the particles evaporated from the surface of the dendrites are heated to a high temperature. A method for producing ultrafine aluminum nitride particles, characterized in that ultrafine particles of aluminum nitride are passed through a reactive plasma. (Operation of the invention) The present invention uses nitrogen, hydrogen, or a compound of nitrogen and hydrogen as components of the atmosphere and high-temperature plasma, and an inert gas added as necessary, and converts these gases into high-temperature plasma using high-frequency energy. Metal aluminum is placed on a water-cooled hearth stand in the tail flame part of the plasma flame, which has a relatively low temperature of 2500 to 3000 K, and is melted and evaporated, and the aluminum vapor is activated in the plasma. In the process of reacting with the nitrogen species of the group to become aluminum nitride nuclei and diffusing into an atmosphere consisting of nitrogen, hydrogen, or a compound of nitrogen and hydrogen, and an inert gas added as necessary, some of the aluminum nitride They scatter as ultrafine particles, and some of them do not scatter but settle on the surface of the molten aluminum to form dendritic products, and the formation of the dendritic products has a cooling effect on the water-cooled hearth stand. The extremely large surface area of the dendritic product is located in the frame close to the center, where temperatures reach approximately 3000-5000 K, and the nitriding process is carried out at a high rate. It has the effect of producing ultrafine aluminum particles. In this case, the inert gas stabilizes the plasma and the hydrogen mainly intervenes in the growth of the above-mentioned dendritic products, and the compound of nitrogen and hydrogen that is added or formed by the reaction seems to promote the nitriding reaction. be. (Examples) The method of the present invention will be described in detail below according to Examples. FIG. 1 shows an example of an apparatus for carrying out the method of the present invention, where Ch is a chamber and 10 is a chamber Ch.
This is a high-frequency induction high-temperature plasma generator placed on top of the The high-frequency induction high-temperature plasma generator 10 includes a torch 11 made of a heat-resistant material, a high-frequency power source E, and an induction coil C connected to the high-frequency power source E,
The torch 11 is a double tube shown as an outer tube 111 and an inner tube 112. One end surface of the outer tube 111 is open at the upper part of the chamber Ch, and the inner tube 112 passes through the other end surface which is a closed end surface. Open in position. The induction coil C is wound around the outer circumference of the outer tube 111 close to the single layered chamber Ch. The torch 11 includes an inner tube 112 and an outer tube 1.
High-temperature plasma generation gas is supplied from the conduit 12 that opens close to the end surface of the portion outside the 11, for example.
(hereinafter referred to as core gas) is nitrogen or a mixed gas G of nitrogen and an inert gas such as argon.
1 is also a mixed gas of nitrogen and hydrogen as a cooling gas G2, which serves both for cooling the tube wall of the outer tube 111 and for forming an atmosphere in the chamber Ch, from a conduit 13 that opens near the closed end surface of the outer tube 111. G2 can further introduce ammonia gas G3, which is a compound of nitrogen and hydrogen, for forming an atmosphere inside the chamber Ch from a slit in the annular jacket shown as 14 inserted at the connection between the outer tube 111 and the chamber Ch. It is configured. The chamber Ch is equipped with a hearth stand H configured to slidably penetrate the bottom surface facing the opening of the outer tube 111 and rise or fall to a predetermined position inside the chamber Ch. Conduit 2 is open. The hearth stand H has a cooling structure in which cooling fluid circulates inside, and the outer pipe 11
For example, a depression is formed on the end face opposite to the opening of 1 so that the bulk 1 of metal aluminum can be placed thereon. The exhaust gas conduit 2 is connected via a collector 3 equipped with a filter 31 to a gas suction device (not shown). Using the device with the above configuration, the hearth stand H
A case will be described below in which ultrafine particles of aluminum nitride are produced from a bulk 1 of metal aluminum placed on a substrate. With the hearth stand H in a downward displacement state, the chamber Ch
After exhausting the air inside the chamber and replacing it with G3 flowing in from the jacket 14 to form a predetermined atmosphere in the chamber Ch, the core gas G1 is flowed out from the conduit 12, and then the high frequency power source E is turned on and the induction coil C is turned on.
energize. The core gas G1 is ignited in a high-frequency energy application region within the outer tube 111 around which the induction coil C is wound, and turns into high-temperature plasma. At the same time, gas G2 is introduced from the conduit 13 to cool the tube wall of the outer tube 111 and adjust the atmosphere inside the chamber Ch. Next, the supply amount of the core gas G1 is sequentially increased to a predetermined amount to adjust the high temperature plasma flame P to reach the inside of the chamber Ch. In this state, the temperature at the center of the high-temperature plasma flame P reaches approximately 10,000K, and the leading edge of the tip portion (tail flame portion) shown as Pe is 2,500 to 3,000K, and the temperature near the center is about 5,000K, and the temperature of the flame P In the region above 5000K, the nitrogen component is in an active state with high enthalpy. In addition, the atmospheric gas consisting of the mixed gas G2 of nitrogen and hydrogen and the ammonia gas G3 in contact with the peripheral portion of the frame P is also activated by the high temperature. At this point, the hearth stand H is displaced upward to position the metal aluminum bulk 1 on the end face of the hearth stand H within the tail flame portion Pe of the high temperature plasma flame P. The metal aluminum bulk 1 is melted from the surface,
The molten aluminum then evaporates. A part of the evaporated aluminum vapor reacts with nitrogen in a highly active state to become aluminum nitride nuclei, and in the process of diffusing into the atmospheric gas G3 outside the plasma flame P, it scatters as ultrafine aluminum nitride particles. In addition, some of the evaporated aluminum vapor reacts with activated nitrogen in the tail flame section Pe and then descends, or it descends without reacting and gradually forms dendritic products on the molten surface as shown in Figure B. Form. Although it is difficult to confirm the composition of the dendritic product as it is in the high temperature plasma flame P during the upper air reaction operation,
A composition check conducted after the reaction operation was stopped revealed that aluminum nitride crystals and solidified aluminum were mixed together. The dendritic products have an extremely large surface area compared to the surface area of the bulk 1, and extend from the cooled hearth table H toward the center of the frame P, so they receive almost no cooling effect and are exposed to high temperatures of 3000 to 5000 K. The decomposition and evaporation of aluminum nitride (crystals) and the melting and evaporation of aluminum occur actively from the vast surface exposed to water, resulting in a large amount of evaporation. The molten aluminum and dendritic products in the above state are completely surrounded by the plasma flame P, so the probability that the vapor encounters nitrogen in a highly active state is extremely high. Aluminum nitride nuclei generated by such a phenomenon in the plasma flame P are exposed to the atmospheric gas G.
While diffusing and floating in the chamber Ch, they are cooled and aggregated into ultrafine particles of 1 μm or less, which are discharged from the exhaust gas conduit 2 that opens into the chamber Ch to the outside of the chamber Ch along with the exhaust gas, and pass through the filter 31 of the collector 3.
is separated from exhaust gas and collected. On the other hand, since the bulk 1 is sequentially melted from the surface, the evaporation and loss from the dendritic products is replenished by repeating the above phenomenon, and the bulk 1 gradually becomes smaller and cools as it comes into contact with the cooling hearth table H. When the amount decreases to the point where only the bottom surface that receives the effect is left, supply stops and the generation of ultrafine aluminum nitride particles ends. The size of the above-mentioned dendritic products is controlled because if it is too large, a large residue of aluminum nitride will be left on the hearth table H, and if it is too small, the production rate of ultrafine aluminum nitride particles will decrease. It is preferable to do so. The size can be controlled, for example, by adjusting the amount of hydrogen involved in the reaction, adjusting the plasma temperature using high frequency energy, etc. For example, if the plasma temperature is increased, the amount of hydrogen is reduced, and if the plasma temperature is low, the amount of hydrogen is increased. It should be noted that the appropriate size of the dendritic product is related to the size of the plasma flame P that can be formed, and is therefore determined depending on the individual equipment and equipment that is available. Further, the gas pressure of the atmospheric gas G3 in the chamber Ch may be set to a pressure that can stably obtain the plasma flame P at the required temperature, for example, normal pressure, and the lower limit is usually about 100 Torr. (Experimental Examples) Several examples from among the many experiments conducted by the present inventor are shown below. ☆ Equipment used: The equipment shown in Figure 1 was used. ☆Power supply: Frequency…13.56MHz Output…5KW ☆Raw material: Metallic aluminum purity…99.99% ☆Experimental method: Using the above equipment and equipment, the nitrogen surroundings contained in each of gases G1, G2, and G3 were
Ultrafine aluminum nitride particles were produced by adjusting the flow rates of N2, argon: Ar, hydrogen: H2, and ammonia: NH3, and the production rate, yield, and particle size were investigated. The generation operation for each condition is that when the generation of aluminum nitride ultrafine particles from the raw material stops in one operation, the residue on the hearth table H is removed, a new raw material is placed, and the generation operation is repeated multiple times. The above investigation was conducted by Hitoshi, who repeated the investigation and summarized the results. ☆ Experimental results: The results were as shown in the attached table. Furthermore, ultrafine aluminum nitride particles of high purity were obtained in all experiments conducted under each condition. A SEM micrograph (×50,000) of the obtained ultrafine particles is shown in FIG. 2, and an X-ray diffraction diagram is shown in FIG. 3.
【表】
上記実験結果から、表中のに示す適正な大き
さの樹枝状生成物が形成される状態時には、極め
て高能率で窒化アルミニウム超微粒子の生成が行
われることが明確にされた。
（他の実施例）
上記実施例では、ハース台Ｈ上に金属アルミニ
ウムバルク１を載置して窒化アルミニウム超微粒
子を生成する例を挙げて説明したが、例えばチヤ
ンバCh内のプラズマフレームＰに影響されない
所定位置に所定大きさのバルクまたはタブレツト
を貯蔵しておき、間欠的にハース台Ｈ上の溶融ア
ルミニウムに補給をするように構成して生成操作
を連続的に行うようにすることも可能である。
さらに第４図ａおよびｂに示される如く、ハー
ス台Hpとして中央に所定内径の貫通孔４を備え
た周囲が冷却水循環路５となつている二重管構成
としたものを用い、上記貫通孔４に摺動可能な外
径の金属アルミニウム線材1wを挿通し、操作開
始時には端部所定長さ部分を貫通孔４外に裸出さ
せてプラズマフレームＰの尾炎部に位置せしめ、
溶融・蒸発に伴つて順次貫通孔４内をせりあげて
蒸発分を補給するように設定すれば、生成操作を
長時間連続して実施しうる。
尚、上記実施例では、不活性ガスとしてアルゴ
ンを使用したが、ヘリウム、キセノンその他の元
素を使用してもよく、かつ高周波エネルギーが強
大で高温プラズマフレームの安定化が維持できれ
ば、不活性ガスを添加する必要はない。また上記
実施例では、窒素と水素との化合物としてアンモ
ニアを添加する場合を挙げているが、アンモニア
以外の窒素と水素との化合物でもよく、さらには
上記と同様強大な高周波エネルギーが得られれ
ば、窒素と水素との化合物の添加なしで上記実施
例と同様な過程のもとに窒素アルミニウム超微粒
子の生成が可能である。
（発明の効果）
本発明によれば、副生成物を一切含まない高純
度の窒化アルミニウム超微粒子を、高効率で製造
可能であり、しかも簡易かつコンパクトな設備で
量産が可能であるので、低廉で生産しうることと
なり、当該素材の具える優れた性質を現在よりも
さらに広い産業分野で安価に利用し得ることとな
り、齎される効果は甚大である。[Table] From the above experimental results, it was made clear that ultrafine aluminum nitride particles were produced with extremely high efficiency under the conditions in which dendritic products of appropriate size as shown in the table were formed. (Other Examples) In the above example, the metal aluminum bulk 1 is placed on the hearth table H to generate aluminum nitride ultrafine particles. It is also possible to store bulk or tablets of a predetermined size at a predetermined location where the aluminum is not used, and to replenish the molten aluminum on the hearth table H intermittently, so that the production operation can be performed continuously. be. Furthermore, as shown in FIGS. 4a and 4b, the hearth stand Hp has a double pipe structure with a through hole 4 having a predetermined inner diameter in the center and a cooling water circulation path 5 around the center, and the through hole A metal aluminum wire 1w with a slidable outer diameter is inserted into the through hole 4, and at the start of operation, a predetermined length of the end is exposed outside the through hole 4 and positioned at the tail flame part of the plasma flame P.
If the setting is made so that the inside of the through hole 4 is raised sequentially as the material melts and evaporates to replenish the evaporated material, the production operation can be carried out continuously for a long time. In the above example, argon was used as the inert gas, but helium, xenon, and other elements may also be used.If the high-frequency energy is strong and the high-temperature plasma flame can be stabilized, the inert gas may be used. No need to add. In addition, in the above embodiment, ammonia is added as a compound of nitrogen and hydrogen, but a compound of nitrogen and hydrogen other than ammonia may be used. Furthermore, if strong high frequency energy can be obtained as in the above, Nitrogen aluminum ultrafine particles can be produced in the same process as in the above embodiment without adding a compound of nitrogen and hydrogen. (Effects of the Invention) According to the present invention, high purity ultrafine aluminum nitride particles containing no by-products can be produced with high efficiency, and can be mass-produced with simple and compact equipment, so it is inexpensive. This means that the excellent properties of this material can be used at a lower cost in a wider range of industrial fields than at present, and the effects will be enormous.
第１図は本発明方法を説明するための一実施例
装置の断面正面図、第２図および第３図はそれぞ
れ本発明方法で生成した窒化アルミニウム超微粒
子のSEM顕微鏡写真およびＸ線回折線図、第４
図ａおよびｂはそれぞれ本発明方法で窒化アルミ
ニウム超微粒子の連続的生成を行う場合に使用さ
れるハース台の一実施例の断面正面図およびＡ−
Ａ線断面図である。
１……金属アルミニウム、Ｐ……高温プラズマ
フレーム、Pe……尾炎部、Ｇ１……コアガス、
Ｇ２，Ｇ３……雰囲気ガス、Ｈ……水冷ハース
台、Ｂ……樹枝状生成物。
FIG. 1 is a cross-sectional front view of an example device for explaining the method of the present invention, and FIGS. 2 and 3 are SEM micrographs and X-ray diffraction diagrams of ultrafine aluminum nitride particles produced by the method of the present invention, respectively. , 4th
Figures a and b are a cross-sectional front view of an embodiment of a hearth stand used in the continuous production of ultrafine aluminum nitride particles by the method of the present invention, and Figures A-
It is an A-line sectional view. 1...metal aluminum, P...high temperature plasma flame, Pe...tail flame part, G1...core gas,
G2, G3...atmosphere gas, H...water-cooled hearth stand, B...dendritic product.
Claims (1)
ギーによる高温プラズマを発生させ、発生した高
温プラズマフレームで金属アルミニウムを溶融・
蒸発させて窒化アルミニウムの超微粒子を得る場
合において、上記雰囲気および高温プラズマの成
分を窒素、水素または窒素と水素との化合物およ
び必要に応じて添加される不活性ガスとし、発生
させた高温プラズマフレームの尾炎部に水冷ハー
ス台上の金属アルミニウムを位置せしめ、雰囲気
および高周波エネルギーを所定の如く制御するこ
とにより溶融・蒸発するアルミニウムが溶融面上
に樹枝状物を形成するように設定し、当該樹枝状
物表面から蒸発する粒子が高温反応性プラズマ中
に通過するようにしたことを特徴とする窒化アル
ミニウム超微粒子の製造方法。1 High-temperature plasma is generated using high-frequency energy in an atmosphere mainly composed of nitrogen, and the generated high-temperature plasma flame melts and melts aluminum metal.
In the case of obtaining ultrafine particles of aluminum nitride by evaporation, the components of the atmosphere and high-temperature plasma are nitrogen, hydrogen, or a compound of nitrogen and hydrogen, and an inert gas added as necessary, and a high-temperature plasma flame is generated. Metal aluminum is placed on a water-cooled hearth table at the tail flame of the metal, and the atmosphere and high-frequency energy are controlled in a predetermined manner so that the melted and evaporated aluminum forms dendrites on the molten surface. A method for producing ultrafine aluminum nitride particles, characterized in that particles evaporated from the surface of a dendritic material are passed through a high-temperature reactive plasma.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1266885A JPS61174107A (en) | 1985-01-28 | 1985-01-28 | Production of ultrafine aluminum nitride particle |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1266885A JPS61174107A (en) | 1985-01-28 | 1985-01-28 | Production of ultrafine aluminum nitride particle |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61174107A JPS61174107A (en) | 1986-08-05 |
| JPH0458404B2 true JPH0458404B2 (en) | 1992-09-17 |
Family
ID=11811747
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1266885A Granted JPS61174107A (en) | 1985-01-28 | 1985-01-28 | Production of ultrafine aluminum nitride particle |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61174107A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0649566B2 (en) * | 1985-08-16 | 1994-06-29 | 日本電気株式会社 | Method for synthesizing aluminum nitride |
| JPS62148311A (en) * | 1985-12-19 | 1987-07-02 | Chugai Ro Kogyo Kaisha Ltd | Process and device for preparing aluminum nitride powder |
| JPS62283805A (en) * | 1986-05-31 | 1987-12-09 | Natl Res Inst For Metals | Production of extremely fine aluminum nitride powder |
| JPS6395103A (en) * | 1986-10-03 | 1988-04-26 | Nec Corp | Readily sinterable aluminum nitride powder and production thereof |
| FR2764163B1 (en) * | 1997-05-30 | 1999-08-13 | Centre Nat Rech Scient | INDUCTIVE PLASMA TORCH WITH REAGENT INJECTOR |
-
1985
- 1985-01-28 JP JP1266885A patent/JPS61174107A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61174107A (en) | 1986-08-05 |
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| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |