JPH0352402B2 - - Google Patents
Info
- Publication number
- JPH0352402B2 JPH0352402B2 JP59127340A JP12734084A JPH0352402B2 JP H0352402 B2 JPH0352402 B2 JP H0352402B2 JP 59127340 A JP59127340 A JP 59127340A JP 12734084 A JP12734084 A JP 12734084A JP H0352402 B2 JPH0352402 B2 JP H0352402B2
- Authority
- JP
- Japan
- Prior art keywords
- nitriding
- ultrafine
- powder
- gas
- ultrafine metal
- 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 - Lifetime
Links
- 229910052751 metal Inorganic materials 0.000 claims description 104
- 239000002184 metal Substances 0.000 claims description 104
- 239000000843 powder Substances 0.000 claims description 98
- 238000005121 nitriding Methods 0.000 claims description 92
- 239000007789 gas Substances 0.000 claims description 72
- 150000004767 nitrides Chemical class 0.000 claims description 38
- 229910052710 silicon Inorganic materials 0.000 claims description 15
- 238000004519 manufacturing process Methods 0.000 claims description 13
- 238000002844 melting Methods 0.000 claims description 13
- 230000008018 melting Effects 0.000 claims description 13
- 238000010438 heat treatment Methods 0.000 claims description 11
- 238000000926 separation method Methods 0.000 claims description 11
- 239000012298 atmosphere Substances 0.000 claims description 10
- 239000012159 carrier gas Substances 0.000 claims description 5
- 229910052739 hydrogen Inorganic materials 0.000 claims description 5
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- 229910052719 titanium Inorganic materials 0.000 claims description 3
- 229910052726 zirconium Inorganic materials 0.000 claims description 3
- 229910052796 boron Inorganic materials 0.000 claims description 2
- 229910052804 chromium Inorganic materials 0.000 claims description 2
- 229910052742 iron Inorganic materials 0.000 claims description 2
- 229910052748 manganese Inorganic materials 0.000 claims description 2
- 229910052758 niobium Inorganic materials 0.000 claims description 2
- 229910052720 vanadium Inorganic materials 0.000 claims description 2
- 229910052750 molybdenum Inorganic materials 0.000 claims 1
- 238000009832 plasma treatment Methods 0.000 claims 1
- 238000000034 method Methods 0.000 description 18
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 17
- 238000006243 chemical reaction Methods 0.000 description 15
- 239000002245 particle Substances 0.000 description 14
- 238000002441 X-ray diffraction Methods 0.000 description 12
- 239000010703 silicon Substances 0.000 description 12
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 9
- 239000000203 mixture Substances 0.000 description 9
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 9
- 229910052581 Si3N4 Inorganic materials 0.000 description 8
- 229910052757 nitrogen Inorganic materials 0.000 description 8
- 238000010298 pulverizing process Methods 0.000 description 8
- 239000011863 silicon-based powder Substances 0.000 description 8
- 229910004298 SiO 2 Inorganic materials 0.000 description 7
- 238000011109 contamination Methods 0.000 description 7
- 239000000919 ceramic Substances 0.000 description 6
- 239000002994 raw material Substances 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 239000006185 dispersion Substances 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 230000006698 induction Effects 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 238000004062 sedimentation Methods 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 238000005229 chemical vapour deposition Methods 0.000 description 3
- 239000000460 chlorine Substances 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 229910001873 dinitrogen Inorganic materials 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- 229910003902 SiCl 4 Inorganic materials 0.000 description 2
- IDCBOTIENDVCBQ-UHFFFAOYSA-N TEPP Chemical compound CCOP(=O)(OCC)OP(=O)(OCC)OCC IDCBOTIENDVCBQ-UHFFFAOYSA-N 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 150000003949 imides Chemical class 0.000 description 2
- 239000002923 metal particle Substances 0.000 description 2
- 239000012299 nitrogen atmosphere Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 150000003377 silicon compounds Chemical class 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910001111 Fine metal Inorganic materials 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 238000003917 TEM image Methods 0.000 description 1
- -1 Ti and Zr Chemical class 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 229910021417 amorphous silicon Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- SLLGVCUQYRMELA-UHFFFAOYSA-N chlorosilicon Chemical compound Cl[Si] SLLGVCUQYRMELA-UHFFFAOYSA-N 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000012770 industrial material Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 150000004756 silanes Chemical class 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 238000001308 synthesis method Methods 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
- 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
-
- 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
- C01B21/068—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 silicon
- C01B21/0682—Preparation by direct nitridation of silicon
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
- C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
- C01P2004/03—Particle morphology depicted by an image obtained by SEM
-
- 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
- C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Nanotechnology (AREA)
- Inorganic Chemistry (AREA)
- Composite Materials (AREA)
- Materials Engineering (AREA)
- Crystallography & Structural Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Physics & Mathematics (AREA)
- Physical Or Chemical Processes And Apparatus (AREA)
- Ceramic Products (AREA)
Description
（産業上の利用分野）
本発明はセラミツクス成形体の製造に供される
超微粉金属窒化物の製造方法並びに製造装置に関
するものである。
セラミツクス成形体は高温強度が大きいこと、
耐熱衝撃性が優れていること、更に高耐食性であ
ることなど通常の金属より優れている点が見い出
されて、工業材料として多くの用途が開発されて
きている。セラミツクス成形体は主としてセラミ
ツクス粉末を焼結することによつて製造される
が、その強度をより大きなものにするためには、
成形体の組成を微細かつ均質なものとする必要が
ある。そのために、セラミツクス成形体用原料粉
末はより以上に粒度の細かいもの、例えば通常超
微粉と呼ばれている粒径1μm以下のものが最近特
に要求されてきており、窒化物セラミツクスにお
いても同様である。
（従来技術）
窒化物粉末は窒化物粉末の還元窒化、また金属
粉末の窒化によつて製造されているが、何れも窒
化物粉末の粒度を細かくすることには限度があ
り、その上窒化工程で焼結したりするため、窒化
物とした、ボールミル、アトリツシヨンミルある
いはジエツトミルなどによつて粉砕して製造され
ている。しかし、このような機械的粉砕には限界
があり、粒径1μm以下の超微粉を得ることは極め
て困難である。その上、粉砕機の材質による汚染
があり、純粋な超微粉を得ることはほとんど不可
能である。
従来の窒化物粉末の製造方法は、Si3N4を例に
とれば、
(1) Si直接窒化法
(2) SiO2還元窒化法
(3) イミド熱分解法
(4) CVD法
に分類出来る。
まず、Si直接窒化法は下記反応式(1)により
3Si＋2N2→Si3N4 ……(1)
金属シリコンを微粉砕し、窒素雰囲気中で加熱
窒化して製造される。その際、微粉砕から窒化前
までの工程で金属シリコンの表面が酸化を受け、
これが窒化されると酸窒化珪素となり純粋な
Si3N4は得難い。また、窒化反応が発熱反応であ
るため焼結し、窒化後再び粉砕が必要となる。発
熱が急激な場合には原料金属シリコンの融点
（1410℃）以上に原料温度が上昇して溶解し、大
きな粒状となるため窒素ガスが内部まで拡散出来
ず、未反応シリコンが残留してしまうこともあ
る。
窒化後の粉砕には、ボールミル、アトリツシヨ
ンミル、ジエツトミルなどの微粉砕機が用いられ
るが、3μm程度が限度であり、1μm以下の粒度を
得ることは極めて困難である。また、微粉砕中に
粉砕装置による汚染もあり好ましくない。
また、Si3N4粉末の場合、α型の結晶形態のも
のは焼結性が比較的良く、β型のものは焼結性が
劣るとされている。すなわち焼結性の良いSi3N4
粉末はα型のみあるいはα／β比の高いものが望
ましいが、Si直接窒化法ではα／（α＋β）比で
90％以上のものを得ることが非常に困難である。
次にSiO2還元窒化法によるSi3N4粉末は下記(2)
式により製造される。
3SiO2＋6C＋2N2→Si3N4＋6CO ……(2)
すなわち、SiO2粉と炭素粉の混合物を窒素気
流中で加熱還元窒化するものであるが、反応を十
分進行させるためには過剰の炭素の配合が不可欠
であり、反応終了後残留炭素を除去するため加熱
酸化処理を行うとSiO2を生成して、このSiO2は
ふつ化水素酸等の処理を行つても完全に除去する
ことは困難である。
また、粒度調整は粉砕によらねばならず、1μm
以下の粒度は困難であり、不純物による汚染の問
題もある。更にα／（α＋β）比を高くするため
には反応温度が低いことが望ましいが、低い反応
温度では反応速度が遅いためある程度の高温反応
をよぎなくされるので、α型Si3N4を高能率で製
造することには限界がある。
次にイミド熱分解法は
SiCl4＋NH3→Si（NH）2＋NH4Cl ……(3)
Si（NH）2→Si3N4＋NH3 ……(4)
なる反応により合成される。この方法によるもの
は高純度超微粉が得られるが、工程が複雑でコス
ト高になる点は如何ともし難い。
CVD法（気相合成法）は、例えば
SiCl4＋NH3→Si3N4＋NH4Cl ……(5)
なる反応により合成され、0.5〜2.0μm程度の微粉
が得られるが、原料にシリコン化合物を使用する
ため、例えば(5)式のように塩化物の場合は塩素の
混入があり、焼結体を作るときの焼結性が悪いと
されている。また、CVD法ではシリコン化合物
としてシラン類（SiH4、SiHCl3など）も良く使
われるが、これらのガスは爆発性ガスで危険であ
り、工業的生産方法としては適当でない。
更に、最近プラズマジエツトにより発生した金
属超微粉を直接その超微粉発生装置内で窒化する
方法が提案された（特開昭59−57904）。しかしこ
の方法では窒化物となりにくい金属、例えばSiや
Alなどでは雰囲気ガスとして100％N2を使用して
も完全窒化は出来ず、金属窒化物と金属の混合し
た超微粉が得られるのみである。また雰囲気ガス
中の微量の酸素などによる汚染を抑制するために
雰囲気ガス中に水素を添加することが好ましい
が、N2ガスの量が減少するとそれに従つて窒化
物の生成量も減少するという欠点もある。
（発明が解決しようとする問題点）
本発明は上記のような欠点がなく、簡単かつ安
価に超微粉金属窒化物を能率良く製造する方法な
らびにその製造装置を提供するものである。
（問題点を解決するための手段）
上述の如き問題点を解決するために、本発明
は、
窒化物となり得る金属を、第１段階の処理とし
て、搬送ガスとしても使うAr、H2、N2のなかか
ら選ばれるいずれか少なくとも１つの常圧ガス雰
囲気下でプラズマトーチを用いて加熱溶融するこ
とにより、プラズマガスを、一旦溶融金属中に溶
解させた、そして溶融金属低温域で過飽和になる
ことによる前記プラズマガスの放出を導いて、該
金属の超微粉を発生させ、
次いでこの金属超微粉を、気密下で前記搬送ガ
スにより搬出すると同時に、ガス流と生成超微粉
とを分別してから別の窒化ガス雰囲気下に導き、
さらに、第２段階の処理として、第１段階で生
成した前記金属超微粉を、N2、NH3のうち少な
くとも１つの窒化用ガスを充満させた高温容器中
に供給して窒化することを特徴とする超微粉金属
窒化物の製造方法、
を提案する。
そして、上記提案とかかる製造方法を実施する
のに有効な手段として、
金属超微粉発生手段と該金属超微粉の窒化手段
およびそれらの各手段を搬送手段を介して連結し
てなるものにおいて、
前記金属超微粉発生手段を、ArやH2、N2など
の搬送ガスを充満させた密閉容器内に、金属溶解
台とこれに臨んで設置した一対のプラズマ発生装
置とを内装したもので構成し、
前記金属超微粉窒化手段を、内部にはそれぞれ
N2やNH3の如き窒化用ガスを充満させると共に
高温加熱のために流動層、充填層もしくは高周波
誘導プラズマ発生装置を用いた高温窒化炉で構成
し、そして、
前記搬送手段を、前記金属超微粉発生手段の出
側と前記金属超微粉の入側とを分別手段を介挿さ
せた搬送管で気密に接続するもので構成した、
ことを特徴とする超微粉金属窒化物の製造装置、
を提案する。
（発明の構成）
金属超微粉発生装置を用いて製造した金属超微
粉を窒化して超微粉金属窒化物を製造する本発明
方法について説明する。
金属超微粉発生手段は通常使用されている方法
によるが、例えば特開昭56−9304で開示されてい
る方法は、H2及び／又はN2を含む熱プラズマに
より前記H2及び／又はN2を溶融金属中に原子ま
たはイオンに解離して溶解し、溶融金属プールの
直接アークの当つている部分から外れたときにガ
スの溶解度が下がり、急激にH2及び／又はN2ガ
スが放出され、その時超微粉を発生させるもので
ある。すなわち、上記雰囲気中でプラズマを発生
させると、生成したプラズマガス（H2、N2のイ
オン化したもの）が溶融金属中に溶解するが、こ
のH+、N+が低温になる溶融プールの周縁部で
は、過飽和状態となり、そのためにH2ガス、N2
ガスとなつて該溶融金属から飛び出すとき、まわ
りの溶融金属をはじき飛ばして（破裂）超微細化
した金属粉を発生するのであり、プラズマを使う
ことの特有の作用である。
ここで発生する金属超微粉の粒度は金属の種類
と雰囲気ガス組成によつても変わるが、ほぼ５〜
300nmである。
使用される金属は窒化物となり得るもので、
Ｂ、Al、Si、Ti、Ｖ、Cr、Mn、Fe、Zr、Nb、
Moから選ばれる何れか少なくとも１つである。
雰囲気ガスとしてN2またはNH3を使用した場合、
Ti、Zrなどの窒化物を作りやすい元素の場合は、
この金属超微粉発生手段においてほゞ100％窒化
物として得られるが、Si、Alのような窒化物形
成能の小さい元素はこの段階で完全な窒化物を得
ることはできない。Siの場合は化学分析の結果に
よると発生したシリコン超微粉中に約３％の窒素
が検出されたが、Ｘ線回折ではSi3N4のピークは
検出されない。Alの場合は生成した超微粉中約
30重量％がAlNであり、約70％は金属Alである。
このようにして発生させた金属超微粉は外気に
よる汚染をさけ、直接窒化手段に搬送される。
窒化手段における窒化温度と窒化時間と窒化率
の関係をシリコンの場合について実験した結果を
第４図に示した。同図より、窒化反応は900℃附
近から始まり、1150℃〜1350℃附近で反応が急激
に進むことが分かる。また、窒化後の超微粉につ
いてＸ線回折を行つた結果、1300℃以下で窒化し
たものにはβ型の窒化珪素は認められないが、
1350℃以上で窒化したものはβ型の窒化珪素が認
められ、その上Siの回折線も認められた。これは
急激な反応による発熱のため、材料温度が雰囲気
温度よりかなり高くなり、Siの溶融と高温型であ
るβ型結晶の析出が生じたものと考えられる。従
つて窒化条件としては900℃以上、1350℃以下の
温度とする必要があり、1200℃〜1300℃の温度範
囲が反応速度及び生成物の形態の点から最も好ま
しい。窒化条件における保持時間については窒化
が完結するに要する時間保持すれば良いが、Si超
微粉では1200℃の場合で約30分である。こうして
得られた窒化珪素超微粉は粒径５〜300nm、窒素
含有量38％以上（窒化率95％以上）である。
次にAlの場合には、Ar−H2−N2雰囲気でAlN
とAlの混合した超微粉を生成させた後、前記超
微粉を前記雰囲気ガス気流によつて窒化手段に搬
送し、窒化炉には窒化用ガスとしてNH3を送入
しながら窒化を行えば良い。窒化条件は温度950
℃で１時間保持すれば、Ｘ線回折によりAlNの
みが検出される超微粉を得ることができる。
つぎに本発明の製造装置について第１図〜第３
図を用いて詳細に説明する。
本発明の製造装置は金属超微粉発生手段に直接
連結された金属超微粉窒化手段とを有する。
本発明の装置に含まれる金属超微粉発生手段の
１例を第１図に示した。
１は密閉容器で、前記密閉容器１の器壁にプラ
ズマ放電用電極２及び雰囲気ガス導入管３が傾斜
した角度の位置に配置され、更に前記密閉容器１
の下部に金属溶解台５、その上部に雰囲気ガス搬
送管７が配設されており、前記搬送管７によつて
窒化手段に接続されている。
前記密閉容器１を前記ガス導入管３からAr−
H2、Ar−N2ガスの少なくとも１つを導入するこ
とによつて前記ガス雰囲気とし、前記電極２から
発生するプラズマ放電により前記金属溶解台５の
上に置かれている金属４を溶解して金属超微粉を
発生させる。発生した金属超微粉は雰囲気ガスの
上昇気流に乗つて飛び出して来る金属超微粉だけ
を回収するため、前記密閉容器１の上部に雰囲気
ガスの吸引口を設けて粒子の大きな飛散した金属
粒などは混入しないようになつている。前記金属
超微粉は前記ガス流とともに吸引口から取出さ
れ、搬送管７を経由して窒化手段に搬送される。
前記密閉容器１内の圧力はガス導入量と搬送管７
の途中に取付けられている圧力調整器８によつて
調整され、その圧力は前記密閉容器１の器壁に取
付けられている圧力計P1によつてチエツクされ
る。
つぎに前記金属超微粉の窒化は流動層窒化、充
填層窒化または高周波誘導プラズマによる窒化が
用いられるが、その概略図を第１図〜第３図にそ
れぞれ示した。
第１図は流動層窒化手段を用いる場合の超微粉
金属窒化物の製造装置の全体図である。前記窒化
手段の上部に前記ガス流とガス流中に含まれてい
る金属超微粉との分別手段１０が付設されてお
り、前記分別手段１０は雰囲気ガスと前記雰囲気
ガス中に含まれている金属超微粉を分別するため
のフイルター１１を内蔵しており、更に分別され
た金属超微粉をはらい落とすための振動機１２が
配設されている。窒化炉は縦型炉１３で、前記炉
１３の下部に流動層形成のための分散板１４が設
けられており、前記炉１３の周囲に加熱手段１５
が配設されている。窒化炉の温度は熱電対温度計
１６で測定、調節され、前記分別手段及び窒化炉
内部の圧力測定ならびに調整のためそれぞれの器
壁に圧力計P2、P3が付設されている。
前記ガス流搬送管７によつて搬送された金属超
微粉を含むガス流は、分別手段１０にて金属超微
粉と雰囲気ガスに分別される。前記金属超微粉は
窒化炉内に落ち込み、１部フイルター１１に付着
したものは振動機１２で払い落して窒化炉内に入
れる。窒化炉の下部から窒化用ガスを導入して窒
化炉内の金属超微粉を流動させながら所定温度に
保ち窒化する。
更に分別手段１０で分別された雰囲気ガスと前
記窒化用ガスは分別手段の上部から排気ポンプ１
７によつて吸引排気される。ここで吸引排気され
たガスはAr−H2−N2の混合比率調製を行つた
後、金属超微粉発生手段の雰囲気ガスとして一部
または全量を循環使用することができ、そのよう
にすることによつてガス使用量を大巾に節減する
ことができる。
上述のような操業において、金属超微粉発生手
段の圧力P1、窒化手段の入口部分すなわち分別
手段１０の圧力P2ならびに窒化炉の圧力P3の関
係はP1＝P3＞P2となるように制御される。但し、
P1は常圧である。
窒化炉の操業は断続、連続何れでも良い。断続
式の場合は一定時間毎に生成物を取り出し、連続
式の場合は流動層分散板１４を傾斜させて設置し
ておき、金属超微粉は窒化すると重量が増加する
ため窒化したものは分散板１４の低い個所に集ま
つて流動化しなくなるので、その部分を抜き出す
ことによつて連続操業ができる。
第２図に充填層窒化炉の１例を示した。充填層
窒化炉は縦型炉１８で、前記炉１８の周囲に加熱
手段１５が配設されており、その下部に生成した
窒化物の排出手段１９及び窒化用ガス導入管２０
が配設されている。前記炉１８の上部から分別手
段によつて雰囲気ガスと分別された金属超微粉が
前記炉内に装入され、充填され、窒化用ガスによ
つて窒化される。一定時間所定温度にて保持し、
窒化物となつた生成物は下部から取り出される。
次に高周波誘導プラズマ発生装置を用いた場合
の超微粉金属窒化物の製造装置の全体図を第３図
に示した。
金属超微粉発生手段からの雰囲気ガス及びその
中に含まれている金属超微粉は前記雰囲気ガス気
流により搬送管７を経由して高周波誘導プラズマ
発生装置２１に直接導入され、前記装置２１内に
発生させたプラズマアーク２３のなかを通過する
際、連続的に窒化される。その際、金属超微粉を
含有するガス流が完全に前記プラズマアークのな
かを通過するように、また器壁への生成物の付着
を防止する目的で高周波誘導コイルの内壁面にシ
ールガスとしてH2を流しておくのが良い。生成
した窒化物は前記高周波プラズマ発生装置２１の
下部に設けられた沈降捕集容器２２において沈降
捕集されその下部に堆積し、雰囲気ガス及びシー
ルガスは前記捕集容器２２の上部器壁から排気ポ
ンプ１７によつて吸引排気される。その排気ガス
は循環使用できることは勿論である。
実施例 １
第１図に示した装置を用いて実験した。金属超
微粉発生手段の密閉容器１は直径300mm、高さ
は300mm、金属溶解台５は70mmの皿型で銅製
の水冷式のものを用いた。プラズマ放電用電源は
100V、1000mAのものを使用した。分別手段に
はテトロン製のフイルターバツグを用い、周期的
に払い落しを行つて金属超微粉を回収するように
した。流動層窒化炉は炉芯管として内径30mmの
石英管を用い、下部の分散板はアルミナ製のもの
を設置し、炉芯管の周囲に環状の電気抵抗炉を設
置した。
金属超微粉発生手段内の金属溶解台５の上に粒
度10〜20mmの金属シリコン100gを置き、密閉し
た後、装置内を排気し真空とする。ついで装置内
に雰囲気ガスとしてH225％、N225％、Ar50％の
ガスを導入管３より導入し、装置内の圧力を１気
圧（常圧）に戻し、以後排気ポンプ１７で排気し
ながら雰囲気ガスを40／minの割合で連続的に
供給し、分別手段部分の圧力P2を−200〜−300
mm水柱に保つように調節する。更に窒化炉は所定
温度に加熱した後、窒化用ガスとして0.2／
minの割合で窒素ガスを供給した。
以上のような準備を行つた後、プラズマ放電用
電極２に電圧80V、電流450Aを印加してプラズ
マトーチを発生させ、それにより前記金属シリコ
ンを加熱溶融して金属シリコン超微粉を15分間発
生させた。この間、分別手段のテトロンバツグは
２分間毎に払い落しを行い、窒化炉に入つたもの
から順次流動層を形成せしめて窒化した。窒化温
度1100℃、1200℃、1300℃の３水準で窒化を実施
した。窒化時間は金属超微粉発生手段の通電を始
めてから１時間行つた。
生成した窒化珪素超微粉は装置内を窒素ガスで
置換した後、取出してＸ線回折などの測定に供し
た。その調査結果は第１表に示した。
(Field of Industrial Application) The present invention relates to a method and apparatus for producing ultrafine metal nitride powder used in producing ceramic molded bodies. Ceramic molded bodies have high high-temperature strength;
It has been discovered that it has superior properties over ordinary metals, such as excellent thermal shock resistance and high corrosion resistance, and has been developed for many uses as an industrial material. Ceramic molded bodies are mainly manufactured by sintering ceramic powder, but in order to increase its strength,
It is necessary to make the composition of the molded body fine and homogeneous. For this reason, there has recently been a particular demand for raw material powder for ceramic molded bodies to be of even finer grain size, for example, grain size of 1 μm or less, which is usually called ultrafine powder, and the same is true for nitride ceramics. . (Prior art) Nitride powder is produced by reduction nitriding of nitride powder or nitriding of metal powder, but in both cases there is a limit to making the particle size of nitride powder fine, and in addition, the nitriding process It is manufactured by pulverizing it into nitride using a ball mill, an attrition mill, a jet mill, etc. for sintering. However, there are limits to such mechanical pulverization, and it is extremely difficult to obtain ultrafine powder with a particle size of 1 μm or less. Moreover, there is contamination due to the material of the grinder, and it is almost impossible to obtain pure ultrafine powder. Taking Si 3 N 4 as an example, conventional methods for producing nitride powder can be classified into (1) Si direct nitriding, (2) SiO 2 reduction nitriding, (3) imide pyrolysis, (4) CVD. . First, in the Si direct nitriding method, 3Si+2N 2 →Si 3 N 4 (1) is produced by pulverizing metallic silicon and heating and nitriding it in a nitrogen atmosphere according to the following reaction formula (1). At that time, the surface of metal silicon undergoes oxidation during the process from pulverization to before nitriding.
When this is nitrided, it becomes pure silicon oxynitride.
Si 3 N 4 is difficult to obtain. In addition, since the nitriding reaction is an exothermic reaction, sintering occurs and pulverization is required again after nitriding. If heat generation is rapid, the temperature of the raw material rises above the melting point (1410℃) of the raw metal silicon, causing it to melt and form large particles, making it impossible for nitrogen gas to diffuse into the interior, resulting in unreacted silicon remaining. There is also. For pulverization after nitriding, a fine pulverizer such as a ball mill, attrition mill, or jet mill is used, but the particle size is limited to about 3 μm, and it is extremely difficult to obtain a particle size of 1 μm or less. Further, contamination caused by the grinding device during pulverization is also undesirable. Furthermore, in the case of Si 3 N 4 powder, it is said that the α-type crystal form has relatively good sinterability, and the β-type crystal form has poor sinterability. In other words, Si 3 N 4 with good sinterability
It is preferable that the powder be α-type only or one with a high α/β ratio, but in the Si direct nitriding method, powder with an α/(α+β) ratio is preferable.
It is very difficult to get anything above 90%. Next, the Si 3 N 4 powder produced by the SiO 2 reduction nitriding method is as follows (2)
Manufactured by the formula. 3SiO 2 ＋6C＋2N 2 →Si 3 N 4 ＋6CO ...(2) In other words, a mixture of SiO 2 powder and carbon powder is heated, reduced, and nitrided in a nitrogen stream, but in order for the reaction to proceed sufficiently, excessive carbon must be present. It is essential to have a mixture of SiO 2 and SiO 2 is generated when heat oxidation treatment is performed to remove residual carbon after the reaction is completed, and this SiO 2 cannot be completely removed even by treatment with hydrofluoric acid, etc. Have difficulty. In addition, the particle size must be adjusted by pulverization, and the particle size must be 1μm.
Particle sizes below are difficult and there are problems with contamination by impurities. Furthermore, in order to further increase the α/(α+β) ratio, it is desirable that the reaction temperature be low, but at low reaction temperatures, the reaction rate is slow and a certain amount of high temperature reaction is avoided . There are limits to manufacturing efficiency. Next, in the imide thermal decomposition method, it is synthesized by the following reaction: SiCl 4 +NH 3 →Si(NH) 2 +NH 4 Cl ……(3) Si(NH) 2 →Si 3 N 4 +NH 3 ……(4). Although this method yields highly pure ultrafine powder, the process is complicated and the cost is high. In the CVD method (vapor phase synthesis method), for example, SiCl 4 + NH 3 → Si 3 N 4 + NH 4 Cl (5) is synthesized, and a fine powder of about 0.5 to 2.0 μm is obtained, but the raw material is a silicon compound. For example, in the case of chloride as in formula (5), chlorine is mixed in, which is said to cause poor sinterability when making a sintered body. Additionally, silanes (SiH 4 , SiHCl 3 , etc.) are often used as silicon compounds in the CVD method, but these gases are explosive and dangerous and are not suitable as an industrial production method. Furthermore, a method has recently been proposed in which ultrafine metal powder generated by a plasma jet is directly nitrided in the ultrafine powder generator (Japanese Patent Application Laid-open No. 57904-1983). However, with this method, metals that are difficult to form into nitrides, such as Si,
Even if 100% N 2 is used as an atmospheric gas, complete nitridation cannot be achieved with Al, etc., and only ultrafine powder containing a mixture of metal nitride and metal is obtained. Additionally, it is preferable to add hydrogen to the atmospheric gas in order to suppress contamination caused by trace amounts of oxygen in the atmospheric gas, but the drawback is that as the amount of N2 gas decreases, the amount of nitrides produced also decreases. There is also. (Problems to be Solved by the Invention) The present invention is free from the above-mentioned drawbacks and provides a method for efficiently producing ultrafine metal nitride simply and inexpensively, as well as an apparatus for producing the same. (Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention uses Ar, H 2 , and N which are also used as carrier gases to treat metals that can become nitrides in the first stage of treatment. By heating and melting using a plasma torch in an atmospheric pressure gas atmosphere of at least one selected from 2 , the plasma gas is once dissolved in the molten metal, and becomes supersaturated in the molten metal low temperature range. The ultrafine powder of the metal is generated by the discharge of the plasma gas, and the ultrafine metal powder is then carried out by the carrier gas in an airtight manner, and at the same time, the gas flow and the generated ultrafine powder are separated and then separated. Further, as a second stage treatment, the ultrafine metal powder produced in the first stage is placed in a high temperature container filled with at least one nitriding gas of N 2 and NH 3 . We propose a method for producing ultrafine metal nitride, which is characterized by supplying and nitriding the metal nitride. As an effective means for carrying out the above proposal and the manufacturing method, there is provided a method in which an ultrafine metal powder generating means, a means for nitriding the ultrafine metal powder, and each of these means are connected via a conveying means. The ultrafine metal powder generation means consists of a metal melting table and a pair of plasma generators installed facing the table in a closed container filled with a carrier gas such as Ar, H2 , N2, etc. , the metal ultrafine powder nitriding means is inside, respectively.
A high-temperature nitriding furnace filled with a nitriding gas such as N 2 or NH 3 and using a fluidized bed, a packed bed, or a high-frequency induced plasma generator for high-temperature heating, and An apparatus for producing ultrafine metal nitride, characterized in that the output side of the fine powder generation means and the input side of the ultrafine metal powder are airtightly connected by a conveying pipe in which a separation means is inserted.
propose. (Structure of the Invention) The method of the present invention for producing ultrafine metal nitride by nitriding ultrafine metal powder produced using an ultrafine metal powder generator will be described. The means for generating ultrafine metal powder may be a commonly used method. For example, the method disclosed in Japanese Patent Application Laid-Open No. 56-9304 uses thermal plasma containing H 2 and/or N 2 to generate the H 2 and/or N 2 . is dissociated and dissolved into atoms or ions in the molten metal, and when it leaves the part of the molten metal pool that is directly hit by the arc, the solubility of the gas decreases and H 2 and/or N 2 gas is suddenly released. At that time, ultrafine powder is generated. In other words, when plasma is generated in the above atmosphere, the generated plasma gas (ionized H 2 and N 2 ) is dissolved in the molten metal, but the H + and N + are at the periphery of the molten pool where the temperature is low. In the part, supersaturation occurs, so H 2 gas, N 2
When it becomes a gas and flies out of the molten metal, it repels the surrounding molten metal (ruptures) and generates ultra-fine metal powder, which is a unique effect of using plasma. The particle size of the ultrafine metal powder generated here varies depending on the type of metal and the atmospheric gas composition, but it is approximately 5 to
It is 300nm. The metal used can be a nitride,
B, Al, Si, Ti, V, Cr, Mn, Fe, Zr, Nb,
At least one selected from Mo.
When using N2 or NH3 as the atmosphere gas,
For elements that easily form nitrides, such as Ti and Zr,
Although almost 100% nitride is obtained using this ultrafine metal powder generation means, complete nitride cannot be obtained from elements such as Si and Al, which have a low nitride forming ability, at this stage. In the case of Si, according to the results of chemical analysis, approximately 3% nitrogen was detected in the generated silicon ultrafine powder, but no Si 3 N 4 peak was detected in X-ray diffraction. In the case of Al, the ultrafine powder produced is approximately
30% by weight is AlN and about 70% is metallic Al. The ultrafine metal powder thus generated is directly transported to the nitriding means, avoiding contamination by outside air. FIG. 4 shows the results of an experiment on the relationship between nitriding temperature, nitriding time, and nitriding rate in the case of silicon in the nitriding means. From the figure, it can be seen that the nitriding reaction starts around 900°C, and the reaction rapidly progresses around 1150°C to 1350°C. In addition, as a result of X-ray diffraction on the ultrafine powder after nitriding, β-type silicon nitride was not observed in those nitrided at temperatures below 1300°C.
In those nitrided at 1350°C or higher, β-type silicon nitride was observed, and Si diffraction lines were also observed. This is thought to be due to the heat generated by the rapid reaction, which caused the material temperature to become much higher than the ambient temperature, causing melting of Si and precipitation of high-temperature β-type crystals. Therefore, the nitriding conditions must be at a temperature of 900°C or higher and 1350°C or lower, and a temperature range of 1200°C to 1300°C is most preferred from the viewpoint of reaction rate and product form. Regarding the holding time under nitriding conditions, it is sufficient to hold for the time required to complete nitriding, but for ultrafine Si powder, it is about 30 minutes at 1200°C. The ultrafine silicon nitride powder thus obtained has a particle size of 5 to 300 nm and a nitrogen content of 38% or more (nitridation rate of 95% or more). Next, in the case of Al, AlN in an Ar−H 2 −N 2 atmosphere
After generating a mixture of ultrafine powder and Al, the ultrafine powder is transported to the nitriding means by the atmospheric gas flow, and nitriding is performed while feeding NH 3 as a nitriding gas into the nitriding furnace. . Nitriding conditions are temperature 950
If kept at ℃ for 1 hour, ultrafine powder in which only AlN can be detected by X-ray diffraction can be obtained. Next, the manufacturing apparatus of the present invention will be explained in Figures 1 to 3.
This will be explained in detail using figures. The manufacturing apparatus of the present invention has an ultrafine metal powder nitriding means directly connected to an ultrafine metal powder generating means. An example of the ultrafine metal powder generating means included in the apparatus of the present invention is shown in FIG. Reference numeral 1 denotes a closed container, in which a plasma discharge electrode 2 and an atmospheric gas introduction tube 3 are arranged at an inclined angle on the wall of the closed container 1;
A metal melting table 5 is disposed at the bottom of the table 5, and an atmospheric gas conveying pipe 7 is disposed above the table 5, and is connected to the nitriding means by the conveying pipe 7. The airtight container 1 is connected to the gas introduction pipe 3 by Ar-
The gas atmosphere is created by introducing at least one of H 2 and Ar-N 2 gas, and the metal 4 placed on the metal melting table 5 is melted by plasma discharge generated from the electrode 2. to generate ultrafine metal powder. In order to collect only the generated ultrafine metal powder that flies out on the upward current of atmospheric gas, a suction port for the atmospheric gas is provided at the top of the sealed container 1 to remove large scattered metal particles. It is designed to prevent contamination. The ultrafine metal powder is taken out from the suction port together with the gas flow, and is transported to the nitriding means via the transport pipe 7.
The pressure inside the sealed container 1 is determined by the amount of gas introduced and the conveying pipe 7.
The pressure is regulated by a pressure regulator 8 installed in the middle of the closed container 1, and the pressure is checked by a pressure gauge P1 installed on the wall of the closed container 1. Next, for nitriding the ultrafine metal powder, fluidized bed nitriding, packed bed nitriding, or nitriding using high frequency induced plasma is used, and schematic diagrams thereof are shown in FIGS. 1 to 3, respectively. FIG. 1 is an overall view of an apparatus for producing ultrafine metal nitride using fluidized bed nitriding means. A means 10 for separating the gas flow and ultrafine metal powder contained in the gas flow is attached above the nitriding means, and the separation means 10 separates the atmospheric gas and the metal contained in the atmospheric gas. It has a built-in filter 11 for separating ultrafine powder, and is further provided with a vibrator 12 for shaking off the separated ultrafine metal powder. The nitriding furnace is a vertical furnace 13, a dispersion plate 14 for forming a fluidized bed is provided at the bottom of the furnace 13, and a heating means 15 is provided around the furnace 13.
is installed. The temperature of the nitriding furnace is measured and regulated by a thermocouple thermometer 16, and pressure gauges P 2 and P 3 are attached to the walls of each chamber to measure and adjust the pressure inside the separation means and the nitriding furnace. The gas flow containing ultrafine metal powder conveyed by the gas flow conveyance pipe 7 is separated into ultrafine metal powder and atmospheric gas by a separating means 10. The ultrafine metal powder falls into the nitriding furnace, and a portion of the metal particles adhering to the filter 11 is shaken off by a vibrator 12 and placed into the nitriding furnace. A nitriding gas is introduced from the lower part of the nitriding furnace to flow the ultrafine metal powder in the nitriding furnace while maintaining it at a predetermined temperature for nitriding. Further, the atmospheric gas and the nitriding gas separated by the separation means 10 are passed through the exhaust pump 1 from the upper part of the separation means.
It is sucked and exhausted by 7. After adjusting the Ar-H 2 -N 2 mixing ratio of the gas sucked and exhausted here, part or all of the gas can be recycled and used as an atmospheric gas for the ultrafine metal powder generating means, and it is possible to do so. This makes it possible to significantly reduce gas consumption. In the above operation, the relationship among the pressure P 1 of the ultrafine metal powder generating means, the pressure P 2 of the inlet portion of the nitriding means, that is, the separation means 10, and the pressure P 3 of the nitriding furnace is P 1 = P 3 > P 2. controlled as follows. however,
P 1 is normal pressure. The operation of the nitriding furnace may be either intermittent or continuous. In the case of an intermittent type, the product is taken out at regular intervals, and in the case of a continuous type, the fluidized bed dispersion plate 14 is installed at an angle. Since the fluid collects in the low points of 14 and is no longer fluidized, continuous operation can be performed by extracting that portion. Figure 2 shows an example of a packed bed nitriding furnace. The packed bed nitriding furnace is a vertical furnace 18, and a heating means 15 is arranged around the furnace 18, and a discharge means 19 for nitride produced and a nitriding gas introduction pipe 20 are provided at the bottom of the heating means 15.
is installed. The ultrafine metal powder that has been separated from the atmospheric gas by the separating means is introduced into the furnace from the upper part of the furnace 18, filled, and nitrided with a nitriding gas. Hold at a specified temperature for a certain period of time,
The product, which has become a nitride, is taken out from the bottom. Next, FIG. 3 shows an overall diagram of an apparatus for producing ultrafine metal nitride using a high-frequency induced plasma generator. The atmospheric gas from the ultrafine metal powder generating means and the ultrafine metal powder contained therein are directly introduced into the high frequency induction plasma generator 21 via the conveying pipe 7 by the atmospheric gas flow, and are generated within the device 21. When passing through the plasma arc 23, it is continuously nitrided. At that time, in order to ensure that the gas flow containing ultrafine metal powder completely passes through the plasma arc, and to prevent the products from adhering to the vessel wall, H It is better to leave 2 . The generated nitrides are collected by sedimentation in the sedimentation collection container 22 provided at the lower part of the high-frequency plasma generator 21 and deposited in the lower part, and the atmospheric gas and seal gas are exhausted from the upper wall of the collection container 22. The pump 17 sucks and exhausts the air. Of course, the exhaust gas can be recycled. Example 1 An experiment was conducted using the apparatus shown in FIG. The closed container 1 of the ultrafine metal powder generating means was 300 mm in diameter and 300 mm in height, and the metal melting table 5 was a 70 mm dish-shaped copper water-cooled one. The power supply for plasma discharge is
I used one with 100V and 1000mA. A filter bag manufactured by Tetron was used as the separation means, and the ultrafine metal powder was recovered by periodically shaking it off. The fluidized bed nitriding furnace used a quartz tube with an inner diameter of 30 mm as the furnace core tube, the lower dispersion plate was made of alumina, and an annular electric resistance furnace was installed around the furnace core tube. 100 g of metal silicon with a particle size of 10 to 20 mm is placed on the metal melting table 5 in the ultrafine metal powder generating means, and after the device is sealed, the inside of the device is evacuated to create a vacuum. Next, a gas containing 25% H 2 , 25% N 2 , and 50% Ar was introduced into the device as atmospheric gas through the introduction pipe 3, and the pressure inside the device was returned to 1 atmosphere (normal pressure), after which it was evacuated using the exhaust pump 17. while continuously supplying atmospheric gas at a rate of 40/min, the pressure P2 in the separation means was -200 to -300.
Adjust to maintain mm water column. Furthermore, after heating the nitriding furnace to a predetermined temperature, 0.2/
Nitrogen gas was supplied at a rate of min. After making the above preparations, a voltage of 80 V and a current of 450 A are applied to the plasma discharge electrode 2 to generate a plasma torch, thereby heating and melting the metal silicon to generate ultrafine metal silicon powder for 15 minutes. Ta. During this time, the Tetoron bag serving as the separation means was shaken off every 2 minutes, and a fluidized bed was sequentially formed and nitrided starting from those entering the nitriding furnace. Nitriding was carried out at three levels of nitriding temperature: 1100°C, 1200°C, and 1300°C. The nitriding time was 1 hour after the start of energization of the ultrafine metal powder generating means. After replacing the inside of the apparatus with nitrogen gas, the produced ultrafine silicon nitride powder was taken out and subjected to measurements such as X-ray diffraction. The survey results are shown in Table 1.
【表】
更に生成した窒化珪素超微粉のTEM写真を第
５〜７図に示し、そのＸ線回折結果の１例を第８
図に示した。そのＸ線回折結果によると、回折角
20.8度前後のバツクグランドが高いが、これは非
晶質の窒化珪素を含むことを示していると考えら
れる。
比較例
実施例１の装置（第１図参照）において、流動
層窒化炉を取り外して生成した超微粉の回収装置
を設け、実施例１と同様の条件で金属シリコン超
微粉を発生させて回収した。前記金属シリコン超
微粉を大気中に約１時間放置したものを充填層窒
化炉（第２図参照）に装入して1200℃と1300℃で
窒化した。窒化時間は１時間行つた。
生成した窒化物のＸ線回折結果は、第９図に示
したように、1200℃、１時間の窒化ではSiと
SiO2のピークが現われており、窒化がほとんど
進んでいないこと、また1300℃、１時間の場合は
α−Si3N4と未反応のSiが検出された。このこと
から表面が酸素で汚染された金属シリコン超微粉
は窒化温度を高くしなければ窒化しないことが分
つた。完全に窒化させるにはより以上窒化温度を
上げる必要があり、焼結体製造用原料粉として不
適当であるとされているβ型窒化珪素の生成をよ
ぎなくされることとなり、また粒度も大きくなつ
てくる。
更に、金属シリコン超微粉を大気中に３日間放
置した場合について、同様に充填層窒化炉で1300
℃、１時間の窒化を行つた結果ではＸ線回折で酸
窒化珪素（Si2N2O）が検出された。
実施例 ２
窒化手段として、高周波誘導プラズマ発生装置
を用いた装置（第３図参照）で実験した。金属超
微粉発生手段は実施例１と同じであり、高周波誘
導プラズマ発生装置の出力は35KWのものを用い
た。
装置内全体を真空排気し、Arガスで置換した
後、雰囲気ガス導入管３より15／minの流量で
Arガスを流しながら実施例１と同様にして金属
シリコン超微粉を発生させた。次に高周波誘導プ
ラズマ発生装置を通電し、安定なプラズマ流を形
成させた。前記超微粉発生手段への導入ガス組成
をAr100％から徐々にN2、H2を増加し、最終的
にN225％、H225％、Ar50％の組成として連続的
に超微粉の製造及びその窒化を行つた。
沈降捕集容器２２に堆積した生成物を取り出し
てＸ線回折を行つた結果、α−Si3N4のみが検出
された。また、その化学組成はＮ＝38.1％であ
り、窒化率＝95.3％であつた。
実施例 ３
実施例１の装置を用いて窒化アルミニウムの製
造を試みた。操作は実施例１と同じであるが、窒
化炉の温度は950℃に設定した。
生成物は6.5gで、そのＸ線回折を行つた結果、
AlNであることが確認され、化学分析の結果、
Ｎ＝33.7％（窒化率98.6％）であつた。また生成
窒化物の粒径は10〜500nmであつた。
なお、雰囲気ガスと金属超微粉の分別手段のテ
トロン製バツグに付着した金属超微粉、すなわち
窒化炉に入る前の生成物を実験終了後に取出して
化学分析を行つた結果、Al＝89.8％、Ｎ＝10.2％
であり、金属超微粉発生装置で生成したものは
N225％の雰囲気ガスの条件では窒化率で30％程
度であり、本発明の窒化手段を用いることによつ
て初めて完全に窒化した超微粉窒化物を得ること
ができることが分つた。
本発明方法ならびに装置によれば、Ar−H2、
Ar−N2あるいはAr−H2−N2系ガスを使用した
熱プラズマにより生成した金属超微粉が空気中の
酸素によつて汚染することなく直接窒化物とする
ことができるので、極めて純度の良い超微粉金属
窒化物を製造することが可能であり、かつ原料と
して純金属を使用するのでCVD法のようにハロ
ゲンによつて汚染されることもない。
更に製造装置の操業は装置内の圧力が500Torr
〜大気圧で行えるので、装置が簡単で操作も容易
である。[Table] TEM photographs of the ultrafine silicon nitride powder produced are shown in Figures 5 to 7, and an example of the X-ray diffraction results is shown in Figure 8.
Shown in the figure. According to the X-ray diffraction results, the diffraction angle
The background is high at around 20.8 degrees, which is thought to indicate that amorphous silicon nitride is included. Comparative Example In the apparatus of Example 1 (see Figure 1), the fluidized bed nitriding furnace was removed and a recovery device for the generated ultrafine powder was installed, and ultrafine metal silicon powder was generated and recovered under the same conditions as Example 1. . The ultrafine metal silicon powder was left in the atmosphere for about one hour, then charged into a packed bed nitriding furnace (see Figure 2) and nitrided at 1200°C and 1300°C. The nitriding time was 1 hour. As shown in Figure 9, the X-ray diffraction results of the generated nitride show that nitriding at 1200°C for 1 hour is similar to Si.
A SiO 2 peak appeared, indicating that nitridation had hardly progressed, and in the case of 1 hour at 1300°C, α-Si 3 N 4 and unreacted Si were detected. This indicates that ultrafine metallic silicon powder whose surface is contaminated with oxygen cannot be nitrided unless the nitriding temperature is raised. In order to achieve complete nitridation, it is necessary to raise the nitriding temperature even higher, which leads to the formation of β-type silicon nitride, which is considered unsuitable as a raw material powder for producing sintered bodies, and the particle size is also large. I'm getting old. Furthermore, regarding the case where ultrafine metallic silicon powder was left in the atmosphere for 3 days, it was similarly treated in a packed bed nitriding furnace at 1300
As a result of nitriding at ℃ for 1 hour, silicon oxynitride (Si 2 N 2 O) was detected by X-ray diffraction. Example 2 An experiment was conducted using an apparatus (see FIG. 3) using a high-frequency induction plasma generator as a nitriding means. The ultrafine metal powder generating means was the same as in Example 1, and a high frequency induced plasma generator with an output of 35 KW was used. After evacuating the entire inside of the device and replacing it with Ar gas, evacuate it from the atmospheric gas introduction pipe 3 at a flow rate of 15/min.
Metallic silicon ultrafine powder was generated in the same manner as in Example 1 while flowing Ar gas. Next, the high-frequency induction plasma generator was energized to form a stable plasma flow. The gas composition introduced into the ultrafine powder generating means is gradually increased from Ar 100% to N 2 and H 2 , and finally the composition is changed to 25% N 2 , 25% H 2 , and 50% Ar to continuously produce ultrafine powder. and its nitriding. When the product deposited in the sedimentation collection container 22 was taken out and subjected to X-ray diffraction, only α-Si 3 N 4 was detected. Further, its chemical composition was N=38.1%, and the nitridation rate was 95.3%. Example 3 Using the apparatus of Example 1, an attempt was made to produce aluminum nitride. The operation was the same as in Example 1, but the temperature of the nitriding furnace was set at 950°C. The product was 6.5g, and as a result of X-ray diffraction,
It was confirmed that it was AlN, and as a result of chemical analysis,
N=33.7% (nitriding rate 98.6%). The particle size of the produced nitrides was 10 to 500 nm. Furthermore, after the experiment was completed, the ultrafine metal powder adhering to the Tetron bag used to separate the atmospheric gas and the ultrafine metal powder, that is, the product before entering the nitriding furnace, was taken out and chemically analyzed. As a result, Al = 89.8%, N =10.2%
The material produced by the ultrafine metal powder generator is
Under the condition of an atmospheric gas of 25% N 2 , the nitriding rate was about 30%, and it was found that a completely nitrided ultrafine powder nitride could be obtained for the first time by using the nitriding means of the present invention. According to the method and apparatus of the present invention, Ar-H 2 ,
Ultrafine metal powder generated by thermal plasma using Ar-N 2 or Ar-H 2 -N 2 gas can be directly converted into nitride without being contaminated by oxygen in the air, resulting in extremely pure nitrides. It is possible to produce high-quality ultrafine metal nitride powder, and since pure metal is used as a raw material, there is no contamination with halogens unlike in the CVD method. Furthermore, when operating the manufacturing equipment, the pressure inside the equipment is 500 Torr.
~Since it can be carried out at atmospheric pressure, the equipment is simple and easy to operate.
第１図は本発明の１つの態様を示す超微粉金属
窒化物の製造装置の説明図、第２図は本発明の１
つの態様を示す充填層窒化炉の縦断面説明図、第
３図は本発明のさらに１つの態様を示す超微粉金
属窒化物の製造装置説明図、第４図はSi超微粉の
窒化に及ぼす反応温度と保持時間の関係を示す
図、第５，６および７図はそれぞれ窒化温度1100
℃、1200℃、1300℃で本発明によつて製造された
超微粉窒化珪素の粒子構造を示す透過型電子顕微
鏡写真（第５，６図の倍率をそれぞれ10万倍、第
７図の倍率８万倍）、第８図は本発明によつて製
造された超微粉窒化珪素のＸ線回折結果を示す
図、第９図は大気中の酸素で汚染されたSi超微粉
から製造した超微粉窒化珪素のＸ線回折結果を示
す図である。
１……密閉容器、２……プラズマ放電用電極、
３……雰囲気ガス導入管、４……金属、５……金
属溶解台、７……搬送管、８……圧力調整器、１
０……分別手段、１１……フイルター、１２……
振動器、１３……縦型炉、１４……分散板、１５
……加熱手段、１６……熱電対温度計、１７……
排気ポンプ、１８……縦型炉、１９……排出手
段、２０……窒化用ガス導入管、２１……高周波
誘導プラズマ発生装置、２２……沈降捕集容器、
２３……プラズマアーク、P1，P2およびP3……
圧力計。
FIG. 1 is an explanatory diagram of an apparatus for producing ultrafine metal nitride showing one embodiment of the present invention, and FIG.
FIG. 3 is an explanatory diagram of a manufacturing apparatus for ultrafine metal nitride showing another embodiment of the present invention, and FIG. 4 is a reaction on nitriding of ultrafine Si powder. Figures 5, 6 and 7 showing the relationship between temperature and holding time are for the nitriding temperature of 1100
Transmission electron micrographs showing the particle structure of ultrafine silicon nitride produced according to the present invention at temperatures of Figure 8 shows the X-ray diffraction results of ultrafine silicon nitride powder produced according to the present invention, and Figure 9 shows ultrafine nitride powder produced from ultrafine Si powder contaminated with oxygen in the atmosphere. It is a figure showing the X-ray diffraction result of silicon. 1... Airtight container, 2... Plasma discharge electrode,
3...Atmospheric gas introduction pipe, 4...Metal, 5...Metal melting table, 7...Transport pipe, 8...Pressure regulator, 1
0...Separation means, 11...Filter, 12...
Vibrator, 13...Vertical furnace, 14...Dispersion plate, 15
... Heating means, 16 ... Thermocouple thermometer, 17 ...
Exhaust pump, 18... Vertical furnace, 19... Discharge means, 20... Nitriding gas introduction pipe, 21... High frequency induction plasma generator, 22... Sedimentation collection container,
23... Plasma arc, P 1 , P 2 and P 3 ...
Pressure gauge.
Claims (1)
して、搬送ガスとしても使うAr、H2、N2のなか
から選ばれるいずれか少なくとも１つの常圧ガス
雰囲気下でプラズマトーチを用いて加熱溶融する
ことにより、プラズマガスを、一旦溶融金属中に
溶解させ、そして溶融金属低温域で過飽和になる
ことによる前記プラズマガスの放出を導いて、該
金属の超微粉を発生させ、 次いでこの金属超微粉を、気密下で前記搬送ガ
スにより搬出すると同時に、ガス流と生成超微粉
とを分別してから別の窒化ガス雰囲気下に導き、 さらに、第２段階の処理として、第１段階で生
成した前記金属超微粉を、N2、NH3のうち少な
くとも１つの窒化用ガスを充満させた高温容器中
に供給して窒化することを特徴とする超微粉金属
窒化物の製造方法。 ２ 前記金属が、Ｂ、Al、Si、Ti、Ｖ、Cr、
Mn、Fe、Zr、Nb、Moから選ばれる少なくとも
１つであることを特徴とする特許請求の範囲第１
項に記載の製造方法。 ３ 前記金属超微粉を窒化させる際に、流動層窒
化を行うことを特徴とする特許請求の範囲第１〜
２項のいずれか１つに記載の製造方法。 ４ 前記金属超微粉を窒化させる際に、充填層窒
化を行うことを特徴とする特許請求の範囲第１〜
２項のいずれか１つに記載の製造方法。 ５ 前記金属超微粉を窒化させる際に、高周波誘
導プラズマを用いて連続的に窒化することを特徴
とする特許請求の範囲第１〜２項のいずれか１つ
に記載の製造方法。 ６ 金属超微粉発生手段と該金属超微粉の窒化手
段およびそれらの各手段を搬送手段を介して連結
してなるものにおいて、 前記金属超微粉発生手段を、ArやH2、N2など
の搬送ガスを充満させた密閉容器内に、金属溶解
台とこれに臨んで設置した一対のプラズマ発生装
置とを内装したもので構成し、 前記金属超微粉窒化手段を、内部にはそれぞれ
N2やNH3の如き窒化用ガスを充満させると共に
高温加熱のために流動層、充填層もしくは高周波
誘導プラズマ発生装置を用いた高温窒化炉で構成
し、そして、 前記搬送手段を、前記金属超微粉発生手段の出
側と前記金属超微粉の入側とを分別手段を介挿さ
せた搬送管で気密に接続するもので構成した、 ことを特徴とする超微粉金属窒化物の製造装置。 ７ 前記搬送手段には、必要に応じてフイルター
の如き分別手段を設けることを特徴とする特許請
求の範囲第６項記載の製造装置。[Claims] 1. A metal that can become a nitride is subjected to plasma treatment in an atmosphere of at least one atmospheric pressure gas selected from Ar, H 2 and N 2 which is also used as a carrier gas as a first stage treatment. By heating and melting using a torch, the plasma gas is once dissolved in the molten metal, and the molten metal becomes supersaturated in a low temperature range, leading to the release of the plasma gas and generating ultrafine powder of the metal. Next, this ultrafine metal powder is carried out by the carrier gas under airtight conditions, and at the same time, the gas flow and the generated ultrafine powder are separated, and then introduced into another nitriding gas atmosphere. A method for producing ultrafine metal nitride, characterized in that the ultrafine metal powder produced in the step is nitrided by being supplied into a high-temperature container filled with at least one nitriding gas of N 2 and NH 3 . 2 The metal is B, Al, Si, Ti, V, Cr,
Claim 1 characterized in that it is at least one selected from Mn, Fe, Zr, Nb, and Mo.
The manufacturing method described in section. 3. Claims 1 to 3, characterized in that fluidized bed nitriding is performed when the ultrafine metal powder is nitrided.
The manufacturing method according to any one of Item 2. 4. Claims 1 to 4, characterized in that when the ultrafine metal powder is nitrided, packed bed nitridation is performed.
The manufacturing method according to any one of Item 2. 5. The manufacturing method according to any one of claims 1 to 2, wherein the ultrafine metal powder is continuously nitrided using high-frequency induced plasma. 6. In a device in which an ultrafine metal powder generating means , a means for nitriding the ultrafine metal powder, and each of these means are connected via a conveying means, It consists of a metal melting table and a pair of plasma generators installed facing the metal melting table in a closed container filled with gas, each of which contains the ultrafine metal powder nitriding means.
A high-temperature nitriding furnace filled with a nitriding gas such as N 2 or NH 3 and using a fluidized bed, a packed bed, or a high-frequency induced plasma generator for high-temperature heating, and 1. An apparatus for producing ultrafine metal nitride, characterized in that the output side of the fine powder generation means and the input side of the ultrafine metal powder are airtightly connected by a conveying pipe in which a separation means is inserted. 7. The manufacturing apparatus according to claim 6, wherein the conveyance means is provided with a sorting means such as a filter, if necessary.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12734084A JPS6110012A (en) | 1984-06-22 | 1984-06-22 | Production of ultrafine metal nitride and production unit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12734084A JPS6110012A (en) | 1984-06-22 | 1984-06-22 | Production of ultrafine metal nitride and production unit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6110012A JPS6110012A (en) | 1986-01-17 |
| JPH0352402B2 true JPH0352402B2 (en) | 1991-08-09 |
Family
ID=14957495
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP12734084A Granted JPS6110012A (en) | 1984-06-22 | 1984-06-22 | Production of ultrafine metal nitride and production unit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6110012A (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61200850A (en) * | 1985-02-28 | 1986-09-05 | Daido Steel Co Ltd | Production of ultra-fine particulate compound |
| JPS62102828A (en) * | 1985-10-28 | 1987-05-13 | Daido Steel Co Ltd | Production of fine grain of compound |
| JPS62168542A (en) * | 1986-01-21 | 1987-07-24 | Daido Steel Co Ltd | Production of ultrafine particulate compound |
| US4800183A (en) * | 1986-04-09 | 1989-01-24 | The United States Of America As Represented By The United States Department Of Energy | Method for producing refractory nitrides |
| JPS62282635A (en) * | 1986-05-31 | 1987-12-08 | Natl Res Inst For Metals | Production of mixture of ultra-fine aluminum nitride powder and ultra-fine oxidation-resistant aluminum powder |
| FR2687393B1 (en) * | 1992-02-18 | 1994-04-15 | Elf Atochem Sa | CONTINUOUS PROCESS FOR THE PREPARATION OF SILICON NITRIDE BY CARBONITRURATION AND THE SILICON NITRIDE THUS OBTAINED. |
| TWI290177B (en) | 2001-08-24 | 2007-11-21 | Nippon Steel Corp | A steel sheet excellent in workability and method for producing the same |
| KR101266776B1 (en) * | 2004-08-20 | 2013-05-28 | 미쓰비시 가가꾸 가부시키가이샤 | Metal nitrides and process for production thereof |
| JP5082213B2 (en) * | 2004-08-20 | 2012-11-28 | 三菱化学株式会社 | Metal nitride and method for producing metal nitride |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58150427A (en) * | 1982-03-01 | 1983-09-07 | Toyota Motor Corp | Preparation of fine powder of metal compound |
-
1984
- 1984-06-22 JP JP12734084A patent/JPS6110012A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58150427A (en) * | 1982-03-01 | 1983-09-07 | Toyota Motor Corp | Preparation of fine powder of metal compound |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6110012A (en) | 1986-01-17 |
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