JPS5926910A - Preparation of powder - Google Patents

Abstract

PURPOSE:To prepare high-purity fine WC powder in bulk, by spraying molten WO3 to a quenching member, and heat-treating the quenched WO3 in an atmosphere having reduced pressure and containing plasma of a mixture of H2 and CH4. CONSTITUTION:Molten WO3 is sprayed to a quenching member to effect the quenching at a rate of >=10<4> deg.C/sec. The quenched WO3 is heated at >=800 deg.C in a reduced-pressure atmosphere at 0.1-20Torr containing the plasma of a gaseous mixture of H2 and CH4 at a ratio of 1/10-100/1. The plasma is generated by the application of external electrical energy. The reduction and carbonization reaction of quenched WO3 having a large amount of strain energy generated by quenching, is accelerated in the gaseous phase containing the plasma, and a high- purity fine powder of WC having a particle diameter of about <=1.0mum can be synthesized at a relatively low temperature.

Description

【発明の詳細な説明】 本発明は超硬およびサーメットの硬質相として利用され
る原料炭化物粉末の製造方法に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a raw material carbide powder used as a hard phase in cemented carbides and cermets.

炭化物の一般的な製造方法としては、 ■金属粉末と炭素の同相反応 ■金属粉末と炭素の固相、気相反応 ■メンストラム法 ■ハロゲン化物と炭化水素の反応 等が知られている。しかしながら、これら従来方法は、
例えば上記■の方法では高温で反応させるため機械的な
粉砕を行なうが、有害不純物の混入なしに１μｌ以下の
大きさになるまで粉砕を行なうことは困難であること、
合成粉末の粒度は固形炭素の大きさに左右されること、
および固形炭素からの不純物混入が避けられないことな
どの困ガ［さがある。しかし、超硬合金の主原料である
ＷＣは、この方法によるものが最も一般的である。それ
はＷＣ合成粉の粒度調整が容易であること、および結合
炭素率が高いことなどの理由による。As general methods for producing carbides, the following methods are known: 1) In-phase reaction between metal powder and carbon, 2) Solid phase or gas phase reaction between metal powder and carbon, 2) Menstrum process, and 4) Reaction between halides and hydrocarbons. However, these conventional methods
For example, in method (2) above, mechanical pulverization is performed in order to cause the reaction to occur at high temperatures, but it is difficult to pulverize to a size of 1 μl or less without contaminating harmful impurities.
that the particle size of the synthetic powder depends on the size of the solid carbon;
There are also problems such as the unavoidable contamination of impurities from solid carbon. However, WC, which is the main raw material for cemented carbide, is most commonly produced by this method. This is because the particle size of the WC synthetic powder is easy to adjust and the bonded carbon content is high.

■の方法は、例えば、Ｗメタル粉末とＣｌ−１＋ガスの
反応によりＷＣ粉末を合成する場合に一部用いられるが
、炭化速度が遅いことに加え金属粉末の粒子の大きさに
よって合成粉の粒度が決定されるという欠点があった。Method (2) is partially used, for example, when WC powder is synthesized by the reaction of W metal powder and Cl-1+ gas, but in addition to the slow carbonization rate, the particle size of the synthesized powder depends on the size of the metal powder particles. The disadvantage was that the

■の方法は高温で反応されることが必要なため、得られ
る粒子は１００μｍ前後の粗粒単結晶となり、微細な粉
末を得ることは困難である。また、■の方法では数百オ
ングストロームの微細で高純度の粉末が得られる。しか
し実用超硬合金用の原料には０．１〜１０μｍ程度の粒
度が好ましく、数面Ａンクストロームの粉末は工業上の
メリットが少ない。Since the method (2) requires the reaction to be carried out at high temperatures, the resulting particles are coarse single crystals of around 100 μm, making it difficult to obtain fine powder. Further, in the method (2), a fine and highly pure powder of several hundred angstroms can be obtained. However, as a raw material for practical cemented carbide, a particle size of about 0.1 to 10 μm is preferable, and powder with several A Angstrom faces has little industrial merit.

本発明は上記従来技術の欠点を解消し、量産性に優れ、
しかも１．０μｍ以下の微粒子を得る新しい製造方法を
提供することを目的と覆る。The present invention eliminates the drawbacks of the above-mentioned prior art, has excellent mass productivity,
Moreover, the aim is to provide a new manufacturing method for obtaining fine particles of 1.0 μm or less.

本発明は上記目的を達成するために、急冷酸化物粉末を
還元と同時に炭化雰囲気中で処理して、微粒の粉末を得
る方法で、特に気相と反応させる場合にプラズマ状態下
で処理することにより活性化し微粒の粉末を合成すると
いう新規な方法である。In order to achieve the above object, the present invention is a method for obtaining fine powder by treating rapidly cooled oxide powder in a carbonizing atmosphere at the same time as reduction, and in particular, when reacting with a gas phase, the treatment is performed under plasma conditions. This is a novel method of activating and synthesizing fine powder.

本発明において、ＷＣ３よりＷＣを合成する場合には、
還元性ガスとしてＨ２を用いることが好ましく、また炭
化ガスとしてはＣｌ−１４が望ましい。In the present invention, when synthesizing WC from WC3,
It is preferable to use H2 as the reducing gas, and Cl-14 is preferable as the carbonizing gas.

また、Ｈ２とＣＨ４の混合比が１／１０〜１００／１の
範囲であれば、十分好ましい合成粉末が得られる。Ｈ２
／　ＣＨ４＜　１／　１０では十分な還元反応が進行せ
ず、またＨ２／ＣＨ４〉　１００／１では逆に炭化速度
が遅くなり工業的に好ましくない。Moreover, if the mixing ratio of H2 and CH4 is in the range of 1/10 to 100/1, a sufficiently preferable synthetic powder can be obtained. H2
/CH4<1/10, the reduction reaction does not proceed sufficiently, and H2/CH4>100/1, on the contrary, the carbonization rate becomes slow, which is not preferred industrially.

また、本発明において、プラズマ化する場合にハ０．１
〜２０１ｏｒ＋・の減圧とづることが必要である。In addition, in the present invention, when converting into plasma, H is 0.1
It is necessary to reduce the pressure to ~201 or+.

この圧力範囲外ではプラズマの発生が困難だからである
。また、合成温度は８００℃以上が必要であり、８００
℃未満ではｊＷ元が十分進行しない。This is because it is difficult to generate plasma outside this pressure range. In addition, the synthesis temperature needs to be 800°C or higher;
If the temperature is less than 0.degree. C., the jW element will not proceed sufficiently.

本発明による方法は、すべて同相−気相反応に基づくた
め、非常に純度の高いものが得られる利点がある。また
、）Ｗ元−炭化のための混合カスをプラズマ状態として
反応に寄与させた場合、従来法に比べて、炭化反応が非
常に促進されることがわかった。このため合成温度を低
下させること、合成粉末の炭素結合率を大きくすること
が容易であること、その結果として均質な、かつ粒度の
細かい粉末の製造が可能となることなどのメリットがあ
ることが確認できた。Since the method according to the invention is entirely based on in-phase-gas-phase reactions, it has the advantage of obtaining very high purity. Furthermore, it has been found that the carbonization reaction is greatly accelerated compared to the conventional method when the W element-carbonization mixture is made to contribute to the reaction in a plasma state. Therefore, it is easy to lower the synthesis temperature, increase the carbon bonding rate of the synthesized powder, and as a result, it is possible to produce homogeneous and fine-grained powder. It could be confirmed.

また、ＷＯ３を冷却速度１０４℃／秒以上で冷却したの
らＷＣを前述の方法で合成した場合、市販のＷＯ３粉末
を炭化する場合に比べて気相との反応が極めて活性化す
る利点がある。これは、おそらくは急冷することにより
蓄えられた多量の歪エネルギーが気相との反応に寄与す
るためと考えられる。ともあれ、急冷Ｗ０３を用いると
、従来困難とされていた微粒のＷＣが容易に製造可能と
なる。さらに反応雰囲気をプラズマ化すると、反応はよ
り活性化し平均粒度０．１μｍ程度のものまで製造可能
どなる。Furthermore, when WC is synthesized by the method described above after cooling WO3 at a cooling rate of 104°C/sec or more, there is an advantage that the reaction with the gas phase becomes extremely active compared to when carbonizing commercially available WO3 powder. . This is probably because a large amount of strain energy stored by rapid cooling contributes to the reaction with the gas phase. In any case, by using quenched W03, it becomes possible to easily produce fine WC, which has been considered difficult in the past. Furthermore, when the reaction atmosphere is turned into plasma, the reaction becomes more active and particles with an average particle size of about 0.1 μm can be produced.

また、本発明において、ＷＯ３の冷却速度を１０℃／秒
より遅くすると、蓄えられる歪エネルギーが小さく上述
の効果が少ない。Further, in the present invention, if the cooling rate of WO3 is lower than 10° C./sec, the strain energy stored is small and the above-mentioned effect is less.

以下、本発明を実施例により詳細に説明する。Hereinafter, the present invention will be explained in detail with reference to Examples.

実施例１ 先端をノズル状にしぼった石英管にＷＯ３粉末を入れ、
これを１４８０℃に昇温しＩζ炉内に入れて５分間保持
したのち、急速“に下方炉外に移動ざし同時に前記石英
管内に２．５Ｋ（］　／ｃｍ　　のＡｒガスを導入して
溶融ＷＯ３を石英管先端部より噴出させた。石英管先端
部の直下２ｍｍには、予め周速３０ｍ／　ｓｅｃで回転
する外形３００ｍｍの銅製回転冷却体の最上部を位置さ
せ、噴出ＷＯ３をこの回転体に衝突させることにより急
冷し、薄片状のＷＯ３を得た。次に、この薄片状急冷Ｗ
Ｏ３をカーボン容器に入れＨ２／ＣＨ，＝　１／１の混
合ガス雰囲気内に設置した。このときの圧力は１０Ｔｏ
ｒｒであった。次に外部より高周波加熱を行ない、該カ
ーボン容器を８００℃に加熱すると同時にＨ２／ｃＨ４
混合ガスをプラズマ化した。この状態で１時間保持し還
元および炭化反応を十分に促進させた後、高周波加熱を
終了した。冷却後合成粉末を取出した。Example 1 WO3 powder was put into a quartz tube with a nozzle-shaped tip,
After raising the temperature to 1480°C, placing it in the Iζ furnace and holding it for 5 minutes, it was rapidly moved downward to the outside of the furnace, and at the same time, Ar gas of 2.5 K (] /cm 2 was introduced into the quartz tube to melt WO3. was ejected from the tip of the quartz tube.The top of a copper rotary cooling body with an outer diameter of 300 mm that rotates at a circumferential speed of 30 m/sec was placed in advance 2 mm directly below the tip of the quartz tube, and the ejected WO3 was injected into this rotating body. It was quenched by collision to obtain flaky WO3.Next, this flaky quenched W
O3 was placed in a carbon container and placed in a mixed gas atmosphere of H2/CH, = 1/1. The pressure at this time is 10To
It was rr. Next, high frequency heating is applied from the outside to heat the carbon container to 800°C and at the same time H2/cH4
The mixed gas was turned into plasma. After maintaining this state for 1 hour to sufficiently promote the reduction and carbonization reactions, the high frequency heating was terminated. After cooling, the synthetic powder was taken out.

この合成粉末は、Ｘ線回折によりＷＣであることが確認
できた。またＣ分析の結果、結合Ｃ量が６．１３重量％
であることを、Ｓ　Ｅ　Ｍ　（Ｓ　ｃａｎｎｉｎｇＥ　
１ｅｃｔｒｏｎ　　Ｍ　１ｃｒｏｓｃｏｐｅ　）で、平
均粒度が０．１μｍであることをそれぞれ確認できた。This synthetic powder was confirmed to be WC by X-ray diffraction. Furthermore, as a result of C analysis, the amount of bound C was 6.13% by weight.
That is, S E M (S canningE
It was confirmed that the average particle size of each sample was 0.1 μm using a micrometer (1ectron M1croscope).

さらに、Ｉ　ＣＰ　（［ｎｄｕｃｔｉｖｅｌｙ　　　Ｃ
ｏｕｐｌｅｄＰ　Ｉａｓｍａ　　３　ｐｅｃｔｒｏｐｂ
ｏｔｏｍｅｔｅｒ）を用い、微量分析を市販ＷＣと比較
して行った。Furthermore, I CP ([nductively C
oupledP Iasma 3 pectropb
Microanalysis was performed using a commercially available WC.

第１表にその測定結果の一部を示す。Table 1 shows some of the measurement results.

第１表 このように、気相反応により合成したＷＣは極めて純度
が高いことがわかる。特に、超硬合金の原料として用い
た場合に、多大の悪影響を及ばツＳは本発明によるＷＣ
では極めて含有量が少ないことは注目すべき効果である
。As shown in Table 1, it can be seen that WC synthesized by gas phase reaction has extremely high purity. In particular, when used as a raw material for cemented carbide, the WC according to the present invention may have a significant adverse effect.
The extremely low content is a noteworthy effect.

このように、急冷したＷＯ３をＨとＣを含む混合ガス雰
囲気下におき、外部より電気エネルギーを印加してプラ
ズマ状態とし、炭化させる本発明方法は、微細でかつ不
純物が極めて少ないＷＣ粉末を得ることができるため、
その工業上の効果は大である。As described above, the method of the present invention, in which rapidly cooled WO3 is placed in a mixed gas atmosphere containing H and C, and electrical energy is applied from the outside to bring it into a plasma state and carbonize it, obtains fine WC powder with extremely low impurities. Because you can
Its industrial effects are great.

Claims (1)

【特許請求の範囲】[Claims] 溶融ＷＯ，を冷却体に噴射して冷却速度１０　　°Ｃ／
秒以上で急冷したのち、この急冷ＷＯｊをＨ２とＣＩ−
１４の混合比が１／１０〜１００／　１の混合ガスに外
部より電気エネルギーを加えてプラズマ化した０、１〜
２０Ｔ　Ｏｒｒの減圧雰囲気下において、８００℃以上
に加熱することを特徴とするＷＣ粉末の製造方法。Molten WO was injected into the cooling body at a cooling rate of 10 °C/
After quenching for more than a second, this quenched WOj is mixed with H2 and CI-
0, 1 to 14, which are made into plasma by applying electrical energy from the outside to a mixed gas with a mixing ratio of 1/10 to 100/1.
A method for producing WC powder, which comprises heating to 800°C or higher in a reduced pressure atmosphere of 20T Orr.