JP2002220601A - Production method for low oxygen spherical metal powder using dc thermal plasma processing - Google Patents
Production method for low oxygen spherical metal powder using dc thermal plasma processingInfo
- Publication number
- JP2002220601A JP2002220601A JP2001019722A JP2001019722A JP2002220601A JP 2002220601 A JP2002220601 A JP 2002220601A JP 2001019722 A JP2001019722 A JP 2001019722A JP 2001019722 A JP2001019722 A JP 2001019722A JP 2002220601 A JP2002220601 A JP 2002220601A
- Authority
- JP
- Japan
- Prior art keywords
- metal powder
- thermal plasma
- oxygen
- gas
- ppm
- 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.)
- Pending
Links
- 239000000843 powder Substances 0.000 title claims abstract description 112
- 229910052751 metal Inorganic materials 0.000 title claims abstract description 85
- 239000002184 metal Substances 0.000 title claims abstract description 85
- 239000001301 oxygen Substances 0.000 title claims abstract description 59
- 229910052760 oxygen Inorganic materials 0.000 title claims abstract description 59
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 title claims abstract description 48
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 27
- 238000012545 processing Methods 0.000 title abstract description 11
- 239000007789 gas Substances 0.000 claims abstract description 39
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 21
- 239000001257 hydrogen Substances 0.000 claims abstract description 14
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 14
- 239000002994 raw material Substances 0.000 claims abstract description 9
- 239000011261 inert gas Substances 0.000 claims abstract description 8
- 238000002844 melting Methods 0.000 claims abstract description 8
- 230000008018 melting Effects 0.000 claims abstract description 8
- 238000000034 method Methods 0.000 claims description 24
- 238000009832 plasma treatment Methods 0.000 claims description 18
- 230000000717 retained effect Effects 0.000 abstract 1
- 230000000694 effects Effects 0.000 description 6
- 230000001603 reducing effect Effects 0.000 description 5
- 238000000227 grinding Methods 0.000 description 3
- 238000009776 industrial production Methods 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 238000007664 blowing Methods 0.000 description 2
- 238000004817 gas chromatography Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000002105 nanoparticle Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- 238000004737 colorimetric analysis Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000005674 electromagnetic induction Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052762 osmium Inorganic materials 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 1
- -1 platinum group metals Chemical class 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- 238000007751 thermal spraying Methods 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、熱プラズマ処理に
よる低酸素球状金属粉末の製造方法に関し、主としてＤ
Ｃ熱プラズマを用いた金属粉末の球状化に関するもので
ある。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a low-oxygen spherical metal powder by a thermal plasma treatment, and mainly relates to a method for producing a D-shaped metal powder.
The present invention relates to spheroidization of metal powder using C thermal plasma.
【０００２】[0002]
【従来の技術】熱プラズマ中に金属粉末を投入、通過さ
せることによって、その表面張力により金属粉末を球状
化する技術は広く知られている。これは、真空ないしは
雰囲気保持の可能なタンク内に発生させたプラズマ中に
原料金属粉末を投入、通過させ、その原料金属粉末が飛
行している短時間のうちに溶融、球状化、凝固させて、
堆積した金属粉末を回収するという製造技術である。本
技術に関して、例えば特開昭６３−４５３０９、特開昭
６３−２４３２１１、特開昭６３−２４３２１２などの
手段が提案されている。2. Description of the Related Art There is widely known a technique in which a metal powder is injected into and passed through a thermal plasma to make the metal powder spheroidized by its surface tension. In this method, the raw metal powder is put into and passed through a plasma generated in a tank capable of holding a vacuum or an atmosphere, and the raw metal powder is melted, spheroidized, and solidified in a short time while the raw metal powder is flying. ,
This is a manufacturing technique for collecting deposited metal powder. For this technique, for example, means such as JP-A-63-45309, JP-A-63-243211, and JP-A-63-243212 have been proposed.
【０００３】一例の概略を図１に示す。原料金属粉末
は、給粉機１から給粉パイプ２を通じてプラズマガン３
に給粉される。そして、その原料金属粉末をプラズマ火
炎４に吹き込むことによって、溶融しながら飛行、プラ
ズマ火炎を外れた時点で凝固し、軌跡５を描いて回収ボ
ックス６内に球状金属粉末７として堆積する。この際、
タンク８によって大気と遮断されているため、粉末の酸
化は抑えられる。FIG. 1 schematically shows an example. The raw metal powder is supplied from a powder feeder 1 to a plasma gun 3 through a feed pipe 2.
Is fed. By blowing the raw metal powder into the plasma flame 4, it flies while melting, solidifies at the point when the plasma flame is released, and deposits as a spherical metal powder 7 in the collection box 6 along a trajectory 5. On this occasion,
Since it is isolated from the atmosphere by the tank 8, the oxidation of the powder is suppressed.
【０００４】プラズマの発生方法は、高周波電源を使用
するＲＦ法と、直流電源を使用するＤＣ法の二種類が知
られている。そして、どちらの方法もプラズマ動作ガス
には、Ａｒなどの不活性ガス、水素などの還元性ガスが
使用される。[0004] Two types of plasma generation methods are known: an RF method using a high-frequency power supply and a DC method using a DC power supply. In both methods, an inert gas such as Ar or a reducing gas such as hydrogen is used as a plasma operating gas.
【０００５】ＲＦ法は、コイルからの電磁誘導によって
加熱するために、電極が不要であり、そして、ガスの流
速が遅く、ガス使用量も少ない。更に、プラズマ発生領
域の上部に別段の加熱機器を設置する必要が無いため、
原料金属粉末の投入が容易である。また、プラズマ火炎
がコイル内部全体で発生するために、局所的な高温部位
が発生し難いという特徴を持つ。反面、電源効率が低
く、電源を大型化し難いという課題がある。In the RF method, since heating is performed by electromagnetic induction from a coil, no electrode is required, and the gas flow rate is low and the amount of gas used is small. Furthermore, since there is no need to install a separate heating device above the plasma generation area,
It is easy to feed the raw metal powder. Further, since the plasma flame is generated in the entire inside of the coil, there is a feature that a local high-temperature portion is hardly generated. On the other hand, there is a problem that power supply efficiency is low and it is difficult to increase the size of the power supply.
【０００６】これに対して、ＤＣ法は電極の消耗、プラ
ズマ温度分布の不均一といった課題があるも、電源効率
に優れ、装置の大型化が可能であるという利点を持つこ
とから、工業的量産の上で有利な方法である。[0006] On the other hand, the DC method has problems such as exhaustion of electrodes and non-uniform plasma temperature distribution, but has the advantages of excellent power supply efficiency and the possibility of increasing the size of the apparatus. This is an advantageous method.
【０００７】[0007]
【発明が解決しようとする課題】ＤＣ法での熱プラズマ
処理は、球状金属粉末の量産製造の上で有効である。し
かし、ＤＣ法で発生させたプラズマは、プラズマガンか
ら遷音速〜超音速の速度で吹き出しており、その中心部
が最も高温で、１００００℃以上にも達する。つまり、
ガス流速が極めて速いために、粉末表面における熱伝達
係数が大きく、かつ、極めて高温な領域を通過するため
に、原料金属粉末が過熱し、その一部が蒸発してしま
う。蒸発した原料金属は、比較的低温な領域で処理後の
粉末表面に再凝縮し、ナノサイズの超微粉を発生する
が、この超微粉は表面エネルギーが極めて高いために、
大気（空気）中へ取り出した時点で容易に酸化され、金
属粉末の酸素量を増大させるという問題がある。The thermal plasma treatment by the DC method is effective in mass-producing spherical metal powder. However, the plasma generated by the DC method is blown out of the plasma gun at a transonic speed to a supersonic speed, and its central portion has the highest temperature and reaches 10,000 ° C. or more. That is,
Since the gas flow velocity is extremely high, the heat transfer coefficient on the powder surface is large, and the powder passes through a region of extremely high temperature, so that the raw metal powder is overheated and a part thereof is evaporated. The evaporated raw metal re-condenses on the powder surface after processing in a relatively low temperature region and generates nano-sized ultrafine powder, but since this ultrafine powder has extremely high surface energy,
There is a problem in that it is easily oxidized when taken out into the atmosphere (air), thereby increasing the amount of oxygen in the metal powder.
【０００８】さらに、要求される金属粉末の酸素量が１
０００ｐｐｍオーダー以下になってくると、プラズマ動
作ガス自体からの酸素持ち込みも問題となる。この問題
を防止するために、還元力の強い水素ガスを混合して用
いることもあるが、水素ガスは分子解離するエンタルピ
ーが必要であるため、安易な混合は不可避的に投入電力
の増加を招き、電極消耗の加速、プラズマ温度の上昇と
いった問題を引き起こす。Further, the required amount of oxygen in the metal powder is 1
When the concentration becomes lower than the order of 000 ppm, the incorporation of oxygen from the plasma operating gas itself becomes a problem. In order to prevent this problem, hydrogen gas with a strong reducing power may be mixed and used.However, since hydrogen gas needs enthalpy for molecular dissociation, easy mixing inevitably leads to an increase in input power. This causes problems such as accelerated electrode consumption and an increase in plasma temperature.
【０００９】ＲＦ法の場合には、電極が無いために、電
極消耗の問題は無い。また、ガス流速が遅いために、熱
伝達係数が比較的小さく、局所的な高温領域も発生しに
くいために、超微粉があまり発生しない。したがって、
ＲＦ法では比較的容易に実現できる１０００ｐｐｍ以下
の低酸素金属粉末処理であるが、ＤＣ法では極めて困難
な状態である。それであっても、溶射ガンや溶接用途と
して実績があり、大型化が可能なＤＣ法が工業的な生産
には好適であるため、ＤＣ法による球状金属粉末の製造
方法の抱える問題点を検討・解決する必要がある。In the case of the RF method, since there is no electrode, there is no problem of electrode consumption. In addition, since the gas flow rate is low, the heat transfer coefficient is relatively small, and a local high-temperature region is not easily generated, so that very little fine powder is generated. Therefore,
The RF method is a low-oxygen metal powder treatment of 1000 ppm or less which can be relatively easily realized, but the DC method is extremely difficult. Even so, the DC method, which has a proven track record in thermal spraying guns and welding applications, and is capable of upsizing is suitable for industrial production. Need to be resolved.
【００１０】そこで、本発明は、ＤＣ熱プラズマ処理に
よる酸素量１０００ｐｐｍ以下の低酸素球状金属粉末の
製造方法を提供することを目的とする。Accordingly, an object of the present invention is to provide a method for producing a low-oxygen spherical metal powder having an oxygen content of 1000 ppm or less by DC thermal plasma treatment.
【００１１】本発明者は、ＤＣ法による熱プラズマ処理
に適用される各種条件について、その金属粉末の低酸素
化に与える影響を調査した。その結果、使用されるプラ
ズマ動作ガス、そして処理温度の影響が大きいことを突
きとめ、その最適条件を見いだすことで、本発明に到達
した。The present inventors investigated the effects of various conditions applied to the thermal plasma treatment by the DC method on the reduction of oxygen in the metal powder. As a result, the present inventors have found that the influence of the used plasma operating gas and the processing temperature is great, and have found the optimum conditions, thereby achieving the present invention.
【００１２】すなわち、本発明の第１の発明は、直流電
源の使用にて発生させたＤＣ熱プラズマ中に原料金属粉
末を通過させて処理する、酸素量が１０００ｐｐｍ以下
の球状金属粉末の製造方法であって、そのプラズマ動作
ガスに純度９９．９ｖｏｌ％以上の不活性ガスと純度９
９．９ｖｏｌ％以上の水素ガスの混合ガスを用い、かつ
その混合ガスの水素量を０．５〜２０ｖｏｌ％とするこ
とを特徴とするＤＣ熱プラズマ処理による低酸素球状金
属粉末の製造方法である。That is, the first invention of the present invention is a method for producing a spherical metal powder having an oxygen content of 1000 ppm or less, in which a raw metal powder is passed through a DC thermal plasma generated by using a DC power supply for treatment. And an inert gas having a purity of 99.9 vol% or more and a purity of 9
A method for producing a low-oxygen spherical metal powder by DC thermal plasma treatment, wherein a mixed gas of hydrogen gas of 9.9 vol% or more is used and the hydrogen amount of the mixed gas is 0.5 to 20 vol%. .
【００１３】さらに、本発明の第２の発明は、直流電源
の使用にて発生させたＤＣ熱プラズマ中に原料金属粉末
を通過させて処理する、酸素量が１０００ｐｐｍ以下の
球状金属粉末の製造方法であって、原料金属粉末の通過
するＤＣ熱プラズマ領域の最高温度を原料金属粉末の融
点以上、１００００℃以下とすることを特徴とするＤＣ
熱プラズマ処理による低酸素球状金属粉末の製造方法で
ある。Further, a second invention of the present invention is a method for producing a spherical metal powder having an oxygen content of 1000 ppm or less, in which a raw metal powder is passed through a DC thermal plasma generated by using a DC power supply and treated. Wherein the maximum temperature of the DC thermal plasma region through which the raw metal powder passes is set to not less than the melting point of the raw metal powder and not more than 10,000 ° C.
This is a method for producing low oxygen spherical metal powder by thermal plasma treatment.
【００１４】加えて、上記第１の発明と第２の発明を組
み合わせることを特徴とするＤＣ熱プラズマ処理による
低酸素球状金属粉末の製造方法である。そして、これら
本発明について、具体的には、原料金属粉末の酸素量を
１０００ｐｐｍ以下とする。In addition, there is provided a method for producing a low-oxygen spherical metal powder by DC thermal plasma treatment, which is a combination of the first and second aspects. In the present invention, specifically, the oxygen content of the raw metal powder is set to 1000 ppm or less.
【００１５】[0015]
【発明の実施の形態】本発明の特徴は、工業生産の上で
有利なＤＣ法による熱プラズマ処理（以下、ＤＣ熱プラ
ズマ処理とも言う）に重点を置いて、それによる酸素量
１０００ｐｐｍ以下の球状金属粉末を達成し得るに必要
な条件を明確化したところにある。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The feature of the present invention is to focus on a thermal plasma treatment by a DC method (hereinafter, also referred to as a DC thermal plasma treatment) which is advantageous in industrial production, and a spherical shape having an oxygen content of 1000 ppm or less. The conditions necessary for achieving a metal powder have been clarified.
【００１６】上述の通り、ＤＣ熱プラズマ処理による低
酸素球状金属粉末の製造にてその酸素量の増加の原因
は、処理系内への酸素の持ち込みと、超微粉が発生する
ことにある。そこで、この二点について対策を検討し
た。As described above, the cause of the increase in the amount of oxygen in the production of low-oxygen spherical metal powder by DC thermal plasma treatment is due to the introduction of oxygen into the treatment system and the generation of ultrafine powder. Therefore, measures were considered for these two points.
【００１７】まず、処理系内への酸素の持ち込み抑制に
ついて述べる。タンク（処理系）内に残存する酸素を減
少させるためには、まずタンクの気密性を高め、そして
ポンプ容量を大きくして、到達真空度を上げることが好
ましい。この場合、容器サイズもあって、通常は０．１
〜１０Ｐａ程度となる。そして、不活性ガス置換、水素
プラズマの空吹きなどで残存酸素量を更に低減すること
が望ましい。しかし、これらの対策だけでは、処理後の
金属粉末の酸素量は低下するものの、その１０００ｐｐ
ｍ以下にまで引き下げることは困難である。First, the suppression of the introduction of oxygen into the processing system will be described. In order to reduce the oxygen remaining in the tank (processing system), it is preferable to first increase the airtightness of the tank, increase the pump capacity, and increase the ultimate vacuum. In this case, there is also a container size, usually 0.1
It becomes about 10 Pa. Then, it is desirable to further reduce the residual oxygen amount by inert gas replacement, hydrogen plasma blowing, or the like. However, with these measures alone, although the amount of oxygen in the metal powder after treatment decreases, the amount
It is difficult to reduce it below m.
【００１８】そこで、本発明者は、プラズマの発生に使
用するプラズマ動作ガスの調整に注視して、その諸条件
による実験・検討を行なった。その結果、使用する動作
ガスに純度９９．９ｖｏｌ％以上に高めた不活性ガスと
水素ガスの混合ガスを適用し、かつその混合ガスに含ま
れる水素の添加量を０．５〜２０ｖｏｌ％に調整するこ
とで、その製造される球状金属粉末の酸素含有量を１０
００ｐｐｍ以下に低減でき得ることを見いだした。Therefore, the present inventor paid attention to the adjustment of the plasma operating gas used for generating the plasma, and conducted experiments and studies under various conditions. As a result, a mixed gas of an inert gas and a hydrogen gas whose purity has been increased to 99.9 vol% or more is applied to the working gas to be used, and the amount of hydrogen contained in the mixed gas is adjusted to 0.5 to 20 vol%. By doing so, the oxygen content of the produced spherical metal powder is reduced to 10
It has been found that it can be reduced to not more than 00 ppm.
【００１９】具体的には、本発明の第１発明として、直
流電源の使用にて発生させたＤＣ熱プラズマ中に原料金
属粉末を通過させて処理する、酸素量が１０００ｐｐｍ
以下の球状金属粉末の製造方法であって、そのプラズマ
動作ガスに純度９９．９ｖｏｌ％以上の不活性ガスと純
度９９．９ｖｏｌ％以上の水素ガスの混合ガスを用い、
かつその混合ガスの水素量を０．５〜２０ｖｏｌ％とす
るＤＣ熱プラズマ処理による低酸素球状金属粉末の製造
方法である。Specifically, as the first invention of the present invention, the raw material metal powder is passed through a DC thermal plasma generated by using a DC power supply for treatment, and the oxygen content is 1000 ppm.
A method for producing a spherical metal powder as described below, wherein a mixed gas of an inert gas having a purity of 99.9 vol% or more and a hydrogen gas having a purity of 99.9 vol% or more is used as the plasma operating gas,
In addition, this is a method for producing low oxygen spherical metal powder by DC thermal plasma treatment in which the hydrogen content of the mixed gas is 0.5 to 20 vol%.
【００２０】まず、本発明に使用するプラズマ動作ガス
には、Ａｒといった不活性ガスに、還元性付与のための
水素を混合したものを使用する。これにおいて、ガスの
純度が９９．９ｖｏｌ％を切ると、原料金属粉末の含有
し得る酸素量に対するガス中の酸素量が過剰になり、金
属粉末の酸化が激しくなる。ガス純度は高い方が無論望
ましいが、コストとの関係から、９９．９〜９９．９９
９９ｖｏｌ％程度の範囲の精製度で充分である。この
際、ガスに含まれる不純物については酸素量だけではな
く、酸素源となり得る物質、例えば水、二酸化炭素など
の量を低く抑えることも重要である。First, an inert gas such as Ar mixed with hydrogen for imparting a reducing property is used as the plasma operating gas used in the present invention. In this case, when the purity of the gas falls below 99.9 vol%, the amount of oxygen in the gas becomes excessive with respect to the amount of oxygen that can be contained in the raw metal powder, and the oxidation of the metal powder becomes severe. Higher gas purity is of course desirable, but from the viewpoint of cost, it is 99.9 to 99.99.
A degree of purification in the range of about 99 vol% is sufficient. At this time, it is important to reduce not only the amount of oxygen contained in the gas but also the amount of substances that can be an oxygen source, for example, water and carbon dioxide.
【００２１】そして、本発明にて重要となるのが、上記
混合したガス中に占める水素量である。これが０．５ｖ
ｏｌ％を下回ると、水素混合による還元力効果が不足す
る。しかし、２０ｖｏｌ％上回ると、プラズマ温度が上
がり過ぎるため、上述したナノサイズの超微粉の発生助
長、最終的には処理後の球状金属粉末の酸素量増大につ
ながる。よって、本発明では、その混合ガスの水素量を
０．５〜２０ｖｏｌ％とすることが適正である。なお、
本発明におけるガス純度の測定方法としては、例えばガ
スクロマトグラフィなどで分析すればよい。水素添加量
については、流量計で調整することができる。What is important in the present invention is the amount of hydrogen occupying in the mixed gas. This is 0.5v
When the amount is less than ol%, the reducing power effect by the hydrogen mixing becomes insufficient. However, if it exceeds 20 vol%, the plasma temperature will be too high, which will lead to the generation of the above-mentioned nano-sized ultrafine powder and ultimately an increase in the oxygen content of the spherical metal powder after the treatment. Therefore, in the present invention, it is appropriate to set the hydrogen content of the mixed gas to 0.5 to 20 vol%. In addition,
As a method for measuring gas purity in the present invention, for example, analysis may be performed by gas chromatography or the like. The amount of hydrogen added can be adjusted with a flow meter.
【００２２】次に、超微粉の発生抑制について述べる。
上記提案した本発明の第１の発明は、酸素量１０００ｐ
ｐｍ以下の球状金属粉末を得るに効果を有するが、ＤＣ
法による、特に処理開始直後の多量の超微粉発生を抑制
する手段も低酸素球状金属粉末の達成に有効となる。上
記発生した多量の超微粉は、粉末表面や容器壁などに付
着する。特に容器壁に付着した粉末は、これが処理後の
金属粉末に混入すると、酸素量が再度上昇する大きな原
因となる。この場合、トータルの処理粉末量を増やすこ
とで、混入する超微粉の比率を実質的に問題無いレベル
まで薄めることは可能であるが、本質的な解決方法では
ない。Next, suppression of generation of ultrafine powder will be described.
The first invention of the invention proposed above has an oxygen content of 1000 p
pm or less, but has the effect of
Means for suppressing the generation of a large amount of ultrafine powder by the method, particularly immediately after the start of the treatment, is also effective for achieving a low-oxygen spherical metal powder. The generated large amount of ultrafine powder adheres to the powder surface, the container wall, and the like. In particular, if the powder adhering to the container wall mixes with the treated metal powder, it causes a large increase in the amount of oxygen again. In this case, by increasing the total amount of the treated powder, it is possible to reduce the ratio of the ultrafine powder to be mixed to a level at which there is substantially no problem, but this is not an essential solution.
【００２３】まず、超微粉の発生原因について調査した
ところ、投入した原料金属粉末がプラズマ火炎中心部の
１００００℃を越える高温部分を通過する際に、超微粉
が著しく発生することを明らかにした。そこで、原料金
属粉末がこのような高温のプラズマ火炎部分を通過しな
いよう制御すれば、超微粉の発生を抑制できる。First, when the cause of the generation of the ultrafine powder was investigated, it was found that the ultrafine powder was remarkably generated when the charged raw material metal powder passed through a high temperature portion exceeding 10,000 ° C. in the center of the plasma flame. Therefore, by controlling the raw metal powder so as not to pass through such a high-temperature plasma flame portion, the generation of ultrafine powder can be suppressed.
【００２４】具体的には、本発明の第２の発明として、
直流電源の使用にて発生させたＤＣ熱プラズマ中に原料
金属粉末を通過させて処理する、酸素量が１０００ｐｐ
ｍ以下の球状金属粉末の製造方法であって、原料金属粉
末の通過するＤＣ熱プラズマ領域の最高温度を原料金属
粉末の融点以上、１００００℃以下とするＤＣ熱プラズ
マ処理による低酸素球状金属粉末の製造方法である。Specifically, as a second invention of the present invention,
The raw material metal powder is passed through a DC thermal plasma generated by using a DC power supply for processing.
m or less, wherein the maximum temperature of the DC thermal plasma region through which the raw metal powder passes is from the melting point of the raw metal powder to 10,000 ° C. or less. It is a manufacturing method.
【００２５】なお、原料金属粉末がプラズマの高温部分
を通過しないようにするには、その投入方法（位置、角
度）を変更すれば良い。この他にも、原料金属粉末搬送
用のキャリアガスやプラズマ動作ガスの流量を増やす、
投入電力を下げる、タンク内圧を下げる、プラズマ動作
ガス中の水素量を可能な限り少なくする等の方法もプラ
ズマ温度を低下させるのに有効である。In order to prevent the raw metal powder from passing through the high-temperature portion of the plasma, the charging method (position and angle) may be changed. In addition, the flow rate of the carrier gas for transporting the raw metal powder and the plasma operating gas is increased,
Methods such as lowering the input power, lowering the tank internal pressure, and reducing the amount of hydrogen in the plasma operating gas as much as possible are also effective in lowering the plasma temperature.
【００２６】また、プラズマ動作ガスの流量は、投入電
力との比で決まる。ガス／電力比は、少なくとも１（Ｎ
Ｌ／ｋＷ・ｍｉｎ）以上、望ましくは２（ＮＬ／ｋＷ・
ｍｉｎ）以上が良い。但し、高すぎると未処理金属粉末
が出来るため、高くても１０（ＮＬ／ｋＷ・ｍｉｎ）程
度が上限となる。なお、ここで挙げたガス／電力比の上
下限は、処理する金属粉末の融点、沸点をも考慮して決
定することが望ましい。例えば、ステンレス粉末の球状
化処理の場合、５〜１０（ＮＬ／ｋＷ・ｍｉｎ）、Ｍｏ
粉末の球状化処理の場合、４〜８（ＮＬ／ｋＷ・ｍｉ
ｎ）がよい。Further, the flow rate of the plasma operating gas is determined by the ratio with the input power. The gas / power ratio should be at least 1 (N
L / kW · min) or more, preferably 2 (NL / kW · min)
min) or more is good. However, if it is too high, untreated metal powder is formed, so the upper limit is about 10 (NL / kW · min) at most. Note that the upper and lower limits of the gas / power ratio mentioned here are desirably determined in consideration of the melting point and boiling point of the metal powder to be treated. For example, in the case of spheroidizing stainless steel powder, 5 to 10 (NL / kW · min), Mo
In the case of powder spheroidizing treatment, 4 to 8 (NL / kW · mi
n) is preferred.
【００２７】処理中のタンク内圧は、６５０００Ｐａ以
下、望ましくは１００００Ｐａ以下とするのがよい。タ
ンク内圧はプラズマ温度や残存酸素の調整の面で低けれ
ば低いほど良いが、タンク内圧を下げると、プラズマ火
炎の長さが長くなり、粉末の壁面との衝突によって異形
粉が発生する原因となる。この意味からは、例えば１０
Ｐａ以上とすればよいが、これについてはタンク寸法、
ポンプ容量、ポンプ油寿命などとの兼ね合いで決定する
ことが望ましく、工業的実績も考慮すると、３０００Ｐ
ａ以上とするのが妥当である。The internal pressure of the tank during the treatment is preferably 65,000 Pa or less, more preferably 10,000 Pa or less. The lower the tank internal pressure, the better in terms of adjusting the plasma temperature and residual oxygen, but the lower the tank internal pressure, the longer the plasma flame becomes, causing irregular powder due to collision with the powder wall. . In this sense, for example, 10
Pa or more may be used, but for this, the tank size,
It is desirable to determine it in consideration of pump capacity, pump oil life, etc., and 3000P
It is appropriate to set it to a or more.
【００２８】なお、本発明の製造方法に供する原料金属
粉末であるが、その含有する酸素量は低ければ低いほど
望ましい。本発明の酸素量増加の抑制効果を発揮するた
めにも、１０００ｐｐｍ以下、さらには６００ｐｐｍ以
下としておくことが望ましい。The raw metal powder used in the production method of the present invention is preferably as low as possible in the amount of oxygen contained therein. In order to exhibit the effect of suppressing an increase in the amount of oxygen of the present invention, the content is desirably 1000 ppm or less, and more desirably 600 ppm or less.
【００２９】その他、本発明の製造方法に適用できる金
属粉末についても述べておくと、例えば上述したものに
加えて、種々の高融点金属（Ｗ，Ｔａなど）、白金族金
属（Ｐｔ，Ｉｒ，Ｒｕ，Ｏｓなど）、その他の金属（Ｆ
ｅ，Ｃｕ，Ｎｉ，Ａｇ）、およびこれらの合金等、あら
ゆる金属粉末が可能である。In addition, metal powders applicable to the production method of the present invention are also described. For example, in addition to those described above, various high melting point metals (W, Ta, etc.) and platinum group metals (Pt, Ir, Ru, Os, etc.) and other metals (F
e, Cu, Ni, Ag), and alloys thereof, and any metal powder is possible.
【００３０】[0030]
【実施例】本実施例に使用したＤＣ熱プラズマ処理装置
について、そのプラズマガン部分の概略形状を図２に示
す。図２中、９はアノード電極、１０は給粉リング（ノ
ズルガイド）、１１は給粉ポート、１２はカソード電極
を表している。図２（ａ）は本発明の製造方法を達成す
べく、そのノズルガイドを延長し、給粉位置をノズル出
口から５ｃｍの位置とし、プラズマ火炎中心の高温部分
を避けるような角度で給粉するものである。なお、図２
（ｂ）は従来型のプラズマガン部分である。FIG. 2 shows a schematic configuration of a plasma gun portion of a DC thermal plasma processing apparatus used in this embodiment. In FIG. 2, 9 is an anode electrode, 10 is a powder supply ring (nozzle guide), 11 is a powder supply port, and 12 is a cathode electrode. FIG. 2 (a) shows that, in order to achieve the manufacturing method of the present invention, the nozzle guide is extended, the powder supply position is set at a position 5 cm from the nozzle outlet, and powder is supplied at an angle that avoids the high temperature portion at the center of the plasma flame. Things. Note that FIG.
(B) is a conventional plasma gun part.
【００３１】これら仕様による装置を用いて、酸素量５
００ｐｐｍのＭｏ原料粉末（融点：２６１０℃）をＤＣ
熱プラズマ処理した。その処理後の球状金属粉末の酸素
量を、処理条件含め、表１にまとめる。なお、原料金属
粉末の供粉位置については、プラズマ火炎中心部を高温
部とし、その周辺を低温部として表記、その具体的温度
については分光測色法により算出した（高温部：１２０
００℃、低温部：６０００℃）。高温部への給粉はプラ
ズマガン（ｂ）にて、低温部への給粉はプラズマガン
（ａ）にて行なった。また、各ガス純度はガスクロマト
グラフィによって測定し、混合ガス中の水素量は流量計
にて調整した。処理に供した原料金属粉末は１ｋｇであ
り、その含有酸素量は、処理後の球状金属粉末も同様、
１０ｇのサンプリングを３回行なうことで測定した。単
位はｐｐｍ（質量比）である。Using an apparatus according to these specifications, an oxygen amount of 5
00 ppm Mo raw material powder (melting point: 2610 ° C.)
Thermal plasma treatment was performed. Table 1 summarizes the oxygen content of the spherical metal powder after the treatment, including the treatment conditions. In addition, as for the feeding position of the raw metal powder, the central portion of the plasma flame is described as a high-temperature portion, and the periphery thereof is described as a low-temperature portion. The specific temperature was calculated by a spectral colorimetric method (high-temperature portion: 120
00 ° C, low temperature part: 6000 ° C). Powdering to the high temperature part was performed by the plasma gun (b), and powdering to the low temperature part was performed by the plasma gun (a). The purity of each gas was measured by gas chromatography, and the amount of hydrogen in the mixed gas was adjusted with a flow meter. The raw metal powder subjected to the treatment is 1 kg, and the oxygen content thereof is the same as that of the spherical metal powder after the treatment.
The measurement was performed by sampling 10 g three times. The unit is ppm (mass ratio).
【００３２】[0032]
【表１】 [Table 1]
【００３３】表１より、本発明の混合ガスあるいは熱プ
ラズマ処理温度にて得られた球状金属粉末の酸素含有量
はいずれも１０００ｐｐｍ以下であって、本発明の酸素
量増加の抑制効果が得られているものである。特に、本
発明の混合ガスと熱プラズマ処理温度を満たすものは更
なる効果が達成されており、７００ｐｐｍ以下にまで酸
素量の増加を抑えている。中でも条件の好ましいもの
は、原料粉末とほぼ同等か、寧ろ低いレベルまで、酸素
量を低減することが出来る。From Table 1, it can be seen that the oxygen content of the spherical metal powder obtained at the mixed gas or thermal plasma treatment temperature of the present invention is not more than 1000 ppm, and the effect of suppressing the increase of the oxygen amount of the present invention can be obtained. Is what it is. In particular, those satisfying the mixed gas and the thermal plasma processing temperature of the present invention achieve further effects, and suppress the increase in the amount of oxygen to 700 ppm or less. Among them, preferred conditions are such that the oxygen amount can be reduced to a level substantially equal to or rather lower than that of the raw material powder.
【００３４】[0034]
【発明の効果】本発明によれば、ＤＣ熱プラズマ処理に
て酸素量の増加を抑えた金属粉末の球状化が達成でき、
具体的には酸素量１０００ｐｐｍ以下の低酸素球状金属
粉末を製造することが可能である。工業的生産にとって
欠くことのできない技術となり、本発明の価値は高い。According to the present invention, it is possible to achieve spheroidization of a metal powder in which an increase in the amount of oxygen is suppressed by DC thermal plasma treatment.
Specifically, it is possible to produce a low oxygen spherical metal powder having an oxygen content of 1000 ppm or less. The technology is indispensable for industrial production, and the value of the present invention is high.
【図１】熱プラズマ処理による球状金属粉末の製造装置
の一例を示す概略図である。FIG. 1 is a schematic view showing an example of an apparatus for producing spherical metal powder by thermal plasma processing.
【図２】本発明の実施例に使用したＤＣ熱プラズマ処理
装置のプラズマガン部分を示す概略図である。FIG. 2 is a schematic view showing a plasma gun part of a DC thermal plasma processing apparatus used in an embodiment of the present invention.
１．給粉機、２．給粉パイプ、３．プラズマガン、４．
プラズマ火炎、５．粉末の飛行軌跡、６．回収ボック
ス、７．球状金属粉末、８．タンク、９．アノード電
極、１０．給粉リング（ノズルガイド）、１１．給粉ポ
ート、１２．カソード電極1. Powdering machine, 2. 2. Feeding pipe, 3. Plasma gun,
4. Plasma flame; 5. flight trajectory of the powder; Collection box, 7. 7. spherical metal powder; Tank, 9. Anode electrode, 10. 10. Feeding ring (nozzle guide); Feeding port, 12. Cathode electrode
Claims (4)
ラズマ中に原料金属粉末を通過させて処理する、酸素量
が１０００ｐｐｍ以下の球状金属粉末の製造方法であっ
て、そのプラズマ動作ガスに純度９９．９ｖｏｌ％以上
の不活性ガスと純度９９．９ｖｏｌ％以上の水素ガスの
混合ガスを用い、かつその混合ガスの水素量を０．５〜
２０ｖｏｌ％とすることを特徴とするＤＣ熱プラズマ処
理による低酸素球状金属粉末の製造方法。1. A method for producing a spherical metal powder having an oxygen content of 1000 ppm or less, wherein a raw metal powder is passed through a DC thermal plasma generated by using a direct current power source for treatment. A mixed gas of an inert gas having a purity of 99.9 vol% or more and a hydrogen gas having a purity of 99.9 vol% or more is used, and the amount of hydrogen in the mixed gas is 0.5 to
A method for producing a low-oxygen spherical metal powder by DC thermal plasma treatment, wherein the volume is 20 vol%.
ラズマ中に原料金属粉末を通過させて処理する、酸素量
が１０００ｐｐｍ以下の球状金属粉末の製造方法であっ
て、原料金属粉末の通過するＤＣ熱プラズマ領域の最高
温度を原料金属粉末の融点以上、１００００℃以下とす
ることを特徴とするＤＣ熱プラズマ処理による低酸素球
状金属粉末の製造方法。2. A method for producing a spherical metal powder having an oxygen content of 1000 ppm or less, wherein the raw metal powder is processed by passing the raw metal powder through a DC thermal plasma generated by using a DC power supply. A method of producing a low-oxygen spherical metal powder by a DC thermal plasma treatment, wherein a maximum temperature of a DC thermal plasma region to be heated is set to be equal to or higher than the melting point of the raw metal powder and equal to or lower than 10,000 ° C.
ことを特徴とするＤＣ熱プラズマ処理による低酸素球状
金属粉末の製造方法。3. A method for producing low-oxygen spherical metal powder by DC thermal plasma treatment, which comprises combining the production methods according to claim 1 and 2.
以下であることを特徴とする請求項１ないし３のいずれ
かに記載のＤＣ熱プラズマ処理による低酸素球状金属粉
末の製造方法。4. The raw material metal powder has an oxygen content of 1000 ppm.
The method for producing a low-oxygen spherical metal powder by DC thermal plasma treatment according to any one of claims 1 to 3, wherein:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001019722A JP2002220601A (en) | 2001-01-29 | 2001-01-29 | Production method for low oxygen spherical metal powder using dc thermal plasma processing |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001019722A JP2002220601A (en) | 2001-01-29 | 2001-01-29 | Production method for low oxygen spherical metal powder using dc thermal plasma processing |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2002220601A true JP2002220601A (en) | 2002-08-09 |
Family
ID=18885554
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2001019722A Pending JP2002220601A (en) | 2001-01-29 | 2001-01-29 | Production method for low oxygen spherical metal powder using dc thermal plasma processing |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2002220601A (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007122684A1 (en) * | 2006-04-14 | 2007-11-01 | Hitachi Metals, Ltd. | Process for producing low-oxygen metal powder |
| JP2009173461A (en) * | 2008-01-21 | 2009-08-06 | Tosoh Corp | Method for producing ceramic bead having smooth surface |
| JP2010084199A (en) * | 2008-09-30 | 2010-04-15 | Nisshin Seifun Group Inc | METHOD FOR PRODUCING FINE PARTICLE OF Ni-W-BASED ALLOY, AND METHOD FOR PRODUCING FINE PARTICLE OF Ni-W ALLOY |
| CN103990792A (en) * | 2014-03-28 | 2014-08-20 | 燕山大学 | Method for preparing particle strengthening metal matrix nanocomposite |
| JP2016028176A (en) * | 2014-02-14 | 2016-02-25 | 三井金属鉱業株式会社 | Method for manufacturing copper powder |
| JP2016185887A (en) * | 2015-03-27 | 2016-10-27 | 三井金属鉱業株式会社 | Method for manufacturing silicon containing powder |
| JP2021503041A (en) * | 2017-11-14 | 2021-02-04 | パイロジェネシス・カナダ・インコーポレーテッド | Methods and equipment for producing fine spherical powders from coarse and angular powder feedstocks. |
| CN117483772A (en) * | 2023-12-29 | 2024-02-02 | 西安赛隆增材技术股份有限公司 | Powder preparation method of plasma atomization powder preparation equipment |
-
2001
- 2001-01-29 JP JP2001019722A patent/JP2002220601A/en active Pending
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007122684A1 (en) * | 2006-04-14 | 2007-11-01 | Hitachi Metals, Ltd. | Process for producing low-oxygen metal powder |
| US8012235B2 (en) | 2006-04-14 | 2011-09-06 | Hitachi Metals, Ltd. | Process for producing low-oxygen metal powder |
| JP2009173461A (en) * | 2008-01-21 | 2009-08-06 | Tosoh Corp | Method for producing ceramic bead having smooth surface |
| JP2010084199A (en) * | 2008-09-30 | 2010-04-15 | Nisshin Seifun Group Inc | METHOD FOR PRODUCING FINE PARTICLE OF Ni-W-BASED ALLOY, AND METHOD FOR PRODUCING FINE PARTICLE OF Ni-W ALLOY |
| JP2016028176A (en) * | 2014-02-14 | 2016-02-25 | 三井金属鉱業株式会社 | Method for manufacturing copper powder |
| CN103990792A (en) * | 2014-03-28 | 2014-08-20 | 燕山大学 | Method for preparing particle strengthening metal matrix nanocomposite |
| JP2016185887A (en) * | 2015-03-27 | 2016-10-27 | 三井金属鉱業株式会社 | Method for manufacturing silicon containing powder |
| JP2021503041A (en) * | 2017-11-14 | 2021-02-04 | パイロジェネシス・カナダ・インコーポレーテッド | Methods and equipment for producing fine spherical powders from coarse and angular powder feedstocks. |
| EP3710180A4 (en) * | 2017-11-14 | 2021-03-31 | Pyrogenesis Canada Inc. | Method and apparatus for producing fine spherical powders from coarse and angular powder feed material |
| JP7330963B2 (en) | 2017-11-14 | 2023-08-22 | パイロジェネシス・カナダ・インコーポレーテッド | Method and Apparatus for Producing Fine Spherical Powders from Coarse and Angular Powder Feed Materials |
| CN117483772A (en) * | 2023-12-29 | 2024-02-02 | 西安赛隆增材技术股份有限公司 | Powder preparation method of plasma atomization powder preparation equipment |
| CN117483772B (en) * | 2023-12-29 | 2024-03-29 | 西安赛隆增材技术股份有限公司 | Powder preparation method of plasma atomization powder preparation equipment |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP5052291B2 (en) | Alloy fine particles and method for producing the same | |
| CN104070172B (en) | A kind of preparation method of spherical chromium powder | |
| US20040065170A1 (en) | Method for producing nano-structured materials | |
| US20030108459A1 (en) | Nano powder production system | |
| CN107900366B (en) | Device and method for continuously preparing titanium or titanium alloy powder for 3D printing through gas atomization | |
| JP2004036005A (en) | Fine and ultrafine metal powder | |
| CN108637267A (en) | A kind of device and method preparing spherical metal powder using metal wire material | |
| US20120027955A1 (en) | Reactor and method for production of nanostructures | |
| KR20140027335A (en) | Low cost processing to produce spherical titanium and titanium alloy powder | |
| US4787934A (en) | Hydrometallurgical process for producing spherical maraging steel powders utilizing spherical powder and elemental oxidizable species | |
| CN105057688B (en) | A kind of production method of ultra-fine Pb-free coating glass putty | |
| Stein et al. | Effect of carrier gas composition on transferred arc metal nanoparticle synthesis | |
| CN110181066A (en) | High sphericity 3D printing tantalum powder, preparation method and application | |
| US5114471A (en) | Hydrometallurgical process for producing finely divided spherical maraging steel powders | |
| CN108526472A (en) | A kind of free arc system for spherical metal powder device and method | |
| CN113145855A (en) | Device and method for preparing high-melting-point alloy powder by electric arc | |
| CN108163821B (en) | Preparation method of spherical titanium nitride | |
| US4859237A (en) | Hydrometallurgical process for producing spherical maraging steel powders with readily oxidizable alloying elements | |
| JP2002220601A (en) | Production method for low oxygen spherical metal powder using dc thermal plasma processing | |
| US20050150759A1 (en) | Powder and coating formation method and apparatus | |
| CN104550903A (en) | Hydrogen plasma deoxidation method for chromium powder | |
| US4913731A (en) | Process of making prealloyed tungsten alloy powders | |
| JP2012246203A (en) | Method for manufacturing spherical titanium oxide particle | |
| JPH0625717A (en) | Method and device for producing globular grain by high-frequency plasma | |
| JP7142241B2 (en) | Microparticle manufacturing apparatus and microparticle manufacturing method |