JP4354566B2 - Process for producing inorganic compounds by combustion synthesis reaction - Google Patents
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Description
【０００１】
【発明の属する技術分野】
この発明は、燃焼合成方法によって高純度で微細な無機化合物を製造する方法に関するものである。
【０００２】
【従来の技術】
燃焼合成方法は、２種以上の固体−固体原料あるいは気体原料中で固体原料の一端を加熱することにより化学反応を起こさせ、その際に発生する生成熱によって燃焼波を生じさせ、自発的に伝播する燃焼波が次層の未反応部を励起するという連鎖反応を繰り返すことによって化合物を得る方法である。かかる燃焼合成方法は、短時間で大量の化合物粉末を得ることができると共に、化学反応熱を利用する燃焼合成反応を開始させる着火時を除いて外部加熱が不要であり、数百℃の低い予熱で燃焼合成反応が起こるため、通常の高温外部加熱による合成方法と比較して経済的であるといった利点を有する。
【０００３】
従来、かかる燃焼合成反応は、反応温度がおおよそ１７００℃の反応系でなければ着火させることが困難であり、１７００℃以下の反応温度の反応系の無機化合物の合成には燃焼合成反応を使用することができないとされている。
【０００４】
また、１７００℃という高い反応温度で燃焼合成を行った場合、得られる化合物粉末の粒径が大きくなり、焼結用に求められる微細で粒径の均一な粉末を得るためには、燃焼合成後に、得られた合成粉末を粉砕しなければならず、この粉砕処理にコストがかかる上、粉砕中に不純物が混入するという問題があった。
【０００５】
また、従来、固体原料粉末に燃焼合成反応を開始させる加熱方法としては、カーボンヒータ、金属線を用いた電気抵抗加熱、あるいは５ｋＶ以上の高圧電源を使用した電極棒によるアーク放電加熱が用いられているが、これらの加熱方法ではカーボンヒータや、金属線、電極棒を構成する成分元素が生成物に不純物として取り込まれるため、高純度の化合物粉末を得ることができないという問題もあった。
【０００６】
そこで、この発明は、従来、燃焼合成反応が行えないとされていた１７００℃以下の反応温度の反応系において、燃焼合成反応を可能とすることにより、粉砕しなくても微細な化合物粉末が得られ、しかも着火用の加熱部材からの不純物の混入もない、高純度の無機化合物を製造する方法を提供しようとするものである。
【０００７】
【課題を解決するための手段】
この発明は、出力を０．５Ｗ〜５００Ｗで７７０ｎｍよりも長い波長を有するレーザーを原料粉末に照射することにより、反応温度が５００℃〜１７００℃の反応系の無機化合物の燃焼合成反応を開始させるようにしたものである。
【０００８】
上記の方法により、５００℃〜１７００℃という低い反応温度で燃焼合成反応を行うことが可能となり、粒成長が抑制された微細な化合物粉末が得られる。
【０００９】
したがって、粉砕工程による不純物混入と、着火の際の不純物混入が避けられるため、高純度の無機化合物を製造することができるし、粉砕工程の省略によってコストも低減することができる。
【００１０】
この発明において燃焼合成反応を開始させる着火の際に用いるレーザとしては、出力０．５Ｗ〜５００Ｗで７７０ｎｍよりも長い波長を有するものであれば特に限定されず、市販の炭酸ガス（ＣＯ2 ）レーザーやイットリア・アルミナ・ガーネット（ＹＡＧ）レーザーを用いることができる。
【００１１】
レーザーの照射時間は、レーザーの波長や出力、および出発原料粉末の吸収率や粒径、粒子表面の酸化度合によって変化するが、出発原料粉末の表面を直径数ミリメートル程の局所加熱を行うことにより、遅くとも数十秒以内に着火が起こり、着火後はレーザー照射を止めても、発熱反応による燃焼波が連鎖的に進行して、所定の化合物が燃焼合成された。例えば、Ｔｉ粉末、Ａｌ粉末、ＴｉＡｌ粉末を０．５（Ｔｉ＋Ａｌ）＋０．５ＴｉＡｌ＝ＴｉＡｌの反応式に従って混合した出発原料を用いた場合、熱力学計算から求めた反応温度は７２０℃と低いため、出発原料粉末の表面を、近接させたカーボンヒータによって２０秒間電気抵抗加熱を行っても、また、１５ｋＶの高圧電源の電極棒によるアーク放電加熱を５ｍｍの距離から３０秒間行っても着火は起こらないが、出力３ＷのＣＯ2 レーザーを照射した場合には、約１秒後に着火が起こり、試料全体に燃焼波が広がって化合物が燃焼合成された。
【００１２】
この発明において、真空中で燃焼合成を行う場合、真空容器を用い、非酸化雰囲気中で燃焼合成を行う場合には、ガス置換が可能な反応容器が用いられる。また、高圧不活性ガスを用いる場合は耐圧容器が用いられる。これらの容器内の出発原料へのレーザー照射は、容器に設けたガラス窓やガラスファイバを介して行われるが、このような場合、ガラスに吸収されにくいＹＡＧレーザーを用いることが好ましいが、ＣＯ2 レーザーでもほぼ同じ設定条件で着火が可能である。
【００１３】
この発明では、７７０ｎｍよりも長い波長を有するレーザーを使用するが、この波長よりも短い波長のレーザーでは、着火せず、燃焼合成反応が開始しなかった。
【００１４】
また、この発明で使用するレーザーの出力は、０．５Ｗ〜５００Ｗとするが、これは、０．５Ｗ以下では着火せず、５００Ｗ以上ではエネルギー密度が高すぎて、出発原料粉末表面から微小粉末がはじき飛ばされて着火しないためである。
【００１５】
また、７７０ｎｍよりも長い波長のレーザーを照射しても、熱力学計算から求めた反応温度が５００℃未満の反応系の場合には、着火は起こらなかった。
【００１６】
【実施例】
以下の実施形態はいずれも、出発原料粉末表面に近接または接触させたカーボンヒーターや金属線を用いた電気抵抗加熱、あるいは５ｋＶ以上の高圧電源を使用して出発原料粉末表面とわずかに離した電極棒間のアーク放電加熱を用いた方法では、着火が著しく困難もしくは不可能な反応系について、この発明によって、燃焼合成が可能となった事例を列挙してある。
【００１７】
【実施例１】
Ｔｉ＋Ａｌ＝ＴｉＡｌの反応式に従って、Ｔｉ粉末とＡｌ粉末を乾式混合した出発原料を、カーボン製坩堝に相対密度がおおよそ５０％となるように充填した。大気中で、その出発原料の表面に出力０．５ＷのＣＯ2 レーザーを照射したところ、約２秒後に着火が起こった。レーザー照射を止めた後も、連鎖的に燃焼波が試料全体に広がり、化合物が燃焼合成された。粉末Ｘ線回析装置を用いて、得られた生成物を同定したところ、ＴｉＡｌ単一相の粉末となっており、未反応のＴｉやＡｌは検出されなかった。
【００１８】
【実施例２】
０．５Ｔｉ＋０．５Ａｌ＋０．５ＴｉＡｌ＝ＴｉＡｌの反応式に従って、Ｔｉ粉末とＡｌ粉末とＴｉＡｌ粉末を乾式混合した出発原料を、カーボン製坩堝に相対密度がおおよそ５０％となるように充填した。大気中で、その出発原料の表面に出力３ＷのＣＯ2 レーザーを照射したところ、約１秒後に着火が起こった。レーザー照射を止めた後も、連鎖的に燃焼波が試料全体に広がり、化合物が燃焼合成された。試料中央部に埋め込んだ熱電対で反応温度を測定した所、７００℃であった。粉末Ｘ線回析装置を用いて、得られた生成物を同定したところ、ＴｉＡｌに少量のＴｉ3 ＡｌとＴｉＡｌ3 が混合した複合粉末となっていた。
【００１９】
【実施例３】
実施例２と同じ出発原料を充填したカーボン製坩堝を反応容器内に置き、真空中でガラスファイバーを介して反応容器内に導入した出力３ＷのＹＡＧレーザーを出発原料表面に照射したところ、約１秒後に着火が起こった。反応温度および得られた生成物は、実施例２と同様の結果であった。
【００２０】
【実施例４】
０．７５Ｔｉ＋０．１５ＴｉＨ2 ＋Ａｌ＝ＴｉＡｌ＋０．１５Ｈ2 の反応式に従って、Ｔｉ粉末とＴｉＨ2 粉末とＡｌ粉末を乾式混合した出発原料を充填したカーボン製坩堝を、反応容器内に置いた。１気圧のＡｒガス雰囲気中で、ガラスファイバーを介して反応容器内に導入した出力５ＷのＹＡＧレーザーを出発原料表面に照射したところ、約１秒後に着火が起こった。レーザー照射を止めた後も、連鎖的に燃焼波が試料全体に広がり、化合物が燃焼合成された。粉末Ｘ線回析装置を用いて、得られた生成物を同定したところ、ＴｉＡｌ単一相の粉末となっており、未反応のＴｉやＡｌは検出されなかった。生成物の平均粒径は２０ｍｉｃｒｏｎであり、均一で微細な粉末となっていた。燃焼合成後の反応容器内のガス分析を行った結果、Ａｒガス以外にＨ2 ガスが検出された。
【００２１】
【実施例５】
Ｓｉ＋Ｃ＝ＳｉＣの反応式に従って、Ｓｉ粉末とＣ粉末を乾式混合した出発原料を充填したカーボン製坩堝を、反応容器内に置いた。１気圧のＡｒガス雰囲気中で、ガラスファイバーを介して反応容器内に導入した出力５ＷのＹＡＧレーザーを出発原料表面に照射したところ、約１秒後に着火が起こった。レーザー照射を止めた後も、連鎖的に燃焼波が試料全体に広がり、化合物が燃焼合成された。粉末Ｘ線回析装置を用いて、得られた生成物を同定したところ、ＳｉＣ単一相の粉末となっていた。生成物の平均粒径は５ｍｉｃｒｏｎであり、均一で微細な粉末となっていた。
【００２２】
【実施例６】
２Ｓｉ＋Ｃ＝Ｓｉ＋ＳｉＣの反応式に従って、Ｓｉ粉末とＣ粉末を乾式混合した出発原料を充填したカーボン製坩堝を、反応容器内に置いた。１気圧のＡｒガス雰囲気中で、ガラスファイバーを介して反応容器内に導入した出力５ＷのＹＡＧレーザーを出発原料表面に照射したところ、約２秒後に着火が起こった。レーザー照射を止めた後も、連鎖的に燃焼波が試料全体に広がり、化合物が燃焼合成された。粉末Ｘ線回析装置を用いて、得られた生成物を同定したところ、ＳｉとＳｉＣの複合粉末となっていた。
【００２３】
【実施例７】
３Ｔｉ＋Ｓｉ＋２Ｃ＝Ｔｉ3 ＳｉＣ2 の反応式に従って、Ｔｉ粉末とＳｉ粉末とＣ粉末を乾式混合した出発原料を充填したカーボン製坩堝を、反応容器内に置いた。１気圧のＡｒガス雰囲気中で、ガラスファイバーを介して反応容器内に導入した出力５ＷのＹＡＧレーザーを出発原料表面に照射したところ、約２秒後に着火が起こった。レーザー照射を止めた後も、連鎖的に燃焼波が試料全体に広がり、化合物が燃焼合成された。粉末Ｘ線回析装置を用いて、得られた生成物を同定したところ、Ｔｉ3 ＳｉＣ2 単一相の粉末となっていた。生成物の平均粒径は５ｍｉｃｒｏｎであり、均一で微細な粉末となっていた。
【００２４】
【実施例８】
Ｍｏ＋２Ｓｉ＝ＭｏＳｉ2 の反応式に従って、Ｍｏ粉末とＳｉ粉末を乾式混合した出発原料を充填したカーボン製坩堝を、反応容器内に置いた。１気圧のＡｒガス雰囲気中で、ガラスファイバーを介して反応容器内に導入した出力５ＷのＹＡＧレーザーを出発原料表面に照射したところ、約２秒後に着火が起こった。レーザー照射を止めた後も、連鎖的に燃焼波が試料全体に広がり、化合物が燃焼合成された。粉末Ｘ線回析装置を用いて、得られた生成物を同定したところ、ＭｏＳｉ2 単一相の粉末となっていた。生成物の平均粒径は１０ｍｉｃｒｏｎであり、均一で微細な粉末となっていた。
【００２５】
【実施例９】
Ｆｅ＋２Ｓｉ＝ＦｅＳｉ2 の反応式に従って、Ｆｅ粉末とＳｉ粉末を乾式混合した出発原料を充填したカーボン製坩堝を、反応容器内に置いた。１気圧のＡｒガス雰囲気中で、ガラスファイバーを介して反応容器内に導入した出力５ＷのＹＡＧレーザーを出発原料表面に照射したところ、約２秒後に着火が起こった。レーザー照射を止めた後も、連鎖的に燃焼波が試料全体に広がり、化合物が燃焼合成された。粉末Ｘ線回析装置を用いて、得られた生成物を同定したところ、ＦｅＳｉ2 単一相の粉末となっていた。生成物の平均粒径は１０ｍｉｃｒｏｎであり、均一で微細な粉末となっていた。
【００２６】
【実施例１０】
２Ｍｇ＋Ｎｉ＝Ｍｇ2 Ｎｉの反応式に従って、Ｍｇ粉末とＮｉ粉末を乾式混合した出発原料を充填したカーボン製坩堝を、反応容器内に置いた。１気圧のＡｒガス雰囲気中で、ガラスファイバーを介して反応容器内に導入した出力１０ＷのＹＡＧレーザーを出発原料表面に照射したところ、約２秒後に着火が起こった。レーザー照射を止めた後も、連鎖的に燃焼波が試料全体に広がり、化合物が燃焼合成された。粉末Ｘ線回析装置を用いて、得られた生成物を同定したところ、Ｍｇ2 Ｎｉ単一相の粉末となっていた。生成物の平均粒径は２０ｍｉｃｒｏｎであり、均一で微細な粉末となっていた。
【００２７】
【実施例１１】
３Ｎｂ＋Ａｌ＝Ｎｂ3 Ａｌの反応式に従って、Ｎｂ粉末とＡｌ粉末を乾式混合した出発原料を充填したカーボン製坩堝を、反応容器内に置いた。１気圧のＡｒガス雰囲気中で、ガラスファイバーを介して反応容器内に導入した出力５ＷのＹＡＧレーザーを出発原料表面に照射したところ、約２秒後に着火が起こった。レーザー照射を止めた後も、連鎖的に燃焼波が試料全体に広がり、化合物が燃焼合成された。粉末Ｘ線回析装置を用いて、得られた生成物を同定したところ、Ｎｂ3 Ａｌ単一相の粉末となっていた。
【００２８】
【実施例１２】
ＴｉＨ2 ＋Ｃ＝ＴｉＣ＋Ｈ2 の反応式に従って、ＴｉＨ2 粉末とＣ粉末を乾式混合した出発原料を充填したカーボン製坩堝を、反応容器内に置いた。真空中で、ガラスファイバーを介して反応容器内に導入した出力１０ＷのＹＡＧレーザーを出発原料表面に照射したところ、約２秒後に着火が起こった。レーザー照射を止めた後も、連鎖的に燃焼波が試料全体に広がり、化合物が燃焼合成された。粉末Ｘ線回析装置を用いて、得られた生成物を同定したところ、ＴｉＣ単一相の粉末となっていた。燃焼合成後の反応容器内のガス分析を行った結果、Ｈ2 ガスが形成された。
【００２９】
【実施例１３】
ＴｉＨ2 ＋２Ｂ＝ＴｉＢ2 ＋Ｈ2 の反応式に従って、ＴｉＨ2 粉末とＢ粉末を乾式混合した出発原料を充填したカーボン製坩堝を、反応容器内に置いた。真空中で、ガラスファイバーを介して反応容器内に導入した出力１０ＷのＹＡＧレーザーを出発原料表面に照射したところ、約２秒後に着火が起こった。レーザー照射を止めた後も、連鎖的に燃焼波が試料全体に広がり、化合物が燃焼合成された。粉末Ｘ線回析装置を用いて、得られた生成物を同定したところ、ＴｉＢ2 単一相の粉末となっていた。燃焼合成後の反応容器内のガス分析を行った結果、Ｈ2 ガスが形成された。
【００３０】
【発明の効果】
この発明によれば、以上のように、従来では着火が起こらないとされていた１７００℃以下の反応系の無機化合物を燃焼合成することができるので、粉砕しなくても微細な無機化合物粉末が得られる。したがって、粉砕による不純物の混入もなく、また着火用の加熱部材からの不純物の混入もないので、高純度の無機化合物を製造することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a fine inorganic compound with high purity by a combustion synthesis method.
[0002]
[Prior art]
In the combustion synthesis method, a chemical reaction is caused by heating one end of a solid raw material in two or more kinds of solid-solid raw materials or gas raw materials, and a combustion wave is generated by generated heat generated at that time. In this method, a compound is obtained by repeating a chain reaction in which a propagating combustion wave excites an unreacted portion of the next layer. This combustion synthesis method can obtain a large amount of compound powder in a short time, and does not require external heating except during ignition to start the combustion synthesis reaction using the heat of chemical reaction. Since the combustion synthesis reaction takes place in this case, it has the advantage of being economical compared with a synthesis method using ordinary high-temperature external heating.
[0003]
Conventionally, such a combustion synthesis reaction is difficult to ignite unless the reaction temperature is approximately 1700 ° C., and the combustion synthesis reaction is used to synthesize inorganic compounds in reaction systems having a reaction temperature of 1700 ° C. or lower. It is said that it cannot be done.
[0004]
In addition, when combustion synthesis is performed at a high reaction temperature of 1700 ° C., the particle size of the obtained compound powder becomes large, and in order to obtain a fine and uniform particle size powder required for sintering, The obtained synthetic powder must be pulverized, and this pulverization process is costly, and impurities are mixed during the pulverization.
[0005]
Conventionally, as a heating method for starting a combustion synthesis reaction on a solid raw material powder, an electric resistance heating using a carbon heater, a metal wire, or an arc discharge heating by an electrode rod using a high voltage power source of 5 kV or more is used. However, these heating methods have a problem that a high purity compound powder cannot be obtained because the constituent elements constituting the carbon heater, the metal wire, and the electrode rod are incorporated as impurities into the product.
[0006]
Therefore, the present invention provides a fine compound powder without pulverization by enabling a combustion synthesis reaction in a reaction system having a reaction temperature of 1700 ° C. or lower, which has been conventionally considered to be unable to perform a combustion synthesis reaction. In addition, an object of the present invention is to provide a method for producing a high-purity inorganic compound that does not contain impurities from a heating member for ignition.
[0007]
[Means for Solving the Problems]
In this invention, a raw material powder is irradiated with a laser having an output of 0.5 W to 500 W and a wavelength longer than 770 nm, thereby starting a combustion synthesis reaction of an inorganic compound in a reaction system having a reaction temperature of 500 ° C. to 1700 ° C. It is what I did.
[0008]
By the above method, it is possible to perform a combustion synthesis reaction at a reaction temperature as low as 500 ° C. to 1700 ° C., and a fine compound powder in which grain growth is suppressed is obtained.
[0009]
Accordingly, since contamination by impurities during the pulverization step and contamination during ignition can be avoided, a high-purity inorganic compound can be produced, and cost can be reduced by omitting the pulverization step.
[0010]
In the present invention, the laser used for ignition for starting the combustion synthesis reaction is not particularly limited as long as it has an output of 0.5 W to 500 W and a wavelength longer than 770 nm, and is a commercially available carbon dioxide (CO 2 ) laser. Or yttria-alumina-garnet (YAG) laser can be used.
[0011]
The laser irradiation time varies depending on the wavelength and output of the laser, the absorption rate and particle size of the starting raw material powder, and the degree of oxidation of the particle surface, but by locally heating the surface of the starting raw material powder to a diameter of several millimeters The ignition occurred within several tens of seconds at the latest, and even after the ignition, even when the laser irradiation was stopped, the combustion wave due to the exothermic reaction proceeded in a chain, and the predetermined compound was combusted and synthesized. For example, when using a starting material obtained by mixing Ti powder, Al powder, TiAl powder according to the reaction formula of 0.5 (Ti + Al) + 0.5TiAl = TiAl, the reaction temperature obtained from thermodynamic calculation is as low as 720 ° C., Even if the surface of the starting material powder is heated by electric resistance for 20 seconds with a carbon heater close to the surface, or if arc discharge heating is performed for 30 seconds from a distance of 5 mm by an electrode rod of a high voltage power source of 15 kV, ignition does not occur. However, when a CO 2 laser with an output of 3 W was irradiated, ignition occurred after about 1 second, and a combustion wave spread over the entire sample to synthesize the compound.
[0012]
In the present invention, when combustion synthesis is performed in a vacuum, a vacuum vessel is used, and when combustion synthesis is performed in a non-oxidizing atmosphere, a reaction vessel capable of gas replacement is used. Moreover, when using a high-pressure inert gas, a pressure-resistant container is used. Laser irradiation of the starting materials for these vessel is carried out through a glass window or a glass fiber provided in the container, in such a case, it is preferable to use a poorly absorbed YAG laser glass, CO 2 A laser can be ignited under almost the same setting conditions.
[0013]
In the present invention, a laser having a wavelength longer than 770 nm is used. However, a laser having a wavelength shorter than this wavelength did not ignite and the combustion synthesis reaction did not start.
[0014]
The power of the laser used in the present invention is 0.5 W to 500 W. However, this does not ignite at 0.5 W or less, and the energy density is too high at 500 W or more. This is because it is blown off and does not ignite.
[0015]
In addition, even when a laser having a wavelength longer than 770 nm was irradiated, ignition did not occur in the case of a reaction system having a reaction temperature obtained from thermodynamic calculation of less than 500 ° C.
[0016]
【Example】
In any of the following embodiments, the electrode is slightly separated from the surface of the starting material powder using an electric resistance heating using a carbon heater or a metal wire close to or in contact with the surface of the starting material powder, or a high voltage power source of 5 kV or more. In the method using arc discharge heating between the rods, examples of cases in which combustion synthesis is possible by the present invention for reaction systems in which ignition is extremely difficult or impossible are listed.
[0017]
[Example 1]
In accordance with the reaction formula of Ti + Al = TiAl, a starting material obtained by dry mixing Ti powder and Al powder was charged into a carbon crucible so that the relative density was approximately 50%. When the surface of the starting material was irradiated with a CO 2 laser having an output of 0.5 W in the atmosphere, ignition occurred after about 2 seconds. Even after the laser irradiation was stopped, the combustion wave spread throughout the sample and the compound was burned and synthesized. When the obtained product was identified using a powder X-ray diffraction apparatus, it became a TiAl single-phase powder, and unreacted Ti and Al were not detected.
[0018]
[Example 2]
In accordance with a reaction formula of 0.5Ti + 0.5Al + 0.5TiAl = TiAl, a starting material obtained by dry-mixing Ti powder, Al powder, and TiAl powder was charged into a carbon crucible so that the relative density was approximately 50%. When the surface of the starting material was irradiated with a CO 2 laser with an output of 3 W in the atmosphere, ignition occurred after about 1 second. Even after the laser irradiation was stopped, the combustion wave spread throughout the sample and the compound was burned and synthesized. It was 700 degreeC when the reaction temperature was measured with the thermocouple embedded in the center part of the sample. When the obtained product was identified using a powder X-ray diffraction apparatus, it was a composite powder in which a small amount of Ti 3 Al and TiAl 3 were mixed in TiAl.
[0019]
[Example 3]
A carbon crucible filled with the same starting material as in Example 2 was placed in the reaction vessel, and the surface of the starting material was irradiated with a YAG laser having an output of 3 W introduced into the reaction vessel through a glass fiber in a vacuum. Ignition occurred a second later. The reaction temperature and the obtained product were the same as in Example 2.
[0020]
[Example 4]
According to the reaction formula of 0.75Ti + 0.15TiH 2 + Al = TiAl + 0.15H 2 , a carbon crucible filled with a starting material obtained by dry-mixing Ti powder, TiH 2 powder and Al powder was placed in a reaction vessel. When the surface of the starting material was irradiated with a 5 W YAG laser introduced into the reaction vessel through a glass fiber in an atmosphere of Ar gas at 1 atm, ignition occurred after about 1 second. Even after the laser irradiation was stopped, the combustion wave spread throughout the sample and the compound was burned and synthesized. When the obtained product was identified using a powder X-ray diffraction apparatus, it became a TiAl single-phase powder, and unreacted Ti and Al were not detected. The average particle size of the product was 20 micron and was a uniform and fine powder. As a result of analyzing the gas in the reaction vessel after the combustion synthesis, H 2 gas was detected in addition to Ar gas.
[0021]
[Example 5]
According to the reaction formula of Si + C = SiC, a carbon crucible filled with a starting material obtained by dry mixing Si powder and C powder was placed in a reaction vessel. When the surface of the starting material was irradiated with a 5 W YAG laser introduced into the reaction vessel through a glass fiber in an atmosphere of Ar gas at 1 atm, ignition occurred after about 1 second. Even after the laser irradiation was stopped, the combustion wave spread throughout the sample and the compound was burned and synthesized. When the obtained product was identified using the powder X-ray diffraction apparatus, it became a SiC single phase powder. The average particle size of the product was 5 micron and was a uniform and fine powder.
[0022]
[Example 6]
According to the reaction formula of 2Si + C = Si + SiC, a carbon crucible filled with a starting material obtained by dry mixing Si powder and C powder was placed in a reaction vessel. When the surface of the starting material was irradiated with a 5 W YAG laser introduced into the reaction vessel through a glass fiber in an Ar gas atmosphere at 1 atm, ignition occurred after about 2 seconds. Even after the laser irradiation was stopped, the combustion wave spread throughout the sample and the compound was burned and synthesized. When the obtained product was identified using a powder X-ray diffraction apparatus, it was a composite powder of Si and SiC.
[0023]
[Example 7]
According to the reaction formula 3Ti + Si + 2C = Ti 3 SiC 2 , a carbon crucible filled with a starting material obtained by dry-mixing Ti powder, Si powder and C powder was placed in a reaction vessel. When the surface of the starting material was irradiated with a 5 W YAG laser introduced into the reaction vessel through a glass fiber in an Ar gas atmosphere at 1 atm, ignition occurred after about 2 seconds. Even after the laser irradiation was stopped, the combustion wave spread throughout the sample and the compound was burned and synthesized. When the obtained product was identified using a powder X-ray diffraction apparatus, it was a Ti 3 SiC 2 single-phase powder. The average particle size of the product was 5 micron and was a uniform and fine powder.
[0024]
[Example 8]
According to the reaction formula of Mo + 2Si = MoSi 2 , a carbon crucible filled with a starting material obtained by dry-mixing Mo powder and Si powder was placed in a reaction vessel. When the surface of the starting material was irradiated with a 5 W YAG laser introduced into the reaction vessel through a glass fiber in an Ar gas atmosphere at 1 atm, ignition occurred after about 2 seconds. Even after the laser irradiation was stopped, the combustion wave spread throughout the sample and the compound was burned and synthesized. When the obtained product was identified using a powder X-ray diffraction apparatus, it was a MoSi 2 single-phase powder. The average particle size of the product was 10 micron and was a uniform and fine powder.
[0025]
[Example 9]
According to the reaction formula of Fe + 2Si = FeSi 2 , a carbon crucible filled with a starting material obtained by dry mixing Fe powder and Si powder was placed in a reaction vessel. When the surface of the starting material was irradiated with a 5 W YAG laser introduced into the reaction vessel through a glass fiber in an Ar gas atmosphere at 1 atm, ignition occurred after about 2 seconds. Even after the laser irradiation was stopped, the combustion wave spread throughout the sample and the compound was burned and synthesized. When the obtained product was identified using a powder X-ray diffraction apparatus, it became a FeSi 2 single-phase powder. The average particle size of the product was 10 micron and was a uniform and fine powder.
[0026]
[Example 10]
According to the reaction formula of 2Mg + Ni = Mg 2 Ni, a carbon crucible filled with a starting material obtained by dry mixing Mg powder and Ni powder was placed in a reaction vessel. When the surface of the starting material was irradiated with a YAG laser having an output of 10 W introduced into the reaction vessel through a glass fiber in an Ar gas atmosphere at 1 atm, ignition occurred after about 2 seconds. Even after the laser irradiation was stopped, the combustion wave spread throughout the sample and the compound was burned and synthesized. When the obtained product was identified using a powder X-ray diffraction apparatus, it became a Mg 2 Ni single phase powder. The average particle size of the product was 20 micron and was a uniform and fine powder.
[0027]
Example 11
According to the reaction formula of 3Nb + Al = Nb 3 Al, a carbon crucible filled with a starting material obtained by dry mixing Nb powder and Al powder was placed in a reaction vessel. When the surface of the starting material was irradiated with a 5 W YAG laser introduced into the reaction vessel through a glass fiber in an Ar gas atmosphere at 1 atm, ignition occurred after about 2 seconds. Even after the laser irradiation was stopped, the combustion wave spread throughout the sample and the compound was burned and synthesized. Using powder X-ray diffractometer, it was identified and the resulting product has been a powder of Nb 3 Al single phase.
[0028]
Example 12
According to the reaction formula of TiH 2 + C = TiC + H 2 , a carbon crucible filled with a starting material obtained by dry-mixing TiH 2 powder and C powder was placed in a reaction vessel. When the surface of the starting material was irradiated with a YAG laser having an output of 10 W introduced into the reaction vessel through a glass fiber in a vacuum, ignition occurred after about 2 seconds. Even after the laser irradiation was stopped, the combustion wave spread throughout the sample and the compound was burned and synthesized. When the obtained product was identified using a powder X-ray diffraction apparatus, it became a TiC single phase powder. As a result of analyzing the gas in the reaction vessel after the combustion synthesis, H 2 gas was formed.
[0029]
Example 13
According to the reaction formula of TiH 2 + 2B = TiB 2 + H 2 , a carbon crucible filled with a starting material obtained by dry-mixing TiH 2 powder and B powder was placed in a reaction vessel. When the surface of the starting material was irradiated with a YAG laser having an output of 10 W introduced into the reaction vessel through a glass fiber in a vacuum, ignition occurred after about 2 seconds. Even after the laser irradiation was stopped, the combustion wave spread throughout the sample and the compound was burned and synthesized. When the obtained product was identified using a powder X-ray diffraction apparatus, it became a TiB 2 single-phase powder. As a result of analyzing the gas in the reaction vessel after the combustion synthesis, H 2 gas was formed.
[0030]
【The invention's effect】
According to the present invention, as described above, an inorganic compound in a reaction system of 1700 ° C. or lower, which has been conventionally considered not to be ignited, can be burned and synthesized, so that a fine inorganic compound powder can be obtained without pulverization. can get. Therefore, there is no mixing of impurities due to pulverization and no mixing of impurities from the heating member for ignition, so that a high-purity inorganic compound can be produced.
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