JP2005179185A - Magnetite-iron composite powder, production method therefor and wave absorber - Google Patents
Magnetite-iron composite powder, production method therefor and wave absorber Download PDFInfo
- Publication number
- JP2005179185A JP2005179185A JP2004376199A JP2004376199A JP2005179185A JP 2005179185 A JP2005179185 A JP 2005179185A JP 2004376199 A JP2004376199 A JP 2004376199A JP 2004376199 A JP2004376199 A JP 2004376199A JP 2005179185 A JP2005179185 A JP 2005179185A
- Authority
- JP
- Japan
- Prior art keywords
- powder
- magnetite
- iron
- composite powder
- reduction
- 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.)
- Granted
Links
Images
Abstract
Description
本発明は、マグネタイト−鉄複合粉末およびその製造方法、ならびにマグネタイト−鉄複合粉末の磁性を利用した電波吸収体に関する。 The present invention relates to a magnetite-iron composite powder, a method for producing the same, and a radio wave absorber utilizing the magnetism of the magnetite-iron composite powder.
微細な鉄粉は、粉末冶金、圧粉磁心や電波吸収体などの磁性体材料、触媒，食品添加物、酸化防止剤、複写機トナー用キャリア、土壌などの浄化などに利用されている。微細な鉄粉とその利用の一端である、該鉄粉を還元剤として用いる土壌などの浄化方法、および該鉄粉の磁性特性を利用する電波吸収体についての従来技術を下記する。 Fine iron powder is used for powder metallurgy, magnetic materials such as dust cores and radio wave absorbers, catalysts, food additives, antioxidants, copier toner carriers, and soil purification. The following is a description of a conventional technique for a fine iron powder and a purification method for soil using the iron powder as a reducing agent, which is one of the uses thereof, and a radio wave absorber using the magnetic properties of the iron powder.
［第一の従来技術／還元剤］
有機ハロゲン化合物により汚染された土壌、地下水を無害化する方法は、（１）汚染土壌、汚染地下水を現状維持したまま処理する方法（原位置分解法）、（２）汚染土壌中の気体または汚染地下水を一旦地上に引き上げて処理する方法（原位置抽出後処理法）、（３）汚染土壌を掘削して処理する方法（掘削除去法）に分類される。
[First prior art / reducing agent]
The methods of detoxifying soil and groundwater contaminated with organic halogen compounds are as follows: (1) Method of treating contaminated soil and contaminated groundwater while maintaining the current status (in-situ decomposition method), (2) Gas or contamination in contaminated soil It is classified into a method of once raising groundwater to the ground (post-processing method after in situ extraction) and (3) a method of excavating and treating contaminated soil (excavation removal method).
従来から、有機ハロゲン化合物の脱ハロゲンを行い、無害化するに際し、鉄粉を還元剤として用いる方法が提案されている。例えば、土壌内に鉄粉分散層を形成し、これに地下水等を接触させ、有機ハロゲン化合物を無害化する土壌および土壌水分の浄化方法（［特許文献１］、［特許文献２］）や、土壌または掘削した土壌に鉄粉を添加混合して、有機塩素系化合物を分解して土壌を浄化する方法（［特許文献３］）が提案されている。 Conventionally, a method has been proposed in which iron powder is used as a reducing agent when dehalogenating an organic halogen compound to render it harmless. For example, an iron powder dispersion layer is formed in the soil, groundwater or the like is contacted therewith, and the soil and soil moisture purification method ([Patent Document 1], [Patent Document 2]) detoxifying the organic halogen compound, There has been proposed a method ([Patent Document 3]) in which iron powder is added to and mixed with soil or excavated soil to decompose organic chlorinated compounds to purify the soil.
前者の公報における鉄粉は、鉄切断過程で生じる屑鉄などを使用するものであり、鉄粉の成分、組織を有機ハロゲン化合物の還元剤に適するように制御できないため、その効果が不十分であった。また、前者の公報には、土壌中の酸素により鉄表面に酸化物が生成し、鉄粉の還元力が低下することが記載され、そのために、還元性物質を土壌中に散布して、鉄粉近傍の脱酸素を図ることが記載されている。つまり、鉄粉は還元力の持続性に問題があることが示されている。 The iron powder in the former publication uses scrap iron generated during the iron cutting process and cannot control the components and structure of the iron powder to be suitable for the reducing agent of the organic halogen compound. It was. In addition, the former publication describes that oxygen in the soil generates oxides on the iron surface and reduces the reducing power of iron powder. It is described that deoxygenation in the vicinity of the powder is attempted. That is, it is shown that iron powder has a problem in the sustainability of reducing power.
後者の方法では、炭素を０．１重量％以上含有し、比表面積が５００ｃｍ2 ／ｇ以上で、１５０μｍのふるい通過分が５０重量％以上の粒度である、結晶構造としてパーライト組織を有する海綿鉄が使用されているが、成分が最適化されていないため、脱ハロゲン化が十分でない場合があった。 In the latter method, sponge iron having a pearlite structure as a crystal structure containing 0.1% by weight or more of carbon, having a specific surface area of 500 cm 2 / g or more, and having a particle size of passing through a 150 μm sieve of 50% by weight or more. However, since the components are not optimized, dehalogenation may not be sufficient.
また、排水中のリン化合物を効率よく除去できる鉄粉として、リン、イオウまたはホウ素を０．０２０〜０．５重量％含有する鉄粉が提案されている（［特許文献４］）。該鉄粉は特定元素を微量含有するために、排水への鉄の溶出速度が早く、リン化合物の除去性能が高い。しかしながら、その狙いとする効果は鉄の溶出速度を速めることで、排水中のリン除去を促進することである。すなわち、溶出した鉄イオンと排水中のリンとの間で溶解度積の小さいリン酸鉄などの難溶性の化合物を形成させて、排水中のリンを沈殿除去するものであり、鉄表面で有害物質を還元分解する技術とは、利用する化学反応が原理的に全く異なるものである。また、該公報には土壌、地下水への適用が記載されていない。 Moreover, iron powder containing 0.020 to 0.5% by weight of phosphorus, sulfur or boron has been proposed as iron powder that can efficiently remove phosphorus compounds in wastewater ([Patent Document 4]). Since the iron powder contains a small amount of a specific element, the elution rate of iron into the wastewater is high, and the phosphorus compound removal performance is high. However, the targeted effect is to accelerate the removal of phosphorus in waste water by increasing the elution rate of iron. In other words, it forms a poorly soluble compound such as iron phosphate with a low solubility product between the eluted iron ions and phosphorus in the wastewater, and precipitates and removes phosphorus in the wastewater. In principle, the chemical reaction used is completely different from the technology for reductively decomposing. In addition, this publication does not describe application to soil or groundwater.
さらに、土壌および／または地下水中の有機塩素化合物を効率よく除去できる鉄粉として、銅を０．１〜１０重量％含有する鉄粉が提案されている（［特許文献５］）。しかし、銅は有害金属であり、二次汚染の危険性がある。 Furthermore, iron powder containing 0.1 to 10% by weight of copper has been proposed as iron powder that can efficiently remove organic chlorine compounds in soil and / or groundwater ([Patent Document 5]). However, copper is a hazardous metal and there is a risk of secondary contamination.
上記いずれの鉄粉も、基本的には０価の鉄（Ｆｅ0 ）を主成分としており、有機ハロゲン化合物の分解能力が不十分であった。また、従来平均一次粒径が１μｍ未満の鉄粉は入手困難であり、上記用途には、平均一次粒径が８０μｍ程度の大粒径のものが使用されていた。鉄粉が大粒径であるため、土壌、地下水系への分散が困難である上、比表面積が小さいため、有機ハロゲン化合物の分解効率が不十分であるという問題もあった。
一般に、排水の場合より汚染源の特定が困難な地下水の場合は、一段と重大な被害をもたらすことがあるので、汚染地下水の迅速な無害化、還元剤の活性の持続等の要求が一層強い。また土壌中、空気中には、排水、地下水の場合と異なり、気体の有機ハロゲン化合物が存在するので、これの効率的な無害化方法の確立が求められている。そこで、本発明では有機ハロゲン化合物を迅速に分解する方法に適した微細な複合鉄粉を提供することを目的としている。
Any of the above iron powders was basically composed of zero-valent iron (Fe 0 ) as a main component, and the decomposition ability of the organic halogen compounds was insufficient. Conventionally, iron powder having an average primary particle size of less than 1 μm is difficult to obtain, and for the above-mentioned uses, those having a large particle size having an average primary particle size of about 80 μm have been used. Since the iron powder has a large particle size, it is difficult to disperse it in the soil and groundwater systems, and the specific surface area is small, so that the decomposition efficiency of the organic halogen compound is insufficient.
In general, groundwater in which it is difficult to identify the source of pollution than in the case of drainage may cause even more serious damage. Therefore, demands such as quick detoxification of contaminated groundwater and sustained reductant activity are even stronger. In addition, unlike organic wastewater and groundwater, gaseous organohalogen compounds exist in soil and air, and therefore, establishment of an efficient detoxification method is required. Accordingly, an object of the present invention is to provide fine composite iron powder suitable for a method for rapidly decomposing an organic halogen compound.
［第二の従来技術／磁性材料］
一方、電子機器、通信機器に用いられる磁性材料としては、カルボニル鉄を還元して得たカルボニル鉄粉や、ゲートサイト鉄（針状酸化鉄）を還元して得た針状鉄などが広く用いられているが、近年、電子機器、通信機器の発達に伴なって、高周波帯で機能を発揮する磁性材料のニーズが高まっている。
[Second prior art / magnetic material]
On the other hand, carbonyl iron powder obtained by reducing carbonyl iron and needle iron obtained by reducing gate site iron (acicular iron oxide) are widely used as magnetic materials used in electronic equipment and communication equipment. However, in recent years, with the development of electronic devices and communication devices, there is an increasing need for magnetic materials that exhibit functions in a high frequency band.
カルボニル鉄粉は粒径が数μｍ程度の粉末で、粒子が比較的大きいので、周波数が増加すると透磁率が低下する。そのため、ＧＨｚの高周波帯では、ノイズフィルターや電波吸収体などに使用することができない。
また、針状鉄は粒径が０．１μｍ程度の粉末で、粒径が小さいものの、凝集し易いので、実質的には粒径が大きくなり、上記カルボニル鉄粉と同様に用途が制限される。
さらに、カルボニル鉄やゲートサイト鉄は大量生産の技術が確立しておらず、高価であるから、カルボニル鉄粉や針状鉄の製造コストも上昇するという問題があった。
Carbonyl iron powder is a powder having a particle size of about several μm, and since the particles are relatively large, the permeability decreases as the frequency increases. Therefore, it cannot be used for a noise filter or a radio wave absorber in the high frequency band of GHz.
Needle-like iron is a powder having a particle size of about 0.1 μm, and although it has a small particle size, it tends to agglomerate. Therefore, the particle size is substantially increased, and the use is limited in the same manner as the carbonyl iron powder. .
Furthermore, since carbonyl iron and gate site iron have not been established in mass production technology and are expensive, there has been a problem that the production cost of carbonyl iron powder and needle-shaped iron also increases.
特にＧＨｚの高周波帯で使用する電波吸収体に限定すると、Ｆｅ−Ｓｉ合金粉、センダスト粉、ステンレス鋼粉などを扁平に加工した扁平粉末を樹脂に混合して、成形してなるシートが使用されている。しかし、これらの扁平粉末は、素材となる粉末が高価である上に、扁平に加工する費用も嵩むので、電波吸収体の製造コストが上昇する問題があった。 In particular, when limited to radio wave absorbers used in the high frequency band of GHz, a sheet formed by mixing flat powder obtained by flattening Fe-Si alloy powder, sendust powder, stainless steel powder, etc. into resin is used. ing. However, these flat powders have a problem that the manufacturing cost of the radio wave absorber is increased because the powder as a raw material is expensive and the cost of processing into a flat shape increases.
また、帯鋼の酸洗装置より回収して得た酸化鉄を水素ガス還元して、不純物および酸化膜の少ない還元鉄粉を製造する方法が提案されている（［特許文献６］）。しかしながら、得られた純鉄の微細な粒子（粒径０．１〜３．０μｍ）は、大気中では直ちに酸化され、発熱による自己燃焼という問題があった。
［第一の課題／還元剤］
一般に、排水の場合より汚染源の特定が困難な地下水の場合は、一段と重大な被害をもたらすことがあるので、汚染地下水の迅速な無害化、還元剤の活性の持続等の要求が一層強い。また土壌中、空気中には、排水、地下水の場合と異なり、気体の有機ハロゲン化合物が存在するので、これの効率的な無害化方法の確立が求められている。そこで、本発明では有機ハロゲン化合物を迅速に分解する方法に適した微細な複合鉄粉を提供することを目的としている。
[First issue / reducing agent]
In general, groundwater in which it is difficult to identify the source of pollution than in the case of drainage may cause even more serious damage. Therefore, demands such as quick detoxification of contaminated groundwater and sustained reductant activity are even stronger. In addition, unlike organic wastewater and groundwater, gaseous organohalogen compounds exist in soil and air, and therefore, establishment of an efficient detoxification method is required. Accordingly, an object of the present invention is to provide fine composite iron powder suitable for a method for rapidly decomposing an organic halogen compound.
［第二の課題／磁性材料］
また、本発明は、第二の従来技術で説明したような問題を解消し、高周波帯で機能を発揮できる安価な磁性材料であり、大気中でも酸化、発熱がしない複合磁性鉄粉とその製造方法、およびそれを用いた電波吸収体を提供することを目的としている。
[Second issue / magnetic materials]
In addition, the present invention solves the problems described in the second prior art, is an inexpensive magnetic material that can exhibit its function in a high frequency band, and is a composite magnetic iron powder that does not oxidize or generate heat in the atmosphere, and a method for producing the same And an electromagnetic wave absorber using the same.
上記二つの目的は、本発明者が、酸化鉄の還元により、従来の微細な鉄粉とは異なる成分を含有し、異なる構造を有する複合鉄粉を製造し、これの特性を見出したことに基づく下記の発明により達成される。 The above-mentioned two purposes are that the present inventor has produced a composite iron powder containing a component different from the conventional fine iron powder by reducing iron oxide and having a different structure, and has found the characteristics thereof. The following invention is achieved.
第一の発明は、マグネタイトを含有し、平均一次粒径が０．０１〜１０μｍであることを特徴とするマグネタイト−鉄複合粉末である。なお第一の発明のマグネタイト−鉄複合粉末を単に複合粉末とも称す。 A first invention is a magnetite-iron composite powder containing magnetite and having an average primary particle size of 0.01 to 10 μm. The magnetite-iron composite powder of the first invention is also simply referred to as composite powder.
好ましい第一の発明は、α−Ｆｅに対するマグネタイトのＸ線回折の強度比が０．００１〜５０であるマグネタイト−鉄複合粉末である。 A preferred first invention is a magnetite-iron composite powder having an intensity ratio of X-ray diffraction of magnetite to α-Fe of 0.001 to 50.
好ましい第一の発明は、前記マグネタイト−鉄複合粉末が、ニッケルを含有するマグネタイト−鉄複合粉末である。 In a preferred first invention, the magnetite-iron composite powder is a magnetite-iron composite powder containing nickel.
第二の発明は、平均一次粒径が０．０１〜１０μｍのヘマタイト粉末を還元性ガス中で加熱し、還元する際に、ヘマタイト粉末の還元を途中で停止し、粉末にマグネタイトを含有せしめることを特徴とするマグネタイト−鉄複合粉末の製造方法である。 In the second invention, when the hematite powder having an average primary particle size of 0.01 to 10 μm is heated in a reducing gas and reduced, the reduction of the hematite powder is stopped halfway and the magnetite is contained in the powder. Is a method for producing a magnetite-iron composite powder.
また、第三の発明は、平均一次粒径が０．０１〜１０μｍのヘマタイト粉末を還元性ガス中で加熱し、ヘマタイト粉末の還元を完了した後、酸素含有ガスで表面を酸化して、粉末にマグネタイトを含有せしめることを特徴とするマグネタイト−鉄複合粉末の製造方法である。 Further, the third invention is a method in which a hematite powder having an average primary particle size of 0.01 to 10 μm is heated in a reducing gas, and after the reduction of the hematite powder is completed, the surface is oxidized with an oxygen-containing gas, This is a method for producing a magnetite-iron composite powder characterized by containing magnetite in
第二〜第三の発明において、α−Ｆｅに対するマグネタイトのＸ線回折の強度比が０．００１〜５０であることが好ましく、前記還元性ガスは水素ガス、または一酸化炭素ガスが好ましく、これらの混合ガス、またはさらにメタンやエタンなどの炭化水素ガスを含んでいてもよい。 In the second to third inventions, the intensity ratio of X-ray diffraction of magnetite to α-Fe is preferably 0.001 to 50, and the reducing gas is preferably hydrogen gas or carbon monoxide gas. Or a hydrocarbon gas such as methane or ethane.
さらに、第二〜第三の発明のマグネタイト−鉄複合粉末として、ニッケルを含有するものを用いるのが好ましい。 Furthermore, it is preferable to use a nickel-containing powder as the magnetite-iron composite powder of the second to third inventions.
また、還元ガスが水素または一酸化炭素であるのが好ましい。 The reducing gas is preferably hydrogen or carbon monoxide.
第四の発明は、第一の発明のマグネタイト−鉄複合粉末を、樹脂および/ またはゴムと混合し、成形してなる電磁波吸収体である。 The fourth invention is an electromagnetic wave absorber formed by mixing the magnetite-iron composite powder of the first invention with a resin and / or rubber and molding the mixture.
該樹脂は熱硬化性樹脂または熱可塑性樹脂であるのが好ましい。 The resin is preferably a thermosetting resin or a thermoplastic resin.
高周波帯で使用する磁性材料として使用できる複合粉末を得ることができる。該複合粉末を用いて成形した磁性材料は、高周波帯で安定した透磁率や電磁波減衰率を安定して維持できる。
また、有機ハロゲン化合物の脱ハロゲンに使用される従来の鉄粉に比べ、比表面積が大きく、活性サイトが多いので、脱ハロゲン化速度が早く、活性が長期間持続する。よって、汚染土壌、汚染地下水、汚染空気の浄化の実用化に適している。
A composite powder that can be used as a magnetic material used in a high frequency band can be obtained. A magnetic material formed using the composite powder can stably maintain a stable magnetic permeability and electromagnetic wave attenuation rate in a high frequency band.
In addition, since the specific surface area is large and the number of active sites is larger than that of conventional iron powder used for dehalogenation of organic halogen compounds, the dehalogenation rate is high and the activity lasts for a long time. Therefore, it is suitable for practical use of purification of contaminated soil, contaminated groundwater, and contaminated air.
［土壌などの有機ハロゲン化合物の脱ハロゲン］
本発明者は、従来の鉄粉粒子において、鉄とともにマグネタイト相を共存させると、有機ハロゲン化合物の脱ハロゲン（還元）が促進され、有機ハロゲン化合物の無害化が促進されることを見い出した。したがって、本発明は表面の一部または全部にマグネタイトが露出した、一次粒径が０．０１〜１０μｍのマグネタイト−鉄複合粉末（以下、単に複合粉末とも称す）である。この複合粉末が有効な理由は、いまだ完全に解明された訳ではないが、マグネタイト相が鉄粉の表面に露出し、かつ鉄と接合界面を持って共存すると、露出したマグネタイト相の表面が、局部カソードとして作用することにより局部電池反応を促進しているためと推定される。なお、粒径は走査型電子顕微鏡（ＳＥＭ）で観察して測定した値である。
[Dehalogenation of organic halogen compounds such as soil]
The present inventor has found that in conventional iron powder particles, when a magnetite phase is allowed to coexist with iron, dehalogenation (reduction) of an organic halogen compound is promoted and detoxification of the organic halogen compound is promoted. Therefore, the present invention is a magnetite-iron composite powder (hereinafter, also simply referred to as composite powder) having a primary particle size of 0.01 to 10 μm with magnetite exposed on part or all of the surface. The reason why this composite powder is effective is not yet completely elucidated, but when the magnetite phase is exposed on the surface of the iron powder and coexists with iron and the bonding interface, the surface of the exposed magnetite phase becomes It is presumed that the local cell reaction is promoted by acting as a local cathode. The particle diameter is a value measured by observation with a scanning electron microscope (SEM).
すなわち、複合粉末表面近傍に、アノードとカソードが形成され、アノードでは鉄の酸化が、カソードでは有機ハロゲン化合物の還元が対になって起こる（局部電池反応）。該局部電池反応において、アノード・カソード間で電子の授受が行われる。したがって、局部カソードとして機能する相は、電気伝導性を有することが必須である。該還元により、脱ハロゲンされた有機化合物が生成されるため、汚染された土壌、地下水などの水、空気などのガスの浄化がなるものと推定される。 That is, an anode and a cathode are formed near the surface of the composite powder, and iron oxidation occurs at the anode and reduction of the organic halogen compound occurs at the cathode (local cell reaction). In the local cell reaction, electrons are transferred between the anode and the cathode. Therefore, it is essential that the phase functioning as the local cathode has electrical conductivity. The reduction produces a dehalogenated organic compound, which is presumed to purify contaminated soil, water such as groundwater, and gas such as air.
本発明の複合粉末はフェライト相単相であるのが好ましいが、オーステナイト相が５０質量％以下含有していてもよい。複合粉末の耐食性を向上させるため、フェライト相にニッケルを含有させることが好ましい。ニッケルの含有量は複合粉末の５０質量％以下であり、好ましくは５〜１０質量％である。 The composite powder of the present invention is preferably a ferrite phase single phase, but the austenite phase may contain 50% by mass or less. In order to improve the corrosion resistance of the composite powder, it is preferable to contain nickel in the ferrite phase. The content of nickel is 50% by mass or less of the composite powder, preferably 5 to 10% by mass.
本発明の複合粉末は、その平均一次粒径が１０μｍ以下であることが、鉄粉の比表面積を大きくでき、しいては有機ハロゲン化合物の還元能力を増大できることから重要である。平均一次粒径が１０μｍを超えると比表面積が低下し、前記還元能力が減少する。一方、平均一次粒径が０．０１μｍ未満であると、粒子間の付着力が増大し、粒子相互が凝集し、有機ハロゲン化合物の分解の場となる水や土への分散性が低下する。好ましいのは０．１〜１０μｍであり、特に好ましいのは０．２〜０．８μｍである。 It is important that the composite powder of the present invention has an average primary particle size of 10 μm or less because the specific surface area of the iron powder can be increased and the reducing ability of the organic halogen compound can be increased. When the average primary particle size exceeds 10 μm, the specific surface area decreases and the reducing ability decreases. On the other hand, if the average primary particle size is less than 0.01 μm, the adhesion between the particles increases, the particles agglomerate with each other, and the dispersibility in water and soil, which is a place for the decomposition of the organic halogen compound, decreases. Preferable is 0.1 to 10 μm, and particularly preferable is 0.2 to 0.8 μm.
本発明の複合粉末の磁性特性を活用する場合には、複合粉末が凝集していてもよく、特に鎖状に連結し、細長くなっているものが、磁性体としての異方性が強くなり、高周波域での透磁率が高くなるためと推考される。
磁性体として使用する場合の複合粉末の平均一次粒径は０．０５〜３μｍであるのが好ましく、０．１〜１μｍであるとさらに好ましい。
When utilizing the magnetic properties of the composite powder of the present invention, the composite powder may be agglomerated, especially those that are connected in a chain and elongated, increasing the anisotropy of the magnetic material, This is presumably because the permeability in the high frequency range is high.
The average primary particle size of the composite powder when used as a magnetic material is preferably 0.05 to 3 μm, and more preferably 0.1 to 1 μm.
本発明の複合粉末中のマグネタイト相は、粒子内部に存在しても、粒子表面を被覆する形態で存在しても差し支えないが、有機ハロゲン化合物の還元を目的とする場合は、局部カソードとなるマグネタイト相が複合粉末の表面に露出することが好ましい。複合粉末中のマグネタイト相の存在量は、Ｘ線回折による、α−Ｆｅに対するマグネタイトの回折強度比が０．００１〜５０の範囲である。より好ましくは０．０１〜５０である。０．００１未満であると、マグネタイト相による、還元の促進効果が低下し、５０を超えると、表面に露出する鉄の比率が低下し、同じく還元能力が低下する。 The magnetite phase in the composite powder of the present invention may be present inside the particle or in a form covering the particle surface, but when it is intended to reduce the organic halogen compound, it becomes a local cathode. It is preferable that the magnetite phase is exposed on the surface of the composite powder. The abundance of the magnetite phase in the composite powder is such that the diffraction intensity ratio of magnetite to α-Fe is 0.001 to 50 by X-ray diffraction. More preferably, it is 0.01-50. If it is less than 0.001, the effect of promoting reduction by the magnetite phase is reduced, and if it exceeds 50, the ratio of iron exposed to the surface is reduced, and the reducing ability is also reduced.
本発明の複合粉末は、酸化鉄としてマグネタイト（Ｆｅ3 Ｏ4 ）の他に、ウスタイト（ＦｅＯ）を含有していてもよい。 The composite powder of the present invention may contain wustite (FeO) in addition to magnetite (Fe 3 O 4 ) as iron oxide.
本発明の複合粉末の製造原料となる酸化鉄（ヘマタイト；Ｆｅ2 Ｏ3 ）は例えば、塩化鉄、硫酸鉄、硝酸鉄などの水溶液の噴霧焙焼によって製造される。焙焼条件を調整することにより、平均一次粒径が０．０１〜１０μｍ、好ましくは０．１〜１μｍの酸化鉄粉を製造することができる。酸化鉄粉の平均一次粒径が１０μｍを超えると、粒径が大きいため、複合粉末として用いた場合、高周波帯では透磁率が低下するので磁性材料として使用できない。また、平均一次粒径が０．０１μｍ未満となるとゴムや樹脂への分散性が悪くなり、電波吸収体などへの成形性が低下する。 The iron oxide (hematite; Fe 2 O 3 ) that is a raw material for producing the composite powder of the present invention is produced, for example, by spray roasting of an aqueous solution of iron chloride, iron sulfate, iron nitrate or the like. By adjusting the roasting conditions, it is possible to produce iron oxide powder having an average primary particle size of 0.01 to 10 μm, preferably 0.1 to 1 μm. When the average primary particle size of the iron oxide powder exceeds 10 μm, the particle size is large, so when used as a composite powder, the magnetic permeability is lowered in the high frequency band and cannot be used as a magnetic material. On the other hand, when the average primary particle size is less than 0.01 μm, the dispersibility in rubber or resin is deteriorated, and the moldability to a radio wave absorber is lowered.
Ｎｉ換算値で５０質量％を超えるＮｉ含有量のヘマタイトを還元して得た複合粉末は、高周波帯で磁性材料として使用できなくなるので、ヘマタイトのニッケル含有量は５０質量％以下であるのが好ましい。なお、鉄粉が純鉄粉であっても、複合粉末がＧＨｚの高周波帯で常に安定した透磁率や誘電率を維持することができる。 The composite powder obtained by reducing Ni content hematite exceeding 50% by mass in terms of Ni cannot be used as a magnetic material in the high frequency band, and therefore the nickel content of hematite is preferably 50% by mass or less. . Even if the iron powder is pure iron powder, the composite powder can always maintain stable permeability and dielectric constant in the high frequency band of GHz.
［複合粉末の製造方法］
本発明の複合粉末は、平均一次粒径が０．０１〜１０μｍのヘマタイト（Ｆｅ2 Ｏ3 ）を主成分とする酸化鉄を、例えば水素含有ガス中、２００〜７００℃で、１分〜３時間加熱還元して製造される。２００℃未満では、ヘマタイト粉末の還元が遅くなり、複合粉末の生産性が低下し、７００℃を超えると還元した鉄粉末が焼結して粒径が大きくなる。
還元によって得られる複合粉末は、平均一次粒径が０．０１〜１０μｍであり、粒子表面の一部または全部にマグネタイト相が露出し、残部は０価の鉄（Ｆｅ0 ）である。
[Production method of composite powder]
The composite powder of the present invention comprises iron oxide mainly composed of hematite (Fe 2 O 3 ) having an average primary particle size of 0.01 to 10 μm, for example, in a hydrogen-containing gas at 200 to 700 ° C. for 1 minute to 3 minutes. Manufactured by time reduction. When the temperature is lower than 200 ° C., the reduction of the hematite powder is slowed down, and the productivity of the composite powder is reduced.
The composite powder obtained by the reduction has an average primary particle size of 0.01 to 10 μm, the magnetite phase is exposed on part or all of the particle surface, and the balance is zero-valent iron (Fe 0 ).
還元温度が２００℃未満であると、還元反応速度が遅くなり、逆に還元温度が７００℃を超えると共存するウスタイトが増加し、マグネタイトの比率が低下する上、生成した複合粉末の焼結が進行する。好ましい還元温度は、十分な反応速度で還元が進行し、平衡状態でα−Ｆｅとマグネタイトの２相が共存する３００〜５７０℃である。また還元時間が１分未満の場合、還元が不十分でα−Ｆｅの存在比率が低い。逆に還元時間が３時間を超えると、還元が進みすぎ、複合粉末中の酸化鉄がＸ線回折による検出限界以下まで減少するうえ、生成した複合粉末の焼結が進行する。好ましい還元時間は５分〜１時間である。 If the reduction temperature is less than 200 ° C., the reduction reaction rate becomes slow. Conversely, if the reduction temperature exceeds 700 ° C., the coexisting wustite increases, the ratio of magnetite decreases, and the resulting composite powder is sintered. proceed. A preferable reduction temperature is 300 to 570 ° C. in which reduction proceeds at a sufficient reaction rate and two phases of α-Fe and magnetite coexist in an equilibrium state. When the reduction time is less than 1 minute, the reduction is insufficient and the abundance ratio of α-Fe is low. On the other hand, when the reduction time exceeds 3 hours, the reduction proceeds excessively, the iron oxide in the composite powder decreases to below the detection limit by X-ray diffraction, and sintering of the generated composite powder proceeds. The preferred reduction time is 5 minutes to 1 hour.
還元性ガスとして一酸化炭素ガスを用いる場合は、還元温度は３００〜９００℃であるのが好ましい。３００℃未満では、ヘマタイト粉末の還元が遅くなり、複合粉末の生産性が低下し、９００℃を超えると還元した鉄微細粉末が焼結して粒径が大きくなるからである。 When carbon monoxide gas is used as the reducing gas, the reduction temperature is preferably 300 to 900 ° C. When the temperature is lower than 300 ° C., the reduction of the hematite powder is slowed down, and the productivity of the composite powder is lowered. When the temperature exceeds 900 ° C., the reduced iron fine powder is sintered and the particle size is increased.
複合粉末中のマグネタイト相の存在量は、加熱還元時の還元温度と還元時間によって制御される。すなわち、還元温度を低く、および／または、還元時間を短くすることで、マグネタイト相の存在量を増加させることができ、還元温度を高く、および／または、還元時間を長くすることで還元を加速させ、マグネタイト相の存在量を低下させ、鉄単相を得ることも可能である。複合粉末を有機ハロゲン化合物の還元に使用する場合は、該複合粉末中のマグネタイト相の存在量は、Ｘ線回折による、α−Ｆｅに対するマグネタイトの回折強度比で０．００１〜５０の範囲であり、好ましくは０．０１〜５０、特に好ましくは０．５〜１．５の範囲である。もちろん、用途によっては、この比率に限定されることはない。 The abundance of the magnetite phase in the composite powder is controlled by the reduction temperature and reduction time during heat reduction. That is, the amount of magnetite phase can be increased by lowering the reduction temperature and / or shortening the reduction time, and the reduction can be accelerated by increasing the reduction temperature and / or lengthening the reduction time. It is also possible to reduce the abundance of the magnetite phase and obtain an iron single phase. When the composite powder is used for reduction of an organic halogen compound, the abundance of the magnetite phase in the composite powder is in the range of 0.001 to 50 in terms of the diffraction intensity ratio of magnetite to α-Fe by X-ray diffraction. , Preferably 0.01 to 50, particularly preferably 0.5 to 1.5. Of course, depending on the application, the ratio is not limited.
該回折強度比を得るための好適方法の第一は、ヘマタイトの加熱還元が１００％完了し、鉄単相となる以前に停止させることである。還元の進行程度は、予め還元温度における原料水素の露点Ｔd i を測定し、ヘマタイト還元中の排気水素中の露点Ｔd を観測することによって知ることができる。すなわち、ヘマタイトの加熱還元が完了する以前の段階では、還元によって発生する水の発生により、Ｔd がＴd i より高くなる。そこで、Ｔd ＞Ｔd i である間に反応を中断させればよい。 The first of the preferred methods for obtaining the diffraction intensity ratio is to stop the heat reduction of the hematite before it is 100% complete and becomes an iron single phase. Progress degree of reduction can be known by preliminarily the dew point T d i of raw hydrogen in the reduction temperature was measured, to observe the dew point T d in the exhaust hydrogen in hematite reduction. That is, before the heat reduction of hematite is completed, T d becomes higher than T d i due to the generation of water generated by the reduction. Therefore, it is sufficient to suspend the reaction between a T d> T d i.
該回折強度比を得るための好適方法の第二は、Ｔd ＞Ｔd i で還元を終了し、ヘマタイトを１００％還元して鉄単相とした後、水素ガスを一旦遮断し、不活性ガスと置換した後、鉄、マグネタイトの２相平衡共存領域である５７０℃以下の温度で、酸素含有ガスで鉄粒子を酸化して、マグネタイト相の比率を上げることによって行う。
なお、ヘマタイトを還元した後、急激な酸化による発熱や発火を防止するために、得られた複合粉末の表面を、酸素含有率の低い弱酸化性ガス雰囲気中で僅かに酸化するのが好ましい。
Second preferred method for obtaining a diffraction intensity ratio, and ends the reduction in T d> T d i, hematite 100% reduction to the after iron single phase, once cut off the hydrogen gas, inert After replacing the gas, the iron particles are oxidized with an oxygen-containing gas at a temperature of 570 ° C. or lower, which is a two-phase equilibrium coexistence region of iron and magnetite, and the ratio of the magnetite phase is increased.
After reducing the hematite, it is preferable to slightly oxidize the surface of the obtained composite powder in a weakly oxidizing gas atmosphere with a low oxygen content in order to prevent heat generation and ignition due to rapid oxidation.
［土壌などの浄化方法］
本発明の複合粉末が適用できる有機ハロゲン化合物は分子中に塩素などのハロゲンが結合したものであり、例えば、トリクロロエチレン（ＴＣＥと略記することがある）、テトラクロロエチレン、１，１，１−トリクロロエタン、１，１，２−トリクロロエタン、ジクロロエチレン、ジクロロエタン、ジクロロメタン、四塩化炭素等の揮発性の有機ハロゲン化合物が主であるが、ＰＣＢ，ダイオキシン等も対象とすることができる。
有機ハロゲン化合物は通常タンク、排水溝等から漏洩し、土壌に浸透して滞留するが、一部は土壌水分や地下水に僅かずつ溶解して存在し、他の一部は土壌中、空気中に気体で存在する。
[Soil purification methods]
The organic halogen compounds to which the composite powder of the present invention can be applied are those in which halogen such as chlorine is bonded in the molecule, such as trichloroethylene (sometimes abbreviated as TCE), tetrachloroethylene, 1,1,1-trichloroethane, 1 Volatile organic halogen compounds such as 1,2,2-trichloroethane, dichloroethylene, dichloroethane, dichloromethane, carbon tetrachloride are mainly used, but PCB, dioxin and the like can also be targeted.
Organohalogen compounds usually leak from tanks, drains, etc. and permeate and stay in the soil, but some are dissolved in soil moisture and groundwater little by little, and others are in the soil and air. Present in gas.
有機ハロゲン化合物は複合粉末により還元されて、非ハロゲン化合物のような無害な化合物とハロゲン化水素に変わる。例えばＴＣＥは複合粉末表面で電子を受け取り（還元され）、β脱離によりクロロアセチレンなどの中間体を経由して、アセチレンのような塩素を含まない化合物に変化して無害化される。あるいは、さらに還元が進む場合もあるが、いずれにしても複合粉末表面で電子を受け取る（還元される）ことを契機として反応が進み、結果として無害な化合物に変化する。 The organic halogen compound is reduced by the composite powder to be converted into a harmless compound such as a non-halogen compound and a hydrogen halide. For example, TCE receives (reduces) electrons on the surface of the composite powder, and is converted to a harmless compound such as acetylene through β-elimination via an intermediate such as chloroacetylene. Alternatively, the reduction may proceed further, but in any case, the reaction proceeds upon receiving (reducing) electrons on the surface of the composite powder, and as a result, the compound is changed to a harmless compound.
本発明の複合粉末は微細であり、しかも表面の一部または全部にマグネタイトが露出しているので、微細であるにも係わらず凝集が少なく、比表面積が大きく、有機ハロゲン化合物の還元能力が大きい。そのため、汚染土壌などの浄化のための使用量の低減が可能になる。 The composite powder of the present invention is fine, and because magnetite is exposed on part or all of the surface, it is fine but has little aggregation, a large specific surface area, and a large reducing ability of the organic halogen compound. . Therefore, it is possible to reduce the amount used for purification of contaminated soil and the like.
本発明の複合粉末は、従来公知の方法で、汚染土壌、汚染地下水、汚染空気に適用される。例えば、汚染土壌および／または汚染地下水に対しては、複合粉末または複合粉末のスラリーを散布、混合、圧入等の手段により適用し、複合粉末と有機ハロゲン化合物が接触するようにすればよい。土壌の含水率は４０質量％以上であるのが好ましい。その際、還元促進物質などを併用してもよい。 The composite powder of the present invention is applied to contaminated soil, contaminated groundwater and contaminated air by a conventionally known method. For example, a composite powder or a slurry of composite powder may be applied to contaminated soil and / or contaminated groundwater by means such as spraying, mixing, and press-fitting so that the composite powder and the organic halogen compound come into contact with each other. The moisture content of the soil is preferably 40% by mass or more. At that time, a reduction promoting substance may be used in combination.
掘削された汚染土壌に適用する場合も同様に、含水率、土質、土圧などを考慮して複合粉末、複合粉末混合物またはこれらのスラリーを散布、混合、圧入等の手段により適用し、複合粉末と有機ハロゲン化合物が接触するようにすればよい。掘削土壌が粘性で大粒径の場合は、土壌を予め粉砕して小粒径にしてから、複合粉末または複合粉末混合物を適用するのが好ましい。複合粉末または複合粉末混合物を添加した透過性の地中の層に地下水を通過させてもよい。 Similarly, when applied to excavated contaminated soil, the composite powder, composite powder mixture or slurry thereof is applied by means of spraying, mixing, press-fitting, etc. in consideration of moisture content, soil quality, earth pressure, etc. And the organic halogen compound may be in contact with each other. When the excavated soil is viscous and has a large particle size, it is preferable to apply the composite powder or composite powder mixture after the soil is previously pulverized to a small particle size. Groundwater may be passed through a permeable underground layer to which the composite powder or composite powder mixture has been added.
複合粉末の土壌、地下水に対する使用量は、汚染土壌の無害化処理方法のタイプ、汚染度合い等により適宜決定されるが、（１）汚染土壌、汚染地下水を現場で直接処理する方法の場合も、（２）汚染地下水を現場から汲み上げて（抽出）処理する方法の場合も、（３）汚染土壌を掘削して処理する方法の場合も一般的には０．１〜１０質量％、好ましくは０．５〜５質量％である。 The amount of composite powder used for soil and groundwater is appropriately determined according to the type of detoxification method for contaminated soil, the degree of contamination, etc. (1) In the case of direct treatment of contaminated soil and contaminated groundwater, (2) In the case of the method of pumping contaminated groundwater from the site (extraction) and the method of (3) the method of excavating and treating the contaminated soil, generally 0.1 to 10% by mass, preferably 0 0.5 to 5% by mass.
本発明の複合粉末を汚染空気に適用する場合は、例えば、複合粉末または複合粉末混合物を入れた容器に該空気を通過させ、接触さればよい。その場合、複合粉末表面が湿潤されている必要があるが、吸着水があれば良く、単分子層以上の水分子層が形成されているのが好ましい。空気の湿度は５０％以上であるのが好ましい。容器には、複合粉末の他に充填剤、還元促進物質などを混合してもよい。 When the composite powder of the present invention is applied to contaminated air, for example, the air may be passed through a container containing the composite powder or composite powder mixture and contacted. In this case, the surface of the composite powder needs to be moistened, but it is sufficient if there is adsorbed water, and it is preferable that a water molecule layer of a monomolecular layer or more is formed. The humidity of the air is preferably 50% or more. In addition to the composite powder, a filler, a reduction promoting substance, and the like may be mixed in the container.
種々の形状を有する磁性材料（例えば、電波吸収体）を製造する場合は、複合粉末にゴムおよび／または樹脂を混合して成形する。成形は加圧成形、射出成形、シート成形などの従来から公知の成形方法による。樹脂はポリエチレン、ポリプロピレン、ナイロン、エチレン−酢酸ビニル樹脂などの熱可塑性樹脂やエポキシ樹脂、フェノール樹脂などの熱硬化性樹脂が好ましい。ゴムはウレタンゴム、シリコーンゴムなどが好ましく、アクリル系エラストマー、スチレン−ブタジエン系エラストマーでも差し支えない。 When manufacturing magnetic materials (for example, radio wave absorbers) having various shapes, rubber and / or resin is mixed with the composite powder and molded. The molding is performed by a conventionally known molding method such as pressure molding, injection molding, or sheet molding. The resin is preferably a thermoplastic resin such as polyethylene, polypropylene, nylon, or ethylene-vinyl acetate resin, or a thermosetting resin such as epoxy resin or phenol resin. The rubber is preferably urethane rubber or silicone rubber, and may be an acrylic elastomer or a styrene-butadiene elastomer.
また、複合粉末を有機溶媒と混合して塗料化し、建物、容器、ケースなどの内壁や外壁に塗装して用いることもできる。このようにして製造した磁性材料は、数ＧＨｚの高周波域で安定した透磁率や電磁波減衰率が得られる。 Alternatively, the composite powder can be mixed with an organic solvent to form a paint, which can be used on the inner wall or outer wall of a building, container, case, or the like. The magnetic material manufactured in this manner can obtain a stable permeability and electromagnetic wave attenuation rate in a high frequency range of several GHz.
本発明の複合粉末の用途は前記に限定されない。例えば、硝酸の形態である窒素などの還元剤としても有効である。 The use of the composite powder of the present invention is not limited to the above. For example, it is also effective as a reducing agent such as nitrogen in the form of nitric acid.
［発明例１〜３、比較例１〜３］
［複合粉末の製造］
表１に示す平均一次粒径のヘマタイト粉末を、下記する条件（還元温度、還元時間、露点）で水素還元をし、あるいはさらに、下記する条件（温度、酸素分圧、酸化時間）の酸素酸化を行い（製法１〜２）、複合粉末を得た。
表１に還元停止時の排気水素中の露点と、酸化後の複合粉末のＸ線回折強度比を示した。
[Invention Examples 1-3, Comparative Examples 1-3]
[Production of composite powder]
The hematite powder having an average primary particle size shown in Table 1 is subjected to hydrogen reduction under the following conditions (reduction temperature, reduction time, dew point), or further, oxygen oxidation under the following conditions (temperature, oxygen partial pressure, oxidation time). (Production methods 1 and 2) to obtain a composite powder.
Table 1 shows the dew point in the exhaust hydrogen when the reduction is stopped and the X-ray diffraction intensity ratio of the composite powder after oxidation.
製法１： バッチ炉内で、原料ヘマタイト５０ｇを、水素中、４５０℃で還元した。予め測定した４５０℃での水素の露点は−３０℃であった。排気管の途中に露点計を配置し、露点が−３０℃以上の状態で還元を停止し、水素を遮断した後、不活性ガスに置換し、冷却した。常温に冷却された粉末に、５vol ％の酸素含有窒素を２時間当てた後、炉から取り出した。 Production Method 1: In a batch furnace, 50 g of raw material hematite was reduced at 450 ° C. in hydrogen. The dew point of hydrogen at 450 ° C. measured in advance was −30 ° C. A dew point meter was placed in the middle of the exhaust pipe. After the dew point was −30 ° C. or higher, the reduction was stopped, the hydrogen was shut off, and then replaced with an inert gas and cooled. After 5 hours of oxygen-containing nitrogen was applied to the powder cooled to room temperature for 2 hours, the powder was removed from the furnace.
製法２： バッチ炉内で、原料ヘマタイト５０ｇを、水素中、４５０℃で還元した。予め測定した５５０℃での水素の露点は−３０℃であった。排気管の途中に露点計を配置し、露点が−３０℃の状態で還元を停止し、水素を遮断した後、不活性ガスに置換し、冷却した。常温に冷却された粉末を、１０vol ％酸素含有窒素ガス中に６〜２４時間放置した後、炉から取り出した。 Production Method 2: In a batch furnace, 50 g of raw material hematite was reduced at 450 ° C. in hydrogen. The dew point of hydrogen measured at 550 ° C. in advance was −30 ° C. A dew point meter was placed in the middle of the exhaust pipe, and when the dew point was −30 ° C., the reduction was stopped and the hydrogen was shut off, and then replaced with an inert gas and cooled. The powder cooled to room temperature was left in 10 vol% oxygen-containing nitrogen gas for 6 to 24 hours, and then taken out from the furnace.
［複合粉末の構造］
還元、または還元−酸化して得られた複合粉末について、Ｘ線回折を行い、相の同定を行った。α−Ｆｅ、γ−Ｆｅ、酸化鉄の最強ピークの回折強度比（α−Ｆｅに対する強度比）を求めた。
また、各粉末の平均一次粒径はＳＥＭ写真から求めた。
[Structure of composite powder]
The composite powder obtained by reduction or reduction-oxidation was subjected to X-ray diffraction to identify phases. The diffraction intensity ratio of the strongest peaks of α-Fe, γ-Fe, and iron oxide (intensity ratio relative to α-Fe) was determined.
Moreover, the average primary particle diameter of each powder was calculated | required from the SEM photograph.
［複合粉末の性能／還元剤]
（１）１００mlのガラスバイアル瓶に４０mg/lの炭酸カルシウム、８０mg/lの亜硫酸ナトリウム、および５mg/lのＴＣＥの水溶液５０mlを入れ、さらに複合粉末５ｇを入れ、フッ素樹脂シール付きのブチルゴム栓とアルミキャップを用いて封入した。２３±２℃に管理した恒温室内で、該バイアル瓶の鉛直軸方向に１８０rpm で震とうした。震とう開始後、所定時間毎にそれぞれの瓶のヘッドスペースのＴＣＥガスの濃度をガス検知管を用いて分析し、ＴＣＥ水溶液中の濃度を算出した。一度開栓した瓶はその後の分析には供しなかった。
横軸に震とう時間（反応時間）、縦軸にＴＣＥ濃度をプロットし、初期濃度の半分の濃度になるまでの時間（ｈｒ）で、還元能力を評価した。結果を表１に示した。
[Composite powder performance / reducing agent]
(1) A 50 ml aqueous solution of 40 mg / l calcium carbonate, 80 mg / l sodium sulfite, and 5 mg / l TCE is placed in a 100 ml glass vial, and 5 g of composite powder is added. Encapsulated with an aluminum cap. In a thermostatic chamber controlled at 23 ± 2 ° C., the vial was shaken at 180 rpm in the vertical axis direction. After the start of shaking, the concentration of TCE gas in the head space of each bottle was analyzed using a gas detector tube every predetermined time, and the concentration in the TCE aqueous solution was calculated. Once opened, the bottle was not subjected to further analysis.
The abscissa time (reaction time) was plotted on the horizontal axis and the TCE concentration was plotted on the vertical axis, and the reducing ability was evaluated by the time (hr) until the concentration reached half of the initial concentration. The results are shown in Table 1.
（２）４０ｇのローム層土壌にＴＣＥ水溶液を加え、１００mg/kg のＴＣＥ汚染土壌を調製し、この土壌に、質量比１％の複合粉末を混合した。得られた土壌を、１２０mlのガラスバイアル瓶に封入した。該瓶を、２３±２℃に管理した恒温室に保管し、所定時間毎に瓶のヘッドスペースのＴＣＥガスの濃度をガスクロ／質量分析計を用いて分析した。複合粉末を添加していない土壌の濃度に対する、複合粉末を添加した土壌の濃度比をＴＣＥ残存率と見なし、保管（反応）を開始してから３日後の残存率で評価した。 (2) A TCE aqueous solution was added to 40 g of loam layer soil to prepare 100 mg / kg of TCE-contaminated soil, and a composite powder with a mass ratio of 1% was mixed with this soil. The obtained soil was sealed in a 120 ml glass vial. The bottle was stored in a thermostatic chamber controlled at 23 ± 2 ° C., and the concentration of TCE gas in the bottle headspace was analyzed using a gas chromatograph / mass spectrometer every predetermined time. The concentration ratio of the soil to which the composite powder was added relative to the concentration of the soil to which the composite powder was not added was regarded as the TCE residual rate, and the residual rate after 3 days from the start of storage (reaction) was evaluated.
［発明例４］
［複合粉末の製造]
平均粒径０．３μｍのヘマタイトを環状炉内で、露点−４０℃の水素中、５５０℃で還元した。還元中、発生する水分量の変化を把握するため、環状炉内の露点を露点計で測定した。露点はヘマタイトの還元時に発生する水分によって、一旦上昇するが、反応の終了時は−４０℃に収束するため、これを反応終了とみなした。その後、炉を常温まで冷却した後、雰囲気を一旦窒素に置換し、さらにその後、５vol ％酸素−窒素に再置換し、得られた金属粉末の表面を僅かに酸化させ、マグネタイトを形成させ、複合粉末を得た。
[Invention Example 4]
[Production of composite powder]
Hematite with an average particle size of 0.3 μm was reduced in a ring furnace at 550 ° C. in hydrogen having a dew point of −40 ° C. During the reduction, the dew point in the annular furnace was measured with a dew point meter in order to grasp the change in the amount of water generated. Although the dew point once rises due to moisture generated during the reduction of hematite, it converged to −40 ° C. at the end of the reaction, and this was regarded as the end of the reaction. Then, after cooling the furnace to room temperature, the atmosphere was once replaced with nitrogen, and then further replaced with 5 vol% oxygen-nitrogen, and the surface of the obtained metal powder was slightly oxidized to form magnetite. A powder was obtained.
［複合粉末の性能／電波吸収体]
得られた複合粉末の空気透過法による平均一次粒径は０．５５μｍであった。粉末のＸ線回折パターンを測定し、マグネタイトが０．２vol ％、残部がα−Ｆｅ単相であることが確認された（α−Ｆｅに対するマグネタイトの強度比＝０．００２）。複合粉末の磁化を振動試料式磁束計により、８００kA/mで測定した。
[Performance of composite powder / Radio wave absorber]
The average primary particle size of the obtained composite powder by the air permeation method was 0.55 μm. The X-ray diffraction pattern of the powder was measured, and it was confirmed that the magnetite was 0.2 vol% and the balance was an α-Fe single phase (magnetite to α-Fe strength ratio = 0.002). The magnetization of the composite powder was measured at 800 kA / m with a vibrating sample magnetometer.
複合粉末にエポキシ樹脂を１．２５質量％、ステアリン酸亜鉛を０．２５質量％混合し、外径１２mm、内径８mm、厚さ２mmのリング状に成形した後、樹脂を１８０℃で熱硬化させて、圧粉磁心を得た。圧粉磁心の比初透磁率は、インピーダンスアナライザーによって複素インピーダンスを測定することによって求めた。測定周波数は１０kHz 〜１GHz とし、１０kHz での比初透磁率（μri／μ0 ：１０k ）と、これが８割まで減少する周波数（臨界周波数 fcr）を測定した。以上の測定結果を表２に示した。
比較のため、市販のカルボニル鉄粉（平均粒径３．００μｍ）についても同様に成形し、測定した。結果を表２に合わせて示す。
The composite powder is mixed with 1.25% by mass of epoxy resin and 0.25% by mass of zinc stearate and formed into a ring shape with an outer diameter of 12 mm, an inner diameter of 8 mm, and a thickness of 2 mm, and the resin is thermoset at 180 ° C. Thus, a dust core was obtained. The relative initial permeability of the dust core was determined by measuring the complex impedance with an impedance analyzer. The measurement frequency was 10 kHz to 1 GHz, and the relative initial magnetic permeability (μ ri / μ 0 : 10k) at 10 kHz and the frequency at which this decreased to 80% (critical frequency f cr ) were measured. The above measurement results are shown in Table 2.
For comparison, a commercially available carbonyl iron powder (average particle size of 3.00 μm) was similarly molded and measured. The results are shown in Table 2.
粉末の磁化は、どちらも純鉄の磁化の値（２．１５８０Wb/m2 ）と同等であり、磁気的に純鉄であることが確認された。圧粉磁心とした場合、同一密度で比較すると、発明例２４の複合鉄粉の方が、カルボニル鉄粉よりも僅かに比初透磁率が低いが、臨界周波数は高く、高周波域まで比初透磁率が安定であることが確認された。 Both of the magnetizations of the powder were equivalent to the magnetization value of pure iron (2.1580 Wb / m 2 ), and it was confirmed that the powder was magnetically pure iron. In the case of a dust core, when compared at the same density, the composite iron powder of Invention Example 24 has a slightly lower relative initial permeability than carbonyl iron powder, but the critical frequency is higher and the relative initial permeability up to the high frequency range. It was confirmed that the magnetic susceptibility is stable.
［発明例５］
［複合粉末の製造]
表３に示す平均一次粒径のヘマタイト粉末を、箱型炉中、表３に示す条件で水素ガス還元し、室温まで冷却した後、５Vol%酸素−窒素混合ガス中で２時間酸化した。
得られた粉末をＸ線回折し、観測された各相の最大ピークの比より、各相の体積比を求めた。結果を表３に示した。複合粉末は、α−Ｆｅ、マグネタイトが主相である。つぎに、ＳＥＭ−ＥＤＸより鉄粉と非鉄粉末を識別しつつ、各々の平均一次粒径を測定した、結果を表３に示した。
[Invention Example 5]
[Production of composite powder]
The hematite powder having an average primary particle size shown in Table 3 was reduced with hydrogen gas in a box furnace under the conditions shown in Table 3, cooled to room temperature, and then oxidized in a 5 Vol% oxygen-nitrogen mixed gas for 2 hours.
The obtained powder was subjected to X-ray diffraction, and the volume ratio of each phase was determined from the observed ratio of the maximum peak of each phase. The results are shown in Table 3. The composite powder is mainly composed of α-Fe and magnetite. Next, the average primary particle size of each was measured while identifying iron powder and non-ferrous powder from SEM-EDX. The results are shown in Table 3.
［複合粉末の性能／電波吸収体]
つぎに、得られた複合粉末をエチレンー酢酸ビニル樹脂と各質量比で混合し、０．５mm厚さのシートとし、１．８〜１８GHz での電磁波の減衰率を測定した。
表３より、発明例５では、良好な電磁波の減衰率が得られたことがわかる。
[Performance of composite powder / Radio wave absorber]
Next, the obtained composite powder was mixed with ethylene-vinyl acetate resin at various mass ratios to obtain a 0.5 mm thick sheet, and the attenuation factor of electromagnetic waves at 1.8 to 18 GHz was measured.
From Table 3, it can be seen that in Invention Example 5, a good electromagnetic wave attenuation rate was obtained.
１：円筒容器
２：ヘマタイト
３：コークス粉および炭酸カルシウムの混合粉
1: Cylindrical container 2: Hematite 3: Mixed powder of coke powder and calcium carbonate
Claims (6)
An electromagnetic wave absorber formed by mixing and molding the magnetite-iron composite powder according to any one of claims 1 to 3 and rubber and / or resin.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2004376199A JP4158768B2 (en) | 2000-11-30 | 2004-12-27 | Magnetite-iron composite powder, method for producing the same, and radio wave absorber |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000364966 | 2000-11-30 | ||
| JP2001038954 | 2001-02-15 | ||
| JP2001038957 | 2001-02-15 | ||
| JP2004376199A JP4158768B2 (en) | 2000-11-30 | 2004-12-27 | Magnetite-iron composite powder, method for producing the same, and radio wave absorber |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2001366521A Division JP3867562B2 (en) | 2000-11-30 | 2001-11-30 | Magnetite-iron composite powder mixture, production method thereof, and radio wave absorber |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2005179185A true JP2005179185A (en) | 2005-07-07 |
| JP4158768B2 JP4158768B2 (en) | 2008-10-01 |
Family
ID=34799684
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2004376199A Expired - Fee Related JP4158768B2 (en) | 2000-11-30 | 2004-12-27 | Magnetite-iron composite powder, method for producing the same, and radio wave absorber |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4158768B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100429023C (en) * | 2006-09-20 | 2008-10-29 | 电子科技大学 | Magnetic micro powder and method for making same |
| KR100874370B1 (en) | 2007-03-28 | 2008-12-18 | 한국과학기술연구원 | Removal method of chlorine compound by soil mineral with transition metal added |
| JP2009088496A (en) * | 2007-09-12 | 2009-04-23 | Seiko Epson Corp | Method of manufacturing oxide-coated soft magnetic powder, oxide-coated soft magnetic powder, dust core, and magnetic element |
-
2004
- 2004-12-27 JP JP2004376199A patent/JP4158768B2/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100429023C (en) * | 2006-09-20 | 2008-10-29 | 电子科技大学 | Magnetic micro powder and method for making same |
| KR100874370B1 (en) | 2007-03-28 | 2008-12-18 | 한국과학기술연구원 | Removal method of chlorine compound by soil mineral with transition metal added |
| JP2009088496A (en) * | 2007-09-12 | 2009-04-23 | Seiko Epson Corp | Method of manufacturing oxide-coated soft magnetic powder, oxide-coated soft magnetic powder, dust core, and magnetic element |
Also Published As
| Publication number | Publication date |
|---|---|
| JP4158768B2 (en) | 2008-10-01 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP3867562B2 (en) | Magnetite-iron composite powder mixture, production method thereof, and radio wave absorber | |
| US6827757B2 (en) | Magnetite-iron based composite powder, magnetite-iron based powder mixture, method for producing the same, method for remedying polluted soil, water or gases and electromagnetic wave absorber | |
| Yu et al. | Oxygen-defective MnO2− x rattle-type microspheres mediated singlet oxygen oxidation of organics by peroxymonosulfate activation | |
| US7220366B2 (en) | Process for purifying contaminated soil or groundwater with iron particles | |
| Kim et al. | Aging characteristics and reactivity of two types of nanoscale zero-valent iron particles (FeBH and FeH2) in nitrate reduction | |
| Moura et al. | Highly reactive species formed by interface reaction between Fe0–iron oxides particles: an efficient electron transfer system for environmental applications | |
| Do et al. | Persulfate reactivity enhanced by Fe2O3–MnO and CaO–Fe2O3–MnO composite: identification of composite and degradation of CCl4 at various levels of pH | |
| JP5299983B2 (en) | Porous iron powder, method for producing porous iron powder, electromagnetic wave absorber | |
| Magalhães et al. | Novel highly reactive and regenerable carbon/iron composites prepared from tar and hematite for the reduction of Cr (VI) contaminant | |
| JP4158768B2 (en) | Magnetite-iron composite powder, method for producing the same, and radio wave absorber | |
| JP2007046074A (en) | Fine metal particle and manufacturing method therefor | |
| JP4639029B2 (en) | Soil contaminated with toxic substances such as heavy metals, iron composite particle powder for purification treatment of soil and groundwater, its manufacturing method, purification agent containing the iron composite particle powder, its manufacturing method and soil contaminated with toxic substances such as heavy metals Groundwater purification method | |
| JP4352215B2 (en) | Iron composite particle powder for purification treatment of soil and groundwater containing aromatic halogen compounds, its production method, purification agent containing said iron composite particle powder, its production method, and purification treatment of soil and groundwater containing aromatic halogen compounds Method | |
| JP4433173B2 (en) | Iron composite particle powder for purification treatment of soil and groundwater, production method thereof, purification agent containing the iron composite particle powder, production method thereof, and purification treatment method of soil and groundwater | |
| JP3804680B2 (en) | Purification of contaminated soil, water and gas with magnetite-iron composite powder | |
| JP4626762B2 (en) | Noble metal-carrying iron complex for soil and groundwater purification treatment, purification agent containing noble metal-carrying iron complex, and soil and groundwater purification method | |
| JP2004331996A (en) | Sponge iron for reducing agent, its production method and its application | |
| Lee et al. | Ferromagnetic multiphase FeNi oxide and pure Fe3O4 induced by water-gas shift reaction: Magnetization and supercapacitor application | |
| JP5148824B2 (en) | Magnetite powder, method for producing magnetite powder | |
| JP4106545B2 (en) | Iron composite particle powder for the purification treatment of soil and groundwater containing an organic halogen compound, its production method, a purification agent containing the iron composite particle powder, its production method and a purification method for soil and groundwater containing an organic halogen compound | |
| JP4833505B2 (en) | Iron powder for purification | |
| JP2013208527A (en) | Iron composite particle powder for purifying soil, ground water, and waste water, purifying agent including the iron composite particle powder, and method for purifying soil, ground water, and waste water contaminated by organic halogen compound | |
| JP4557126B2 (en) | Iron composite particle powder for purification treatment of soil and groundwater contaminated with organic halogen compounds, its production method, purification agent containing the iron composite particle powder, its production method and purification treatment of soil and groundwater contaminated with organic halogen compounds Method | |
| WO2007029736A1 (en) | Porous iron powder, process for producing the same and radio wave absorber | |
| Peng et al. | Microwave-assisted synthesis and high dechlorination activity of magnetic FeNi broom-like nanostructures |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20080408 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20080603 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20080624 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20080707 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 Ref document number: 4158768 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110725 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110725 Year of fee payment: 3 |
|
| S111 | Request for change of ownership or part of ownership |
Free format text: JAPANESE INTERMEDIATE CODE: R313113 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110725 Year of fee payment: 3 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110725 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120725 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120725 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130725 Year of fee payment: 5 |
|
| LAPS | Cancellation because of no payment of annual fees |