JP2018170330A - Soft magnetic metal powder - Google Patents
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本発明は、高周波帯域の電磁波吸収シートなどの製品に使用される扁平形状を有する軟磁性金属粉体に関し、特に、比較的大なる比表面積を有しながらも難燃性に優れて取り扱いの容易な軟磁性金属粉体に関する。 The present invention relates to a soft magnetic metal powder having a flat shape used for products such as an electromagnetic wave absorbing sheet in a high frequency band, and in particular, has a relatively large specific surface area and is excellent in flame retardancy and easy to handle. It relates to a soft magnetic metal powder.
電磁波を吸収する電磁波吸収シートは、電子機器の筐体の内面に沿って与えられて、内部基板等からの電磁波を筐体外部へ漏出することを防ぎ、あるいは筐体外部からの電磁波から内部基板を保護する目的で使用され得る。かかる電磁波吸収シートのうち、ゴムや樹脂からなる可撓性を有するシート体の内部に扁平形状に加工された軟磁性金属粉体を配向分散させた複合電磁波吸収シートは、小型・軽量化を要求される通信電子機器などに広く用いられている。 The electromagnetic wave absorbing sheet that absorbs electromagnetic waves is provided along the inner surface of the housing of the electronic device, and prevents electromagnetic waves from the internal substrate etc. from leaking to the outside of the housing or from the electromagnetic waves from the outside of the housing. Can be used for the purpose of protecting. Among such electromagnetic wave absorbing sheets, a composite electromagnetic wave absorbing sheet in which soft magnetic metal powder processed into a flat shape is oriented and dispersed inside a flexible sheet made of rubber or resin requires a reduction in size and weight. Widely used in communication electronic devices.
例えば、特許文献１では、アスペクト比を３以上とし表面に酸化物層からなる絶縁被膜を与えたＦｅ−Ｓｉ−Ａｌ系合金粉体を結合剤や難燃剤とともに混和物としてロール成形して得られる複合電磁波吸収シートを開示している。かかる複合電磁波吸収シートは、高周波帯域の電磁波吸収シートとして、これを用いた電子機器が出火するような万一の場合に備え、米国ＵＬ規格の難燃性を確保すべく、難燃剤をシート体に与えたものである。 For example, in Patent Document 1, an Fe—Si—Al alloy powder having an aspect ratio of 3 or more and provided with an insulating film composed of an oxide layer on the surface is roll-formed as an admixture together with a binder and a flame retardant. A composite electromagnetic wave absorbing sheet is disclosed. Such a composite electromagnetic wave absorbing sheet is used as a high frequency band electromagnetic wave absorbing sheet in the event that an electronic device using the same catches fire, and in order to ensure the flame resistance of the US UL standard, a flame retardant is used as a sheet body. It is given to.
ところで、微小粉体が大気中で急激に酸化して自然発火する現象が知られているが、Ｆｅ−Ｓｉ系などの軟磁性金属粉体では、製造工程においてその表面に不可避的に酸化皮膜が形成されるため、簡単には大気中でも発火しない。 By the way, a phenomenon is known in which fine powders are rapidly oxidized in the atmosphere and spontaneously ignited. In soft magnetic metal powders such as Fe-Si, an oxide film is inevitably formed on the surface in the manufacturing process. Because it is formed, it does not ignite easily in the atmosphere.
例えば、特許文献２では、Ｆｅ−Ｓｉ−Ａｌ系合金粉体において、バインダとともに圧縮成形したときに、粉体表面にＡｌ２Ｏ３、Ｆｅ３Ｏ４、ＳｉＯ２などの酸化皮膜が不可避的に形成されることを開示している。粉体の厚さを１０〜３０μｍ、且つアスペクト比を３〜２０となるように扁平化すると、粉体表面の酸化皮膜の厚さは０．０５μｍ程度となったとしている。 For example, in Patent Document 2, when an Fe—Si—Al alloy powder is compression-molded with a binder, an oxide film such as Al 2 O 3 , Fe 3 O 4 , or SiO 2 is inevitably formed on the powder surface. It is disclosed that it is formed. When the powder is flattened so as to have a thickness of 10 to 30 μm and an aspect ratio of 3 to 20, the thickness of the oxide film on the powder surface is about 0.05 μm.
Ｆｅ−Ｓｉ系などの軟磁性金属粉体は、比較的低い電気抵抗値であるため、高い周波数の電磁波ほど電流が粉体の表面だけに集中しやすくなる（表皮効果）。そのため、高周波帯域の電磁波の良好な吸収を得られるようにするためには、軟磁性金属粉体をより小さく、又はより扁平化しなければならない。このとき、粉体の比表面積が大きくなってより酸化しやすくなり、粉体表面にある程度の酸化皮膜が形成されていたとしても発火し易くなるため、その取り扱いは難しくなる。加えて、電磁波吸収シートなどの製品に適用する場合に保磁力が低いことも磁気特性として必要とされ、その低い保磁力も維持されなければならない。 Since soft magnetic metal powders such as Fe—Si have a relatively low electric resistance value, the higher the frequency of electromagnetic waves, the easier the current is concentrated on the surface of the powder (skin effect). Therefore, in order to obtain good absorption of electromagnetic waves in the high frequency band, the soft magnetic metal powder must be made smaller or flatter. At this time, the specific surface area of the powder is increased and the powder is more easily oxidized, and even if a certain amount of oxide film is formed on the powder surface, the powder is easily ignited, so that the handling becomes difficult. In addition, when applied to a product such as an electromagnetic wave absorbing sheet, a low coercive force is also required as a magnetic property, and the low coercive force must be maintained.
そこで、高周波帯域の電磁波吸収シートなどの製品に使用される扁平形状を有する軟磁性金属粉体については、その酸化皮膜と比表面積、及び難燃性（燃焼性）との間の関係を考慮することが必要となる。なお、この点、特許文献１では、酸化物層の厚みに比表面積を積算した酸化物量について述べているが、非磁性成分である酸化物量が多くなると、磁性成分が減じられ電磁干渉抑制作用を得られなくなることを述べているに過ぎず、難燃性（燃焼性）との間の関係について述べられたものではない。 Therefore, regarding the soft magnetic metal powder having a flat shape used for products such as electromagnetic wave absorbing sheets in a high frequency band, the relationship between the oxide film, specific surface area, and flame retardancy (combustibility) is considered. It will be necessary. In this regard, Patent Document 1 describes the amount of oxide obtained by adding the specific surface area to the thickness of the oxide layer. However, when the amount of the non-magnetic component oxide increases, the magnetic component is reduced and the electromagnetic interference suppression action is achieved. It merely states that it cannot be obtained, and does not describe the relationship between flame retardancy (flammability).
本発明は、以上のような状況に鑑みてなされたものであって、その目的とするところは、扁平形状を有する軟磁性金属粉体において、電磁波吸収能（電磁シールド性）に優れるよう保磁力を低く維持することはもちろんのこと、その酸化皮膜と比表面積、及び難燃性（燃焼性）との間の関係を考慮し、比較的大なる比表面積を有しながらも難燃性に優れて取り扱いの容易な軟磁性金属粉体を提供することにある。 The present invention has been made in view of the situation as described above. The object of the present invention is to provide a soft magnetic metal powder having a flat shape so as to have excellent electromagnetic wave absorption capability (electromagnetic shielding properties). Considering the relationship between the oxide film, specific surface area, and flame retardancy (combustibility), it is excellent in flame retardancy while having a relatively large specific surface area. Another object is to provide a soft magnetic metal powder that is easy to handle.
本発明による軟磁性金属粉体は、Ｆｅ−Ｓｉ−Ｃｒ系合金又はＦｅ−Ｓｉ−Ａｌ系合金からなり、平均粒径Ｄ５０を３０μｍ以下でアスペクト比を１０以上とする扁平形状に加工されて保磁力Ｈｃを２０Ｏｅ以下とする軟磁性金属粉体であって、表面酸化皮膜を有し、比表面積ＢＥＴ値（ｍ２／ｇ）と表面から１０ｎｍ深さまでのＯの積算量値（原子％）との積を２１００以下とするように加工されていることを特徴とする。 The soft magnetic metal powder according to the present invention is made of a Fe—Si—Cr alloy or a Fe—Si—Al alloy, and is processed into a flat shape having an average particle diameter D50 of 30 μm or less and an aspect ratio of 10 or more. A soft magnetic metal powder having a magnetic force Hc of 20 Oe or less, having a surface oxide film, a specific surface area BET value (m 2 / g) and an integrated amount value (atomic%) of O from the surface to a depth of 10 nm It is processed so that the product of may be 2100 or less.
かかる発明によれば、保磁力を低く維持しつつ、表面酸化皮膜によって比較的大なる比表面積を有しながらも難燃性を得られ、取り扱いが容易なのである。 According to this invention, while maintaining the coercive force low, flame retardancy can be obtained while having a relatively large specific surface area by the surface oxide film, and handling is easy.
上記した発明において、質量％で、Ｓｉを３〜２０％、Ｃｒを１〜４％でそれぞれ含み、残部Ｆｅ及び不可避的不純物からなる成分組成のＦｅ−Ｓｉ−Ｃｒ系合金からなることを特徴としてもよい。かかる発明によれば、表面酸化皮膜としてＣｒ酸化物からなる不働態皮膜を比較的容易に形成させ得て、保磁力を低く維持しつつ、表面酸化皮膜によって比較的大なる比表面積を有しながらも難燃性を得られ、取り扱いが容易なのである。 In the above-described invention, it is characterized by comprising Fe-Si-Cr-based alloy having a component composition comprising 3 to 20% of Si and 1 to 4% of Cr, and the balance of Fe and inevitable impurities. Also good. According to this invention, a passive film made of Cr oxide can be formed relatively easily as a surface oxide film, and the surface oxide film has a relatively large specific surface area while maintaining a low coercive force. It is easy to handle.
上記した発明において、質量％で、Ｓｉ：５〜２０％、Ａｌを５．０〜６．５％でそれぞれ含み、残部Ｆｅ及び不可避的不純物からなる成分組成のＦｅ−Ｓｉ−Ａｌ系合金からなることを特徴としてもよい。かかる発明によれば、表面酸化皮膜としてＡｌの酸化物からなる皮膜を比較的容易に形成させ得て、保磁力を低く維持しつつ、表面酸化皮膜によって比較的大なる比表面積を有しながらも難燃性を得られ、取り扱いが容易なのである。 In the above-mentioned invention, it is composed of a Fe—Si—Al-based alloy having a component composition comprising, by mass%, Si: 5 to 20% and Al of 5.0 to 6.5%, and the balance Fe and unavoidable impurities. This may be a feature. According to this invention, a film made of an oxide of Al can be formed relatively easily as a surface oxide film, and while maintaining a low coercive force, the surface oxide film has a relatively large specific surface area. It is flame retardant and easy to handle.
上記した発明において、ビッカース硬さを３００ＨＶ以上とすることを特徴としてもよい。更に、比表面積ＢＥＴ値（ｍ２／ｇ）を６以下とすることを特徴としてもよい。かかる発明によれば、確実に難燃性を得られ、取り扱いがより容易なのである。 In the above-described invention, the Vickers hardness may be 300 HV or more. Furthermore, the specific surface area BET value (m 2 / g) may be 6 or less. According to this invention, flame retardance can be reliably obtained, and handling is easier.
本発明による１つの実施例としての軟磁性金属粉体について、図１を用いて説明する。 A soft magnetic metal powder as one embodiment according to the present invention will be described with reference to FIG.
図１は、後述する実施例３の扁平形状の軟磁性金属粉体１を樹脂に埋め込んで研磨した断面顕微鏡写真である。軟磁性金属粉体１は、表面酸化皮膜に覆われており、この表面酸化皮膜によって粉体同士の絶縁が得られるとともに、難燃性が確保されるのである。この点については後述する。また、軟磁性金属粉体１は、その平均粒径Ｄ５０を３０μｍ以下とし、そのアスペクト比を１０以上とする扁平形状に加工されており、例えば電磁波吸収シートに用いられる場合、ゴムや樹脂などからなる薄膜状のシートの主面に沿って配向するように埋め込まれる。なお、例えば、数ＭＨｚ〜数十ＧＨｚの高周波帯域の電磁波吸収シートの用途において、軟磁性金属粉体１の保磁力Ｈｃは２０Ｏｅ（エルステッド）以下、平均粒径Ｄ５０は１０〜２０μｍの範囲内とすることが好ましい。 FIG. 1 is a cross-sectional photomicrograph obtained by embedding a flat soft magnetic metal powder 1 of Example 3 described later in a resin and polishing it. The soft magnetic metal powder 1 is covered with a surface oxide film. The surface oxide film provides insulation between the powders and ensures flame retardancy. This point will be described later. The soft magnetic metal powder 1 is processed into a flat shape having an average particle diameter D50 of 30 μm or less and an aspect ratio of 10 or more. For example, when used for an electromagnetic wave absorbing sheet, the soft magnetic metal powder 1 is made of rubber or resin. It is embedded so as to be oriented along the main surface of the thin film sheet. For example, in the use of an electromagnetic wave absorbing sheet in a high frequency band of several MHz to several tens GHz, the coercive force Hc of the soft magnetic metal powder 1 is 20 Oe (Oersted) or less, and the average particle diameter D50 is in the range of 10 to 20 μm. It is preferable to do.
特に、軟磁性金属粉体１は、比表面積であるＢＥＴ値（ｍ２／ｇ）が所定値になるように加工されるが、表面から１０ｎｍ深さまでのＯの積算量値（原子％）にこのＢＥＴ値を掛け合わせた積が２１００以下となるように加工されている。これにより、上記したような保磁力を維持できて、例えば電磁波吸収シートに組み込まれたときに、数ＭＨｚ〜数十ＧＨｚの高周波帯域の電磁波に対する高い電磁波吸収能を得られる。その一方、粉体としては消防法第２類第１種可燃性固体に該当せず、その取り扱いが容易となるのである。 In particular, the soft magnetic metal powder 1 is processed so that the BET value (m 2 / g), which is a specific surface area, becomes a predetermined value, but the accumulated amount value (atomic%) of O from the surface to a depth of 10 nm. The product obtained by multiplying the BET values is processed to be 2100 or less. Thereby, the above-mentioned coercive force can be maintained, and when it is incorporated into an electromagnetic wave absorbing sheet, for example, a high electromagnetic wave absorbing ability with respect to electromagnetic waves in a high frequency band of several MHz to several tens GHz can be obtained. On the other hand, the powder does not fall under the Fire Service Law Type 2 Class 1 flammable solid, and its handling becomes easy.
なお、ＢＥＴ値を大きくするように軟磁性金属粉体１を加工すると、粉体がより酸化し易く燃焼しやすくなるため、表面酸化皮膜をより確実に与えることが必要となる。一方、表面酸化皮膜の量が多すぎると磁気特性を劣化させてしまう。そこで、ＢＥＴ値とＯの積算量値との積の上限が規定されるのである。 If the soft magnetic metal powder 1 is processed so as to increase the BET value, the powder is more likely to be oxidized and burned, so that it is necessary to provide a surface oxide film more reliably. On the other hand, if the amount of the surface oxide film is too large, the magnetic properties are deteriorated. Therefore, the upper limit of the product of the BET value and the integrated amount value of O is defined.
ここで、軟磁性金属粉体１は、Ｆｅ−Ｓｉ−Ｃｒ系合金又はＦｅ−Ｓｉ−Ａｌ系合金による軟磁性合金からなる。表面酸化皮膜は、Ｆｅ−Ｓｉ−Ｃｒ系合金ではＣｒ酸化物によるいわゆる不働態酸化皮膜、Ｆｅ−Ｓｉ−Ａｌ系合金ではＡｌの酸化物からなる酸化皮膜となる。 Here, the soft magnetic metal powder 1 is made of a soft magnetic alloy made of Fe—Si—Cr alloy or Fe—Si—Al alloy. The surface oxide film is a so-called passive oxide film made of Cr oxide in the case of an Fe—Si—Cr alloy, and an oxide film made of an oxide of Al in the case of an Fe—Si—Al alloy.
また、このＦｅ−Ｓｉ−Ｃｒ系合金としては、例えば、質量％で、Ｆｅに、Ｓｉを３〜２０％、Ｃｒを１〜４％でそれぞれ含む成分組成であることが好ましい。さらに好ましくは、Ｓｉ：６〜１６％、Ｃｒ：２〜３％の範囲内である。Ｃｒは軟磁性金属粉体１の磁気特性を考慮してその上限を定め得る。また、Ｆｅ−Ｓｉ−Ａｌ系合金としては、例えば、質量％で、Ｆｅに、Ｓｉ：５〜２０％、Ａｌを５．０〜６．５％でそれぞれ含む成分組成であることが好ましい。かかる成分組成とすることで、特別な表面処理を加えることなく比較的容易に上記したような表面酸化皮膜を得られるのである。なお、Ｓｉを含有すると軟磁性金属粉体１の硬さが高くなるが、上記した平均粒径Ｄ５０、アスペクト比、そして加工によって生じる微粉量などをバランスよく得られるようになる。 Moreover, as this Fe-Si-Cr-type alloy, it is preferable that it is a mass composition, for example, and it is the component composition which respectively contains 3-20% of Si and 1-4% of Cr in Fe. More preferably, it is in the range of Si: 6 to 16% and Cr: 2 to 3%. The upper limit of Cr can be determined in consideration of the magnetic properties of the soft magnetic metal powder 1. Moreover, as a Fe-Si-Al type-alloy, it is preferable that it is a component composition which contains Si: 5-20% and Al by 5.0-6.5%, respectively, by mass%, for example. By adopting such a component composition, the surface oxide film as described above can be obtained relatively easily without any special surface treatment. When Si is contained, the hardness of the soft magnetic metal powder 1 is increased, but the above-described average particle diameter D50, aspect ratio, and the amount of fine powder generated by processing can be obtained in a balanced manner.
次に、軟磁性金属粉体１の製造方法について図２に沿って説明するが、上記した数値の範囲を得られれば、製造方法は特に以下に限定されるものではない。 Next, although the manufacturing method of the soft magnetic metal powder 1 is demonstrated along FIG. 2, if the above-mentioned numerical range is obtained, a manufacturing method will not be specifically limited to the following.
図２に示すように、Ｆｅ−Ｓｉ−Ｃｒ系合金又はＦｅ−Ｓｉ−Ａｌ系合金の合金溶湯を粉体化して、合金粉体を得る（Ｓ１）。ここではアトマイズ法により粉体化を行う。すなわち、アトマイズ装置にて合金溶湯を流下させつつ水又はガスを吹きつけて、合金溶湯を分断して落下させ、急冷し凝固させて、合金粉体を得るのである。 As shown in FIG. 2, a molten alloy of Fe—Si—Cr alloy or Fe—Si—Al alloy is pulverized to obtain an alloy powder (S1). Here, pulverization is performed by an atomizing method. That is, water or gas is sprayed while flowing down the molten alloy with an atomizer, and the molten alloy is divided and dropped, rapidly cooled and solidified to obtain an alloy powder.
続いて、合金粉体を扁平化加工処理する（Ｓ２）。詳細には、合金粉体を有機溶媒や、粉砕助剤などとともにアトライター装置の容器内部に投入し、更にこの中に鋼球などの粉砕媒体を装填する。そして、周面に回転羽根を設けられた攪拌棒を回転させて、容器内を攪拌すると、粉砕媒体が合金粉体に衝突し衝撃を与えて合金粉体を粉砕させながら平たく変形させ扁平化させていくのである。 Subsequently, the alloy powder is flattened (S2). Specifically, the alloy powder is put into the container of the attritor apparatus together with an organic solvent and a grinding aid, and a grinding medium such as a steel ball is further loaded therein. Then, when the stirring rod provided with rotating blades on the peripheral surface is rotated and the inside of the container is stirred, the grinding medium collides with the alloy powder and gives an impact to pulverize and flatten the alloy powder. It goes on.
最後に、扁平化加工処理した合金粉体を乾燥させる（Ｓ３）。詳細には、アトライター装置において溶媒等とともに攪拌された合金粉体はスラリー体となっており、これを取り出してバット等の容器に流し込み、加熱しながら静置乾燥させて軟磁性金属粉体１を得る。合金粉体の表面を必要以上に酸化させないよう、ここでは真空雰囲気や不活性ガス雰囲気とした加熱炉等を用いることが好ましい。 Finally, the flattened alloy powder is dried (S3). Specifically, the alloy powder stirred together with the solvent or the like in the attritor apparatus is a slurry body, which is taken out and poured into a container such as a bat, and is allowed to stand and dry while heating to form the soft magnetic metal powder 1. Get. In order not to oxidize the surface of the alloy powder more than necessary, it is preferable here to use a heating furnace in a vacuum atmosphere or an inert gas atmosphere.
以上の工程により、軟磁性金属粉体１が得られる。特に、上記したＢＥＴ値とＯの積算量値との積の上限を満たすように加工することで、軟磁性金属粉体１は、磁気特性の劣化を抑制できるとともに、難燃性を得られるのである。さらに、必要に応じて所定の平均粒径とするように分級処理してもよい。なお、上記したような合金成分とすることで、特に熱処理を加えることなく難燃性の向上に必要な酸化皮膜を得ることができる。 The soft magnetic metal powder 1 is obtained through the above steps. In particular, by processing so as to satisfy the upper limit of the product of the above-described BET value and the integrated amount value of O, the soft magnetic metal powder 1 can suppress deterioration of magnetic properties and obtain flame retardancy. is there. Furthermore, you may classify so that it may become a predetermined | prescribed average particle diameter as needed. In addition, by setting it as the above alloy components, the oxide film required for an improvement of a flame retardance can be obtained, without adding heat processing especially.
［特性評価試験］
図３に示す、実施例１〜７及び比較例１〜３の成分組成の合金からなる粉体を上記した製造方法により得た上で、その特性を評価した。なお、平均粒径をいずれも１５μｍ程度とするように製造した。
[Characteristic evaluation test]
The powders made of the alloys having the component compositions of Examples 1 to 7 and Comparative Examples 1 to 3 shown in FIG. 3 were obtained by the manufacturing method described above, and then the characteristics were evaluated. In addition, it manufactured so that all may have an average particle diameter of about 15 micrometers.
粉体の平均粒径及び微粉量は、レーザー回折式粒度分布測定装置を用いて測定した。ここで平均粒径は累積体積を５０％とする平均粒径Ｄ５０である。微粉量については、粒径を５μｍ以下とする粒子を測定した。また、粉体のアスペクト比は、次のように測定した。すなわち、粉体を樹脂に埋め込んで研磨し、研磨面を金属顕微鏡で観察するが、任意の１００個の粉体についてそれぞれ最大厚みｔｍａｘと最小厚みｔｍｉｎとを計測する。次いで、各々の粒子について最大厚みｔｍａｘ及び最小厚みｔｍｉｎの平均をとり、粒子厚みｔａとする。さらに、１００個の粒子についての粒子厚みｔａの平均値ｔａｖｅにより平均粒径Ｄ５０を除してアスペクト比とした。さらに、粉体硬さは、マイクロビッカース硬さ試験機により測定した。 The average particle size and the fine powder amount of the powder were measured using a laser diffraction particle size distribution analyzer. Here, the average particle diameter is an average particle diameter D50 with a cumulative volume of 50%. For the amount of fine powder, particles having a particle size of 5 μm or less were measured. The aspect ratio of the powder was measured as follows. That is, the powder is embedded in the resin and polished, and the polished surface is observed with a metal microscope. The maximum thickness t max and the minimum thickness t min are measured for each of 100 arbitrary powders. Next, the average of the maximum thickness t max and the minimum thickness t min is taken for each particle to obtain the particle thickness ta. Furthermore, the average particle diameter D50 was divided by the average value t ave of the particle thickness ta for 100 particles to obtain the aspect ratio. Furthermore, the powder hardness was measured with a micro Vickers hardness tester.
粉体の比表面積（ＢＥＴ値）は、比表面積／細孔分布測定装置を用い、窒素ガスを用いたガス吸着法により吸着等温線を得て多点ＢＥＴプロットから求めた。また、Ｏ（酸素）積算量は、オージェ電子分光法で粉体の表面からの深さ０〜５ｎｍまでは０．５ｎｍ毎、深さ５〜１０ｎｍまでは１ｎｍ毎のＯ量を積算し原子％で示した。また、「ＢＥＴ×Ｏ」は、ＢＥＴ値とＯ積算量との数値同士の積である。 The specific surface area (BET value) of the powder was obtained from a multipoint BET plot by using a specific surface area / pore distribution measuring device and obtaining an adsorption isotherm by a gas adsorption method using nitrogen gas. In addition, O (oxygen) accumulated amount is atomic% by integrating O amount every 0.5 nm from 0 to 5 nm from the surface of the powder by Auger electron spectroscopy and every 1 nm from 5 to 10 nm. It showed in. “BET × O” is the product of the numerical values of the BET value and the O accumulated amount.
粉体の保磁力（Ｈｃ）は、ＨＣメータ（東北特殊鋼株式会社製、Ｋ−ＨＣ１０００）を使用して測定した。 The coercive force (Hc) of the powder was measured using an HC meter (Tohoku Special Steel Co., Ltd., K-HC1000).
粉体の難燃性は、消防法に定められる第２類第１種可燃性固体に該当しないことを試験によって判定した。すなわち、小ガス炎着火試験により３秒以内で着火し、燃焼を継続させた場合に第１種可燃性固体に該当し難燃性を有しないと判定し「×」を記録し、それ以外の場合に第１種可燃性固体に該当せず難燃性を有すると判定し「〇」を記録した。 It was determined by a test that the flame retardancy of the powder does not correspond to the Class 2 Class 1 flammable solid defined in the Fire Service Law. In other words, when it is ignited within 3 seconds by a small gas flame ignition test and combustion is continued, it is determined that it falls under Class 1 flammable solid and has no flame retardancy, and "X" is recorded. In this case, it was determined that the substance does not correspond to the first class flammable solid and has flame retardancy, and “◯” was recorded.
実施例１乃至４に示すように、Ｆｅ−Ｓｉ−Ｃｒ系合金の実施例はいずれもＢＥＴ値とＯ積算量の積を２１００以下とし、２０以下の保磁力と難燃性を得ており、総合的な判定（「判定」）は良好（「〇」）であった。また、実施例５乃至７に示すように、Ｆｅ−Ｓｉ−Ａｌ系合金の実施例も同様であった。 As shown in Examples 1 to 4, all examples of Fe-Si-Cr alloys have a product of BET value and O cumulative amount of 2100 or less, and have obtained a coercive force and flame retardancy of 20 or less, The overall judgment (“judgment”) was good (“◯”). In addition, as shown in Examples 5 to 7, the example of the Fe—Si—Al alloy was the same.
すなわち、実施例１乃至７によれば、その酸化皮膜と比表面積、及び難燃性との間の関係から、比較的大なる比表面積を有しながらも難燃性に優れて且つ取り扱いの容易な軟磁性金属粉体となり、扁平形状を有する軟磁性金属粉体１として高周波帯域の電磁波吸収シートなどの製品に用いられ得る。 That is, according to Examples 1 to 7, from the relationship between the oxide film, the specific surface area, and the flame retardancy, it has excellent flame retardancy and is easy to handle while having a relatively large specific surface area. The soft magnetic metal powder can be used as a soft magnetic metal powder 1 having a flat shape in a product such as an electromagnetic wave absorbing sheet in a high frequency band.
これに対し、比較例１は、ＢＥＴ値とＯ積算量との積が大きく、上記したような難燃性を得られなかった。詳細には、Ｃｒ含有量が多く、Ｏ積算量も大きく、表面にＣｒによる酸化皮膜を有していると考えられるものの、微粉量が多くＢＥＴ値が大きかったため十分な難燃性を得られなかったものと考えられる。また、ＢＥＴ値とＯ積算量との積が大きく、Ｃｒの含有量も多いため保磁力が大きく、電磁波吸収シートなどに用いた場合に製品に要求される磁気特性を得られなかった。 On the other hand, in Comparative Example 1, the product of the BET value and the O cumulative amount was large, and the flame retardancy as described above could not be obtained. Specifically, although the Cr content is large, the O cumulative amount is large, and it is thought that the surface has an oxide film made of Cr, sufficient flame retardancy cannot be obtained because the amount of fine powder is large and the BET value is large. It is thought that. Further, since the product of the BET value and the O cumulative amount is large and the content of Cr is large, the coercive force is large, and the magnetic characteristics required for the product cannot be obtained when used for an electromagnetic wave absorbing sheet.
また、比較例２は、ＢＥＴ値とＯ積算量との積が大きく、上記したような難燃性を得られなかった。詳細には、ＣｒやＡｌの酸化皮膜を有さず、加えてＢＥＴ値が比較的大きいこともあって、十分な難燃性を得られなかったものと考えられる。また、ＢＥＴ値とＯ積算量との積が大きく、電磁波吸収シートに用いた場合に透磁率を低くしてしまいやすいと考えられる。 In Comparative Example 2, the product of the BET value and the O cumulative amount was large, and flame retardancy as described above could not be obtained. Specifically, it is considered that sufficient flame retardancy could not be obtained due to the absence of Cr or Al oxide film and the relatively high BET value. Further, the product of the BET value and the O cumulative amount is large, and it is considered that the magnetic permeability tends to be lowered when used for an electromagnetic wave absorbing sheet.
また、比較例３は、Ａｌの添加量が多く、表面における酸化が容易となるためか、表面のＯ積算量が大きかった。つまり、ＢＥＴ値とＯ積算量との積が大きく、保磁力も大きく、電磁波吸収シートなどに用いた場合に製品に要求される磁気特性を得られなかった。 In Comparative Example 3, the amount of Al added was large, and oxidation on the surface was easy, or the amount of accumulated O on the surface was large. That is, the product of the BET value and the O cumulative amount is large, the coercive force is large, and the magnetic characteristics required for the product cannot be obtained when used for an electromagnetic wave absorbing sheet.
上記した結果より、電磁波吸収シートなどの製品に用いた場合に高い透磁率を得られ且つ上記した粉体の難燃性を得る観点から、ＢＥＴ値には上限があり、ＢＥＴ値を６ｍ２／ｇ以下とすることが好ましい。 From the above results, there is an upper limit to the BET value from the viewpoint of obtaining high magnetic permeability when used in products such as electromagnetic wave absorbing sheets and obtaining the flame retardancy of the above powder, and the BET value is 6 m 2 / g or less is preferable.
また、図４に示すように、ＢＥＴ値と粉体硬さとの関係はほぼ線形となっている。比表面積は加工性、すなわち、粉体硬さによって決定されるためと考えられる。この関係は製造条件によっても変化し得るが、同等の平均粒径を得る上で同様の関係になりやすいと考えられる。そこで、上記したＢＥＴ値を得るために、粉体硬さは３００ＨＶ以上とすることが好ましい。 Further, as shown in FIG. 4, the relationship between the BET value and the powder hardness is almost linear. It is considered that the specific surface area is determined by workability, that is, powder hardness. Although this relationship may vary depending on the manufacturing conditions, it is considered that the same relationship is likely to occur when obtaining an equivalent average particle diameter. Therefore, in order to obtain the above BET value, the powder hardness is preferably set to 300 HV or more.
図５には、比較例１の粉体を樹脂に埋め込んで研磨した断面観察顕微鏡写真を示した。図１に示した実施例３の粉体と比較すると、比較例１の粉体は、微粉量が多く、表面平坦度も低いことが判り、ＢＥＴ値が高くなっている。 FIG. 5 shows a cross-sectional observation micrograph of the powder of Comparative Example 1 embedded in a resin and polished. Compared with the powder of Example 3 shown in FIG. 1, it can be seen that the powder of Comparative Example 1 has a large amount of fine powder and low surface flatness, and has a high BET value.
なお、軟磁性金属粉体１は、磁気ヨーク部材、アンテナ部材、通信補助部材、インダクタ、高周波帯域電磁波吸収シートなどに適用可能である。この中でも、高周波帯域電磁波吸収シートへの適用が最も好ましい。 The soft magnetic metal powder 1 can be applied to a magnetic yoke member, an antenna member, a communication auxiliary member, an inductor, a high frequency band electromagnetic wave absorbing sheet, and the like. Among these, application to a high frequency band electromagnetic wave absorbing sheet is most preferable.
以上、本発明の代表的な実施例を説明したが、本発明は必ずしもこれらに限定されるものではなく、当業者であれば、本発明の主旨又は添付した特許請求の範囲を逸脱することなく、種々の代替実施例及び改変例を見出すことができるであろう。 As mentioned above, although the typical Example of this invention was described, this invention is not necessarily limited to these, Those skilled in the art will not deviate from the main point of this invention, or the attached claim. Various alternative embodiments and modifications may be found.
１ 軟磁性金属粉体
1 Soft magnetic metal powder
Claims (5)
表面酸化皮膜を有し、比表面積ＢＥＴ値（ｍ２／ｇ）と表面から１０ｎｍ深さまでのＯの積算量値（原子％）との積を２１００以下とするように加工されていることを特徴とする軟磁性金属粉体。 A soft magnetic metal made of an Fe-Si-Cr alloy or Fe-Si-Al alloy, processed into a flat shape having an average particle diameter D50 of 30 μm or less and an aspect ratio of 10 or more, and a coercive force Hc of 20 Oe or less Powder,
It has a surface oxide film and is processed so that the product of the specific surface area BET value (m 2 / g) and the integrated amount value (atomic%) of O from the surface to a depth of 10 nm is 2100 or less. Soft magnetic metal powder.
5. The soft magnetic metal powder according to claim 4, wherein the specific surface area BET value (m 2 / g) is 6 or less.
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| CN109811268A (en) * | 2019-01-23 | 2019-05-28 | 江西理工大学 | A kind of spherical FeSiCr magnetic Nano absorbing material and preparation method thereof |
| JP2020107781A (en) * | 2018-12-28 | 2020-07-09 | Ｄｏｗａエレクトロニクス株式会社 | Soft magnetic metal powder and magnetic sheet |
| CN113235016A (en) * | 2021-05-16 | 2021-08-10 | 江苏萌达新材料科技有限公司 | Superfine soft magnetic alloy powder and preparation method thereof |
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| JP2016072577A (en) * | 2014-10-02 | 2016-05-09 | 山陽特殊製鋼株式会社 | Soft magnetic flat powder and method for manufacturing the same |
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| CN109811268A (en) * | 2019-01-23 | 2019-05-28 | 江西理工大学 | A kind of spherical FeSiCr magnetic Nano absorbing material and preparation method thereof |
| CN113235016A (en) * | 2021-05-16 | 2021-08-10 | 江苏萌达新材料科技有限公司 | Superfine soft magnetic alloy powder and preparation method thereof |
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