JP2013239459A - Electromagnetic wave absorption heating element and cooking appliance for microwave oven - Google Patents

Electromagnetic wave absorption heating element and cooking appliance for microwave oven Download PDF

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JP2013239459A
JP2013239459A JP2013160593A JP2013160593A JP2013239459A JP 2013239459 A JP2013239459 A JP 2013239459A JP 2013160593 A JP2013160593 A JP 2013160593A JP 2013160593 A JP2013160593 A JP 2013160593A JP 2013239459 A JP2013239459 A JP 2013239459A
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heating element
hexagonal ferrite
electromagnetic wave
type hexagonal
wave absorption
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JP5546671B2 (en
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Mikio Takahashi
幹雄 高橋
Shinichi Kijima
愼一 来島
Satoshi Goto
聡志 後藤
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JFE Chemical Corp
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Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic wave absorption heating element in which the rate of temperature rise is enhanced significantly when compared with a conventional dielectric material or a magnetic material, and temperature rise stops in a range of 200-300°C suitable for heating of food, and to provide a cooking appliance using the same.SOLUTION: As a heating element for absorbing electromagnetic waves, Y type hexagonal ferrite is used. The Y type hexagonal ferrite has a composition represented by a formula:(BaSr)MFeO(in the formula, M is Mg alone, or Mg and one kind or more selected from Ni, Co, Cu and Zn, x:1.8-2.2, y:1.8-2.2, z:11.8-12.2, w:21.8-22.2, n:0.1-0.25).

Description

本発明は、電子レンジなどで使用される2.45GHzの電磁波を吸収して優れた発熱性能を示す発熱体、およびそれを用いた電子レンジ用の調理用器具に関するものである。   The present invention relates to a heating element that exhibits excellent heat generation performance by absorbing electromagnetic waves of 2.45 GHz used in a microwave oven and the like, and a cooking appliance for a microwave oven using the heating element.

電子レンジは、2.45GHzの電磁波を食品に照射して、食品中の水分子が電磁波を吸収し、振動する現象を利用して食品を加熱する調理機器である。しかし、食品の状態によって加熱効率は大きく変動し、食品中の水分量が少ないもの、または冷凍状態のものは加熱されにくい。   A microwave oven is a cooking device that heats food using a phenomenon in which food is irradiated with electromagnetic waves of 2.45 GHz and water molecules in the food absorb the electromagnetic waves and vibrate. However, the heating efficiency varies greatly depending on the state of the food, and the food with a small amount of water or the frozen state is difficult to be heated.

また、電子レンジによる加熱は食品内部からになるため、食品の表面に「焦げ目」を付けることができず、焼き魚やハンバーグのように表面に焦げ目が求められる食品の加熱には適していない。
この点を解決するために、別に電気ヒータを取付けたものがあるが、ヒータ自体の発熱速度が遅いために、調理が迅速にできないという問題が残っていた。
In addition, since the heating by the microwave oven is performed from the inside of the food, the surface of the food cannot be “burned”, and it is not suitable for the heating of food that requires a burnt surface such as grilled fish or hamburger.
In order to solve this problem, there is an electric heater attached separately. However, since the heating speed of the heater itself is slow, there remains a problem that cooking cannot be performed quickly.

これらの問題に対し、特許文献1および特許文献2には、陶磁器などの調理容器の内部または表面に誘電体や磁性体を挿入または塗布することで、電磁波による誘電損失または磁気損失の熱を利用し、調理容器自体を加熱する技術が提案されている。   With respect to these problems, Patent Document 1 and Patent Document 2 utilize the heat of dielectric loss or magnetic loss due to electromagnetic waves by inserting or applying a dielectric or magnetic material into or inside a cooking container such as ceramics. And the technique which heats a cooking container itself is proposed.

特開平5−258857号公報JP-A-5-258857 特開2002−272602号公報JP 2002-272602 A

しかしながら、近年の省電力化要求に対し、特許文献1および特許文献2に記載された技術では、昇温速度がいまだ不足しているという問題を残していた。
本発明は、上記の現状に鑑み開発されたもので、従来の誘電体や磁性体に比べて、昇温速度が格段に向上し、しかも食品の加熱に適した200〜300℃の範囲で昇温が停止する電磁波吸収発熱体およびそれを用いた調理用器具を提供することを目的とする。
However, in response to the recent demand for power saving, the techniques described in Patent Document 1 and Patent Document 2 still have a problem that the rate of temperature rise is still insufficient.
The present invention has been developed in view of the above-mentioned present situation. The temperature rising rate is significantly improved as compared with conventional dielectrics and magnetic materials, and the temperature rises in the range of 200 to 300 ° C. suitable for heating foods. An object of the present invention is to provide an electromagnetic wave absorption heating element whose temperature stops and a cooking utensil using the same.

発明者らは、まず、電磁波による発熱効率を高めるため、磁性体の磁気損失に着目した。磁気損失とは、複素透磁率の虚数成分μ’’に関係し、磁気的な共鳴現象による熱的な損失をいう。従って、磁気損失が大きいほど熱の発生が多くなり、優れた発熱反応を示すことが分かっている。   The inventors first focused on the magnetic loss of the magnetic material in order to increase the heat generation efficiency by the electromagnetic waves. The magnetic loss is related to the imaginary component μ ″ of the complex permeability and refers to a thermal loss due to a magnetic resonance phenomenon. Therefore, it has been found that the greater the magnetic loss, the more heat is generated and the better the exothermic reaction.

また、磁性体には大きく分けて、ケイ素鋼、パーマロイなどの金属系とフェライトと呼ばれる酸化物系がある。ここで、金属系磁性体は電磁波を反射するため、発熱体の利用には適さないことが分かっている。   Magnetic materials are roughly classified into metal systems such as silicon steel and permalloy and oxide systems called ferrite. Here, it has been found that the metal-based magnetic body reflects electromagnetic waves and is not suitable for use as a heating element.

従来から、電磁波吸収発熱体として提案されている磁性体としては、スピネル型と呼ばれるMnZn系、NiZn系立方晶フェライトがある。これらフェライトは一般的に、電子部品であるトランス、チョークコイル、ノイズフィルターなどに使用され、高周波電流・電圧を制御する。
また、電波吸収用途として、テレビゴースト対策用などに利用されるフェライトタイルがある。但し、MnZn系、NiZn系立方晶フェライトは、その特性上、実用の周波数がメガヘルツ帯域である。そのため、電子レンジの2.45GHzでは、磁気的性質が弱まり、複素透磁率の虚数成分μ’’の値が小さくなり、発熱効率も決して高くない。
従って、発熱性能をより高めるには、2.45GHzの周波数帯でより大きなμ’’を示すフェライトが求められている
Conventionally, magnetic materials that have been proposed as electromagnetic wave absorption heating elements include MnZn-based and NiZn-based cubic ferrites called spinel types. These ferrites are generally used in electronic parts such as transformers, choke coils, and noise filters, and control high-frequency current and voltage.
In addition, as a radio wave absorption application, there is a ferrite tile used for TV ghost countermeasures. However, the practical frequency of the MnZn-based and NiZn-based cubic ferrite is in the megahertz band due to their characteristics. Therefore, at 2.45 GHz in the microwave oven, the magnetic properties are weakened, the value of the imaginary component μ ″ of the complex permeability is reduced, and the heat generation efficiency is never high.
Therefore, in order to further improve the heat generation performance, a ferrite showing a larger μ '' in the frequency band of 2.45 GHz is required.

近年、ギガヘルツ帯域用のフェライトとして、六方晶フェライトが研究されている。この六方晶フェライトにはいくつかの結晶構造があり、一番良く知られているのがM型と呼ばれ、永久磁石として広く利用されている。   In recent years, hexagonal ferrite has been studied as a ferrite for the gigahertz band. This hexagonal ferrite has several crystal structures, and the most well known is called M-type, which is widely used as a permanent magnet.

本発明では、六方晶フェライトの中でも、電磁波吸収体として期待ができるY型に着目した。というのは、Y型六方晶フェライトは、ギガヘルツの周波数帯域において、不要ノイズの電磁波吸収体としての用途が従来から考えられていたためである。
しかし、電磁波吸収による発熱体として用いられたことは無かった。
In the present invention, attention is paid to the Y type that can be expected as an electromagnetic wave absorber among hexagonal ferrites. This is because Y-type hexagonal ferrite has been conventionally considered to be used as an electromagnetic wave absorber for unwanted noise in the gigahertz frequency band.
However, it has never been used as a heating element by electromagnetic wave absorption.

Y型六方晶フェライトは、電子レンジの2.45GHzの電磁波中でも磁気的性質を保っていることが知られている。そのため、MnZn系、NiZn系立方晶フェライトよりも大きな発熱特性を示す可能性が考えられる。
また、Y型六方晶フェライトは、強磁性体であるため、温度を上げた場合に、磁気的性質が失われる温度、つまりキュリー温度を有している。そのため、発熱体として利用した場合、その発熱体の温度がキュリー温度近傍で停止することが期待できる。
さらに、Y型六方晶フェライトは、いろいろな元素置換が可能であることから、この元素置換を行うことでキュリー温度を変えることができる。つまり、加熱時の到達温度を制御できる可能性がある。
It is known that Y-type hexagonal ferrite retains magnetic properties even in an electromagnetic wave of 2.45 GHz in a microwave oven. For this reason, there is a possibility that the heat generation characteristics are larger than those of the MnZn-based and NiZn-based cubic ferrites.
Further, since Y-type hexagonal ferrite is a ferromagnetic substance, it has a temperature at which magnetic properties are lost when the temperature is raised, that is, a Curie temperature. Therefore, when used as a heating element, it can be expected that the temperature of the heating element stops near the Curie temperature.
Furthermore, since Y-type hexagonal ferrite can be substituted by various elements, the Curie temperature can be changed by performing this element substitution. That is, there is a possibility that the ultimate temperature during heating can be controlled.

そこで、上述した種々の考察を確認すべく、以下の実験を行った。
まず、Ba2M2Fe12O22になるY型六方晶フェライトの粉末を作製した。なお、Mは、Mg,Ni,Co,CuおよびZnの内から1種または2種以上の組合せを適宜選択(以下、本発明に置いてMは同義に使用する)し、Baを一部Srと置換したものも作製した。このY型六方晶フェライトの粉末を、耐熱性樹脂と混合し、所定の形状に成形した。この成形体を電子レンジ中に入れ、電磁波を印加した時の昇温特性を確認した。
ついで、MnZn系、NiZn系立方晶フェライトおよび各種誘電体も同様にして耐熱性樹脂と混合して成形体を作製し、比較実験を行った。
Therefore, the following experiment was performed to confirm the various considerations described above.
First, a Y-type hexagonal ferrite powder to be Ba 2 M 2 Fe 12 O 22 was prepared. Note that M is one or a combination of two or more selected from Mg, Ni, Co, Cu and Zn as appropriate (hereinafter, M is used synonymously in the present invention), and Ba is partially Sr. The one substituted with was also produced. This Y-type hexagonal ferrite powder was mixed with a heat-resistant resin and molded into a predetermined shape. This molded body was put in a microwave oven, and the temperature rise characteristics when electromagnetic waves were applied were confirmed.
Subsequently, MnZn-based, NiZn-based cubic ferrite and various dielectrics were similarly mixed with a heat-resistant resin to produce a molded body, and a comparative experiment was performed.

その結果、Y型六方晶フェライトの昇温速度が最も大きく、昇温停止温度も、食品加熱に適した200〜300℃に制御できることが分かった。さらに、このY型六方晶フェライトを陶磁器およびガラス製容器の、内部に挿入してまたは表面に塗布することによって、電子レンジで発熱する調理器具として利用できることも合わせて見出した。   As a result, it was found that the rate of temperature increase of Y-type hexagonal ferrite was the highest, and the temperature increase stop temperature could be controlled to 200 to 300 ° C. suitable for food heating. Furthermore, the present inventors have also found that the Y-type hexagonal ferrite can be used as a cooking utensil that generates heat in a microwave oven by being inserted inside or applied to the surface of ceramic and glass containers.

また、通常、金属は電磁波を反射するため、発熱体にはなりにくいが、電磁波が照射される面にY型六方晶フェライトの粉末を塗布する、あるいはY型六方晶フェライトの粉末と耐熱性樹脂とを混合したシートを貼り付けることによって、そのシートが電磁波を吸収し、優れた発熱効果を有し、調理器具に適用できることも見出した。
以上のような知見を得て、本発明を完成させた。
In general, metal reflects electromagnetic waves and is not likely to be a heating element, but Y-type hexagonal ferrite powder is applied to the surface irradiated with electromagnetic waves, or Y-type hexagonal ferrite powder and heat-resistant resin. It has also been found that by adhering a sheet mixed with, the sheet absorbs electromagnetic waves, has an excellent heat generation effect, and can be applied to cooking utensils.
Obtaining the above knowledge, the present invention has been completed.

すなわち、上記知見に基づく本発明の要旨構成は次のとおりである。
(1)電磁波を吸収する発熱体であって、該発熱体がY型六方晶フェライトからなり、
前記Y型六方晶フェライトが、次式
式:(Ba1-nSrFe
Mは、Mg単独、またはMgならびにその一部がNi,Co,CuおよびZnのうちから選ばれた1種または2種以上であり、
x:1.8〜2.2
y:1.8〜2.2
z:11.8〜12.2
w:21.8〜22.2
n:0.1〜0.25
の組成になることを特徴とする電磁波吸収発熱体。
That is, the gist configuration of the present invention based on the above knowledge is as follows.
(1) A heating element that absorbs electromagnetic waves, wherein the heating element is made of Y-type hexagonal ferrite,
The Y-type hexagonal ferrite, the following formula formula: (Ba 1-n Sr n ) x M y Fe z O w
M is Mg alone, or Mg and a part thereof is one or more selected from Ni, Co, Cu and Zn,
x: 1.8 to 2.2
y: 1.8-2.2
z: 11.8 to 12.2
w: 21.8-22.2
n: 0.1-0.25
An electromagnetic wave absorption heating element characterized by having a composition of

(2)前記Y型六方晶フェライトが焼結体であることを特徴とする前記(1)に記載の電磁波吸収発熱体。 (2) The electromagnetic wave absorption heating element as described in (1) above, wherein the Y-type hexagonal ferrite is a sintered body.

(3)前記電磁波吸収発熱体が、前記Y型六方晶フェライトの他さらに樹脂を20〜50mass%の範囲で含有することを特徴とする前記(1)または(2)に記載の電磁波吸収発熱体。 (3) The electromagnetic wave absorption heating element according to (1) or (2), wherein the electromagnetic wave absorption heating element further contains a resin in the range of 20 to 50 mass% in addition to the Y-type hexagonal ferrite. .

(4)調理用器具の少なくとも一部に、前記(1)〜(3)のいずれかに記載の電磁波吸収発熱体を有することを特徴とする電子レンジ用の調理用器具。 (4) A cooking utensil for a microwave oven comprising the electromagnetic wave absorption heating element according to any one of (1) to (3) in at least a part of the cooking utensil.

本発明のY型六方晶フェライトを電磁波吸収発熱体として用いることにより、電子レンジの2.45GHzの電磁波を吸収して急速に加熱すると共に、所定の温度でその昇温を停止することができる。その結果、個々の食品に適した温度で加熱することができる種々の電子レンジ用の調理用器具を提供することができる。   By using the Y-type hexagonal ferrite of the present invention as an electromagnetic wave absorption heating element, it is possible to absorb the 2.45 GHz electromagnetic wave of the microwave oven and rapidly heat it, and to stop the temperature rise at a predetermined temperature. As a result, cooking utensils for various microwave ovens that can be heated at a temperature suitable for individual foods can be provided.

Y型六方晶フェライトを用いた場合の温度測定結果と比較材の温度測定結果とを示した図である。It is the figure which showed the temperature measurement result at the time of using a Y-type hexagonal ferrite, and the temperature measurement result of a comparative material. Y型六方晶フェライト焼結体とそれを装着した耐熱ガラス製皿を示した断面図である。It is sectional drawing which showed the Y-type hexagonal ferrite sintered compact and the heat-resistant glass dish which attached it. Y型六方晶フェライトを用いた場合の温度測定結果と比較材の温度測定結果とを示した図である。It is the figure which showed the temperature measurement result at the time of using a Y-type hexagonal ferrite, and the temperature measurement result of a comparative material. Y型六方晶フェライトとステンレス製容器からなる調理用器具の断面図である。It is sectional drawing of the utensil for cooking which consists of a Y-type hexagonal ferrite and a stainless steel container. Y型六方晶フェライトを用いた場合の温度測定結果と比較材の温度測定結果とを示した図である。It is the figure which showed the temperature measurement result at the time of using a Y-type hexagonal ferrite, and the temperature measurement result of a comparative material.

以下、本発明を具体的に説明する。
本発明は、発熱体が六方晶フェライトの中でも特に、Y型であることが最も重要なところである。
前述したとおり、電磁波を印加した場合、Y型六方晶フェライトは種々の誘電体および磁性体の中でも特に優れた昇温速度を示した。なお、六方晶フェライトは、Y型の他に、M,W,Z型があるが、このY型というのは通常のX線回折法により相同定が可能である。
Hereinafter, the present invention will be specifically described.
In the present invention, it is most important that the heating element is Y type among hexagonal ferrites.
As described above, when electromagnetic waves were applied, the Y-type hexagonal ferrite exhibited a particularly excellent temperature rising rate among various dielectrics and magnetic materials. In addition to the Y type, hexagonal ferrite includes M, W, and Z types. The Y type can be phase-identified by a normal X-ray diffraction method.

ここに、Y型六方晶フェライトの基本組成式は、A22Fe1222(AはBa,Sr等、MはMg,Zn等)で示される。
本発明では、上記の組成で示されるY型六方晶フェライトを発熱体として用いるが、かかるY型六方晶フェライトの中でも、次式で表され、
式:(Ba1-nSrFe
Mは、前述したとおり、Mg単独、またはMgならびにその一部をNi,Co,CuおよびZnのうちから選ばれた1種または2種以上であり、また、係数x、y、z、wおよびnがそれぞれ、
x:1.8〜2.2
y:1.8〜2.2
z:11.8〜12.2
w:21.8〜22.2
n:0.1〜0.25
で示される組成のものがとりわけ有利に適合する。
Here, the basic composition formula of the Y-type hexagonal ferrite is represented by A 2 M 2 Fe 12 O 22 (A is Ba, Sr, etc., M is Mg, Zn, etc.).
In the present invention, the Y-type hexagonal ferrite having the above composition is used as a heating element. Among such Y-type hexagonal ferrites, the Y-type hexagonal ferrite is represented by the following formula:
Formula: (Ba 1-n Sr n ) x M y Fe z O w
As described above, M is Mg alone, or Mg and one or more thereof selected from Ni, Co, Cu and Zn, and coefficients x, y, z, w and n is
x: 1.8 to 2.2
y: 1.8-2.2
z: 11.8 to 12.2
w: 21.8-22.2
n: 0.1-0.25
Are particularly advantageously adapted.

以下に、上記した好適組成範囲の設定理由を説明する。
x:1.8〜2.2
xは、後述するBa+Srの原子比を表す。その値が1.8以上2.2以下の範囲を逸脱すると、Y型相以外に、MFeなどの異相が出現するため、本発明の所定の性質、性能等を発揮できないおそれがある。
The reason for setting the above preferred composition range will be described below.
x: 1.8 to 2.2
x represents an atomic ratio of Ba + Sr described later. If the value deviates from the range of 1.8 or more and 2.2 or less, a heterogeneous phase such as MFe 2 O 4 appears in addition to the Y-type phase, so that the predetermined properties and performance of the present invention may not be exhibited.

y:1.8〜2.2
yは、Mの原子比である。その値が1.8以上2.2以下の範囲を逸脱すると、Y型相以外に、MFeなどの異相が出現するため、本発明の所定の性質、性能等を発揮できないおそれがある。
y: 1.8-2.2
y is the atomic ratio of M. If the value deviates from the range of 1.8 or more and 2.2 or less, a heterogeneous phase such as MFe 2 O 4 appears in addition to the Y-type phase, so that the predetermined properties and performance of the present invention may not be exhibited.

n:0.1〜0.25
nは、Ba中の置換したSrの原子比を表す。その値は、0.25以下に限定することが好ましい、というのは、0.25を超えると、前記したμ’’が低下するため、本発明の所定の性質、性能等を発揮できないおそれがあるからである。
なお、n値の下限は0.1とする。n値が0.1以上の場合、目標温度との差が小さくなるからである。
n: 0.1-0.25
n represents the atomic ratio of substituted Sr in Ba. The value is preferably limited to 0.25 or less, because if it exceeds 0.25, the above-mentioned μ '' is lowered, so that the predetermined properties and performance of the present invention may not be exhibited. .
Note that the lower limit of the n value is 0.1. This is because when the n value is 0.1 or more, the difference from the target temperature is small.

z:11.8〜12.2、w:21.8〜22.2
zはFe、wはOの原子比を表し、いずれもフェライトの主成分である。これらの値は、上記したその他の成分に応じて変動することができる。但し、zは11.8〜12.2、また、wは21.8〜22.2の範囲とすることが好ましい。
z: 11.8-12.2, w: 21.8-22.2
z represents the atomic ratio of Fe, and w represents the atomic ratio of O, both of which are the main components of ferrite. These values can vary depending on the other components described above. However, z is preferably in the range of 11.8 to 12.2, and w is preferably in the range of 21.8 to 22.2.

本発明は、上記のMとして金属元素を有しているところに特徴がある。このMは、種々の組合せが可能であるが、前記した元素またはその組合せ群により、前述したとおりに、いわゆるキュリー温度を適宜変えることができる。つまり、本発明の電磁波吸収発熱体は、その高い昇温速度を維持しながら、昇温停止温度を、100〜400℃のなかで設定することができる。
特に、250℃前後の一般的な食品を加熱するのに最も適した組成は、例えば、上記したMとして、Mg単独またはMgならびにその一部をNi,Co,CuおよびZnとした組成である。
The present invention is characterized by having a metal element as M described above. The M can be variously combined, but the so-called Curie temperature can be appropriately changed as described above depending on the above-described elements or combinations thereof. That is, the electromagnetic wave absorption heating element of the present invention can set the temperature increase stop temperature within 100 to 400 ° C. while maintaining the high temperature increase rate.
In particular, the most suitable composition for heating a general food at around 250 ° C. is, for example, a composition in which M is Mg alone or Mg and a part thereof is Ni, Co, Cu and Zn.

本発明の電磁波吸収発熱体は、粉末または焼結体で供することができるが、樹脂に混合して用いることもできる。
なお、本発明に用いる樹脂は、シリコーン樹脂、PPS(ポリフェニレンサルファイド)樹脂等が挙げられ、樹脂の添加量は、20〜50mass%程度とすることが好ましい。
The electromagnetic wave absorption heating element of the present invention can be provided as a powder or a sintered body, but can also be used by mixing with a resin.
Examples of the resin used in the present invention include a silicone resin and a PPS (polyphenylene sulfide) resin, and the addition amount of the resin is preferably about 20 to 50 mass%.

ついで、本発明の電磁波吸収発熱体の代表的な製造方法について説明する。
まず、Fe2O3、BaCO3、MOを出発原料とする。ついで、各原料をY型六方晶フェライトの組成となるように秤量し、混合器を用いて混合する。その後、1000〜1200℃で焼成する。焼成後は粉砕機等で解砕し、平均粒径を数μm程度の粉末とする。
Next, a representative method for producing the electromagnetic wave absorption heating element of the present invention will be described.
First, Fe 2 O 3 , BaCO 3 and MO are used as starting materials. Next, each raw material is weighed so as to have a composition of Y-type hexagonal ferrite and mixed using a mixer. Then, it bakes at 1000-1200 degreeC. After firing, the powder is crushed with a pulverizer or the like to obtain a powder having an average particle size of about several μm.

焼結体とするためには、上記した粉末に結合剤等を入れ造粒した後、金型等で成形し、1000〜1200℃で再び焼結すればよい。この焼結体は、単独で用いることもできるし、陶磁器等の容器に組込んで使用することもできる。
粉末および焼結体の態様は、用途または使用する調理器具の種類によって、適宜選択される。
In order to obtain a sintered body, a binder or the like is added to the above powder, granulated, then molded with a mold or the like, and sintered again at 1000 to 1200 ° C. This sintered body can be used alone or in a container such as a ceramic.
The mode of the powder and the sintered body is appropriately selected depending on the use or the type of cooking utensil used.

例えば、上記した方法で得られた電磁波吸収発熱体であるY型六方晶フェライト粉末と耐熱樹脂を、混合し、所定の形に成形し、電子レンジの電磁波による発熱体として用いることができる。また、上記のY型六方晶フェライト粉末と耐熱樹脂などを混合し、陶磁器またはガラス製容器の内部に挿入あるいは表面に塗布または接着等することによって、電子レンジの電磁波による発熱体として用いることができる。さらに、上記のY型六方晶フェライト粉末と耐熱樹脂などを混合し、金属製板や金属製容器の電磁波照射面(電磁波に対し対向する面)に塗布あるいは接着等することで、電子レンジの電磁波による発熱体として用いることができる。
ここに、上記した樹脂との混合物は、単独で容器に成形しても用いることもできる。
For example, Y-type hexagonal ferrite powder, which is an electromagnetic wave absorption heating element obtained by the above-described method, and a heat-resistant resin can be mixed and molded into a predetermined shape, and used as a heating element by electromagnetic waves in a microwave oven. Also, by mixing the above Y-type hexagonal ferrite powder and heat-resistant resin and inserting it into a ceramic or glass container, or applying or bonding it to the surface, it can be used as a heating element by electromagnetic waves in a microwave oven. . Furthermore, the above-mentioned Y-type hexagonal ferrite powder and heat-resistant resin are mixed and applied to or adhered to the electromagnetic wave irradiation surface (surface facing the electromagnetic wave) of a metal plate or metal container. It can be used as a heating element.
Here, the above-mentioned mixture with the resin can be used alone or formed into a container.

以下に、本発明の実施例を記載する。
〔参考例1〕
原料として、BaCO3,MgO,Fe2O3を使用し、それらのモル比率がBaCO3:MgO:Fe2O3=2:2:6となるように秤量し、ボールミルで湿式混合する。ついで、乾燥をし、大気中1150℃×3時間で焼成した、その後、焼成体を解砕し、平均粒径が約3.5μmのBa2Mg2Fe12O22のY型六方晶フェライト粉を得た。この粉末にシリコーン樹脂を、フェライト粉:樹脂=75:25の質量比率で混練し、40mm×40mm×1mmのシートを作製した。得られたシートを市販の電子レンジの中に置き、500Wの電磁波を10秒〜120秒間照射した時のシートの温度を赤外放射温度計で測定した。
Examples of the present invention will be described below.
[Reference Example 1]
BaCO 3 , MgO, and Fe 2 O 3 are used as raw materials and weighed so that the molar ratio thereof is BaCO 3 : MgO: Fe 2 O 3 = 2: 2: 6, and wet-mixed with a ball mill. Next, it was dried and fired at 1150 ° C. for 3 hours in the atmosphere. After that, the fired body was crushed and Y type hexagonal ferrite powder of Ba 2 Mg 2 Fe 12 O 22 having an average particle diameter of about 3.5 μm was obtained. Obtained. A silicone resin was kneaded with this powder at a mass ratio of ferrite powder: resin = 75: 25 to prepare a sheet of 40 mm × 40 mm × 1 mm. The obtained sheet was placed in a commercially available microwave oven, and the temperature of the sheet when irradiated with a 500 W electromagnetic wave for 10 seconds to 120 seconds was measured with an infrared radiation thermometer.

次に、比較材として、立方晶フェライトのMnZn系フェライト粉やNiZn系フェライト粉、および誘電体のBaTiO3粉やTiO2粉も同様の工程でシートを作製し、上記と同様に試験を実施した。なお、MnZn系フェライト粉の組成は、酸化物換算でFe2O3=52.8mol%,MnO=35.3mol%,ZnO=11.9mol%とし、NiZn系フェライト粉の組成は、Fe2O3=49.0mol%,NiO=21.9mol%,ZnO=23.1mol%,CuO=6.0mol%とした。
上記したY型六方晶フェライトを用いた場合の測定結果と比較材を用いた場合の測定結果とを図1に示す。
Next, as comparative materials, MnZn ferrite powder and NiZn ferrite powder of cubic ferrite, and BaTiO 3 powder and TiO 2 powder of dielectric were prepared in the same process, and the test was performed in the same manner as above. . The composition of the MnZn ferrite powder is Fe 2 O 3 = 52.8 mol%, MnO = 35.3 mol%, ZnO = 11.9 mol% in terms of oxide, and the composition of the NiZn ferrite powder is Fe 2 O 3 = 49.0 mol%, NiO = 21.9mol%, ZnO = 23.1mol%, CuO = 6.0mol%.
FIG. 1 shows the measurement results when the Y-type hexagonal ferrite described above is used and the measurement results when the comparative material is used.

同図に示したとおり、Y型六方晶フェライト粉のシートは、MnZn系フェライト粉、NiZn系フェライト粉、BaTiO3粉およびTiO2粉のシートに比べて、昇温速度が速いことが分かる。 As shown in the figure, it can be seen that the sheet of Y-type hexagonal ferrite powder has a higher temperature rising rate than the sheets of MnZn ferrite powder, NiZn ferrite powder, BaTiO 3 powder and TiO 2 powder.

〔参考例2〕
原料として、BaCO3,MgO,Fe2O3を使用し、それらのモル比率がBaCO3:MgO:Fe2O3=2:2:6となるように秤量し、振動ミルで乾式混合する。ついで、大気中950℃×2時間で仮焼した、その後、アトライターミルで湿式解砕し、平均粒径が約1.5μmのBa2Mg2Fe12O22のY型六方晶フェライト仮焼粉を得た。この仮焼粉にバインダーとしてPVA水溶液を加え、スプレイドライヤーを用いて、粒径が50〜150μm程度の造粒粉を得た。
[Reference Example 2]
BaCO 3 , MgO, and Fe 2 O 3 are used as raw materials and weighed so that the molar ratio thereof is BaCO 3 : MgO: Fe 2 O 3 = 2: 2: 6, and dry-mixed with a vibration mill. Next, it was calcined at 950 ° C for 2 hours in the atmosphere, then wet-pulverized with an attritor mill, and Ba 2 Mg 2 Fe 12 O 22 Y-type hexagonal ferrite calcined powder with an average particle size of about 1.5 µm Got. A PVA aqueous solution was added as a binder to the calcined powder, and a granulated powder having a particle size of about 50 to 150 μm was obtained using a spray dryer.

次に、この造粒粉を金型に充填し、プレス成形を施した後、大気中1150℃×3時間で焼成し、150mm×150mm×10mmのタイル状の焼結体を作製した。このY型六方晶フェライト焼結体を図2に示す耐熱ガラス製の皿状容器の底部に合うように、120mmφ×7mm厚に加工し、熱硬化性樹脂で装着した。この皿状容器を市販の電子レンジの中に置き、800Wの電磁波を10秒〜300秒間照射した時の、同図に示した皿上面中央部の温度を赤外放射温度計で測定した。   Next, this granulated powder was filled in a mold, press-molded, and then fired in the atmosphere at 1150 ° C. for 3 hours to produce a 150 mm × 150 mm × 10 mm tile-shaped sintered body. This Y-type hexagonal ferrite sintered body was processed into a thickness of 120 mmφ × 7 mm so as to fit the bottom of a heat-resistant glass dish-shaped container shown in FIG. 2, and mounted with a thermosetting resin. The dish-like container was placed in a commercially available microwave oven, and the temperature at the center of the dish upper surface shown in the same figure when irradiated with 800 W of electromagnetic waves for 10 seconds to 300 seconds was measured with an infrared radiation thermometer.

次に、比較材として、同様にNiZn系フェライト焼結体を耐熱ガラス製の皿状容器の底部に装着したもの、および何も装着しない耐熱ガラス製の皿状容器を用意し、上記と同様に試験を実施した。なお、NiZn系フェライト粉の組成は、Fe2O3=49.0mol%,NiO=21.9mol%,ZnO=23.1mol%,CuO=6.0mol%とした。
上記したY型六方晶フェライトを用いた場合の測定結果と比較材を用いた場合の測定結果とを図3に示す。
Next, as a comparative material, similarly prepared a NiZn ferrite sintered body mounted on the bottom of a heat-resistant glass dish-shaped container, and a heat-resistant glass dish-shaped container on which nothing is mounted, as described above. The test was conducted. The composition of the NiZn ferrite powder was Fe 2 O 3 = 49.0 mol%, NiO = 21.9 mol%, ZnO = 23.1 mol%, CuO = 6.0 mol%.
FIG. 3 shows the measurement results when the above Y-type hexagonal ferrite is used and the measurement results when the comparative material is used.

同図に示したとおり、何も装着しない耐熱ガラス製の皿状容器は、ほとんど昇温していないことが分かる。一方、Y型六方晶フェライト焼結体を装着した皿状容器の昇温速度は、NiZn系フェライト焼結体を装着した皿状容器の昇温速度と比べると、極めて速く、また昇温停止温度到達後の温度変動が小さいことが分かる。   As shown in the figure, it can be seen that the temperature of the heat-resistant glass dish-like container on which nothing is mounted is hardly raised. On the other hand, the rate of temperature rise of the dish-shaped container equipped with the Y-type hexagonal ferrite sintered body is much faster than the temperature rise rate of the dish-shaped container equipped with the NiZn-based ferrite sintered body, and the temperature rise stop temperature. It can be seen that the temperature fluctuation after reaching is small.

〔参考例3〕
原料として、BaCO3,MgO,NiO,Fe2O3を使用し、それらのモル比率がBaCO3:MgO:NiO:Fe2O3=2:1.6:0.4:6となるように秤量し、ボールミルで湿式混合する。ついで、乾燥をし、大気中1150℃×3時間で焼成した、その後、焼成体を解砕し、平均粒径が約3.9μmのBa2(Mg0.8Ni0.2)2Fe12O22のY型六方晶フェライト粉を得た。この粉末にシリコーン樹脂を、フェライト粉:樹脂=70:30の重量比率で混練した後、図4に示すステンレス製容器の外側に1mm厚で塗布した。この容器を市販の電子レンジの中に置き、600Wの電磁波を10秒〜180秒間照射した時の、同図に示した容器側面部の温度を赤外放射温度計で測定した。
[Reference Example 3]
BaCO 3 , MgO, NiO, and Fe 2 O 3 are used as raw materials and weighed so that the molar ratio is BaCO 3 : MgO: NiO: Fe 2 O 3 = 2: 1.6: 0.4: 6. Wet mix with. Next, it was dried and calcined at 1150 ° C. for 3 hours in the atmosphere. After that, the calcined product was crushed and Y type of Ba 2 (Mg 0.8 Ni 0.2 ) 2 Fe 12 O 22 having an average particle size of about 3.9 μm Hexagonal ferrite powder was obtained. A silicone resin was kneaded with this powder at a weight ratio of ferrite powder: resin = 70: 30, and then applied to the outside of the stainless steel container shown in FIG. This container was placed in a commercially available microwave oven, and the temperature of the side surface of the container shown in the figure when irradiated with 600 W of electromagnetic waves for 10 seconds to 180 seconds was measured with an infrared radiation thermometer.

次に、比較例として、同様にMnZn系フェライト粉末にシリコーン樹脂を混練したものを塗布したステンレス製容器、および何も塗布しないステンレス製容器を用意し、上記と同様に試験を実施した。なお、MnZn系フェライト粉の組成は、Fe2O3=52.8mol%,MnO=35.3mol%,ZnO=11.9mol%とした。
上記したY型六方晶フェライトを用いた場合の測定結果と比較材を用いた場合の測定結果とを図5に示す。
Next, as a comparative example, a stainless steel container in which MnZn ferrite powder was kneaded with a silicone resin and a stainless steel container in which nothing was applied were prepared, and the test was performed in the same manner as described above. The composition of the MnZn ferrite powder was Fe 2 O 3 = 52.8 mol%, MnO = 35.3 mol%, ZnO = 11.9 mol%.
FIG. 5 shows the measurement results when the above Y-type hexagonal ferrite is used and the measurement results when the comparative material is used.

同図に示したとおり、何も装着しないステンレス製容器は、ほとんど昇温していないことが分かる。一方、Y型六方晶フェライト焼結体を塗布したステンレス製容器の昇温速度は、NiZn系フェライト焼結体を塗布したステンレス製容器の昇温速度に比べると速く、また昇温停止温度到達後の温度変動が小さいことが分かる。   As shown in the figure, it can be seen that the temperature of the stainless steel container in which nothing is mounted is hardly raised. On the other hand, the temperature rise rate of the stainless steel container coated with the Y-type hexagonal ferrite sintered body is faster than the temperature rise rate of the stainless steel container coated with the NiZn ferrite sintered body, and after the temperature rise stop temperature is reached. It can be seen that the temperature fluctuation of is small.

〔実施例1〕
表1に示す組成になるY型六方晶フェライト粉を、参考例1と同様な方法および条件で作製した。この粉末にシリコーン樹脂を、フェライト粉:樹脂=80:20の質量比率で混練し、40mm×40mm×2mmのシートを作製した。得られたシートを市販の電子レンジの中に置き500Wの電磁波を照射して、シートの温度が赤外放射温度計で200℃となるまでの時間を測定した。また、シートの昇温が停止する温度、およびそこまでかかった時間を併せて測定した。
[Example 1]
Y-type hexagonal ferrite powder having the composition shown in Table 1 was produced by the same method and conditions as in Reference Example 1. A silicone resin was kneaded with this powder at a mass ratio of ferrite powder: resin = 80: 20 to prepare a sheet of 40 mm × 40 mm × 2 mm. The obtained sheet was placed in a commercially available microwave oven, irradiated with 500 W of electromagnetic waves, and the time until the sheet temperature reached 200 ° C. was measured with an infrared radiation thermometer. In addition, the temperature at which the temperature of the sheet stopped rising and the time taken up to that point were also measured.

次に、比較例として、表1に示した組成になる立方晶フェライトのMnZn系フェライト粉やNiZn系フェライト粉、および誘電体のMnO2粉やグラファイトも同様の工程でシートとし、上記と同様に試験を実施した。
上記した本発明のY型六方晶フェライトを用いた場合の測定結果と比較例の測定結果とを表1に併記する。
Next, as comparative examples, cubic ferrite MnZn ferrite powder and NiZn ferrite powder having the composition shown in Table 1 and dielectric MnO 2 powder and graphite were formed into sheets in the same process, and the same as above. The test was conducted.
Table 1 shows the measurement results obtained by using the Y-type hexagonal ferrite of the present invention and the measurement results of the comparative example.

Figure 2013239459
Figure 2013239459

同表に示したとおり、本発明のY型六方晶フェライトの昇温特性は、どの比較例と比べても良好で、200℃になるまでの時間、シートの昇温の停止までの時間は共に短く、かつ停止温度は、200〜300℃であり、最も食品の加熱に適した温度域が実現できていることが分かる。
また、同表より、10〜30℃程度の差で、昇温が停止する目標温度を達成できていることが分かる。
As shown in the table, the temperature rise characteristics of the Y-type hexagonal ferrite of the present invention are good compared to any of the comparative examples. Both the time to reach 200 ° C. and the time to stop the temperature rise of the sheet are both It is short and the stop temperature is 200 to 300 ° C., and it can be seen that the temperature range most suitable for heating food is realized.
Moreover, it turns out that the target temperature which temperature rise stops with the difference of about 10-30 degreeC can be achieved from the table.

本発明に従い、Y型六方晶フェライトを電磁波吸収発熱体として用いることで、効果的に電子レンジの電磁波を吸収して、被加熱物を急速に加熱することができる。その結果、電子レンジの使用が短時間で済むため、省エネルギーにも貢献でき、さらに、このような短時間の処理でも「焦げ目」を付けることが可能となる。   According to the present invention, by using Y-type hexagonal ferrite as an electromagnetic wave absorption heating element, the electromagnetic wave in the microwave oven can be effectively absorbed and the heated object can be rapidly heated. As a result, since the microwave oven can be used in a short time, it can contribute to energy saving. Further, even in such a short time processing, it is possible to apply “burnt eyes”.

Claims (4)

電磁波を吸収する発熱体であって、該発熱体がY型六方晶フェライトからなり、
前記Y型六方晶フェライトが、次式
式:(Ba1-nSrFe
Mは、Mg単独、またはMgならびにその一部がNi,Co,CuおよびZnのうちから選ばれた1種または2種以上であり、
x:1.8〜2.2
y:1.8〜2.2
z:11.8〜12.2
w:21.8〜22.2
n:0.1〜0.25
の組成になることを特徴とする電磁波吸収発熱体。
A heating element that absorbs electromagnetic waves, the heating element comprising Y-type hexagonal ferrite,
The Y-type hexagonal ferrite, the following formula formula: (Ba 1-n Sr n ) x M y Fe z O w
M is Mg alone, or Mg and a part thereof is one or more selected from Ni, Co, Cu and Zn,
x: 1.8 to 2.2
y: 1.8-2.2
z: 11.8 to 12.2
w: 21.8-22.2
n: 0.1-0.25
An electromagnetic wave absorption heating element characterized by having a composition of
前記Y型六方晶フェライトが焼結体であることを特徴とする請求項1に記載の電磁波吸収発熱体。   The electromagnetic wave absorption heating element according to claim 1, wherein the Y-type hexagonal ferrite is a sintered body. 前記電磁波吸収発熱体が、前記Y型六方晶フェライトの他さらに樹脂を20〜50mass%の範囲で含有することを特徴とする請求項1または2に記載の電磁波吸収発熱体。   The electromagnetic wave absorption heating element according to claim 1 or 2, wherein the electromagnetic wave absorption heating element further contains a resin in a range of 20 to 50 mass% in addition to the Y-type hexagonal ferrite. 調理用器具の少なくとも一部に、請求項1〜3のいずれかに記載の電磁波吸収発熱体を有することを特徴とする電子レンジ用の調理用器具。   A cooking utensil for a microwave oven comprising the electromagnetic wave absorption heating element according to any one of claims 1 to 3 in at least a part of the cooking utensil.
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