JP2014043357A - Electroconductive ceramic sintered compact and electric and electronic members using the same - Google Patents

Electroconductive ceramic sintered compact and electric and electronic members using the same Download PDF

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JP2014043357A
JP2014043357A JP2012185046A JP2012185046A JP2014043357A JP 2014043357 A JP2014043357 A JP 2014043357A JP 2012185046 A JP2012185046 A JP 2012185046A JP 2012185046 A JP2012185046 A JP 2012185046A JP 2014043357 A JP2014043357 A JP 2014043357A
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sintered body
ceramic sintered
conductive ceramic
oxide particles
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Makoto Okai
誠 岡井
Takashi Kyotani
隆 京谷
Yasuto Hoshikawa
康人 干川
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Hitachi Ltd
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Abstract

PROBLEM TO BE SOLVED: To provide an electroconductive ceramic sintered compact having an electrical conduction property (electrical conductivity of at least 1,000 S/m or more) higher than that of a conventional one by equalizing the dispersion of a carbon material serving as an electroconductive material and the formation of a three-dimensional network.SOLUTION: The electroconductive ceramic sintered compact is an electroconductive ceramic sintered compact in which a carbon thin film is formed in grain boundary regions of the sintered compact of oxide particles. The oxide particles are formed of one or more selected from aluminum oxide, silicon oxide and aluminosilicate. The carbon thin film is composed of a graphene film, deposited parallelly on the surface of each oxide particle to cover the surface by a chemical vapor deposition method using a carbon-containing compound as a raw material, and further, the carbon thin film is three-dimensionally, electrically connected in the sintered compact by sintering the oxide particles each covered with the deposited graphene film by a discharge plasma sintering method, and thereby, the electrical conductivity of the sintered compact is 1,000 S/m or higher.

Description

本発明は、導電性セラミックスの焼結体に関し、特に、焼結体の粒界領域に炭素薄膜が形成された導電性セラミックス焼結体、およびそれを利用した電気・電子部材に関するものである。   The present invention relates to a sintered body of conductive ceramics, and more particularly to a conductive ceramic sintered body in which a carbon thin film is formed in a grain boundary region of the sintered body, and an electric / electronic member using the same.

セラミックス材料およびその焼結体は、一般的に軽量であり、かつ優れた機械的特性・耐熱性・耐食性を有し、電気・電子部材の素材として広く利用されている。近年では、それらの良好な特性に加えて、導電性を有するセラミックス材料が種々研究開発されている。例えば、導電性セラミックスの一種として、従来の絶縁性セラミックス材料に炭素材料(炭素を含む材料)を混合して焼結することにより、炭素成分からなる導電路を絶縁性セラミックス粒子間に形成する試みが行われている。   Ceramic materials and sintered bodies thereof are generally lightweight and have excellent mechanical properties, heat resistance, and corrosion resistance, and are widely used as materials for electric and electronic members. In recent years, in addition to these good characteristics, various ceramic materials having conductivity have been researched and developed. For example, as a kind of conductive ceramics, an attempt is made to form a conductive path composed of carbon components between insulating ceramic particles by mixing a conventional insulating ceramic material with a carbon material (a material containing carbon) and sintering it. Has been done.

特許文献1(特開2005-289695)には、セラミックス粒子(例えば、アルミナ粒子)間に、炭素原子を有する高分子化合物(例えば、ビニル系樹脂、ウレタン樹脂、エポキシ樹脂)の還元焼成物よりなる導電路が形成せしめられてなるセラミックス焼結体からなり、その体積抵抗率が1.0×108Ω・cmより小さいことを特徴とする導電性セラミックス製品が開示されている。特許文献1によると、比較的軽量であり、その電気的性質(体積抵抗率)においても等方性を示す導電性セラミックス製品が得られるとされている。 Patent Document 1 (Japanese Patent Laid-Open No. 2005-289695) is made of a reduced calcined product of a polymer compound (for example, vinyl resin, urethane resin, epoxy resin) having carbon atoms between ceramic particles (for example, alumina particles). There is disclosed a conductive ceramic product comprising a ceramic sintered body formed with a conductive path and having a volume resistivity smaller than 1.0 × 10 8 Ω · cm. According to Patent Document 1, it is said that a conductive ceramic product that is relatively light and exhibits isotropic properties in its electrical properties (volume resistivity) is obtained.

また、特許文献2(特開2009-123691)には、セラミックス粒子(例えば、アルミナ粒子、シリカ粒子、ジルコニア粒子)間に炭素原子を有する高分子化合物(例えば、ビニル系樹脂、ウレタン系樹脂、エポキシ系樹脂)の還元焼成物よりなる三次元網目状の導電路が形成せしめられてなるセラミックス焼結体からなり、その体積抵抗率が0.2Ω・cmより小さく且つグラファイトやガラス質炭素体と同等乃至はそれ以上の耐食性及び触媒性能を有することを特徴とするセラミックス電極材が開示されている。特許文献2によると、比較的軽量であり、電気的性質において等方性を示し、また、優れた耐食性と酸化還元反応における優れた触媒性能とを示すセラミックス電極材が得られるとされている。   Patent Document 2 (Japanese Patent Laid-Open No. 2009-123691) describes a polymer compound (for example, vinyl resin, urethane resin, epoxy) having carbon atoms between ceramic particles (for example, alumina particles, silica particles, zirconia particles). A ceramic sintered body formed with a three-dimensional network-like conductive path made of a reduced calcined resin), and its volume resistivity is less than 0.2 Ω · cm and is equivalent to graphite or a vitreous carbon body. Discloses a ceramic electrode material characterized by having higher corrosion resistance and catalytic performance. According to Patent Document 2, it is said that a ceramic electrode material is obtained that is relatively lightweight, exhibits isotropic electrical properties, and exhibits excellent corrosion resistance and excellent catalytic performance in a redox reaction.

また、非特許文献1(Inam等)には、放電プラズマ焼結法により作製したアルミナ−カーボン導電性ナノ複合体の電気伝導性に関する研究が報告されている。当該アルミナ−カーボン導電性ナノ複合体は、有機分散媒(ジメチルホルムアミド)に分散させたカーボンナノチューブやカーボンブラックをアルミナ微粉末とよく混合して、有機分散媒を完全に乾燥させた後、放電プラズマ焼結法によりペレット状焼結体として作製されている。非特許文献1によると、カーボンナノチューブを混合したナノ複合体の電気伝導性は、カーボンブラックを混合したナノ複合体のそれよりも4倍高く、アルミナの粒径が増大するにつれて向上したと報告されている。   Further, Non-Patent Document 1 (Inam et al.) Reports a study on the electrical conductivity of an alumina-carbon conductive nanocomposite produced by a discharge plasma sintering method. The alumina-carbon conductive nanocomposite is obtained by thoroughly mixing carbon nanotubes or carbon black dispersed in an organic dispersion medium (dimethylformamide) with fine alumina powder and completely drying the organic dispersion medium, and then performing discharge plasma. It is produced as a pellet-shaped sintered body by a sintering method. According to Non-Patent Document 1, the electrical conductivity of the nanocomposite mixed with carbon nanotubes was reported to be 4 times higher than that of the nanocomposite mixed with carbon black, and improved as the particle size of alumina increased. ing.

特開2005−289695号公報JP 2005-289695 A 特開2009−123691号公報JP 2009-123691 A

Fawad Inam, Haixue Yan, Daniel D. Jayaseelan, Ton Peijs, and Michael J. Reece: “Electrically conductive alumina-carbon nanocomposites prepared by Spark Plasma Sintering”, Journal of the European Ceramic Society 30 (2010) 153-157.Fawad Inam, Haixue Yan, Daniel D. Jayaseelan, Ton Peijs, and Michael J. Reece: “Electrically conductive alumina-carbon nanocomposites prepared by Spark Plasma Sintering”, Journal of the European Ceramic Society 30 (2010) 153-157.

導電性セラミックス材料の種々の魅力的な特性から、導電性セラミックス材料はより広い範囲の工業製品への活用が期待されている。上述した特許文献1,2および非特許文献1に記載の導電性セラミックス材料は、その電気伝導性に関して高いポテンシャルを有していると思われるが、焼結体としての電気伝導率が十分とは言えなかった。これは、従来の導電性セラミックス焼結体において、導電材となる炭素材料の分散および三次元ネットワークの形成が不十分であることに起因していると考えられた。   Due to various attractive properties of conductive ceramic materials, conductive ceramic materials are expected to be used in a wider range of industrial products. Although the conductive ceramic materials described in Patent Documents 1 and 2 and Non-Patent Document 1 described above are considered to have a high potential with respect to their electrical conductivity, the electrical conductivity as a sintered body is sufficient. I could not say. This is considered to be caused by insufficient dispersion of the carbon material serving as the conductive material and formation of the three-dimensional network in the conventional conductive ceramic sintered body.

一方、近年では、適用される工業製品の設計の観点から、従来よりも高い電気伝導性(少なくとも1000 S/m以上の電気伝導率)を有する導電性セラミックス焼結体が強く望まれている。   On the other hand, in recent years, there has been a strong demand for a conductive ceramic sintered body having higher electrical conductivity (at least 1000 S / m or more) than the conventional one from the viewpoint of the design of applied industrial products.

したがって、本発明の目的は、導電材となる炭素材料の分散および三次元ネットワークの形成を均等化し、従来よりも高い電気伝導性(少なくとも1000 S/m以上の電気伝導率)を有する導電性セラミックス焼結体を提供することにある。また、そのような導電性セラミックス焼結体を利用した電気・電子部材を提供することにある。   Accordingly, an object of the present invention is to provide a conductive ceramic that equalizes the dispersion of the carbon material as a conductive material and the formation of a three-dimensional network, and has higher electrical conductivity (electrical conductivity of at least 1000 S / m) than before. The object is to provide a sintered body. It is another object of the present invention to provide an electric / electronic member using such a conductive ceramic sintered body.

(I)本発明の一態様は、酸化物粒子焼結体の粒界領域に炭素薄膜が形成された導電性セラミックス焼結体であって、前記酸化物粒子は、アルミニウム酸化物、ケイ素酸化物およびアルミノケイ酸塩のうちのいずれか1種以上からなり、前記炭素薄膜は、前記酸化物粒子のそれぞれの表面上に形成され該表面と平行なグラフェン膜からなり、かつ前記焼結体内で三次元的に電気的接続しており、前記焼結体の電気伝導率が、1000 S/m以上であることを特徴とする導電性セラミックス焼結体を提供する。   (I) One aspect of the present invention is a conductive ceramic sintered body in which a carbon thin film is formed in a grain boundary region of an oxide particle sintered body, and the oxide particles include an aluminum oxide and a silicon oxide. And the carbon thin film is formed of a graphene film formed on each surface of the oxide particles and parallel to the surface, and three-dimensionally in the sintered body. An electrically conductive ceramic sintered body is provided, wherein the sintered ceramic body is electrically connected, and the sintered body has an electric conductivity of 1000 S / m or more.

なお、本発明で言う「グラフェン膜」とは、平均原子層数が30原子層以下のグラフェン膜と定義する。これは、グラフェン膜の平均原子層数が30原子層を超えるとグラファイトと同等の電気的性質を示すようになり、グラフェンの電気的性質の利点(例えば、非常に高い電子移動度)が希薄となるためである。   The “graphene film” in the present invention is defined as a graphene film having an average atomic layer number of 30 atomic layers or less. This means that when the average number of atomic layers of the graphene film exceeds 30 atomic layers, the electrical properties equivalent to those of graphite are exhibited, and the advantages of the electrical properties of graphene (for example, very high electron mobility) are dilute. It is to become.

(II)本発明の他の一態様は、酸化物粒子焼結体の粒界領域に炭素薄膜が形成された導電性セラミックス焼結体であって、前記酸化物粒子は、アルミニウム酸化物、ケイ素酸化物およびアルミノケイ酸塩のうちのいずれか1種以上からなり、前記炭素薄膜は、炭素含有化合物を原料とした化学気相成長法によって前記酸化物粒子のそれぞれの表面上に平行に被覆成膜されたグラフェン膜からなり、かつ前記炭素薄膜は、前記グラフェン膜が被覆成膜された前記酸化物粒子を放電プラズマ焼結法によって焼結することにより、前記焼結体内で3次元的に電気的接続しており、前記焼結体の電気伝導率が、1000 S/m以上であることを特徴とする導電性セラミックス焼結体を提供する。   (II) Another aspect of the present invention is a conductive ceramic sintered body in which a carbon thin film is formed in a grain boundary region of an oxide particle sintered body, wherein the oxide particles include aluminum oxide, silicon The carbon thin film comprises at least one of oxide and aluminosilicate, and the carbon thin film is formed in parallel on each surface of the oxide particles by chemical vapor deposition using a carbon-containing compound as a raw material. The carbon thin film is made of a graphene film, and the carbon thin film is electrically three-dimensionally in the sintered body by sintering the oxide particles coated with the graphene film by a discharge plasma sintering method. Provided is a conductive ceramic sintered body which is connected and has an electric conductivity of 1000 S / m or more.

本発明によれば、導電材となる炭素材料の分散および三次元ネットワークの形成が均等化され、従来よりも高い電気伝導性(少なくとも1000 S/m以上の電気伝導率)を有する導電性セラミックス焼結体を提供することができる。また、そのような導電性セラミックス焼結体を利用することにより、従来よりも設計自由度の高い電気・電子部材を提供することができる。   According to the present invention, the dispersion of the carbon material serving as the conductive material and the formation of the three-dimensional network are equalized, and the conductive ceramics having higher electrical conductivity than that of the prior art (electric conductivity of at least 1000 S / m or more). A ligation can be provided. In addition, by using such a conductive ceramic sintered body, it is possible to provide an electric / electronic member with a higher degree of design freedom than in the past.

本発明に係る導電性セラミックス焼結体の一例を示す断面模式図である。It is a cross-sectional schematic diagram which shows an example of the electroconductive ceramic sintered compact which concerns on this invention. 本発明に係る導電性セラミックス焼結体の製造手順を示すフローチャートである。It is a flowchart which shows the manufacture procedure of the electroconductive ceramic sintered compact which concerns on this invention. 本発明に係る導電性セラミックス焼結体の他の一例を示す断面模式図である。It is a cross-sectional schematic diagram which shows another example of the electroconductive ceramic sintered compact concerning this invention. 焼結体の電気伝導率と炭素含有量との関係を示すグラフである。It is a graph which shows the relationship between the electrical conductivity of a sintered compact, and carbon content. ゼオライト微粒子を用いた場合の焼結体の嵩密度と炭素含有量との関係を示すグラフである。It is a graph which shows the relationship between the bulk density of a sintered compact at the time of using a zeolite fine particle, and carbon content. ゼオライト微粒子を用いた場合の焼結体の熱伝導率と炭素含有量との関係を示すグラフである。It is a graph which shows the relationship between the heat conductivity of a sintered compact at the time of using a zeolite fine particle, and carbon content. 焼結体のゼーベック係数と炭素含有量との関係を示すグラフである。It is a graph which shows the relationship between the Seebeck coefficient of a sintered compact, and carbon content.

本発明は、前述した導電性セラミックス焼結体(I),(II)において、以下のような改良や変更を加えることができる。
(i)前記酸化物粒子が、平均粒径10 nm以上100 nm以下のナノ粒子である。
(ii)前記炭素薄膜の前記焼結体に対する含有率が、6質量%以上30質量%以下である。
(iii)前記焼結体の嵩密度が、1.5 g/cm3以上である。
(iv)前記酸化物粒子が、多孔質体である。
(v)前記アルミノケイ酸塩が、ゼオライトである。
(vi)前記酸化物粒子がゼオライトであり、前記炭素薄膜の前記焼結体に対する含有率が15質量%以上25質量%以下であり、前記焼結体の嵩密度が2.0 g/cm3以上である。
(vii)導電性セラミックス焼結体を利用した電気・電子部材であって、前記導電性セラミックス焼結体が、上記の本発明に係る導電性セラミックス焼結体である。
(viii)前記電気・電子部材が、熱電素子である。
(ix)前記電気・電子部材が、ヒータ部材である。
The present invention can add the following improvements and changes to the above-mentioned conductive ceramic sintered bodies (I) and (II).
(I) The oxide particles are nanoparticles having an average particle size of 10 nm to 100 nm.
(Ii) The content of the carbon thin film with respect to the sintered body is 6% by mass or more and 30% by mass or less.
(Iii) The sintered body has a bulk density of 1.5 g / cm 3 or more.
(Iv) The oxide particles are a porous body.
(V) The aluminosilicate is zeolite.
(Vi) The oxide particles are zeolite, the content of the carbon thin film with respect to the sintered body is 15% by mass or more and 25% by mass or less, and the bulk density of the sintered body is 2.0 g / cm 3 or more. is there.
(Vii) An electric / electronic member using a conductive ceramic sintered body, wherein the conductive ceramic sintered body is the conductive ceramic sintered body according to the present invention.
(Viii) The electric / electronic member is a thermoelectric element.
(Ix) The electric / electronic member is a heater member.

以下、本発明に係る実施形態について、より具体的に説明する。ただし、本発明は、ここで取り上げた実施形態に限定されることはなく、発明の技術的思想を逸脱しない範囲で適宜組み合わせや改良が可能である。   Hereinafter, embodiments according to the present invention will be described more specifically. However, the present invention is not limited to the embodiment taken up here, and can be appropriately combined and improved without departing from the technical idea of the present invention.

(導電性セラミックス焼結体)
図1は、本発明に係る導電性セラミックス焼結体の一例を示す断面模式図である。図1に示したように、本発明の導電性セラミックス焼結体100は、酸化物粒子101の焼結体の粒界領域で、各酸化物粒子101の表面上に該表面と平行に導電材としてのグラフェン膜102が形成されており、該グラフェン膜102が三次元的に電気的接続している。
(Conductive ceramic sintered body)
FIG. 1 is a schematic cross-sectional view showing an example of a conductive ceramic sintered body according to the present invention. As shown in FIG. 1, the conductive ceramic sintered body 100 of the present invention is a conductive material parallel to the surface of each oxide particle 101 in the grain boundary region of the sintered body of oxide particles 101. The graphene film 102 is formed, and the graphene film 102 is electrically connected three-dimensionally.

酸化物粒子101としては、アルミニウム酸化物(例えば、α-アルミナ。また、アルミニウムと酸素との比率が化学量論組成からずれていてもよい)、ケイ素酸化物(例えば、シリカ。また、ケイ素と酸素との比率が化学量論組成からずれていてもよい)、およびアルミノケイ酸塩(例えば、ムライト、ゼオライト)が好ましい。   Examples of the oxide particles 101 include aluminum oxide (for example, α-alumina. The ratio of aluminum and oxygen may be deviated from the stoichiometric composition), silicon oxide (for example, silica. Oxygen ratios may deviate from stoichiometric composition) and aluminosilicates (eg mullite, zeolite).

また、酸化物粒子101は、焼結性向上の観点および比表面積増大の観点から、平均粒径が10 nm以上100 nm以下のナノ粒子が好ましい。酸化物粒子101の平均粒径が100 nm超になると、焼結性が低下する(焼結しにくくなる)とともに、グラフェン膜102による三次元ネットワークの形成が乱れる。一方、酸化物粒子101の平均粒径が10 nm未満になると、各酸化物粒子101の表面活性が高くなり過ぎて強固な凝集体を形成して実質的に大きな粒子として振る舞うため、ナノ粒子を用いることの意義(焼結性向上および比表面積増大)が希薄となる。   The oxide particles 101 are preferably nanoparticles having an average particle size of 10 nm or more and 100 nm or less from the viewpoint of improving the sinterability and increasing the specific surface area. When the average particle diameter of the oxide particles 101 exceeds 100 nm, the sinterability is lowered (sintering is difficult) and the formation of a three-dimensional network by the graphene film 102 is disturbed. On the other hand, when the average particle size of the oxide particles 101 is less than 10 nm, the surface activity of each oxide particle 101 becomes too high and forms a strong aggregate and behaves as a substantially large particle. The significance of use (improving sinterability and increasing specific surface area) becomes dilute.

グラフェン膜102としては、平均原子層数が2原子層以上30原子層以下のグラフェン膜が好ましい。前述したように、グラフェン膜102の平均原子層数が30原子層超になると、グラファイトと同等の電気的性質を示すようになり、グラフェンの電気的性質の利点(例えば、非常に高い電子移動度)が希薄となる。一方、グラフェン膜102の平均原子層数が2原子層未満になると、グラフェン膜102を構成するグラフェン結晶同士の未接合(三次元ネットワークの寸断)が生じ易くなり、焼結体100全体としての電気伝導率が低下する。グラフェン膜102の平均原子層数は、5原子層以上30原子層以下がより好ましい。   As the graphene film 102, a graphene film having an average atomic layer number of 2 atomic layers or more and 30 atomic layers or less is preferable. As described above, when the average number of atomic layers of the graphene film 102 exceeds 30 atomic layers, the electrical properties equivalent to those of graphite are exhibited, and the advantages of the electrical properties of graphene (for example, very high electron mobility) ) Becomes sparse. On the other hand, when the average number of atomic layers of the graphene film 102 is less than two atomic layers, unbonded (severe three-dimensional network) between the graphene crystals constituting the graphene film 102 is likely to occur, and the electric power of the sintered body 100 as a whole Conductivity decreases. The average atomic layer number of the graphene film 102 is more preferably 5 atomic layers or more and 30 atomic layers or less.

(製造方法)
本発明に係る導電性セラミックス焼結体の製造方法について説明する。図2は、本発明に係る導電性セラミックス焼結体の作製手順を示すフローチャートである。はじめに、酸化物粒子101として平均粒径が10 nm以上100 nm以下のナノ粒子を用意する。次に、炭化水素ガスを原料ガスとする化学気相成長法(CVD)により、各酸化物粒子101の表面上に該表面と平行にグラフェン膜102を被覆成膜する。なお、酸化物粒子101の表面と平行とは、グラフェン結晶のc面と酸化物粒子101の表面とがほぼ平行である(実質的に平行と見なせる)ことを意味する。
(Production method)
The manufacturing method of the electroconductive ceramic sintered compact concerning this invention is demonstrated. FIG. 2 is a flowchart showing a procedure for producing a conductive ceramic sintered body according to the present invention. First, nanoparticles having an average particle size of 10 nm to 100 nm are prepared as the oxide particles 101. Next, a graphene film 102 is formed on the surface of each oxide particle 101 in parallel with the surface by chemical vapor deposition (CVD) using a hydrocarbon gas as a source gas. Note that the phrase “parallel to the surface of the oxide particle 101” means that the c-plane of the graphene crystal and the surface of the oxide particle 101 are substantially parallel (can be regarded as substantially parallel).

次に、得られたグラフェン膜被覆酸化物粒子を放電プラズマ焼結法によって焼結して、焼結体を作製する。最後に、当該焼結体に機械加工(例えば、ワイヤー放電加工)を施すことにより、所望の形状の導電性セラミックス焼結体を得る。その後、機械加工を施した焼結体に電極等を形成することにより、導電性セラミックス焼結体を利用した電気・電子部材を得ることができる。   Next, the obtained graphene film-covered oxide particles are sintered by a discharge plasma sintering method to produce a sintered body. Finally, by subjecting the sintered body to machining (for example, wire electric discharge machining), a conductive ceramic sintered body having a desired shape is obtained. Then, an electric / electronic member using the conductive ceramic sintered body can be obtained by forming an electrode or the like on the sintered body subjected to machining.

グラフェン膜102の成膜条件(化学気相成長の条件)の好適な例は、次のとおりである。原料ガスとしてプロピレン、キャリアガスとしてアルゴンを用い、平均原料濃度0.15〜3体積%の混合ガスを平均流速15〜50 cm/min(被成膜物上の平均流速で標準状態換算)で供給し、成長温度450〜1000℃(好ましくは750〜1000℃)で0.1〜60分間の成長を行う。なお、原料としてはプロピレン以外にもアセチレン、メタン、プロパン、エチレン等の他の炭素含有化合物を用いることができる。   A preferred example of the film formation conditions (chemical vapor deposition conditions) of the graphene film 102 is as follows. Propylene is used as the source gas, argon is used as the carrier gas, and a mixed gas with an average source concentration of 0.15 to 3% by volume is supplied at an average flow rate of 15 to 50 cm / min (converted to the standard state with the average flow rate on the film to be deposited). The growth is performed at a growth temperature of 450 to 1000 ° C. (preferably 750 to 1000 ° C.) for 0.1 to 60 minutes. In addition to propylene, other carbon-containing compounds such as acetylene, methane, propane, and ethylene can be used as the raw material.

より具体的な例を示す。平均粒径100 nmのアルミナ微粒子5 gを石英管容器に入れて成長炉の中央付近に配置し、プロピレンガス(流量10 mL/min)とアルゴンガス(流量400 mL/min)とを成長炉に導入した。成長温度および成長時間は、それぞれ800℃および30分間とした。このとき、各アルミナ微粒子の表面をグラフェン膜が均等に被覆するように、アルミナ微粒子を入れた石英管容器を10 rpmの速度で回転させた。得られた粉末の炭素含有量を調べたところ、約13質量%であった。   A more specific example is shown. Place 5 g of alumina fine particles with an average particle size of 100 nm in a quartz tube container and place it near the center of the growth furnace, and use propylene gas (flow rate 10 mL / min) and argon gas (flow rate 400 mL / min) in the growth furnace. Introduced. The growth temperature and growth time were 800 ° C. and 30 minutes, respectively. At this time, the quartz tube container containing the alumina fine particles was rotated at a speed of 10 rpm so that the graphene film uniformly coats the surface of each alumina fine particle. When the carbon content of the obtained powder was examined, it was about 13% by mass.

上記のようにして作製したグラフェン膜被覆アルミナ微粒子を、放電プラズマ焼結(Spark Plasma Sintering)装置を用いて焼結して、導電性セラミックス焼結体100を製造した。具体的には、プレス機で予備整形したペレット試料を、放電プラズマ焼結装置(住友重機械テクノフォート株式会社製、20ton-8000A 中型標準SPS装置)のチャンバー内の治具にセットした。チャンバー内を真空排気した後、アルゴンガスを導入し、アルゴンガス雰囲気下で焼結を行った。焼結の際の昇温速度を50℃/minとし、焼結圧力を80 MPaとし、焼結温度1800℃で5分間の焼結を行った。   The graphene film-coated alumina fine particles produced as described above were sintered using a spark plasma sintering apparatus to produce a conductive ceramic sintered body 100. Specifically, the pellet sample preliminarily shaped with a press machine was set in a jig in a chamber of a discharge plasma sintering apparatus (manufactured by Sumitomo Heavy Industries Technofort Co., Ltd., 20ton-8000A medium standard SPS apparatus). After evacuating the inside of the chamber, argon gas was introduced and sintering was performed in an argon gas atmosphere. Sintering was performed at a heating rate of 50 ° C./min during sintering, a sintering pressure of 80 MPa, and a sintering temperature of 1800 ° C. for 5 minutes.

得られた導電性セラミックス焼結体100は、十分な機械的強度を有しており、ワイヤー放電加工機を用いて所望の形状に機械加工することが可能であった。上記の例では、酸化物粒子101としてアルミナ微粒子を用いたが、シリカ微粒子やムライト微粒子を用いても同様に導電性セラミックス焼結体100が得られ、所望の形状への機械加工が可能であることを別途確認した。   The obtained conductive ceramic sintered body 100 had sufficient mechanical strength, and could be machined into a desired shape using a wire electric discharge machine. In the above example, alumina fine particles are used as the oxide particles 101. However, even if silica fine particles or mullite fine particles are used, the conductive ceramic sintered body 100 can be obtained in the same manner and can be machined into a desired shape. It was confirmed separately.

ここで、アルミニウム−酸素成分は、グラフェン膜102の形成に関して触媒的効果を有することから、アルミナ微粒子およびムライト微粒子に対しては、少ない原料ガス流量(薄い原料ガス濃度)で必要十分な量のグラフェン膜102を被覆成膜することができた。一方、ケイ素−酸素成分は、アルミニウム−酸素成分に比して、グラフェン膜102の形成の触媒的効果が小さいことから(1/10以下程度)、シリカ微粒子に対しては、原料ガス流量(原料ガス濃度)を10倍程度増加させて製造した。なお、成膜されるグラフェン膜102の厚さ(すなわち平均原子層数)は、成長時間と比例関係があることから、成長時間を制御することでグラフェン膜102の平均原子層数が制御可能である。   Here, since the aluminum-oxygen component has a catalytic effect on the formation of the graphene film 102, a necessary and sufficient amount of graphene is required with a small raw material gas flow rate (thin raw material gas concentration) for alumina fine particles and mullite fine particles. The film 102 could be coated. On the other hand, the silicon-oxygen component has a smaller catalytic effect for forming the graphene film 102 than the aluminum-oxygen component (about 1/10 or less). The gas concentration was increased by about 10 times. Note that the thickness (that is, the average number of atomic layers) of the graphene film 102 to be formed is proportional to the growth time, and thus the average number of atomic layers of the graphene film 102 can be controlled by controlling the growth time. is there.

(導電性セラミックス焼結体)
図3は、本発明に係る導電性セラミックス焼結体の他の一例を示す断面模式図である。図3に示したように、本発明の導電性セラミックス焼結体200は、多孔質酸化物粒子201の焼結体の粒界領域に、各多孔質酸化物粒子201の外表面と平行に導電材としてのグラフェン膜202が形成されており、該グラフェン膜202が三次元的に電気的接続している。また、導電性セラミックス焼結体200は、酸化物粒子が多孔質体であることから、多孔質酸化物粒子201の外表面に加えて、多孔質酸化物粒子201の内表面上にも平行にグラフェン膜203が形成されており、より網目の細かい三次元ネットワークが形成されている。導電性セラミックス焼結体200は、前述の焼結体100と同様の手順により製造することができる。
(Conductive ceramic sintered body)
FIG. 3 is a schematic cross-sectional view showing another example of the conductive ceramic sintered body according to the present invention. As shown in FIG. 3, the conductive ceramic sintered body 200 of the present invention is electrically conductive in the grain boundary region of the sintered body of the porous oxide particles 201 in parallel with the outer surface of each porous oxide particle 201. A graphene film 202 as a material is formed, and the graphene film 202 is electrically connected three-dimensionally. In addition, since the conductive ceramic sintered body 200 has a porous oxide particle, in addition to the outer surface of the porous oxide particle 201, the conductive ceramic sintered body 200 is also parallel to the inner surface of the porous oxide particle 201. A graphene film 203 is formed, and a finer three-dimensional network is formed. The conductive ceramic sintered body 200 can be manufactured by the same procedure as the sintered body 100 described above.

ここで、導電性セラミックス焼結体200は、母材(骨格)となる酸化物粒子が多孔質体であることに起因して、より大きな比表面積を有する。そのため、同一のグラフェン成膜条件において、中実球状の酸化物粒子を用いた場合に比較して、形成されるグラフェン膜の厚さが薄くなる(平均原子層数が小さくなる)。言い換えると、中実球状の酸化物粒子を用いた場合(例えば、実施例1)と同等の厚さのグラフェン膜を被覆成膜すると、より多くの炭素含有量を担持させることができる。その結果、より高い電気伝導性を実現できる。また、多孔質酸化物粒子201としては、アルミニウム酸化物、ケイ素酸化物、アルミノケイ酸塩であればいずれを用いてもよいが、孔の制御性の観点からゼオライトの利用は好ましい。   Here, the conductive ceramic sintered body 200 has a larger specific surface area due to the fact that the oxide particles serving as the base material (skeleton) are a porous body. Therefore, compared with the case where solid spherical oxide particles are used under the same graphene film formation conditions, the thickness of the formed graphene film is reduced (the number of average atomic layers is reduced). In other words, when a graphene film having a thickness equivalent to that in the case of using solid spherical oxide particles (for example, Example 1) is coated, a larger carbon content can be supported. As a result, higher electrical conductivity can be realized. In addition, as the porous oxide particles 201, any aluminum oxide, silicon oxide, and aluminosilicate may be used, but use of zeolite is preferable from the viewpoint of controllability of pores.

(導電性セラミックス焼結体の電気伝導性評価および焼結性評価)
酸化物粒子として、アルミナ微粒子(平均粒径10 nm、比表面積120 m2/g)と、シリカ微粒子(平均粒径10 nm、比表面積120 m2/g)と、ゼオライト微粒子(平均粒径10 nm、比表面積1500 m2/g、Y型ゼオライトでアルミニウムとケイ素とのモル比が1:1)とを用い、それぞれ前述した製造方法に沿って、炭素含有量の異なる導電性セラミックス焼結体を作製した。炭素含有量の制御(すなわち、グラフェン膜の平均原子層数の制御)は、主に成長時間を制御することにより行った。得られた各焼結体に対してワイヤー放電加工機を用いて機械加工を施し、ロッド状の測定試料を用意した。各測定試料に対して、電気伝導性評価として四端子法による電気伝導率の測定を行い、焼結性評価として嵩密度の測定を行った。
(Evaluation of electrical conductivity and sinterability of conductive ceramics)
As oxide particles, alumina fine particles (average particle size 10 nm, specific surface area 120 m 2 / g), silica fine particles (average particle size 10 nm, specific surface area 120 m 2 / g), and zeolite fine particles (average particle size 10 Conductive ceramics sintered bodies with different carbon contents according to the above-described production methods, each using nm, specific surface area of 1500 m 2 / g, and Y-type zeolite with a molar ratio of aluminum to silicon of 1: 1) Was made. Control of the carbon content (that is, control of the average number of atomic layers of the graphene film) was performed mainly by controlling the growth time. Each obtained sintered body was machined using a wire electric discharge machine to prepare a rod-shaped measurement sample. For each measurement sample, the electrical conductivity was measured by a four-terminal method as an electrical conductivity evaluation, and the bulk density was measured as a sinterability evaluation.

図4は、焼結体の電気伝導率と炭素含有量との関係を示すグラフである。図4に示したように、酸化物粒子として、アルミナ微粒子、シリカ微粒子、およびゼオライト微粒子のいずれを用いた場合でも、炭素含有量が増加するにつれて焼結体の電気伝導率が向上し、数1000 S/mの電気伝導率を示した。アルミナ微粒子およびシリカ微粒子を用いた場合、約6質量%以上の炭素含有量で1000 S/m以上の電気伝導率を達成した。また、ゼオライト微粒子を用いた場合、約5質量%以上の炭素含有量で1000 S/m以上の電気伝導率を達成した。含有させる炭素量は、10質量%以上がより好ましく、15質量%以上が更に好ましいと言える。特に、ゼオライト微粒子を用い23.3質量%の炭素含有量において、7650 S/mという極めて高い電気伝導率を達成した。なお、ゼオライト微粒子としてL型ゼオライトの微粒子を用いた場合も、同様の結果が得られることを別途確認した。   FIG. 4 is a graph showing the relationship between the electrical conductivity of the sintered body and the carbon content. As shown in FIG. 4, in the case where any of alumina fine particles, silica fine particles, and zeolite fine particles is used as the oxide particles, the electrical conductivity of the sintered body is improved as the carbon content increases. The electrical conductivity of S / m was shown. When alumina fine particles and silica fine particles were used, an electric conductivity of 1000 S / m or more was achieved with a carbon content of about 6% by mass or more. When zeolite fine particles were used, an electric conductivity of 1000 S / m or more was achieved with a carbon content of about 5% by mass or more. The amount of carbon to be contained is more preferably 10% by mass or more, and more preferably 15% by mass or more. In particular, an extremely high electrical conductivity of 7650 S / m was achieved at a carbon content of 23.3% by mass using zeolite fine particles. It was separately confirmed that the same results were obtained when L-type zeolite fine particles were used as the zeolite fine particles.

上記のような高い電気伝導率が得られた要因としては、「炭素薄膜としてグラフェン膜を形成したこと」、「該グラフェン膜を各酸化物粒子の表面に被膜形成したこと」が考えられる。特に、グラフェン膜の成膜を気相成長法によって行ったことにより、各酸化物粒子の外表面に一様なグラフェン膜が形成されたことが寄与していると考えられる。さらに、多孔質酸化物粒子の場合は、外表面に加えて多孔質酸化物粒子の孔の内表面にもグラフェン膜が形成されたことが大きく寄与していると考えられる。これらの結果から、本発明に係る導電性セラミックス焼結体は、従来技術および最新製品から要求される電気伝導性を優に凌駕していることが実証された。   As factors for obtaining the high electrical conductivity as described above, “the graphene film was formed as a carbon thin film” and “the graphene film was formed on the surface of each oxide particle” are considered. In particular, it is considered that the formation of a uniform graphene film on the outer surface of each oxide particle contributes to the formation of the graphene film by vapor deposition. Furthermore, in the case of porous oxide particles, it is considered that the graphene film is greatly contributed to the inner surface of the pores of the porous oxide particles in addition to the outer surface. From these results, it was demonstrated that the conductive ceramic sintered body according to the present invention far surpassed the electrical conductivity required from the prior art and the latest products.

図5は、ゼオライト微粒子を用いた場合の焼結体の嵩密度と炭素含有量との関係を示すグラフである。図5に示したように、炭素含有量が25質量%程度までは、焼結体の嵩密度にほとんど変化がなく、良好な焼結性を有していることが確認された。一方、炭素含有量が25質量%超になると、焼結体の嵩密度が大きく低下し始めており、炭素含有量が多過ぎると(炭素薄膜が厚過ぎると)、酸化物粒子同士の焼結性を劣化させることが判った。図4における電気伝導率の低下領域は、焼結体の嵩密度の低下領域と符合しており、嵩密度の低下に起因して焼結体全体としての電気伝導率が低下したものと考えられた。また、炭素含有量が30質量%超になると、焼結体の形成自体が困難になった。   FIG. 5 is a graph showing the relationship between the bulk density of the sintered body and the carbon content when zeolite fine particles are used. As shown in FIG. 5, it was confirmed that until the carbon content was about 25% by mass, there was almost no change in the bulk density of the sintered body and it had good sinterability. On the other hand, when the carbon content exceeds 25% by mass, the bulk density of the sintered body starts to greatly decrease, and when the carbon content is too large (when the carbon thin film is too thick), the sinterability between the oxide particles. It was found to deteriorate. The region where the electrical conductivity is reduced in FIG. 4 coincides with the region where the sintered body is reduced in bulk density, and it is considered that the electrical conductivity of the sintered body as a whole is reduced due to the reduction in bulk density. It was. In addition, when the carbon content exceeds 30% by mass, formation of the sintered body itself becomes difficult.

これらの結果から、本発明の導電性セラミックス焼結体における炭素含有量の上限および嵩密度の下限は、それぞれ30質量%および1.5 g/cm3と判明した。また、電気伝導率と嵩密度とのバランスから、炭素含有量は15質量%以上25質量%以下が最も好ましく、嵩密度は2.0 g/cm3以上がより好ましい。 From these results, it was found that the upper limit of the carbon content and the lower limit of the bulk density in the conductive ceramic sintered body of the present invention were 30% by mass and 1.5 g / cm 3 , respectively. From the balance between electrical conductivity and bulk density, the carbon content is most preferably 15% by mass or more and 25% by mass or less, and the bulk density is more preferably 2.0 g / cm 3 or more.

(導電性セラミックス焼結体を利用した電気・電子部材)
(1)熱電素子
本発明の導電性セラミックス焼結体を利用した電気・電子部材として、熱電素子に適用する例について説明する。熱電素子において、重要な材料パラメータは、無次元性能指数ZTである。このZTが「ZT≧1」であることが実用上の必須条件である。ここで、Z(単位K-1)は「Z=S2σ/κ」で表される性能指数であり、T(単位K)は使用時の平均温度である。S(単位μV/K)はゼーベック係数、σ(単位S/m)は電気伝導率、κ(単位W/m・K)は熱伝導率である。
(Electrical and electronic materials using conductive ceramics)
(1) Thermoelectric element The example applied to a thermoelectric element is demonstrated as an electric / electronic member using the electroconductive ceramic sintered compact of this invention. In thermoelectric elements, an important material parameter is the dimensionless figure of merit ZT. It is a practically essential condition that this ZT is “ZT ≧ 1”. Here, Z (unit K −1 ) is a performance index expressed by “Z = S 2 σ / κ”, and T (unit K) is an average temperature during use. S (unit μV / K) is the Seebeck coefficient, σ (unit S / m) is electrical conductivity, and κ (unit W / m · K) is thermal conductivity.

性能指数Zを算出するために、先の実施例3で作製した導電性セラミックス焼結体の熱伝導率κとゼーベック係数Sとを測定した。結果を図6,7に示す。図6は、ゼオライト微粒子を用いた場合の焼結体の熱伝導率と炭素含有量との関係を示すグラフである。図6に示したように、炭素含有量が増加するにつれて焼結体の熱伝導率が増大し、例えば、炭素含有量23.3質量%で5.9 W/m・K、29.1質量%で7.5 W/m・Kであった。しかしながら、焼結体の熱伝導率の値自体は、母材であるゼオライト単体の熱伝導率(約30 W/m・K)よりもかなり小さい値でなった。この理由としては、c軸方向の熱伝導率が小さいグラフェン膜によって個々のゼオライト微粒子が被覆されているためと考えられる。   In order to calculate the figure of merit Z, the thermal conductivity κ and Seebeck coefficient S of the conductive ceramic sintered body produced in Example 3 were measured. The results are shown in FIGS. FIG. 6 is a graph showing the relationship between the thermal conductivity of the sintered body and the carbon content when zeolite fine particles are used. As shown in FIG. 6, as the carbon content increases, the thermal conductivity of the sintered body increases. For example, the carbon content is 23.3% by mass, 5.9 W / m · K, and 29.1% by mass is 7.5 W / m.・ It was K. However, the value of the thermal conductivity of the sintered body itself was considerably smaller than the thermal conductivity of the zeolite itself as the base material (about 30 W / m · K). The reason for this is considered that each zeolite fine particle is covered with a graphene film having a low thermal conductivity in the c-axis direction.

図7は、焼結体のゼーベック係数と炭素含有量との関係を示すグラフである。ゼオライト微粒子(平均粒径10 nm、比表面積1500 m2/g)を用いた焼結体とアルミナ微粒子(平均粒径10 nm、比表面積120 m2/g)を用いた焼結体との結果をプロットした。図7に示したように、いずれの場合も、焼結体の炭素含有量を変化させても焼結体のゼーベック係数はほとんど変化しなかったが、用いた酸化物粒子の比表面積に比例してゼーベック係数が増大することが判明した。 FIG. 7 is a graph showing the relationship between the Seebeck coefficient of the sintered body and the carbon content. Results of sintered body using zeolite fine particles (average particle size 10 nm, specific surface area 1500 m 2 / g) and sintered body using alumina fine particles (average particle size 10 nm, specific surface area 120 m 2 / g) Was plotted. As shown in FIG. 7, in any case, the Seebeck coefficient of the sintered body was hardly changed even when the carbon content of the sintered body was changed, but it was proportional to the specific surface area of the oxide particles used. The Seebeck coefficient was found to increase.

ここで、本発明の導電性セラミックス焼結体において熱起電力が発生するメカニズムについて考察する。本発明の導電性セラミックス焼結体の両端に温度差を与えた場合、高温側において、用いた酸化物粒子の表面準位あるいはグラフェン膜の不純物準位からキャリア(電子あるいは正孔)が放出される。該キャリアは、グラフェン膜の三次元ネットワークを通じて低温側に拡散し、低温側の酸化物粒子の表面準位に蓄積される。これにより、高温側と低温側との間で電位差(すなわち起電力)が発生する。この場合、熱起電力の大きさは、表面準位の量に比例すると考えられる。すなわち、用いた酸化物粒子の比表面積に比例して、熱起電力が大きくなると考えられる。   Here, the mechanism by which the thermoelectromotive force is generated in the conductive ceramic sintered body of the present invention will be considered. When a temperature difference is given to both ends of the conductive ceramic sintered body of the present invention, carriers (electrons or holes) are emitted from the surface level of the used oxide particles or the impurity level of the graphene film on the high temperature side. The The carriers diffuse to the low temperature side through a three-dimensional network of graphene films, and accumulate on the surface level of the oxide particles on the low temperature side. Thereby, a potential difference (that is, electromotive force) is generated between the high temperature side and the low temperature side. In this case, the magnitude of the thermoelectromotive force is considered to be proportional to the amount of surface states. That is, it is considered that the thermoelectromotive force increases in proportion to the specific surface area of the oxide particles used.

上記の各種測定結果から、熱電素子における無次元性能指数ZTを算出する。酸化物粒子としてゼオライト微粒子(平均粒径10 nm、比表面積1500 m2/g)を用い、炭素含有量23.3質量%となるように焼結体を作製した場合、電気伝導度7650 S/m、熱伝導度5.9 W/m・K、ゼーベック係数1540μV/Kであった。使用時の平均温度を「T=573 K」とすると、次元性能指数は「ZT=1.8」となり、実用的な熱電素子を実現することが可能である。 From the above measurement results, a dimensionless figure of merit ZT in the thermoelectric element is calculated. When zeolite fine particles (average particle size 10 nm, specific surface area 1500 m 2 / g) are used as oxide particles and a sintered body is produced so that the carbon content is 23.3 mass%, the electric conductivity is 7650 S / m, The thermal conductivity was 5.9 W / m · K, and the Seebeck coefficient was 1540 μV / K. When the average temperature during use is “T = 573 K”, the dimensional figure of merit is “ZT = 1.8”, and a practical thermoelectric device can be realized.

本発明の導電性セラミックス焼結体は、酸化物粒子の表面に被覆成膜するグラフェン膜に異種元素を導入することにより、電気伝導型(すなわちp型またはn型)の制御が可能である。例えば、グラフェン膜を被覆成膜する際に、アクリルニトリル等の窒素含有原料を用いることにより、グラフェン膜内に窒素を構成元素として導入し、グラフェン膜の電気伝導型をn型に制御することができる。また、ジボラン等のホウ素含有原料を用いることにより、グラフェン膜内にホウ素を構成要素として導入し、グラフェン膜の電気伝導型をp型に制御することができる。   The conductive ceramic sintered body of the present invention can be controlled in electrical conductivity type (that is, p-type or n-type) by introducing a different element into the graphene film formed on the surface of the oxide particles. For example, when a graphene film is coated, a nitrogen-containing raw material such as acrylonitrile is used to introduce nitrogen as a constituent element into the graphene film and to control the conductivity type of the graphene film to n-type. it can. Further, by using a boron-containing raw material such as diborane, boron can be introduced into the graphene film as a constituent element, and the electric conductivity type of the graphene film can be controlled to be p-type.

熱電素子においては、p型熱電素子とn型熱電素子とを直列に接続することにより、起電力を倍にすることができる。そこで、本発明の導電性セラミックス焼結体を利用したp型熱電素子(1 mm3)とn型熱電素子(1 mm3)とを作製し、それらを直列に接続してユニットを形成した。さらに、そのユニットを直列に100個並べることにより、熱電パネルを作製した。作製した熱電パネルを300℃の熱源に貼付けて、発電効率を測定した。その結果、20%の発電効率を実現できることが確認された。 In a thermoelectric element, an electromotive force can be doubled by connecting a p-type thermoelectric element and an n-type thermoelectric element in series. Therefore, a p-type thermoelectric element (1 mm 3 ) and an n-type thermoelectric element (1 mm 3 ) using the conductive ceramic sintered body of the present invention were produced and connected in series to form a unit. Furthermore, a thermoelectric panel was produced by arranging 100 units in series. The produced thermoelectric panel was attached to a heat source at 300 ° C., and the power generation efficiency was measured. As a result, it was confirmed that a power generation efficiency of 20% could be realized.

(2)その他の電気・電子部材
上記で説明したように、本発明に係る導電性セラミックス焼結体は、従来よりも高い電気伝導性(数1000 S/mの電気伝導率)を有している。また、焼結体の母材(骨格)となる酸化物が高い耐熱性を有することから、耐熱部材としての適性も有する。すなわち、耐熱性導電部材として高いポテンシャルを有し、例えば、ヒータ部材、放電用部材、半導体製造用部材、金型部材、静電保持部材などに好適に利用できる。
(2) Other electric / electronic members As described above, the conductive ceramic sintered body according to the present invention has a higher electric conductivity (an electric conductivity of several thousand S / m) than before. Yes. Moreover, since the oxide used as the base material (skeleton) of the sintered body has high heat resistance, it also has suitability as a heat-resistant member. That is, it has a high potential as a heat-resistant conductive member, and can be suitably used for, for example, a heater member, a discharging member, a semiconductor manufacturing member, a mold member, an electrostatic holding member, and the like.

100…導電性セラミックス焼結体、101…酸化物粒子、102…グラフェン膜、
200…導電性セラミックス焼結体、201…多孔質酸化物粒子、
202,203…グラフェン膜。
100 ... conductive ceramic sintered body, 101 ... oxide particles, 102 ... graphene film,
200 ... sintered ceramics, 201 ... porous oxide particles,
202, 203 ... Graphene film.

Claims (11)

酸化物粒子焼結体の粒界領域に炭素薄膜が形成された導電性セラミックス焼結体であって、
前記酸化物粒子は、アルミニウム酸化物、ケイ素酸化物およびアルミノケイ酸塩のうちのいずれか1種以上からなり、
前記炭素薄膜は、前記酸化物粒子のそれぞれの表面上に形成され該表面と平行なグラフェン膜からなり、かつ前記焼結体内で3次元的に電気的接続しており、
前記焼結体の電気伝導率が、1000 S/m以上であることを特徴とする導電性セラミックス焼結体。
A conductive ceramic sintered body in which a carbon thin film is formed in the grain boundary region of the oxide particle sintered body,
The oxide particles comprise one or more of aluminum oxide, silicon oxide and aluminosilicate,
The carbon thin film is formed of a graphene film formed on each surface of the oxide particles and parallel to the surface, and is electrically connected three-dimensionally in the sintered body,
An electrically conductive ceramic sintered body, wherein the sintered body has an electric conductivity of 1000 S / m or more.
酸化物粒子焼結体の粒界領域に炭素薄膜が形成された導電性セラミックス焼結体であって、
前記酸化物粒子は、アルミニウム酸化物、ケイ素酸化物およびアルミノケイ酸塩のうちのいずれか1種以上からなり、
前記炭素薄膜は、炭素含有化合物を原料とした化学気相成長法によって前記酸化物粒子のそれぞれの表面上に平行に被覆成膜されたグラフェン膜からなり、
かつ前記炭素薄膜は、前記グラフェン膜が被覆成膜された前記酸化物粒子を放電プラズマ焼結法によって焼結することにより、前記焼結体内で3次元的に電気的接続しており、
前記焼結体の電気伝導率が、1000 S/m以上であることを特徴とする導電性セラミックス焼結体。
A conductive ceramic sintered body in which a carbon thin film is formed in the grain boundary region of the oxide particle sintered body,
The oxide particles comprise one or more of aluminum oxide, silicon oxide and aluminosilicate,
The carbon thin film is composed of a graphene film coated in parallel on each surface of the oxide particles by chemical vapor deposition using a carbon-containing compound as a raw material,
The carbon thin film is electrically connected three-dimensionally in the sintered body by sintering the oxide particles coated with the graphene film by a discharge plasma sintering method.
An electrically conductive ceramic sintered body, wherein the sintered body has an electric conductivity of 1000 S / m or more.
請求項1または請求項2に記載の導電性セラミックス焼結体において、
前記酸化物粒子が、平均粒径10 nm以上100 nm以下のナノ粒子であることを特徴とする導電性セラミックス焼結体。
In the conductive ceramic sintered body according to claim 1 or 2,
The conductive ceramic sintered body, wherein the oxide particles are nanoparticles having an average particle diameter of 10 nm to 100 nm.
請求項1乃至請求項3のいずれかに記載の導電性セラミックス焼結体において、
前記炭素薄膜の前記焼結体に対する含有率が、6質量%以上30質量%以下であることを特徴とする導電性セラミックス焼結体。
In the conductive ceramic sintered body according to any one of claims 1 to 3,
The conductive ceramic sintered body, wherein a content of the carbon thin film with respect to the sintered body is 6% by mass or more and 30% by mass or less.
請求項1乃至請求項4のいずれかに記載の導電性セラミックス焼結体において、
前記焼結体の嵩密度が、1.5 g/cm3以上であることを特徴とする導電性セラミックス焼結体。
In the conductive ceramic sintered body according to any one of claims 1 to 4,
The conductive ceramic sintered body, wherein the sintered body has a bulk density of 1.5 g / cm 3 or more.
請求項1乃至請求項5のいずれかに記載の導電性セラミックス焼結体において、
前記酸化物粒子が、多孔質体であることを特徴とする導電性セラミックス焼結体。
In the conductive ceramic sintered body according to any one of claims 1 to 5,
The conductive ceramic sintered body, wherein the oxide particles are a porous body.
請求項1乃至請求項5のいずれかに記載の導電性セラミックス焼結体において、
前記アルミノケイ酸塩が、ゼオライトであることを特徴とする導電性セラミックス焼結体。
In the conductive ceramic sintered body according to any one of claims 1 to 5,
The conductive ceramic sintered body, wherein the aluminosilicate is zeolite.
請求項1乃至請求項3のいずれかに記載の導電性セラミックス焼結体において、
前記酸化物粒子がゼオライトであり、
前記炭素薄膜の前記焼結体に対する含有率が15質量%以上25質量%以下であり、
前記焼結体の嵩密度が2.0 g/cm3以上であることを特徴とする導電性セラミックス焼結体。
In the conductive ceramic sintered body according to any one of claims 1 to 3,
The oxide particles are zeolite,
The content of the carbon thin film with respect to the sintered body is 15 mass% or more and 25 mass% or less,
A conductive ceramic sintered body, wherein the sintered body has a bulk density of 2.0 g / cm 3 or more.
導電性セラミックス焼結体を利用した電気・電子部材であって、
前記導電性セラミックス焼結体が、請求項1乃至請求項8のいずれかに記載の導電性セラミックス焼結体であることを特徴とする電気・電子部材。
An electric / electronic member using a conductive ceramic sintered body,
An electrical / electronic member, wherein the conductive ceramic sintered body is the conductive ceramic sintered body according to any one of claims 1 to 8.
請求項9に記載の電気・電子部材において、
前記電気・電子部材が、熱電素子であることを特徴とする電気・電子部材。
The electric / electronic member according to claim 9,
The electric / electronic member is a thermoelectric element.
請求項9に記載の電気・電子部材において、
前記電気・電子部材が、ヒータ部材であることを特徴とする電気・電子部材。
The electric / electronic member according to claim 9,
The electric / electronic member is a heater member.
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