JP2001151578A - Porous silicon carbide sintered compact and method of producing the same - Google Patents
Porous silicon carbide sintered compact and method of producing the sameInfo
- Publication number
- JP2001151578A JP2001151578A JP33085199A JP33085199A JP2001151578A JP 2001151578 A JP2001151578 A JP 2001151578A JP 33085199 A JP33085199 A JP 33085199A JP 33085199 A JP33085199 A JP 33085199A JP 2001151578 A JP2001151578 A JP 2001151578A
- Authority
- JP
- Japan
- Prior art keywords
- silicon carbide
- sintering
- porous silicon
- carbide sintered
- sintered body
- Prior art date
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Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
- C04B38/0038—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by superficial sintering or bonding of particulate matter
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Ceramic Products (AREA)
- Porous Artificial Stone Or Porous Ceramic Products (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、多孔質炭化珪素焼
結体およびその製造方法に関する。[0001] The present invention relates to a porous silicon carbide sintered body and a method for producing the same.
【０００２】[0002]
【従来の技術】炭化珪素焼結体は、耐熱温度が高く、熱
伝導性と電気伝導性に優れ、化学的安定性をそなえてい
るため、高温用の各種構造部材として利用されており、
とくに、焼結体の組織構造を多孔質とした多孔質炭化珪
素焼結体は、触媒担体、高温ガス浄化フィルター、溶融
金属濾過用フィルター、マイクロ波吸収発熱体、通気性
断熱材など多様な分野において使用されている。2. Description of the Related Art Sintered silicon carbide has a high heat-resistant temperature, is excellent in thermal conductivity and electric conductivity, and has chemical stability.
In particular, porous silicon carbide sintered bodies with a porous structure structure are used in various fields such as catalyst carriers, high-temperature gas purification filters, filters for molten metal filtration, microwave absorption heating elements, and air-permeable heat insulating materials. Used in
【０００３】多孔質炭化珪素焼結体は、通常、ポリウレ
タンフォームのような三次元網目構造の有機質発泡体に
炭化珪素のスラリーを含浸させ、乾燥した後、高温焼成
して炭化珪素を焼結するとともに、有機質発泡体を焼
却、除去することにより製造されている（例えば、特開
昭５８−１２２０１６号公報など）が、この方法により
製造される多孔質炭化珪素焼結体は、有機質発泡体を焼
却、除去して形成された炭化珪素の骨格体を焼結するも
のであるから、高い気孔率を付与することはできるが、
空孔のサイズが大きく比表面積が小さくなり、機械的強
度および電気伝導率が劣るという難点があり、応用面で
大きな制約となっている。[0003] Generally, a porous silicon carbide sintered body is obtained by impregnating an organic foam having a three-dimensional network structure such as a polyurethane foam with a slurry of silicon carbide, drying it, and then firing it at a high temperature to sinter the silicon carbide. At the same time, it is manufactured by incinerating and removing the organic foam (for example, Japanese Patent Application Laid-Open No. 58-122016), but the porous silicon carbide sintered body manufactured by this method uses an organic foam. Incineration, because it is to sinter the silicon carbide skeleton formed by removal, it can give high porosity,
The pore size is large, the specific surface area is small, and the mechanical strength and electric conductivity are poor. This is a great limitation in application.
【０００４】多孔質炭化珪素焼結体の製造方法として、
炭化珪素の粉末に有機質の樹脂バインダーを加えて混合
し、この混合物を所定形状に成形した後、焼成して炭化
珪素の粉末粒子を粒成長させる方法も提案されており
（特開平３−２１５３７４号公報、特開平３−２１５３
７５号公報など）、この方法によれば、気孔率が５０％
程度の多孔質炭化珪素焼結体を製造することが可能であ
るが、多孔質体を構成する炭化珪素粒子の結合が炭化珪
素微粒子の粒成長のみにより行われるから、機械的強度
が十分でなく、気孔特性と強度特性の両立を図ることが
困難である。[0004] As a method of manufacturing a porous silicon carbide sintered body,
A method has also been proposed in which an organic resin binder is added to and mixed with silicon carbide powder, the mixture is formed into a predetermined shape, and then fired to grow silicon carbide powder particles (Japanese Patent Laid-Open No. 3-215374). Gazette, JP-A-3-2153
According to this method, the porosity is 50%.
Although it is possible to manufacture a porous silicon carbide sintered body of a degree, since the bonding of the silicon carbide particles constituting the porous body is performed only by the growth of silicon carbide fine particles, the mechanical strength is not sufficient. It is difficult to achieve both pore characteristics and strength characteristics.
【０００５】また、メソフェーズ含有ピッチで被覆され
てなる炭化珪素粉末および溶媒からなるスラリー中に均
一に分散安定化された微細泡を生成し、この微細泡含有
スラリーを用いて鋳込み成形により成形体を形成し、こ
の成形体を非酸化性雰囲気下で乾燥、焼成した後、珪素
を含浸させ、ついで、未反応の珪素を除去するという微
細気孔径を有する多孔質炭化珪素焼結体を得ることを目
的とする多孔質炭化珪素焼結体の製造方法も提案されて
いるが（特開平６−２９３５７５号公報）が、この方法
においても、微細泡を均一に分散させたスラリーの調製
が難しいため、均一な気孔が得難く、珪素を含浸させた
後に未反応の珪素を除去する工程を要するため製造工程
が複雑となるという問題点もある。[0005] Further, fine bubbles uniformly dispersed and stabilized in a slurry comprising a silicon carbide powder coated with a mesophase-containing pitch and a solvent, are formed, and a molded article is formed by casting using the slurry containing the fine bubbles. After forming and drying this molded body under a non-oxidizing atmosphere, and impregnating with silicon, then, a porous silicon carbide sintered body having a fine pore diameter of removing unreacted silicon is obtained. Although a method for producing a target porous silicon carbide sintered body has also been proposed (Japanese Patent Application Laid-Open No. 6-293575), it is difficult to prepare a slurry in which fine bubbles are uniformly dispersed even in this method. There is also a problem that it is difficult to obtain uniform pores and a step of removing unreacted silicon after impregnation with silicon is required, which complicates the manufacturing process.
【０００６】発明者らは、多孔質炭化珪素焼結体の製造
における上記従来の問題点を解決して、気孔特性として
高い比表面積を有し、機械的強度および電気伝導率にも
優れた多孔炭化珪素焼結体を得るために、炭化珪素のス
ラリーや炭化珪素の粉末に有機質の樹脂バインダーを加
えた混合物を介して間接的に多孔質炭化珪素焼結体を得
る方法ではなく、サブミクロンサイズの炭化珪素ウイス
カーを直接焼結することにより多孔質炭化珪素焼結体を
得る方法について検討を重ねた。The present inventors have solved the above-mentioned conventional problems in the production of a porous silicon carbide sintered body, and have a porous material having a high specific surface area as a pore characteristic and excellent mechanical strength and electric conductivity. In order to obtain a silicon carbide sintered body, it is not a method of indirectly obtaining a porous silicon carbide sintered body through a mixture of a silicon carbide slurry or a silicon carbide powder with an organic resin binder, but a submicron size. A method of obtaining a porous silicon carbide sintered body by directly sintering the silicon carbide whiskers of Example 1 was repeated.
【０００７】[0007]
【発明が解決しようとする課題】本発明は、上記検討の
過程において、炭化珪素ウイスカーを加圧し、加圧され
た炭化珪素ウイスカーに通電して焼結を行うことによ
り、炭化珪素ウイスカーの形状とサイズを維持しなが
ら、ウイスカー同士を焼結、連結させることができるこ
とを見出したことに基づいてなされたものであり、その
目的は、５０％以上の気孔率をそなえ、ミクロンオーダ
ーの空孔を有し、比表面積が高く、機械的強度および電
気伝導率に優れた多孔質炭化珪素焼結体およびその製造
方法を提供することにある。SUMMARY OF THE INVENTION According to the present invention, the shape of the silicon carbide whisker is improved by pressing the silicon carbide whisker and conducting sintering by applying a current to the pressurized silicon carbide whisker in the course of the above examination. This is based on the finding that whiskers can be sintered and connected while maintaining their size. The purpose is to provide a porosity of 50% or more and to have pores on the order of microns. Another object of the present invention is to provide a porous silicon carbide sintered body having a high specific surface area, excellent mechanical strength and excellent electrical conductivity, and a method for producing the same.
【０００８】[0008]
【課題を解決するための手段】上記の目的を達成するた
めの本発明の請求項１による多孔質炭化珪素焼結体は、
炭化珪素ウイスカー同士が連結されてなり、気孔率が５
０％以上、比表面積が０．７ｍ2 ／ｇ以上の三次元網目
構造をそなえていることを特徴とする。To achieve the above object, a porous silicon carbide sintered body according to claim 1 of the present invention comprises:
Silicon carbide whiskers are connected to each other and have a porosity of 5
It has a three-dimensional network structure of 0% or more and a specific surface area of 0.7 m 2 / g or more.
【０００９】本発明の請求項２による多孔質炭化珪素焼
結体の製造方法は、平均直径１μｍ以下の炭化珪素ウイ
スカー原料に通電し、高温焼結を行うことを特徴とし、
請求項３による多孔質炭化珪素焼結体の製造方法は、炭
化珪素ウイスカーを成形ダイ中に装入し、パンチで圧縮
するとともに、直接通電焼結することを特徴とする。A method for producing a porous silicon carbide sintered body according to a second aspect of the present invention is characterized in that electricity is supplied to a silicon carbide whisker raw material having an average diameter of 1 μm or less to perform high-temperature sintering.
The method of manufacturing a porous silicon carbide sintered body according to claim 3 is characterized in that silicon carbide whiskers are charged into a forming die, compressed by a punch, and directly sintered by electric current.
【００１０】また、本発明の請求項４による多孔質炭化
珪素焼結体の製造方法は、上記請求項２または３におい
て、放電プラズマ焼結法、放電焼結法、プラズマ活性化
焼結法等のパルス通電焼結法を用い、通電がパルス電流
および／または直流電流により行われることを特徴とす
る。[0010] Further, the method for producing a porous silicon carbide sintered body according to claim 4 of the present invention is the method according to claim 2 or 3, wherein a discharge plasma sintering method, a discharge sintering method, a plasma activated sintering method, etc. Is characterized in that energization is performed by a pulse current and / or a DC current.
【００１１】[0011]
【発明の実施の形態】本発明においては、炭化珪素ウイ
スカーに直接通電して焼結し、炭化珪素ウイスカー同士
を互いに連結して、多孔質炭化珪素焼結体とすることを
特徴とするものであり、好ましい実施態様としては、炭
化珪素ウイスカーを、カーボンなどからなる導電性の成
形ダイ中に装入し、例えば上下から導電性のパンチで圧
縮するとともに、パンチを通じて通電を行い焼結する。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is characterized in that silicon carbide whiskers are directly energized and sintered, and the silicon carbide whiskers are connected to each other to form a porous silicon carbide sintered body. In a preferred embodiment, a silicon carbide whisker is charged into a conductive forming die made of carbon or the like, and compressed by a conductive punch from above and below, for example, and sintering is performed by passing current through the punch.
【００１２】本発明の多孔質炭化珪素焼結体を製造する
ための放電焼結装置の概略を図１に示す。放電プラズマ
焼結装置１においては、水冷真空チャンバ２内に、原料
の炭化珪素ウイスカーＷを装填する成形ダイ３および成
形ダイ３内の原料を押圧、圧縮する上下一対のパンチ
（押圧子）４、５が配置されており、パンチ４、５は、
加圧機構により駆動する上下一対の加圧ラム６、７にそ
れぞれ取り付けられている。FIG. 1 schematically shows a spark sintering apparatus for producing the porous silicon carbide sintered body of the present invention. In the spark plasma sintering apparatus 1, a forming die 3 for loading a silicon carbide whisker W as a raw material and a pair of upper and lower punches (pressing elements) 4 for pressing and compressing the raw material in the forming die 3 are placed in a water-cooled vacuum chamber 2. 5 are arranged, and the punches 4 and 5
It is attached to a pair of upper and lower pressure rams 6 and 7 driven by a pressure mechanism.
【００１３】放電プラズマ焼結装置１には、加圧ラムお
よびパンチを通じて成形ダイ内の原料を通電、焼結する
ための焼結用電源、加圧ラム６、７を水冷するための冷
却系、水冷却機構、焼結雰囲気を調整するための雰囲気
制御機構、その他、位置計測機構、温度計測装置、これ
らの機構、装置を制御するための制御装置が配設されて
いる。The discharge plasma sintering apparatus 1 includes a power source for sintering for supplying and sintering the raw material in the forming die through a pressure ram and a punch, a cooling system for water cooling the pressure rams 6 and 7, A water cooling mechanism, an atmosphere control mechanism for adjusting a sintering atmosphere, a position measurement mechanism, a temperature measurement device, and a control device for controlling these mechanisms and devices are provided.
【００１４】炭化珪素ウイスカーは、必要に応じてボー
ルミルなどにより混合、粉砕し、所定の長さに揃える。
炭化珪素ウイスカーとしては、好ましくは平均直径１μ
ｍ以下、さらに好ましくは平均直径０．１〜０．５μ
ｍ、長さ１０〜２０μｍのものが好適に使用される。The silicon carbide whiskers are mixed and pulverized by a ball mill or the like, if necessary, so as to have a predetermined length.
Preferably, the silicon carbide whiskers have an average diameter of 1 μm.
m or less, more preferably an average diameter of 0.1 to 0.5 μm
m and a length of 10 to 20 μm are preferably used.
【００１５】炭化珪素ウイスカーに対して通電焼結を行
うために、図２にその要部を示すように、カーボンなど
からなる導電性の成形ダイ３および成形ダイ３に挿入さ
れる導電性の上パンチ４および下パンチ５が配設され、
成形ダイ３内にサイズを調製した炭化珪素ウイスカーＷ
を装入して、パンチ４、５に加圧ラム６、７を通じて荷
重を付加し、炭化珪素ウイスカーＷを上下から圧縮する
とともに、パンチ４、５を通して炭化珪素ウイスカーＷ
に電圧を印加し通電する。In order to conduct electric current sintering on the silicon carbide whiskers, as shown in FIG. A punch 4 and a lower punch 5 are provided,
Silicon carbide whisker W whose size is adjusted in forming die 3
, And a load is applied to the punches 4 and 5 through the pressing rams 6 and 7 to compress the silicon carbide whiskers W from above and below.
Is applied and a current is applied.
【００１６】炭化珪素ウイスカーの圧縮は、パンチＰに
より１００〜８００ｋｇ／ｃｍ2 の圧力を加えて行うの
が好ましく、通電は、炭化珪素ウイスカーの圧縮後に行
ってもよく、圧縮しながら行ってもよい。通電中は真空
または不活性雰囲気に保持される。The compression of the silicon carbide whiskers is preferably performed by applying a pressure of 100 to 800 kg / cm 2 by the punch P, and the energization may be performed after the compression of the silicon carbide whiskers or may be performed while compressing. . During energization, a vacuum or an inert atmosphere is maintained.
【００１７】通電は、パルス電流または直流電流、交流
電流を利用して行い、通電により発生するジュール熱と
加圧による炭化珪素ウイスカーの塑性流動により焼結が
促進される。とくに、ＯＮ−ＯＦＦ直流パルス電流を印
加した場合には、さらに炭化珪素ウイスカーの間で起き
る火花放電による自己発熱作用によって一層効率のよい
焼結が可能となる。The energization is performed using a pulse current, a DC current, or an AC current, and sintering is promoted by Joule heat generated by the energization and plastic flow of the silicon carbide whiskers by pressurization. In particular, when an ON-OFF DC pulse current is applied, more efficient sintering becomes possible due to the self-heating effect due to spark discharge occurring between the silicon carbide whiskers.
【００１８】通電焼結中における炭化珪素ウイスカーの
昇温速度は５０〜２００Ｋ／分、焼成温度は１９００〜
２３００Ｋ、保持時間は５〜６０分が好ましい。焼結終
了後、圧力を解除し、好ましくは５０〜２００Ｋ／分の
降温速度で冷却する。During the electric sintering, the temperature rise rate of the silicon carbide whiskers is 50 to 200 K / min, and the sintering temperature is 1900 to 10000 K / min.
The holding time is preferably 2300 K and the holding time is 5 to 60 minutes. After sintering is completed, the pressure is released, and the sintering is preferably performed at a cooling rate of 50 to 200 K / min.
【００１９】上記の放電プラズマ焼結装置を用いた直接
通電焼結法は、圧縮された原料ウイスカー自体のジュー
ル熱を利用しているため、誘導加熱や輻射加熱を用いた
焼結法に比べ高い熱効率を有する。また、パルス電流を
通電するとともに、そのピーク電流とパルス幅を制御し
て材料温度を制御しながら圧縮焼結を行うことによっ
て、炭化珪素ウイスカーの形状およびサイズを維持しな
がら多孔質焼結体を製造することができる。また、圧縮
された原料ウイスカーの間隙に生じる放電現象を利用
し、放電プラズマ、放電衝撃圧力などによる粒子表面の
浄化活性化作用および電場に生じる電界拡散効果や、ジ
ュール熱による熱拡散効果など、放電に伴う局所的な高
温によりウイスカー間のネック（頸部）の成長を短時間
に促進させることができる。The direct current sintering method using the above-mentioned spark plasma sintering apparatus utilizes the Joule heat of the compressed raw material whiskers themselves, and is therefore higher than the sintering method using induction heating or radiant heating. Has thermal efficiency. In addition, by applying a pulse current and performing compression sintering while controlling the material temperature by controlling the peak current and the pulse width, the porous sintered body can be formed while maintaining the shape and size of the silicon carbide whiskers. Can be manufactured. Utilizing discharge phenomena generated in the gaps between the compressed raw material whiskers, discharge plasma and discharge impact such as discharge impact pressure, etc. As a result, the growth of the neck (cervix) between the whiskers can be promoted in a short time due to the local high temperature.
【００２０】本発明においては、上記のように、炭化珪
素ウイスカーの形状およびサイズを維持しながら、ウイ
スカー同士が多数の結合点により連結され、ウイスカー
間に点接触で結合されたミクロンサイズの空孔が形成さ
れて、気孔率と比表面積の高い、すなわち、５０％以上
の気孔率と０．７ｍ2 ／ｇ以上、好ましくは０．８ｍ 2
／ｇ以上の比表面積を有する三次元網目構造の多孔質炭
化珪素焼結体を得ることができる。In the present invention, as described above, silicon carbide
While maintaining the shape and size of the raw whisker,
Whiskers where the scars are connected by many points of connection
Micron-sized cavities formed by point contacts between them
High porosity and specific surface area, ie, 50% or more
Porosity and 0.7mTwo/ G or more, preferably 0.8 m Two
/ G porous porous coal having a specific surface area of at least 3 g / g
A silicon nitride sintered body can be obtained.
【００２１】また、本発明の多孔質炭化珪素焼結体は、
きわめて高い比表面積を有しながらも、ウイスカー間の
結合接点の数が多いため優れた機械的強度をそなえ、気
孔特性と強度特性の両立を図ることができ、用途範囲を
大幅に拡げることが可能となる。気孔特性と強度特性の
両立を図るための好ましい気孔特性は、気孔率５０〜８
０％、比表面積０．８〜１．５ｍ2 ／ｇの範囲である。Further, the porous silicon carbide sintered body of the present invention
Despite having a very high specific surface area, it has excellent mechanical strength due to the large number of coupling contacts between whiskers, and can achieve both pore characteristics and strength characteristics, greatly expanding the range of applications. Becomes Preferable porosity characteristics for achieving both porosity characteristics and strength characteristics are porosity of 50 to 8
0%, and the specific surface area is in the range of 0.8 to 1.5 m 2 / g.
【００２２】[0022]
【実施例】以下、本発明の実施例について説明するが、
実施例は本発明の一実施態様を示すものであり、本発明
はこれに限定されるものではない。Hereinafter, embodiments of the present invention will be described.
The example shows one embodiment of the present invention, and the present invention is not limited to this.
【００２３】実施例１ 原料として、平均直径０．１〜０．３μｍ、長さ１０〜
２０μｍの炭化珪素ウイスカーを準備し、このウイスカ
ーの凝集を破壊させるために、アルコール媒体中で１時
間ボールミルで粉砕を行った。粉砕後のウイスカーを乾
燥させた後、図１に示す放電プラズマ焼結機を使用して
通電焼結を行った。Example 1 As raw materials, the average diameter was 0.1 to 0.3 μm and the length was 10 to 10 μm.
A silicon carbide whisker of 20 μm was prepared and pulverized in an alcohol medium for 1 hour by a ball mill in order to break the whisker aggregation. After the pulverized whiskers were dried, electric current sintering was performed using a discharge plasma sintering machine shown in FIG.
【００２４】カーボンの成形ダイ３に、乾燥させた炭化
珪素ウイスカーを充填し、ハンドプレスで仮圧縮した
後、成形ダイ３を放電プラズマ焼結機にセットして、パ
ンチ４、５により軸方向に２００ｋｇ／ｃｍ2 の圧力を
加えた。真空（約１０-3Ｔｏｒｒ）に引いた後、上下の
パンチ４、５を通じて直流パルス電流を印加した。After the dried silicon carbide whiskers are filled in the carbon forming die 3 and preliminarily compressed by a hand press, the forming die 3 is set in a discharge plasma sintering machine. A pressure of 200 kg / cm 2 was applied. After a vacuum (about 10 −3 Torr) was applied, a DC pulse current was applied through the upper and lower punches 4 and 5.
【００２５】通電により、炭化珪素ウイスカーは１２０
Ｋ／分の昇温速度で２０２３Ｋの温度まで昇温し、この
温度で５分間保持した後、圧力を解除して、７０Ｋ／分
の降温速度で室温まで冷却したところ、多孔質炭化珪素
焼結体が得られた。By energization, the silicon carbide whiskers become 120
The temperature was raised to a temperature of 2023 K at a temperature rising rate of K / min, held at this temperature for 5 minutes, and then released from the pressure and cooled to room temperature at a temperature decreasing rate of 70 K / min. The body is obtained.
【００２６】得られた多孔質炭化珪素焼結体の微細構造
のＳＥＭ写真を図３、図４に示す。図２〜３にみられる
ように、炭化珪素ウイスカーの形状、サイズは、図５に
示す焼結前のものと変わらないが、炭化珪素ウイスカー
同士が連結され、また、炭化珪素ウイスカー同士が接す
る接点部分にネックが形成されて互いに連結される様相
が認められる。FIGS. 3 and 4 show SEM photographs of the fine structure of the obtained porous silicon carbide sintered body. As shown in FIGS. 2 and 3, the shape and size of the silicon carbide whiskers are the same as those before sintering shown in FIG. 5, but the silicon carbide whiskers are connected to each other and the contact points where the silicon carbide whiskers are in contact with each other. It can be seen that the necks are formed at the portions and connected to each other.
【００２７】得られた多孔質炭化珪素焼結体の特性を、
ポリウレタンフォームに炭化珪素のスラリーを含浸さ
せ、乾燥した後、高温焼成して炭化珪素を焼結するとと
もに、有機質発泡体を焼却、除去することにより製造さ
れた従来の多孔質炭化珪素焼結体の特性と対比して表１
に示す。表１にみられるように、本発明による多孔質炭
化珪素焼結体は、従来の多孔質炭化珪素焼結体に比べて
優れた圧縮強度、曲げ強度を有し、高い比表面積をそな
えている。The properties of the obtained porous silicon carbide sintered body are as follows:
A conventional porous silicon carbide sintered body manufactured by impregnating a polyurethane foam slurry with silicon carbide slurry, drying and firing at a high temperature to sinter the silicon carbide, and burning and removing the organic foam. Table 1 in comparison with characteristics
Shown in As seen from Table 1, the porous silicon carbide sintered body according to the present invention has superior compressive strength and bending strength as compared with conventional porous silicon carbide sintered bodies, and has a high specific surface area. .
【００２８】[0028]
【表１】 [Table 1]
【００２９】実施例２ 原料として、実施例１と同じ炭化珪素ウイスカーを使用
し、実施例１と同様、このウイスカーの凝集を破壊させ
るために、アルコール媒体中で１時間ボールミルで粉砕
を行った。粉砕後のウイスカーを乾燥させた後、図１に
示す放電プラズマ焼結機を使用して通電焼結を行った。Example 2 As a raw material, the same silicon carbide whisker as in Example 1 was used, and in the same manner as in Example 1, the whisker was pulverized in an alcohol medium for 1 hour with a ball mill in order to destroy the aggregation. After the pulverized whiskers were dried, electric current sintering was performed using a discharge plasma sintering machine shown in FIG.
【００３０】カーボンの成形ダイ３に、乾燥させた炭化
珪素ウイスカーを充填し、ハンドプレスで仮圧縮した
後、仮圧縮した炭化珪素ウイスカーが装入されている成
形ダイ３を放電焼結機にセットして、パンチ４、５によ
り軸方向に加える圧力（焼結圧力）を変え、真空（約１
０-3Ｔｏｒｒ）に引いた後、上下のパンチ４、５を通じ
て直流パルス電流を印加した。焼結温度(Sintering Tem
perature) は２０７３Ｋ、焼結温度での保持時間(Sinte
ring Time)は５分に固定した。After the dried silicon carbide whiskers are filled in the carbon forming die 3 and temporarily compressed by a hand press, the forming die 3 into which the temporarily compressed silicon carbide whiskers are charged is set in an electric discharge sintering machine. Then, the pressure (sintering pressure) applied in the axial direction by the punches 4 and 5 is changed, and a vacuum (about 1
0 -3 Torr), and a DC pulse current was applied through the upper and lower punches 4 and 5. Sintering Tem
perature) is 2073K, holding time at sintering temperature (Sinte
ring Time) was fixed at 5 minutes.
【００３１】５分間保持した後、圧力を解除して、７０
Ｋ／分の降温速度で室温まで冷却し、多孔質炭化珪素焼
結体を得た。得られた多孔質炭化珪素焼結体について、
焼結時の圧力(Sintering Pressure)と気孔率(Porosity)
との関係、焼結時の圧力と曲げ強度(Bending Strength)
および圧縮強度(Compression Strength)との関係を求め
た。結果を図６、図７および図８に示す。After holding for 5 minutes, the pressure was released and 70
It was cooled to room temperature at a rate of K / min to obtain a porous silicon carbide sintered body. Regarding the obtained porous silicon carbide sintered body,
Sintering pressure and porosity during sintering
, Sintering pressure and bending strength
And the relationship with compression strength. The results are shown in FIGS. 6, 7 and 8.
【００３２】また、上記の通電焼結において、焼結温度
を２１２３Ｋ、保持時間を５分とした以外は同じ条件で
作製した多孔質炭化珪素焼結体について、焼結時の圧力
と気孔率および比抵抗との関係を求めた。結果を図９お
よび図１０に示す。なお、使用用途に応じて焼結条件を
選択することにより各種特性を制御することができる。In the above electric current sintering, the pressure, porosity, and porosity of the porous silicon carbide sintered body manufactured under the same conditions except that the sintering temperature was 2123 K and the holding time was 5 minutes. The relationship with the specific resistance was determined. The results are shown in FIGS. 9 and 10. Various characteristics can be controlled by selecting the sintering conditions according to the intended use.
【００３３】実施例３ 実施例１において、焼結圧力を４００ｋｇ／ｃｍ2 、焼
結温度を５分として、焼結温度と気孔率との関係を求め
た。結果を図１１に示す。また、実施例１において、焼
結温度を２２７３Ｋ、焼結圧力を４００ｋｇ／ｃｍ2 と
して、気孔率と焼結時間との関係を求め、また、焼結温
度を１９７３Ｋ、焼結圧力を４００ｋｇ／ｃｍ2 とし
て、曲げ強度と焼結時間との関係を求めた、結果をそれ
ぞれ図１２および図１３に示す。Example 3 In Example 1, the sintering pressure was 400 kg / cm 2 and the sintering temperature was 5 minutes, and the relationship between the sintering temperature and the porosity was determined. The results are shown in FIG. In Example 1, the sintering temperature was 2273 K and the sintering pressure was 400 kg / cm 2 , and the relationship between the porosity and the sintering time was determined. The sintering temperature was 1973 K and the sintering pressure was 400 kg / cm 2. As No. 2 , the relationship between bending strength and sintering time was determined. The results are shown in FIGS. 12 and 13, respectively.
【００３４】図６〜図１０にみられるように、焼結温度
と焼結時間を一定とした場合には、気孔率、曲げ強度お
よび圧縮強度と焼結圧力との間には直線的関係が認めら
れ、図１１に示すように、焼結圧力と焼結温度を一定と
した場合には、焼結温度と気孔率との間に直線的関係が
みられ、また、図１２〜図１３にみられるように、焼結
温度と焼結圧力を一定とした場合には、気孔率および曲
げ強度と焼結時間との間には直線的関係が認められる。
従って、焼結条件を選択することにより、多孔質炭化珪
素焼結体の使用目的に応じて各種特性を制御することが
できる。As shown in FIGS. 6 to 10, when the sintering temperature and the sintering time are fixed, there is a linear relationship between the porosity, bending strength and compressive strength and the sintering pressure. As shown in FIG. 11, when the sintering pressure and the sintering temperature were fixed as shown in FIG. 11, a linear relationship was observed between the sintering temperature and the porosity. As can be seen, when the sintering temperature and the sintering pressure are kept constant, a linear relationship is observed between the porosity and bending strength and the sintering time.
Therefore, by selecting the sintering conditions, various characteristics can be controlled according to the purpose of use of the porous silicon carbide sintered body.
【００３５】[0035]
【発明の効果】本発明の請求項１によれば、気孔率が５
０％以上、比表面積が０．８ｍ2 ／ｇ以上でマイクロオ
ーダーの空孔を有し、機械的強度に優れた三次元網目構
造の多孔質炭化珪素焼結体が得られる。当該多孔質炭化
珪素焼結体は、触媒担体、高温ガス浄化フィルター、溶
融金属濾過用フィルター、マイクロ波吸収発熱体などの
用途に適用可能である。According to the first aspect of the present invention, the porosity is 5%.
A porous silicon carbide sintered body having 0% or more, a specific surface area of 0.8 m 2 / g or more, having pores of micro order and having excellent mechanical strength and a three-dimensional network structure can be obtained. The porous silicon carbide sintered body is applicable to uses such as a catalyst carrier, a high-temperature gas purification filter, a filter for filtering molten metal, and a microwave absorption heating element.
【００３６】本発明の請求項２〜４によれば、炭化珪素
ウイスカーを出発原料とし、これを加圧し、直接通電し
て焼結することによって、炭化珪素ウイスカーの形状お
よびサイズを維持しながら、ウイスカー同士が多数の結
合点により連結され、ウイスカー間に点接触で結合され
たミクロンサイズの空孔が形成されて、気孔率と比表面
積が高く、機械的強度に優れた三次元網目構造の多孔質
炭化珪素焼結体が得られる。According to the second to fourth aspects of the present invention, silicon carbide whiskers are used as a starting material, and are pressurized, directly energized and sintered to maintain the shape and size of the silicon carbide whiskers. Whiskers are connected by a number of bonding points, and micron-sized holes are formed between the whiskers by point contact, forming a three-dimensional network structure with high porosity and specific surface area and excellent mechanical strength. A high-quality silicon carbide sintered body is obtained.
【図面の簡単な説明】[Brief description of the drawings]
【図１】本発明の多孔質炭化珪素焼結体を製造するため
の放電プラズマ焼結装置の概略断面図である。FIG. 1 is a schematic sectional view of a spark plasma sintering apparatus for producing a porous silicon carbide sintered body of the present invention.
【図２】図１の装置構成の要部を示す断面図である。FIG. 2 is a sectional view showing a main part of the device configuration of FIG.
【図３】本発明による通電焼結後の多孔質炭化珪素焼結
体の組織構造を示すＳＥＭ写真である。FIG. 3 is an SEM photograph showing a microstructure of a porous silicon carbide sintered body after electric sintering according to the present invention.
【図４】本発明による通電焼結後の多孔質炭化珪素焼結
体の拡大された組織構造を示すＳＥＭ写真である。FIG. 4 is an SEM photograph showing an enlarged microstructure of a porous silicon carbide sintered body after electric sintering according to the present invention.
【図５】本発明による通電焼結前の多孔質炭化珪素焼結
体の組織構造を示すＳＥＭ写真である。FIG. 5 is an SEM photograph showing a microstructure of a porous silicon carbide sintered body before electric current sintering according to the present invention.
【図６】本発明による多孔質炭化珪素焼結体の気孔率と
焼結圧力との関係を示すグラフである。FIG. 6 is a graph showing a relationship between porosity and sintering pressure of a porous silicon carbide sintered body according to the present invention.
【図７】本発明による多孔質炭化珪素焼結体の曲げ強度
と焼結圧力との関係を示すグラフである。FIG. 7 is a graph showing a relationship between bending strength and sintering pressure of a porous silicon carbide sintered body according to the present invention.
【図８】本発明による多孔質炭化珪素焼結体の圧縮強度
と焼結圧力との関係を示すグラフである。FIG. 8 is a graph showing the relationship between the compressive strength and the sintering pressure of the porous silicon carbide sintered body according to the present invention.
【図９】本発明による多孔質炭化珪素焼結体の気孔率と
焼結圧力との関係を示すグラフである。FIG. 9 is a graph showing the relationship between porosity and sintering pressure of a porous silicon carbide sintered body according to the present invention.
【図１０】本発明による多孔質炭化珪素焼結体の比抵抗
と焼結圧力との関係を示すグラフである。FIG. 10 is a graph showing the relationship between the specific resistance and the sintering pressure of the porous silicon carbide sintered body according to the present invention.
【図１１】本発明による多孔質炭化珪素焼結体の気孔率
と焼結温度との関係を示すグラフである。FIG. 11 is a graph showing the relationship between porosity and sintering temperature of a porous silicon carbide sintered body according to the present invention.
【図１２】本発明による多孔質炭化珪素焼結体の気孔率
と焼結時間との関係を示すグラフである。FIG. 12 is a graph showing the relationship between porosity and sintering time of a porous silicon carbide sintered body according to the present invention.
【図１３】本発明による多孔質炭化珪素焼結体の曲げ強
度と焼結時間との関係を示すグラフである。FIG. 13 is a graph showing a relationship between bending strength and sintering time of a porous silicon carbide sintered body according to the present invention.
１ 放電プラズマ焼結装置 ２ 水冷真空チャンバ ３ 成形ダイ ４ パンチ ５ パンチ ６ 加圧ラム ７ 加圧ラム DESCRIPTION OF SYMBOLS 1 Spark plasma sintering apparatus 2 Water-cooled vacuum chamber 3 Molding die 4 Punch 5 Punch 6 Pressurized ram 7 Pressurized ram
───────────────────────────────────────────────────── フロントページの続き (72)発明者 潘 偉 宮城県仙台市青葉区一番町１−14−25 (72)発明者 陳 立東 宮城県仙台市太白区郡山六丁目５−10− 505 (72)発明者 大森 守 宮城県仙台市泉区高森１−１−42 Ｆターム(参考） 4G001 BA22 BA86 BB22 BC51 BD13 BD22 BE31 BE33 4G019 FA11 GA04 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ban Wei 1-14-25, Ichibancho, Aoba-ku, Sendai, Miyagi Prefecture (72) Inventor Chen Ritsuhigashi 5-10-505, Koriyama, Taishiro-ku, Sendai-city, Miyagi Prefecture (72) Inventor Mamoru Omori 1-1-42 Takamori, Izumi-ku, Sendai, Miyagi F-term (reference) 4G001 BA22 BA86 BB22 BC51 BD13 BD22 BE31 BE33 4G019 FA11 GA04
Claims (4)
り、気孔率が５０％以上、比表面積が０．７ｍ2 ／ｇ以
上のマイクロオーダーの空孔を有する三次元網目構造を
そなえていることを特徴とする多孔質炭化珪素焼結体。1. A three-dimensional network structure in which silicon carbide whiskers are connected to each other and have micropores having a porosity of 50% or more and a specific surface area of 0.7 m 2 / g or more. Characteristic porous silicon carbide sintered body.
カー原料に通電し、高温焼結を行うことを特徴とする多
孔質炭化珪素焼結体の製造方法。2. A method for producing a porous silicon carbide sintered body, comprising applying a current to a silicon carbide whisker raw material having an average diameter of 1 μm or less and performing high-temperature sintering.
し、パンチで圧縮するとともに、通電焼結することを特
徴とする多孔質炭化珪素焼結体の製造方法。3. A method for manufacturing a porous silicon carbide sintered body, comprising charging a silicon carbide whisker into a forming die, compressing the whisker with a punch, and performing electric sintering.
ズマ活性化焼結法等のパルス通電焼結法を用い、通電が
パルス電流および／または直流電流により行われること
を特徴とする請求項２または３記載の多孔質炭化珪素焼
結体の製造方法。4. The method according to claim 1, wherein a pulse current sintering method such as a discharge plasma sintering method, a discharge sintering method, or a plasma activated sintering method is used, and the current is supplied by a pulse current and / or a DC current. Item 4. The method for producing a porous silicon carbide sintered body according to Item 2 or 3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33085199A JP4398027B2 (en) | 1999-11-22 | 1999-11-22 | Porous silicon carbide sintered body |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33085199A JP4398027B2 (en) | 1999-11-22 | 1999-11-22 | Porous silicon carbide sintered body |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2001151578A true JP2001151578A (en) | 2001-06-05 |
| JP4398027B2 JP4398027B2 (en) | 2010-01-13 |
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ID=18237250
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP33085199A Expired - Lifetime JP4398027B2 (en) | 1999-11-22 | 1999-11-22 | Porous silicon carbide sintered body |
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| Country | Link |
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| JP (1) | JP4398027B2 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001206800A (en) * | 2000-01-26 | 2001-07-31 | Masasuke Takada | Zinc oxide single crystal and method of producing the same |
| JP2009179517A (en) * | 2008-01-30 | 2009-08-13 | Taiheiyo Cement Corp | Ceramic joined body for gas jetting port and gas distribution plate, and method of manufacturing the same |
| JP2012236762A (en) * | 2012-07-12 | 2012-12-06 | Taiheiyo Cement Corp | Method for producing ceramic joined body and gas dispersion plate |
| KR101271958B1 (en) * | 2011-05-19 | 2013-06-07 | 주식회사 포스코 | Melting Apparatus |
-
1999
- 1999-11-22 JP JP33085199A patent/JP4398027B2/en not_active Expired - Lifetime
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001206800A (en) * | 2000-01-26 | 2001-07-31 | Masasuke Takada | Zinc oxide single crystal and method of producing the same |
| JP4615657B2 (en) * | 2000-01-26 | 2011-01-19 | 雅介 高田 | Zinc oxide single crystal and method for producing the same |
| JP2009179517A (en) * | 2008-01-30 | 2009-08-13 | Taiheiyo Cement Corp | Ceramic joined body for gas jetting port and gas distribution plate, and method of manufacturing the same |
| KR101271958B1 (en) * | 2011-05-19 | 2013-06-07 | 주식회사 포스코 | Melting Apparatus |
| JP2012236762A (en) * | 2012-07-12 | 2012-12-06 | Taiheiyo Cement Corp | Method for producing ceramic joined body and gas dispersion plate |
Also Published As
| Publication number | Publication date |
|---|---|
| JP4398027B2 (en) | 2010-01-13 |
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