JP4154787B2

JP4154787B2 - Hybrid sintering apparatus and method

Info

Publication number: JP4154787B2
Application number: JP02580599A
Authority: JP
Inventors: 和美森; 智俊望月; 浩一藤田; 康弘茂垣
Original assignee: IHI Corp
Current assignee: IHI Corp
Priority date: 1999-02-03
Filing date: 1999-02-03
Publication date: 2008-09-24
Anticipated expiration: 2019-02-03
Also published as: JP2000226603A

Description

【０００１】
【発明の属する技術分野】
本発明は、焼結型に充填した原料粉末の急速加熱と均一加熱が可能な焼結装置とその方法に関する。
【０００２】
【従来の技術】
セラミックスや金属、炭化物、窒化物などの導電性物体の原料粉末を、焼結型に充填して加熱し一対のパンチで加圧して焼結体の製造が行われる。この焼結体を製造する焼結装置は加熱方式によりいくつかの方式に分類される。
【０００３】
ヒータ加熱方式は焼結型の周囲に抵抗加熱ヒータなどのヒータを配置し焼結型を表面から加熱し、この中の原料粉末を間接的に加熱する方式であり、セラミックスと導電性物質の両方の焼結に適用でき広く用いられている。誘導加熱方式は、焼結型を電磁誘導により直接加熱する加熱方式であり、ヒータ加熱方式に比較し、焼結体の加熱速度が速い利点がある。通電方式は一対のパンチを電極として原料粉末に通電し、原料粉末の抵抗熱で加熱する方式である。なお通電方式については、特開昭６４−５５３０３，特開平５−７０８０４，特開平５−１１７７０７に開示されている。
【０００４】
【発明が解決しようとする課題】
近年の焼結体大型化に伴い焼結型やパンチなどの被加熱物も大型化している。また、特に半導体等の製造のために、薄くて大きい円板状の多結晶材料（例えば厚さ１ｍｍ×直径１００ｍｍ程度）を均一かつ高温（例えば５００℃以上）に加熱・焼結して熱伝導率の低い低伝導材料を製造することが求められることがある。すなわち、電子材料などの機能性材料では、後工程を簡単化するため、焼結厚さを極力薄くする必要がある。また材料によっては熱伝導性が極端に悪いものもある。
【０００５】
かかる多結晶焼結材料は、結晶粒子の大きさや粒子界面の特性に代表される材料微構造により特性が大きく左右される。そのため、低熱伝導材料を得るためには、結晶粒子をできるだけ小さくする必要があり、そこで、できるだけ早い昇温速度が必要になる。また、昇温速度のバラツキにより結晶粒子の大きさにバラツキが生じるため、かかる多結晶材料を均質にするために、全体を均一に加熱する必要がある。
【０００６】
しかし、上述したヒータ加熱方式では、焼結型へのエネルギ伝達は主としてヒータ表面温度とヒータを囲む断熱囲壁の内壁温度できまり、ヒータ材および断熱囲壁材の耐熱性には限界があるため、エネルギ伝達には限界がある。そのため、ある限度以上に加熱時間は短縮できず、かつ外部から加熱されるため被加熱物が大型化するほど中心部との温度差が大きく均一加熱ができない問題点があった。また、誘導加熱方式では、焼結型は直接加熱できるが、被加熱物の材料特性により焼結型との間に温度差が生じるため、ヒータ加熱方式と同様に均一加熱ができない問題点があった。更に、大型で高価な加高周波電力発生装置が必要であり、加熱時間を短縮するには電源設備に費用がかかりすぎる問題点があった。
【０００７】
一方、通電方式は原料粉末を直接加熱するため加熱時間は比較的短いが、原料粉末の種類により加熱条件が異なり、操業が難しい。また温度は原料粉末の中心温度が最も高くなる傾向にあり、焼結体温度制御が難しい。特に薄くて大きい円板状の多結晶材料の場合には、材料自体の発熱が少ないため高速加熱ができず、また材料が薄いために、均一加熱が困難である問題点があった。
【０００８】
言い換えれば、従来のヒータ加熱方式、誘導加熱方式及び通電方式の焼結装置では、熱伝導性が極端に悪い材料で焼結厚さを薄くする場合に、▲１▼急速加熱と▲２▼均一加熱が両立できず、そのため、被処理物の温度分布が悪化し、製品としての歩留りが低下していた。
【０００９】
本発明は、かかる問題点を解決するために創案されたものである。すなわち、本発明の目的は、急速加熱と均一加熱が可能であり、これにより低い熱伝導性材料で薄い焼結材を製造することができる焼結装置及びその方法を提供することにある。
【００１０】
【課題を解決するための手段】
本発明によれば、焼結型（１）を囲むヒータ（２）を有し焼結型を表面からヒータ加熱するヒータ加熱装置（１２）と、焼結型の焼結空間に充填された原料粉末（３）を直接挟持しかつ外周部が焼結型と接触する上下の均熱板（１４）と、該上下均熱板を上下から挟持しかつ外周部が焼結型と接触しない上下の通電発熱体（１６）と、該上下の通電発熱体を一対の電極（４）で挟持しその間を通電加熱する通電加熱装置（１８）とを備え、前記均熱板は、原料粉末よりも熱伝導率及び熱容量が大きく設定されており、かつ前記通電発熱体は、原料粉末よりも電気抵抗が大きく設定されており、これにより、ヒータ加熱と通電加熱を併用して、均熱板を均熱に高速加熱し、その間の原料粉末を加熱・焼結することを特徴とするハイブリッド焼結装置が提供される。
【００１１】
更に本発明によれば、焼結型（１）を囲むヒータ（２）を有し焼結型を表面からヒータ加熱するヒータ加熱装置（１２）と、一対の電極（４）の間に通電加熱する通電加熱装置（１８）とを備え、焼結型の焼結空間に充填された原料粉末（３）を、外周部が焼結型と接触する上下の均熱板（１４）で直接挟持し、かつこの均熱板の熱伝導率及び熱容量を原料粉末よりも大きく設定し、上下均熱板を上下から、外周部が焼結型と接触しない上下の通電発熱体（１６）で挟持し、かつこの通電発熱体の電気抵抗を原料粉末よりも大きく設定し、ヒータ加熱と通電加熱を併用して、均熱板を均熱に高速加熱し、これにより原料粉末を加熱・焼結させることを特徴とするハイブリッド焼結方法が提供される。
【００１２】
上記本発明の装置及び方法によれば、ヒータ加熱と通電加熱を併用し、ヒータ加熱により焼結型の側面から加熱し、通電加熱により上下方向から加熱するので、被処理物（原料粉末）の径が大型化（例えば直径６０ｍｍ以上のアルミナ粉末）する場合でも、半径方向の温度差を低減することができる。
【００１３】
すなわち、原料粉末（３）は、熱伝導率及び熱容量が原料粉末よりも大きい上下の均熱板（１４）で直接挟持されるので、原料粉末の加熱は均熱板からの熱伝導が主となり、原料粉末が薄い場合でも厚さ方向に加熱するので均熱化と高速加熱が可能となる。
【００１４】
また、均熱板の外周部が焼結型（１）と接触しており、この焼結型はヒータ加熱により側面から加熱されるので、均熱板の外周部の温度低下を防ぎ、焼結型から効率よく伝熱させることができる。更に、電気抵抗が原料粉末よりも大きい上下の通電発熱体（１６）で上下均熱板を上下から挟持され、かつ通電発熱体の外周部が焼結型と接触していないので、ヒータ加熱と独立して通電により通電発熱体を発熱させ、その熱で均熱板を厚さ方向に加熱しその中央部を効率よく加熱することができる。従って、ヒータ加熱と通電加熱を併用して、均熱板（１４）を均熱に高速加熱でき、その間に挟持された原料粉末（３）を厚さ方向に急速加熱及び均一加熱し、これにより低い熱伝導性材料で薄い焼結材を製造することができる。
【００１５】
本発明の好ましい実施形態によれば、通電発熱体の中心温度と焼結型の表面温度とを検出する温度センサ（１９ａ，１９ｂ）と、ヒータ加熱装置と通電加熱装置を制御する制御装置（２０）と、を備え、通電発熱体の中心温度と、焼結型の表面温度とを検出して比較し、中心温度が低いときは通電電流を増加させ、表面温度が低いときはヒータ電流を増加させる。これにより、通電発熱体の中心温度と焼結型の表面温度との差を低減して、均熱板全体をほぼ一定の温度で加熱でき、更に、原料粉末（３）が、熱伝導率及び熱容量が原料粉末よりも大きい上下の均熱板（１４）で直接挟持されるので、原料粉末が薄い場合でもこれを厚さ方向に加熱して均熱・高速加熱ができる。
【００１６】
【発明の実施の形態】
以下本発明の実施形態について、図面を参照して説明する。
図１は、本発明のハイブリッド焼結装置の全体構成図である。この図に示すように、本発明のハイブリッド焼結装置１０は、ヒータ加熱装置１２、上下の均熱板１４、上下の通電発熱体１６、及び通電加熱装置１８を備える。
【００１７】
ヒータ加熱装置１２は、焼結型１を囲む抵抗ヒータ２を有し、焼結型１を表面からヒータ加熱する。焼結型１は中空円筒状であり、例えばグラファイトで構成され、内部中央が原料粉末３を充填する焼結空間となっている。抵抗ヒータ２は断熱囲壁（図示せず）により囲まれ断熱性を保持している。ヒータ２は焼結型１の周囲に一定間隔で同心状に配置され、ヒータ電源１３から通電され発熱する。また、この電源１３は、制御装置２０により制御される。
【００１８】
上下の均熱板１４は、焼結型１の焼結空間に充填された原料粉末３を直接挟持する。また、この均熱板１４の外周部は焼結型１の内面に接触している。さらに、この均熱板１４は、原料粉末３よりも熱伝導率及び熱容量が十分に大きく設定されている。
例えば、原料粉末３が厚さ１ｍｍ、直径１００ｍｍ程度の薄い円板状であり、熱伝導率が小さく、熱容量（＝体積×密度×比熱）も小さい場合に、均熱板１４として熱伝導率が数十倍以上高い材料、例えば銅合金を用い、かつその厚さを数十倍以上厚くして、熱容量（＝体積×密度×比熱）が数十倍以上大きくなるように設定する。
この構成により、原料粉末３の加熱は均熱板１４からの熱伝導が主となり、原料粉末３が薄い場合でも厚さ方向に加熱して均熱化と高速加熱が可能となる。
【００１９】
上下の通電発熱体１６は、上下の均熱板１４を上下から挟持し、かつその外周部が焼結型１の内面と接触しないようになっている。また、この通電発熱体１６は、原料粉末３よりも電気抵抗が十分大きく設定されている。
例えば、原料粉末３が薄い円板状であり、電気抵抗が小さく、従って通電による発熱が少ない場合でも、通電発熱体１６として電気抵抗が数十倍以上高い材料、例えばＳｉＣを用い、かつその厚さを数十倍以上厚く設定する。また、この通電発熱体１６を金属板の積層体として構成し、その接触抵抗により発熱するように構成してもよい。
この構成により、ヒータ加熱と独立して通電により通電発熱体１６を発熱させ、その熱で均熱板１４を厚さ方向に加熱しその中央部を効率よく加熱することができる。
【００２０】
通電加熱装置１８は、上下の通電発熱体１６を一対の電極４で挟持し、その間に通電電源２２から直流又は交流を通電して、電極間に挟持された、通電発熱体１６を通電加熱する。
すなわち、焼結型１の内部上下には、中実円筒状の通電発熱体１６が隙間をもって挿入され、通電発熱体１６の上下には電極４が設けられている。電極４は発熱体１６を押圧するパンチを構成するとともに発熱体１６に通電する。
また電極４の上下端には図示しない油圧装置が接続され発熱体１６を加圧するようになっている。
【００２１】
図１に示すように、本発明のハイブリッド焼結装置１０は更に、通電発熱体１６の中心温度と焼結型１の表面温度とを検出する温度センサ１９ａ，１９ｂを備える。温度センサ１９ａ，１９ｂの検出信号は、制御装置２０に入力され、ヒータ加熱装置１２と通電加熱装置１８を制御する。
【００２２】
上述したハイブリッド焼結装置１０を用い、本発明のハイブリッド焼結方法では、（ａ）焼結型１の焼結空間に充填した原料粉末３を、外周部が焼結型と接触する上下の均熱板１４で直接挟持し、（ｂ）この上下均熱板１４を上下から、外周部が焼結型と接触しない上下の通電発熱体１６で挟持し、（ｃ）ヒータ加熱と通電加熱を併用して、均熱板を均熱に高速加熱し、これにより原料粉末を加熱・焼結させる。
【００２３】
また、上述した制御装置２０により、温度センサ１９ａ，１９ｂで検出された通電発熱体の１６の中心温度と焼結型１の表面温度を比較し、中心温度が低いときは通電電流を増加させ、表面温度が低いときはヒータ電流を増加させる。
これにより、通電発熱体１６の中心温度と焼結型１の表面温度との差を低減して、均熱板全体をほぼ一定の温度で加熱でき、更に、原料粉末３が、熱伝導率及び熱容量が原料粉末よりも十分に大きい上下の均熱板１４で直接挟持されるので、原料粉末が薄い場合でもこれを厚さ方向に加熱して均熱・高速加熱ができる。
【００２４】
【実施例】
以下、本発明の実施例を従来例と比較して説明する。
表１は、試験に使用した被処理物（原料粉末）、焼結型（モールド）、電極（ラム）、及び通電発熱体の外形寸法であり、表２はそれらの物性値（密度、熱伝導率、比熱、体積抵抗率）である。なお、均熱板は、直径はモールドの内径と等しく、厚さは通電発熱体と同一とした。
【００２５】
【表１】

【表２】

【００２６】
すなわち、均熱板１４は、原料粉末３よりも数十倍以上熱伝導率及び熱容量が十分に大きく設定されており、かつ通電発熱体１６は、原料粉末３よりも数十倍以上電気抵抗が十分大きく設定されている。
【００２７】
図２は、被処理物の温度変化を示す本発明の実施例である。この図において、Ａ，Ｂは従来のヒータ加熱による被処理物の中心温度（Ａ）と外周温度（Ｂ）、Ｃ，Ｄは従来の通電加熱の場合の中心温度（Ｃ）と外周温度（Ｄ）、Ｅ，Ｆは本発明による中心温度（Ｅ）と外周温度（Ｆ）である。横軸は経過時間（ｍｉｎ）、縦軸は温度（℃）を示している。
この図から、ヒータ加熱の場合には、中心温度（Ａ）と外周温度（Ｂ）の両方の温度上昇に時間がかかり、５００℃以上になるのに少なくとも１時間以上を要することがわかる。
【００２８】
図３は、図２の実施例における被処理物の温度差を示す図である。この図において、（Ａ）は従来のヒータ加熱による被処理物の温度差（中心温度−外周温度）、（Ｂ）は従来の通電加熱の場合の温度差、（Ｃ）は本発明による温度差である。横軸は経過時間（ｍｉｎ）、縦軸は温度差（℃）を示している。
この図から、ヒータ加熱では１時間以上経ても温度差が約７０℃以上あり、通電加熱では温度差が約２０℃以下になるのに６０分以上を要しているのがわかる。これに対して、本発明の装置及び方法では、約２０分で温度差が約２０℃以下までになっている。
【００２９】
図４は、別の実施例における被処理物の温度差を示す図である。この例では、焼結型１の外径／内径が３００／１００ｍｍ、原料粉末３（被処理物）の厚さが１０ｍｍの場合であり、その他は、図１及び図２の場合と同様である。
この図から、原料粉末３が厚い場合でも、均熱板１４が原料粉末３よりも熱伝導率及び熱容量が十分に大きく設定されており、かつ通電発熱体１６が原料粉末３よりも電気抵抗が十分大きく設定されている限りで、従来のヒータ加熱（Ａ）や通電加熱（Ｂ）と比較して、短時間に小さい温度差が達成できることがわかる。
【００３０】
なお、本発明は上述した実施形態及び実施例に限定されず、本発明の要旨を逸脱しない範囲で種々に変更できることは勿論である。
【００３１】
【発明の効果】
上述したように、本発明のハイブリッド焼結装置とその方法では、▲１▼側面だけでなく上下方向から加熱されるため、処理物の径が大型化（例えば直径６０ｍｍ以上、アルミナ粉末）する場合、半径方向での温度偏差を低下でき、温度偏差の縮小時間も短縮できる（従来比の１／２）。また、▲２▼材料の抵抗と熱伝導特性に応じて、通電と外部加熱の最適条件を設定できることにより、あらゆる物理的特性に応じた最適な焼結条件を制御できる。
【００３２】
従って、本発明のハイブリッド焼結装置とその方法は、急速加熱と均一加熱が可能であり、これにより低い熱伝導性材料で薄い焼結材を製造することができる等の優れた効果を有する。
【図面の簡単な説明】
【図１】本発明のハイブリッド焼結装置の全体構成図である。
【図２】被処理物の温度変化を示す本発明の実施例である。
【図３】被処理物の温度差を示す本発明の実施例である。
【図４】被処理物の温度差を示す本発明の別の実施例である。
【符号の説明】
１焼結型
２ヒータ
３原料粉末
４電極
１０ハイブリッド焼結装置
１２ヒータ加熱装置
１３ヒータ電源
１４均熱板
１６通電発熱体
１８通電加熱装置
１９ａ，１９ｂ温度センサ
２０制御装置
２２通電電源[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sintering apparatus and method capable of rapid heating and uniform heating of raw material powder filled in a sintering mold.
[0002]
[Prior art]
A sintered body is manufactured by filling a raw material powder of a conductive object such as ceramics, metal, carbide, or nitride into a sintering mold and heating and pressing with a pair of punches. Sintering apparatuses for manufacturing this sintered body are classified into several systems depending on the heating system.
[0003]
In the heater heating method, a heater such as a resistance heater is placed around the sintering mold, the sintering mold is heated from the surface, and the raw material powder in this is indirectly heated. It can be applied to sintering and is widely used. The induction heating method is a heating method in which the sintered mold is directly heated by electromagnetic induction, and has an advantage that the heating speed of the sintered body is faster than the heater heating method. The energization method is a method in which a raw material powder is energized with a pair of punches as electrodes and heated by the resistance heat of the raw material powder. The energization method is disclosed in JP-A 64-55303, JP-A 5-70804, and JP-A 5-117707.
[0004]
[Problems to be solved by the invention]
With the recent increase in size of sintered bodies, the objects to be heated such as sintering molds and punches are also increasing in size. In particular, for the manufacture of semiconductors, etc., heat conduction is achieved by heating and sintering a thin and large disk-like polycrystalline material (eg, 1 mm thick × 100 mm in diameter) uniformly and at a high temperature (eg, 500 ° C. or higher). It may be required to produce a low conductivity, low conductivity material. That is, in a functional material such as an electronic material, it is necessary to make the sintered thickness as thin as possible in order to simplify the post-process. Some materials have extremely poor thermal conductivity.
[0005]
Such a polycrystalline sintered material is greatly influenced by the material microstructure represented by the size of the crystal grains and the characteristics of the grain interface. Therefore, in order to obtain a low thermal conductivity material, it is necessary to make the crystal particles as small as possible, and therefore, a temperature increase rate as fast as possible is required. Moreover, since the size of the crystal particles varies due to the variation in the heating rate, it is necessary to uniformly heat the whole in order to make the polycrystalline material homogeneous.
[0006]
However, in the heater heating method described above, energy transmission to the sintering mold is mainly determined by the heater surface temperature and the inner wall temperature of the heat insulating enclosure surrounding the heater, and the heat resistance of the heater material and the heat insulating enclosure material is limited. There are limits to transmission. For this reason, the heating time cannot be shortened beyond a certain limit, and since the object to be heated is increased in size, the temperature difference from the central portion increases and uniform heating cannot be achieved. In addition, in the induction heating method, the sintering mold can be heated directly, but due to the material characteristics of the object to be heated, there is a temperature difference from the sintering mold, so that there is a problem that uniform heating is not possible as in the heater heating method. It was. In addition, a large and expensive high-frequency power generator is required, and there is a problem that the power supply equipment is too expensive to shorten the heating time.
[0007]
On the other hand, since the energization method directly heats the raw material powder, the heating time is relatively short, but the heating conditions differ depending on the type of the raw material powder, and the operation is difficult. Further, the temperature tends to be the highest at the center temperature of the raw material powder, and it is difficult to control the sintered body temperature. In particular, in the case of a thin and large disk-like polycrystalline material, there is a problem that high-speed heating cannot be performed because the material itself generates little heat, and uniform heating is difficult because the material is thin.
[0008]
In other words, in the conventional heater heating method, induction heating method and energization method sintering apparatus, when the sintered thickness is reduced with a material having extremely poor thermal conductivity, (1) rapid heating and (2) uniform Heating cannot be achieved at the same time, so that the temperature distribution of the object to be processed is deteriorated and the yield as a product is lowered.
[0009]
The present invention has been developed to solve such problems. That is, an object of the present invention is to provide a sintering apparatus and method capable of producing a thin sintered material with a low thermal conductivity material by which rapid heating and uniform heating are possible.
[0010]
[Means for Solving the Problems]
According to the present invention, the heater (12) having the heater (2) surrounding the sintering mold (1) and heating the sintering mold from the surface, and the raw material filled in the sintering space of the sintering mold Upper and lower soaking plates (14) that directly sandwich the powder (3) and whose outer peripheral portion is in contact with the sintered mold, and upper and lower soaking plates that sandwich the upper and lower soaking plate from above and below and whose outer peripheral portion is not in contact with the sintering die An electric heating element (16) and an electric heating device (18) for holding the upper and lower electric heating elements between a pair of electrodes (4) and energizing and heating between them are provided. conductivity and heat capacity are greatly set, and the energization heater is electrical resistance than the raw material powder has been greatly set, thereby, in combination with electric heating and heater heating the soaking plate Hybrid sintering, characterized by heating at high speed soaking, and heating and sintering the raw material powder in the meantime Location is provided.
[0011]
Furthermore, according to the present invention, the heater (12) having the heater (2) surrounding the sintering mold (1) and heating the sintering mold from the surface is heated between the pair of electrodes (4). The raw material powder (3) filled in the sintering space of the sintering mold is directly sandwiched between upper and lower soaking plates (14) whose outer peripheral portions are in contact with the sintering mold. and the thermal conductivity and heat capacity of the heat equalizing plate is greatly set than the raw material powder, a vertical soaking plate from above and below, and sandwiched between energization heater of the upper and lower outer peripheral portion does not contact the sintered (16) and the electrical resistance of the energization heater is greatly set than the raw material powder, a combination of electrical heating and heater heating, fast heating soaking plate soaking causes thereby heating and sintering the raw material powder A hybrid sintering method is provided.
[0012]
According to the apparatus and method of the present invention, since heater heating and current heating are used in combination, heating is performed from the side of the sintering mold by heater heating, and heating is performed from the top and bottom by current heating. Even when the diameter is increased (for example, alumina powder having a diameter of 60 mm or more), the temperature difference in the radial direction can be reduced.
[0013]
That is, the raw material powder (3), since the thermal conductivity and heat capacity are directly sandwiched by large hearing and below the soaking plate (14) than the raw material powder, heating the raw material powder is heat conduction from the soaking plate main Thus, even when the raw material powder is thin, heating is performed in the thickness direction, so that temperature equalization and high-speed heating are possible.
[0014]
Moreover, since the outer peripheral part of the soaking plate is in contact with the sintering mold (1) and this sintering mold is heated from the side surface by the heater heating, the temperature reduction of the outer peripheral part of the soaking plate is prevented and sintered. Heat can be efficiently transferred from the mold. Furthermore, the electrical resistance from the raw material powder is held between the upper and lower soaking plate from above and below atmospheric heard and below the energization heater (16), and since the outer peripheral portion of the energization heater is not in contact with the sintered type, heater Independently, the energization heating element is heated by energization, and the heat equalizing plate can be heated in the thickness direction by the heat to efficiently heat the central portion. Therefore, by using both heater heating and energization heating, the soaking plate (14) can be heated at high speed soaking, and the raw material powder (3) sandwiched therebetween can be rapidly and uniformly heated in the thickness direction, thereby Thin sintered materials can be manufactured with a low thermal conductivity material.
[0015]
According to a preferred embodiment of the present invention, a temperature sensor (19a, 19b) for detecting the center temperature of the energization heating element and the surface temperature of the sintered mold, and a controller (20 for controlling the heater heating device and the energization heating device). ) To detect and compare the center temperature of the energization heating element and the surface temperature of the sintered mold, increase the energization current when the center temperature is low, and increase the heater current when the surface temperature is low Let As a result, the difference between the center temperature of the energization heating element and the surface temperature of the sintered mold can be reduced, and the entire soaking plate can be heated at a substantially constant temperature. Furthermore, the raw material powder (3) has the thermal conductivity and since the heat capacity is directly sandwiched by large hearing and below the soaking plate (14) than the raw material powder, the raw material powder can soaking, rapid heating by heating it in the thickness direction even when thin.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an overall configuration diagram of a hybrid sintering apparatus of the present invention. As shown in this figure, the hybrid sintering apparatus 10 of the present invention includes a heater heating device 12, upper and lower soaking plates 14, upper and lower energizing heating elements 16, and an energizing heating device 18.
[0017]
The heater heating device 12 includes a resistance heater 2 surrounding the sintering mold 1 and heats the sintering mold 1 from the surface. The sintering die 1 has a hollow cylindrical shape, which is made of, for example, graphite, and has a sintering space in which an inner center is filled with the raw material powder 3. The resistance heater 2 is surrounded by a heat insulating wall (not shown) and maintains heat insulating properties. The heater 2 is disposed concentrically at regular intervals around the sintering die 1 and is energized from the heater power supply 13 to generate heat. The power supply 13 is controlled by the control device 20.
[0018]
The upper and lower soaking plates 14 directly sandwich the raw material powder 3 filled in the sintering space of the sintering die 1. Further, the outer peripheral portion of the soaking plate 14 is in contact with the inner surface of the sintering mold 1. Further, the soaking plate 14 is set to have sufficiently larger thermal conductivity and heat capacity than the raw material powder 3.
For example, when the raw material powder 3 has a thin disk shape with a thickness of about 1 mm and a diameter of about 100 mm, the thermal conductivity is small, and the heat capacity (= volume × density × specific heat) is also small, the thermal conductivity as the soaking plate 14 is A material several tens of times higher than that, for example, a copper alloy is used, and the thickness thereof is increased by several tens of times, so that the heat capacity (= volume × density × specific heat) is set to be several tens of times larger.
With this configuration, the heating of the raw material powder 3 is mainly conducted by the heat conduction from the soaking plate 14, and even when the raw material powder 3 is thin, heating in the thickness direction can be performed so as to perform soaking and high-speed heating.
[0019]
The upper and lower energization heating elements 16 sandwich the upper and lower soaking plates 14 from above and below, and their outer peripheral portions do not come into contact with the inner surface of the sintering mold 1. The energization heating element 16 is set to have a sufficiently larger electric resistance than the raw material powder 3.
For example, even when the raw material powder 3 is thin and has a small electrical resistance, and therefore generates little heat due to energization, the energization heating element 16 is made of a material having a high electrical resistance of several tens of times or more, such as SiC, and its thickness. Set the thickness to several tens of times thicker. Alternatively, the energization heating element 16 may be configured as a laminated body of metal plates so that heat is generated by the contact resistance.
With this configuration, the energization heating element 16 can be heated by energization independently of the heater heating, and the heat equalizing plate 14 can be heated in the thickness direction by the heat to efficiently heat the central portion.
[0020]
The energization heating device 18 sandwiches the upper and lower energization heating elements 16 between the pair of electrodes 4 and energizes the energization heating element 16 sandwiched between the electrodes by energizing direct current or alternating current from the energization power source 22 therebetween. .
In other words, solid cylindrical energization heating elements 16 are inserted above and below the sintering mold 1 with a gap, and electrodes 4 are provided above and below the energization heating element 16. The electrode 4 constitutes a punch that presses the heating element 16 and energizes the heating element 16.
A hydraulic device (not shown) is connected to the upper and lower ends of the electrode 4 so as to pressurize the heating element 16.
[0021]
As shown in FIG. 1, the hybrid sintering apparatus 10 of the present invention further includes

temperature sensors

19 a and 19 b that detect the center temperature of the energization heating element 16 and the surface temperature of the sintering mold 1. Detection signals from the

temperature sensors

19a and 19b are input to the control device 20 to control the heater heating device 12 and the energization heating device 18.
[0022]
In the hybrid sintering method of the present invention using the hybrid sintering apparatus 10 described above, (a) the raw material powder 3 filled in the sintering space of the sintering mold 1 is mixed with the upper and lower uniform parts whose outer peripheral portions are in contact with the sintering mold. (B) The upper and lower soaking plates 14 are sandwiched from above and below by upper and lower energizing heating elements 16 whose outer peripheral portions are not in contact with the sintered mold, and (c) heater heating and energizing heating are used together. Then, the soaking plate is heated at high speed to soaking, whereby the raw material powder is heated and sintered.
[0023]
Further, the control device 20 compares the center temperature of the energization heating element 16 detected by the

temperature sensors

19a and 19b with the surface temperature of the sintering mold 1, and increases the energization current when the center temperature is low. When the surface temperature is low, the heater current is increased.
As a result, the difference between the center temperature of the energization heating element 16 and the surface temperature of the sintering die 1 can be reduced, and the entire soaking plate can be heated at a substantially constant temperature. Since it is directly sandwiched between the upper and lower soaking plates 14 whose heat capacity is sufficiently larger than that of the raw material powder, even if the raw material powder is thin, it can be heated in the thickness direction for soaking and high-speed heating.
[0024]
【Example】
Examples of the present invention will be described below in comparison with conventional examples.
Table 1 shows the dimensions of workpieces (raw materials), sintered molds (molds), electrodes (rams), and energization heating elements used in the tests, and Table 2 shows their physical properties (density, heat conduction). Rate, specific heat, volume resistivity). The soaking plate had the same diameter as the inner diameter of the mold and the same thickness as the energization heating element.
[0025]
[Table 1]

[Table 2]

[0026]
That is, the soaking plate 14 is set to have a thermal conductivity and a heat capacity sufficiently tens of times greater than that of the raw material powder 3, and the electric heating element 16 has an electric resistance of tens of times greater than that of the raw material powder 3. It is set large enough.
[0027]
FIG. 2 is an embodiment of the present invention showing the temperature change of the workpiece. In this figure, A and B are the center temperature (A) and the outer peripheral temperature (B) of the workpiece by conventional heater heating, and C and D are the center temperature (C) and the outer peripheral temperature (D in the case of conventional energization heating. ), E and F are the center temperature (E) and the peripheral temperature (F) according to the present invention. The horizontal axis represents elapsed time (min), and the vertical axis represents temperature (° C.).
From this figure, it can be seen that in the case of heater heating, it takes time to increase both the center temperature (A) and the outer peripheral temperature (B), and it takes at least one hour to reach 500 ° C. or higher.
[0028]
FIG. 3 is a diagram showing the temperature difference of the workpiece in the embodiment of FIG. In this figure, (A) is the temperature difference (center temperature-outside temperature) of the workpiece by conventional heater heating, (B) is the temperature difference in the case of conventional energization heating, and (C) is the temperature difference according to the present invention. It is. The horizontal axis represents elapsed time (min), and the vertical axis represents temperature difference (° C.).
From this figure, it can be seen that the temperature difference is about 70 ° C. or more in the heater heating even after 1 hour or more, and it takes 60 minutes or more for the temperature difference to be about 20 ° C. or less in the energization heating. On the other hand, in the apparatus and method of the present invention, the temperature difference reaches about 20 ° C. or less in about 20 minutes.
[0029]
FIG. 4 is a diagram showing a temperature difference of the workpiece in another example. In this example, the outer diameter / inner diameter of the sintered mold 1 is 300/100 mm, the thickness of the raw material powder 3 (object to be processed) is 10 mm, and the others are the same as in the case of FIGS. .
From this figure, even when the raw material powder 3 is thick, the soaking plate 14 is set to have sufficiently larger thermal conductivity and heat capacity than the raw material powder 3, and the electric heating element 16 has an electric resistance higher than that of the raw material powder 3. As long as it is set sufficiently large, it can be seen that a small temperature difference can be achieved in a short time compared to conventional heater heating (A) and current heating (B).
[0030]
Note that the present invention is not limited to the above-described embodiments and examples, and it is needless to say that various modifications can be made without departing from the gist of the present invention.
[0031]
【The invention's effect】
As described above, in the hybrid sintering apparatus and method of the present invention, (1) when the diameter of the processed product is increased (for example, the diameter of 60 mm or more, alumina powder) because it is heated not only from the side but also from the vertical direction. The temperature deviation in the radial direction can be reduced, and the reduction time of the temperature deviation can be shortened (1/2 of the conventional ratio). In addition, (2) since the optimum conditions for energization and external heating can be set according to the resistance and heat conduction characteristics of the material, the optimum sintering conditions according to all physical characteristics can be controlled.
[0032]
Therefore, the hybrid sintering apparatus and method according to the present invention can perform rapid heating and uniform heating, and thereby have an excellent effect such that a thin sintered material can be manufactured with a low thermal conductivity material.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a hybrid sintering apparatus of the present invention.
FIG. 2 is an embodiment of the present invention showing a change in temperature of an object to be processed.
FIG. 3 is an example of the present invention showing a temperature difference of an object to be processed.
FIG. 4 is another embodiment of the present invention showing a temperature difference of an object to be processed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sintering type 2 Heater 3 Raw material powder 4 Electrode 10 Hybrid sintering apparatus 12 Heater heating apparatus 13 Heater power supply 14 Heat equalizing plate 16 Current heating element 18

Current heating apparatus

19a, 19b Temperature sensor 20 Control apparatus 22 Current supply power

Claims

焼結型（１）を囲むヒータ（２）を有し焼結型を表面からヒータ加熱するヒータ加熱装置（１２）と、焼結型の焼結空間に充填された原料粉末（３）を直接挟持しかつ外周部が焼結型と接触する上下の均熱板（１４）と、該上下均熱板を上下から挟持しかつ外周部が焼結型と接触しない上下の通電発熱体（１６）と、該上下の通電発熱体を一対の電極（４）で挟持しその間を通電加熱する通電加熱装置（１８）とを備え、
前記均熱板は、原料粉末よりも熱伝導率及び熱容量が大きく設定されており、かつ前記通電発熱体は、原料粉末よりも電気抵抗が大きく設定されており、これにより、ヒータ加熱と通電加熱を併用して、均熱板を均熱に高速加熱し、その間の原料粉末を加熱・焼結することを特徴とするハイブリッド焼結装置。A heater heating device (12) having a heater (2) surrounding the sintering mold (1) and heating the sintering mold from the surface, and a raw material powder (3) filled in the sintering space of the sintering mold are directly provided. Upper and lower soaking plates (14) sandwiched and the outer peripheral portion is in contact with the sintered mold, and upper and lower heating elements (16) sandwiching the upper and lower soaking plates from the upper and lower sides and the outer peripheral portion is not in contact with the sintered mold And an energization heating device (18) for sandwiching the upper and lower energization heating elements between a pair of electrodes (4) and energizing and heating between the pair of electrodes (4),
The soaking plate is raw material powder thermal conductivity and heat capacity than has been greatly set, and the energization heater is electrical resistance than the raw material powder has been greatly set, thereby, heater and A hybrid sintering apparatus characterized by heating the soaking plate at high speed soaking, and heating / sintering the raw material powder in the meantime by using electric heating together.

通電発熱体の中心温度と焼結型の表面温度とを検出する温度センサ（１９ａ，１９ｂ）と、ヒータ加熱装置と通電加熱装置を制御する制御装置（２０）と、を備え、検出された中心温度と表面温度を比較し、中心温度が低いときは通電電流を増加させ、表面温度が低いときはヒータ電流を増加させる、ことを特徴とする請求項１に記載のハイブリッド焼結装置。A temperature sensor (19a, 19b) for detecting the center temperature of the energization heating element and the surface temperature of the sintering mold, and a heater heating device and a control device (20) for controlling the energization heating device, and the detected center 2. The hybrid sintering apparatus according to claim 1, wherein the temperature is compared with the surface temperature, the energizing current is increased when the center temperature is low, and the heater current is increased when the surface temperature is low.

焼結型（１）を囲むヒータ（２）を有し焼結型を表面からヒータ加熱するヒータ加熱装置（１２）と、一対の電極（４）の間に通電加熱する通電加熱装置（１８）とを備え、焼結型の焼結空間に充填された原料粉末（３）を、外周部が焼結型と接触する上下の均熱板（１４）で直接挟持し、かつこの均熱板の熱伝導率及び熱容量を原料粉末よりも大きく設定し、上下均熱板を上下から、外周部が焼結型と接触しない上下の通電発熱体（１６）で挟持し、かつこの通電発熱体の電気抵抗を原料粉末よりも大きく設定し、ヒータ加熱と通電加熱を併用して、均熱板を均熱に高速加熱し、これにより原料粉末を加熱・焼結させることを特徴とするハイブリッド焼結方法。A heater heating device (12) having a heater (2) surrounding the sintering die (1) and heating the sintering die from the surface, and an energization heating device (18) for conducting heating between the pair of electrodes (4) The raw material powder (3) filled in the sintering space of the sintering die is directly sandwiched between upper and lower soaking plates (14) whose outer peripheral portions are in contact with the sintering die, the thermal conductivity and thermal capacity and greatly set than the raw material powder, a vertical soaking plate from above and below, and sandwiched between energization heater of the upper and lower outer peripheral portion does not contact the sintered (16), and the energization heater the electrical resistance was greatly set than the raw material powder, hybrid ware in combination with electric heating and heater heating, fast heating soaking plate soaking, thereby characterized thereby heating and sintering the raw material powder Conclusion method.

通電発熱体の中心温度と、焼結型の表面温度とを検出して比較し、中心温度が低いときは通電電流を増加させ、表面温度が低いときはヒータ電流を増加させる、ことを特徴とする請求項３に記載のハイブリッド焼結方法。It is characterized by detecting and comparing the center temperature of the energization heating element and the surface temperature of the sintered mold, increasing the energization current when the center temperature is low, and increasing the heater current when the surface temperature is low. The hybrid sintering method according to claim 3 .