JP3383400B2

JP3383400B2 - Method for producing bottomed ceramic tube and mold for production

Info

Publication number: JP3383400B2
Application number: JP06131094A
Authority: JP
Inventors: 裕二小川; 辰巳秋峯; 充彦越田; 英博鹿倉
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 1993-07-30
Filing date: 1994-03-30
Publication date: 2003-03-04
Anticipated expiration: 2018-03-04
Also published as: JPH0788830A

Description

【発明の詳細な説明】【０００１】【産業上の利用分野】本発明は、固体電解質燃料電池用
支持管等に用いられる、有底セラミックス管の製造方法
及び製造用金型に関するものである。【０００２】【従来の技術】近年、燃料電池発電システムは、エネル
ギー問題、地球環境問題に大きな貢献をするものとし
て、世界的にその期待が高まっている。燃料電池発電シ
ステムは、燃料が有する化学エネルギーを直接電気エネ
ルギーに変換できるシステムであり、高いエネルギー変
換効率を有し、燃料の多様化が可能で、低公害で、しか
も発電効率が設備規模によって影響されず、極めて有望
な技術である。【０００３】特に、固体電解質型燃料電池は、リン酸型
燃料電池や溶融炭酸塩型燃料電池と異なり、液体、融体
を用いないため電池の構成がシンプルであり、高温の排
熱利用も含めるとエネルギー効率８０〜９０％が期待で
きるものである。【０００４】この固体電解質燃料電池に使用されるセル
の構造は、図７に示すように、多孔質ジルコニアセラミ
ックスなどからなる支持管１の外表面に陽極２と、例え
ば多孔質安定化ジルコニアからなる固体電解質３および
陰極４が順次積層された構造を成している。そして、上
記支持管１の内側には空気６を、電池の外側には燃料７
をそれぞれ供給し、これらが固体電解質３を介して反応
するときのエネルギーを直接電力の形で取り出すもので
ある。【０００５】また、図８に示すように、上記支持管１の
内側にはチューブ９を用いて空気６が供給されるが、こ
の空気６は循環中に１０００℃程度に加熱された後、上
部へ排出され排熱利用される。そのため、支持管１の一
方端には循環性を考慮して曲面形状の有底部１ａを備え
ている。さらに、燃料電池は基本単位の出力が１０Ｗ程
度と低いため、商用電源を実現するために、基本単位の
電池をニッケルフェルト８を用いて大量に直列連結する
構造となっている。【０００６】そして、上記支持管１を成す有底セラミッ
クス管の製造方法は、セラミックス原料を管状に押出成
形し、得られた管状成形体の一方端に別途プレス成形し
た封止体を挿入して、必要に応じて両者間にセラミック
スペーストを介在させて一体焼成した後、研削すること
によって有底部１ａを曲面状に加工していた。【０００７】【発明が解決しようとする課題】ところが、上記支持管
１を成す有底セラミックス管は、管状体と封止体を別々
に成形して一体焼成し、有底部１ａとしたものであるた
め、この有底部１ａの接合強度が低いという問題点があ
った。【０００８】特に、燃料電池として用いる場合、図８に
示すように、支持管１の有底部１ａには荷重が加わり、
しかも１０００℃の高温下で作動するため、有底部１ａ
が破損してしまい、ひいては燃料電池の破壊に至るとい
う問題点があった。【０００９】【課題を解決するための手段】上記に鑑みて本発明は、
管状セラミックス成形体を成形し、この管状セラミック
ス成形体の内部に、凸曲面状の曲面部の周囲に直径の１
〜１０％の平坦部を備えた加圧面を有する下パンチを配
置し、下パンチと管状セラミックス成形体で形成される
空間にセラミックス原料を充填し、下パンチの加圧面に
対応した凹曲面状の曲面部の周囲に直径の１〜１０％の
平坦部を備えた加圧面を有する上パンチによってプレス
成形して有底部を一体的に形成した後、有底部の周囲に
焼成収縮率が大きく、管状セラミックス成形体と同じ原
料からなるリング状の押圧部材を配置し、全体を焼成す
ることによって押圧部材が収縮して管状セラミックス成
形体と有底部とを密着させる工程により有底セラミック
ス管を製造するようにしたものである。【００１０】【００１１】【００１２】【００１３】【作用】本発明によれば、管状セラミックス成形体の内
部でセラミックス原料をプレス成形して有底部を形成す
ることにより、該有底部と管状セラミックス成形体が強
固に密着し、焼成後の接合強度を高めることができる。【００１４】また、上記プレス成形時に、一方の加圧面
が凸曲面状で他方の加圧面がこれに対応した凹曲面状を
した上下パンチを用いることにより、加圧力を均一に
し、その後の製造工程中でのクラック発生を防止でき
る。【００１５】さらに、この上下パンチの加圧面の周囲に
平坦部を形成したことによって、周辺部でも強い力で加
圧することができ、また上下パンチ自体の破損を防止で
きる。【００１６】また、管状セラミックス成形体の有底部を
形成した部分の周囲に、押圧部材を備えたことにより、
焼成時に押圧部材の収縮力によって有底部の密着性を高
める方向に力が加わるため、接合強度をより高くするこ
とができる。【００１７】【実施例】以下、本発明を実施例に基づき説明する。【００１８】１５モル％のカルシアを含む安定化ジルコ
ニア原料粉末に、セラミゾール等の分散剤、グリセリン
等の可塑剤、ＰＶＡ等の結合剤、および焼結体の開気孔
率が３８％程度となるように繊維状のセルロース等を加
え、混合攪拌機を用いて混合した。得られた混合材を真
空混練機で減圧下で混練しながら、口金部より混練材を
押出成形し、円筒中空の管状セラミックス成形体を得
た。【００１９】次いで、図１に示すように、得られた管状
セラミックス成形体１５を固定ガイド１４および外部ガ
イド１３中で垂直に支持する。このとき、管状セラミッ
クス成形体１５の内部には、その内径と同じ径で凸曲面
状の加圧面をもった下パンチ１２が備えられている。そ
して、該下パンチ１２と管状セラミックス成形体１５で
形成される空間に、別途バインダーを添加し造粒した同
じ組成のセラミックス原料１６を充填し、油圧プレスに
よって、上パンチ１１を下降させて、セラミックス原料
１６をプレス成形する。【００２０】このとき、セラミックス原料１６は所定形
状にプレス成形されるとともに、その周囲を取り囲む管
状セラミックス成形体１５と強固に接合することにな
り、最終的に、図３に示すように管状セラミックス成形
体１５に有底部１７が強固に接合された成形体を得るこ
とができる。【００２１】また、プレス成形時の成形圧力は、１００
〜２００ｋｇ／ｃｍ²として、有底部１７の生密度が約
３．０ｇ／ｃｍ³と、筒状セラミックス成形体１５と同
程度の生密度になるようにした。【００２２】さらに、得られた管状セラミックス成形体
１５を充分に乾燥させた後、ムライト等の治具を使用し
て焼成炉中に立てて収納し、大気中１５００〜１６００
℃、２〜６時間の条件で焼成した。焼成後、有底部１０
ａの外形をダイヤモンド砥石を用いて曲面形状に加工し
て、本発明の有底セラミックス管１０を得た。【００２３】【００２４】なお、図１に示す上下パンチは、図２に示
すように、管状セラミックス成形体１５の内部でセラミ
ックス原料１６をプレス成形する際に、下パンチ１２の
加圧面１２ａを凸曲面状とし、上パンチ１１の加圧面１
１ａをこれに対応する凹曲面状としてプレス成形すれば
良い。こうすれば、セラミックス原料１６における中央
部１６ａと周辺部１６ｂとの加圧比がほぼ等しくなり、
成形圧力を均一にすることができる。その結果、この後
の製造工程や有底セラミックス管１０としての使用時に
クラック等の発生を防止することができる。また、プレ
ス成形後の外周側（上パンチ１１側）が凸曲面状に成形
されるため、この後の研磨工程を簡略化することもでき
る。【００２５】また、上記上パンチ１１、下パンチ１２の
加圧面１１ａ、１２ａの周辺部には、それぞれ平坦部１
１ｂ、１２ｂを備えている。そのため、周辺部における
加圧力を強化するとともに、上パンチ１１、下パンチ１
２自体の欠けや割れを防止することができる。なお、こ
の平坦部１１ｂ、１２ｂの幅ｔは各パンチの直径に対し
て１％より小さいと上記効果が乏しく、一方１０％を超
えると段形状が大きくなりすぎて所定の曲面形状を得に
くくなる。したがって、平坦部１１ｂ、１２ｂの幅ｔは
各パンチの直径に対して１〜１０％の範囲とすれば良
い。【００２６】このようにして成形した後、焼成し、外周
を研磨加工することによって、図３に示すような有底セ
ラミックス管１０を得ることができるが、有底部１０ａ
の内側には下パンチ１２の平坦部１２ｂに応じた幅の段
部１０ｂを有している。【００２７】また、図４の例では下パンチ１２の加圧面
１２ａを凸曲面状とし、上パンチ１１の加圧面１１ａを
凹曲面状としたが、上下パンチの形状を逆にしてもよ
い。また、曲面部分の曲率半径等は最終製品の形状に応
じて自由に設定すれば良い。【００２８】【００２９】上記実施例と同様にして図３に示す成形体
を得た後、図４に示すように、管状セラミック成形体１
５の有底部１７を形成した部分の周囲に押圧部材１８を
取り付ける。この押圧部材１８は、管状セラミックス成
形体１５と同じ原料からなり、生密度を低くすることで
焼成収縮率を大きくしたものであって、リング状に成形
して接合してある。【００３０】そして、この状態で上記実施例と同様に全
体を焼成すると、上記押圧部材１８が大きく収縮するた
めに、有底部１７と管状セラミックス成形体１５との接
合強度をより高いものとすることができる。なお、この
押圧部材１８は、焼成後の外形研削加工時に取り除き、
最終的には図３に示すような曲面状の外形となる。【００３１】なお、以上の実施例では燃料電池用の支持
管を成す、ジルコニアセラミックス製の有底セラミック
ス管１０について述べたが、本発明の製造方法はこの実
施例に限るものではない。例えば、材料としてはアルミ
ナ、ジルコニア、ムライト、コージライト等のセラミッ
クスを用いることができ、その用途としては各種フィル
タや熱電対用保護管等のさまざまな分野に用いることが
できる。【００３２】実験例１ここで、図１〜３に示す本発明の製造方法により得られ
た有底セラミックス管１０を、図７に示すように治具２
０上に載置し、ヒータ２１で加熱しながら、ロードセル
２２で荷重を加え、有底部１０ａの破壊時の負荷荷重を
測定した。【００３３】また、同時に比較例の有底セラミックス管
として、別途プレス成形した封止体を挿入し一体焼成し
て有底部を形成したもの（比較例１）、比較例１に対し
封止体を低粘性ペーストで接合して一体焼成したもの
（比較例２）、比較例１に対し封止体を高粘性ペースト
で接合して一体焼成したもの（比較例３）についても同
じ実験を行った。【００３４】結果は表１に示す通り、比較例１では１０
００℃での耐荷重値は２２．１ｋｇと低く、またペース
トを用いた比較例２、３でも５３〜５４ｋｇと、規格耐
荷重値５５ｋｇを満足していなかった。これに対し、本
発明実施例では耐荷重値６０ｋｇと規格許容範囲内のも
のを得ることができた。【００３５】【表１】【００３６】実験例２次に、上記と同様にして、外径１８ｍｍ、内径１３ｍｍ
のセラミック管１０を成形し、図２に示す上下パンチを
用いて有底部１０ａの成形を行った。【００３７】その際、用いた上パンチ１１、下パンチ１
２の直径は１２．８５ｍｍ、平坦面１１ｂ、１２ｂの幅
ｔは０．３０ｍｍであり、各パンチの直径に対する比率
は２．３％とした。成形圧力は３５ｋｇ／ｃｍ² でプレ
ス成形したところ、有底部の生密度は３．０ｇ／ｃｍ³
であり、セラミック管１０と同様とした。【００３８】十分な乾燥の後、焼結温度より低い温度で
予備焼成を行い、わずかに焼結させて高温強度を与えた
後、ムライト等の治具を使用して焼成炉中に立てて収納
し、大気中１５５０℃、６時間の保持で焼成した。【００３９】予備焼成後と本焼成後の２回の段階で、先
端の有底部をダイヤ砥石を用いて曲面加工した後、縦方
向に切断してクラックの有無を観察した。【００４０】その結果、いずれの段階でもクラックの発
生は全く認められず、クラックの発生を完全に防止で
き、図１に示す上下パンチはクラック防止に優れた効果
があることがわかる。【００４１】実験例３次に、有底部１７の焼成収縮率を１０％とし、管状セラ
ミックス成形体１５の焼成収縮率を１０〜１６％の範囲
で種々に変化させたものを用意し、それぞれ図２に示す
ように押圧部材を備えずに焼成した場合と、図４に示す
ように焼成収縮率１３％の押圧部材１８を備えて焼成し
た場合について、上記実験例と同様に有底部１７の接合
強度を測定した。【００４２】結果は図８に示す通り、管状セラミックス
成形体１５と有底部１７との収縮率の差が３％より小さ
い場合には、押圧部材１８を備えずに焼成すると接合強
度が低下してしまうことがわかった。これに対し、押圧
部材１８を備えて焼成すれば、両者の収縮率の差に関係
なく、６０ｋｇ以上の高い接合強度を保つことができ
た。したがって、押圧部材１８を備えて焼成することに
より、有底部１７の接合強度を向上できることがわか
る。【００４３】【発明の効果】以上のように本発明によれば、管状セラ
ミックス成形体を成形し、この管状セラミックス成形体
の内部に、凸曲面状の曲面部の周囲に直径の１〜１０％
の平坦部を備えた加圧面を有する下パンチを配置し、下
パンチと管状セラミックス成形体で形成される空間にセ
ラミックス原料を充填した後、下パンチの加圧面に対応
した凹曲面状の曲面部の周囲に直径の１〜１０％の平坦
部を備えた加圧面を有する上パンチによってプレス成形
して有底部を一体的に形成した後、有底部の周囲に焼成
収縮率が大きく、管状セラミックス成形体と同じ原料か
らなるリング状の押圧部材を配置し、全体を焼成するこ
とによって押圧部材が収縮して管状セラミックス成形体
と有底部とを密着させる工程からなることによって、有
底部の接合強度が高いセラミックス管を容易に得ること
ができ、このセラミックス管は特に燃料電池用支持管と
して好適に使用することができる。【００４４】また本発明は、加圧面が凸曲面状で他方の
加圧面がこれに対応した凹曲面状をした上下パンチを用
いてプレス成形するようにしたことによって、成形圧力
を均一にし、その後の製造工程等におけるクラックの発
生を防止できる。【００４５】さらに、本発明は上記上下パンチとして、
加圧面が曲面部と周囲の平坦部からなるものを用いたこ
とにより、パンチ自体の破損等を防止し、周辺部の成形
圧力を高くできる。【００４６】また、上記筒状セラミック成形体の有底部
を形成した部分の周囲に押圧部材を備えて焼成すること
によって、さらに有底部の接合強度を高めることが可能
となる。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a bottomed ceramic tube used for a support tube for a solid oxide fuel cell and a mold for producing the tube. 2. Description of the Related Art In recent years, fuel cell power generation systems are expected to contribute greatly to energy problems and global environmental problems, and their expectations are increasing worldwide. A fuel cell power generation system is a system that can directly convert the chemical energy of fuel into electric energy, has high energy conversion efficiency, can diversify fuels, has low pollution, and power generation efficiency is affected by the scale of equipment Not a very promising technology. In particular, a solid oxide fuel cell differs from a phosphoric acid fuel cell and a molten carbonate fuel cell in that it does not use a liquid or a molten material, so that the structure of the cell is simple and includes utilization of high-temperature exhaust heat. And an energy efficiency of 80 to 90% can be expected. As shown in FIG. 7, the structure of a cell used in this solid electrolyte fuel cell comprises an anode 2 on the outer surface of a support tube 1 made of porous zirconia ceramic or the like and, for example, porous stabilized zirconia. It has a structure in which the solid electrolyte 3 and the cathode 4 are sequentially laminated. Then, air 6 is provided inside the support tube 1 and fuel 7 is provided outside the battery.
Are supplied, and the energy when these react through the solid electrolyte 3 is directly taken out in the form of electric power. As shown in FIG. 8, air 6 is supplied to the inside of the support tube 1 using a tube 9. The air 6 is heated to about 1000 ° C. during circulation, and And the waste heat is used. Therefore, one end of the support tube 1 is provided with a curved bottomed portion 1a in consideration of circulation. Further, since the output of the basic unit of the fuel cell is as low as about 10 W, a large number of the basic unit cells are connected in series using nickel felt 8 in order to realize a commercial power supply. A method of manufacturing the bottomed ceramic tube forming the support tube 1 is to extrude a ceramic raw material into a tubular shape, and insert a separately press-molded sealing body into one end of the obtained tubular molded body. If necessary, a ceramic paste is interposed between the two to integrally fire, and then the bottomed portion 1a is processed into a curved surface by grinding. [0007] However, the bottomed ceramic tube constituting the support tube 1 is one in which a tubular body and a sealing body are separately molded and integrally fired to form a bottomed portion 1a. Therefore, there is a problem that the joining strength of the bottomed portion 1a is low. In particular, when used as a fuel cell, a load is applied to the bottomed portion 1a of the support tube 1 as shown in FIG.
Moreover, since it operates at a high temperature of 1000 ° C., the bottomed portion 1a
However, there is a problem that the fuel cell is damaged, and eventually the fuel cell is destroyed. [0009] In view of the above, the present invention provides
A tubular ceramic molded body is formed, and the inside of the tubular ceramic molded body has a diameter of 1 around a convex curved portion.
A lower punch having a pressing surface with a flat portion of 10% to 10% is arranged, a ceramic material is filled in a space formed by the lower punch and the tubular ceramic molded body, and a concave curved surface corresponding to the pressing surface of the lower punch is formed. After forming a bottomed portion integrally by press forming with an upper punch having a pressurized surface having a flat portion with a diameter of 1 to 10% around a curved portion, a firing shrinkage rate around the bottomed portion is large, and a tubular shape is formed. A ring-shaped pressing member made of the same raw material as the ceramic molded body is arranged, and the pressing member is contracted by baking the entire body to make the tubular ceramic molded body and the bottomed portion adhere to each other to produce a bottomed ceramic tube. It was made. According to the present invention, a ceramic material is press-molded inside a tubular ceramic molded body to form a bottomed portion, whereby the bottomed portion and the tubular ceramics molding are formed. The body firmly adheres, and the bonding strength after firing can be increased. In the above press forming, the pressing force is made uniform by using upper and lower punches, one of which has a convex curved surface and the other has a concave curved surface corresponding thereto. Cracks can be prevented from occurring inside. Further, since a flat portion is formed around the pressing surface of the upper and lower punches, it is possible to press the peripheral portion with a strong force and to prevent the upper and lower punches from being damaged. Further, by providing a pressing member around a portion where the bottomed portion of the tubular ceramic molded body is formed,
Since a force is applied in the direction of increasing the adhesiveness of the bottomed portion due to the contraction force of the pressing member at the time of firing, the joining strength can be further increased. Hereinafter, the present invention will be described with reference to examples. The stabilized zirconia raw material powder containing 15 mol% of calcia is added to a dispersant such as ceramisol, a plasticizer such as glycerin, a binder such as PVA, and a sintered body having an open porosity of about 38%. And fibrous cellulose were added thereto and mixed using a mixing stirrer. While kneading the obtained mixed material with a vacuum kneader under reduced pressure, the kneaded material was extruded from a die to obtain a cylindrical hollow tubular ceramic molded body. Next, as shown in FIG. 1, the obtained tubular ceramic molded body 15 is vertically supported in a fixed guide 14 and an external guide 13. At this time, a lower punch 12 having the same diameter as the inner diameter and having a convex curved pressing surface is provided inside the tubular ceramic molded body 15. Then, a space formed by the lower punch 12 and the tubular ceramic molded body 15 is filled with a ceramic material 16 of the same composition, which is separately added and granulated by adding a binder, and the upper punch 11 is lowered by a hydraulic press so that The raw material 16 is press-formed. At this time, the ceramic raw material 16 is press-formed into a predetermined shape, and is firmly joined to the tubular ceramic molded body 15 surrounding the periphery thereof. Finally, as shown in FIG. A molded body in which the bottomed portion 17 is firmly joined to the body 15 can be obtained. The molding pressure during press molding is 100
As ~200kg / cm ^2, the raw density of the bottom portion 17 is approximately 3.0 g / cm ^3, was set to the raw density of the same level as the cylindrical ceramic body 15. Further, after the obtained tubular ceramic molded body 15 is sufficiently dried, the tubular ceramic molded body 15 is set up in a firing furnace using a jig such as mullite, and stored in the atmosphere at 1500 to 1600 in the atmosphere.
It baked on conditions of 2 ° C and 2-6 hours. After firing, bottomed part 10
The outer shape of a was processed into a curved shape using a diamond grindstone to obtain a bottomed ceramic tube 10 of the present invention. The upper and lower punches shown in FIG. 1 project from the pressing surface 12a of the lower punch 12 when the ceramic raw material 16 is press-formed inside the tubular ceramic molded body 15, as shown in FIG. Pressing surface 1 of upper punch 11 to be curved
What is necessary is just to press-mold 1a as a concave curved surface shape corresponding to this. In this case, the pressing ratio between the central portion 16a and the peripheral portion 16b of the ceramic raw material 16 becomes substantially equal,
The molding pressure can be made uniform. As a result, it is possible to prevent the occurrence of cracks and the like in the subsequent manufacturing process and during use as the bottomed ceramic tube 10. Further, since the outer peripheral side (the upper punch 11 side) after the press forming is formed into a convex curved shape, the subsequent polishing step can be simplified. In addition, flat portions 1 are formed around the pressing surfaces 11a and 12a of the upper punch 11 and the lower punch 12, respectively.
1b and 12b. Therefore, the pressing force in the peripheral portion is strengthened, and the upper punch 11 and the lower punch 1
2 itself can be prevented from being chipped or cracked. When the width t of the flat portions 11b and 12b is smaller than 1% of the diameter of each punch, the above effect is poor. On the other hand, when the width t exceeds 10%, the step shape becomes too large and it becomes difficult to obtain a predetermined curved surface shape. . Therefore, the width t of the flat portions 11b and 12b may be in the range of 1 to 10% with respect to the diameter of each punch. After forming in this manner, firing and polishing the outer periphery, a bottomed ceramic tube 10 as shown in FIG. 3 can be obtained.
Has a step portion 10b having a width corresponding to the flat portion 12b of the lower punch 12. In the example of FIG. 4, the pressing surface 12a of the lower punch 12 has a convex curved surface and the pressing surface 11a of the upper punch 11 has a concave curved surface. However, the shapes of the upper and lower punches may be reversed. Further, the radius of curvature of the curved surface portion may be freely set according to the shape of the final product. After obtaining the compact shown in FIG. 3 in the same manner as in the above embodiment, as shown in FIG.
The pressing member 18 is attached around the portion where the bottomed portion 17 is formed. The pressing member 18 is made of the same raw material as that of the tubular ceramic molded body 15, has a low green density and a high firing shrinkage, and is formed into a ring shape and joined. When the whole is fired in this state in the same manner as in the above embodiment, the pressing member 18 is greatly shrunk, so that the bonding strength between the bottomed portion 17 and the tubular ceramic molded body 15 is further increased. Can be. In addition, this pressing member 18 is removed at the time of outer shape grinding after firing,
The final shape is a curved outer shape as shown in FIG. In the above embodiments, the bottomed ceramic tube 10 made of zirconia ceramics, which constitutes a support tube for a fuel cell, has been described. However, the manufacturing method of the present invention is not limited to this embodiment. For example, as a material, ceramics such as alumina, zirconia, mullite, and cordierite can be used, and as its application, it can be used in various fields such as various filters and thermocouple protection tubes. Experimental Example 1 Here, the bottomed ceramic tube 10 obtained by the manufacturing method of the present invention shown in FIGS.
0, and a load was applied by the load cell 22 while heating with the heater 21 to measure the applied load when the bottomed portion 10a was broken. At the same time, as a bottomed ceramic tube of a comparative example, a separately press-molded sealing body was inserted and integrally fired to form a bottomed part (Comparative Example 1). The same experiment was performed for the case where the sealing body was joined and fired integrally with a low-viscosity paste (Comparative Example 2) and the case where the sealing body was joined and joined with a high-viscosity paste for Comparative Example 1 (Comparative Example 3). As shown in Table 1, the results are 10 in Comparative Example 1.
The load-bearing value at 00 ° C. was as low as 22.1 kg, and Comparative Examples 2 and 3 using the paste were 53 to 54 kg, which did not satisfy the standard load-bearing value of 55 kg. On the other hand, in the example of the present invention, a load resistance value of 60 kg and within the standard allowable range could be obtained. [Table 1] Experimental Example 2 Next, an outer diameter of 18 mm and an inner diameter of 13 mm
Was formed, and the bottomed portion 10a was formed using the upper and lower punches shown in FIG. At this time, the upper punch 11 and the lower punch 1 used
2, the width t of the flat surfaces 11b and 12b was 0.30 mm, and the ratio of each punch to the diameter was 2.3%. Press molding was performed at a molding pressure of 35 kg / cm ² , and the green density at the bottom was 3.0 g / cm ^3.
And the same as the ceramic tube 10. After sufficient drying, pre-sintering is performed at a temperature lower than the sintering temperature to give a high-temperature strength by slightly sintering, and then stored in a firing furnace using a jig such as mullite. Then, firing was performed at 1550 ° C. for 6 hours in the atmosphere. At the two stages after pre-firing and after main firing, the bottomed portion at the tip was subjected to a curved surface processing using a diamond grindstone, and then cut vertically to observe the presence or absence of cracks. As a result, no generation of cracks was observed at any stage, and the generation of cracks could be completely prevented. It can be seen that the upper and lower punches shown in FIG. 1 have an excellent effect of preventing cracks. Experimental Example 3 Next, the firing shrinkage of the bottomed portion 17 was set to 10%, and the firing shrinkage of the tubular ceramic molded body 15 was variously changed in the range of 10 to 16%. In the case of baking without a pressing member as shown in FIG. 2 and the case of baking with a pressing member 18 having a baking shrinkage of 13% as shown in FIG. The strength was measured. As shown in FIG. 8, when the difference in the shrinkage ratio between the tubular ceramic molded body 15 and the bottomed portion 17 is smaller than 3%, when the sintering is performed without the pressing member 18, the bonding strength is reduced. I found out. On the other hand, if the baking was performed with the pressing member 18, a high bonding strength of 60 kg or more could be maintained regardless of the difference in shrinkage between the two. Therefore, it can be understood that the bonding strength of the bottomed portion 17 can be improved by baking with the pressing member 18. As described above, according to the present invention, a tubular ceramic molded body is formed, and the inside of the tubular ceramic molded body is surrounded by a convex curved surface portion with a diameter of 1 to 10%.
After placing a lower punch having a pressing surface with a flat portion and filling a ceramic material in a space formed by the lower punch and the tubular ceramic molded body, a concave curved surface portion corresponding to the pressing surface of the lower punch is provided. After press forming with an upper punch having a pressurized surface having a flat portion with a diameter of 1 to 10% around the bottom, the bottomed portion is integrally formed, and then the firing shrinkage rate around the bottomed portion is large, and the tubular ceramics molding is performed. A ring-shaped pressing member made of the same raw material as that of the body is arranged, and the pressing member is contracted by firing the whole, and a step of bringing the tubular ceramic molded body and the bottomed portion into close contact with each other, so that the bonding strength of the bottomed portion is reduced. A high ceramic tube can be easily obtained, and this ceramic tube can be suitably used particularly as a support tube for a fuel cell. Further, the present invention is characterized in that the molding pressure is made uniform by using the upper and lower punches having a pressing surface having a convex curved surface shape and the other pressing surface having a concave curved surface shape corresponding thereto. Cracks can be prevented in the manufacturing process and the like. Further, according to the present invention, as the above-mentioned upper and lower punches,
By using a pressing surface composed of a curved surface portion and a peripheral flat portion, breakage of the punch itself can be prevented, and the molding pressure in the peripheral portion can be increased. Further, by sintering the cylindrical ceramic molded body with a pressing member provided around the portion where the bottomed portion is formed, it is possible to further increase the bonding strength of the bottomed portion.

【図面の簡単な説明】【図１】本発明の有底セラミックス管の製造方法を説明
するための概略断面図である。【図２】本発明の有底セラミックス管の製造方法を説明
するための断面図である。【図３】本発明の製造方法で得られる有底セラミックス
管を示す断面図である。【図４】本発明の有底セラミックス管の製造方法の実施
例を説明するための断面図である。【図５】一般的な燃料電池に使用されるセルの構造を示
す図である。【図６】一般的な燃料電池の構造を示す図である。【図７】有底セラミックス管の有底部の接合強度を測定
する方法を示す図である。【図８】有底セラミックス管の有底部の接合強度を示す
グラフである。【符号の説明】１０：有底セラミックス管１１：上パンチ１２：下パンチ１３：外部ガイド１４：固定ガイド１５：管状セラミックス成形体１６：セラミックス原料１７：有底部１８：押圧部材BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view for explaining a method of manufacturing a bottomed ceramic tube of the present invention. FIG. 2 is a cross-sectional view illustrating a method for manufacturing a bottomed ceramic tube according to the present invention. FIG. 3 is a sectional view showing a bottomed ceramic tube obtained by the production method of the present invention. FIG. 4 is a cross-sectional view for explaining an embodiment of the method for manufacturing a bottomed ceramic tube of the present invention. FIG. 5 is a view showing a structure of a cell used in a general fuel cell. FIG. 6 is a diagram showing a structure of a general fuel cell. FIG. 7 is a diagram showing a method for measuring the joining strength of a bottomed portion of a bottomed ceramic tube. FIG. 8 is a graph showing the bonding strength of the bottomed portion of the bottomed ceramic tube. [Description of References] 10: bottomed ceramic tube 11: upper punch 12: lower punch 13: external guide 14: fixed guide 15: tubular ceramic molded body 16: ceramic raw material 17: bottomed portion 18: pressing member

───────────────────────────────────────────────────── フロントページの続き (56)参考文献特開昭58−167479（ＪＰ，Ａ) 特開昭49−120850（ＪＰ，Ａ) 特開平１−138179（ＪＰ，Ａ) 特開昭55−7544（ＪＰ，Ａ) 特開昭57−67083（ＪＰ，Ａ) 実開平１−166506（ＪＰ，Ｕ) (58)調査した分野(Int.Cl.⁷，ＤＢ名) B28B 3/02 B28B 11/00 - 11/22 C04B 37/00 ──────────────────────────────────────────────────続き Continuation of the front page (56) References JP-A-58-167479 (JP, A) JP-A-49-120850 (JP, A) JP-A-1-138179 (JP, A) JP-A 55-167 7544 (JP, A) JP-A-57-67083 (JP, A) JP-A-1-166506 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B28B 3/02 B28B 11 / 00-11/22 C04B 37/00

Claims

(57) [Claims 1] A tubular ceramic molded body is formed,
Around the convex curved surface inside the ceramic body
Has a pressurized surface with a flat portion with a diameter of 1 to 10% in the surrounding
Placing the lower punch, the lower punch and the tubular ceramic molded body
Fill the space formed by the ceramic material with the lower pan
Around the concave curved surface corresponding to the pressing surface of the
For upper punch with pressurized surface with 1-10% flat part
Therefore, after forming the bottomed part integrally by press molding,
A large firing shrinkage around the bottom,
Arrange a ring-shaped pressing member made of the same raw material as the shape,
By firing the whole, the pressing member shrinks and the tubular
It consists of the step of bringing the Lamix molded body and the bottomed part into close contact
Manufacturing method of bottomed ceramic tube.