JP4514274B2 - Method for producing porous ceramic structure - Google Patents
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- JP4514274B2 JP4514274B2 JP2000054005A JP2000054005A JP4514274B2 JP 4514274 B2 JP4514274 B2 JP 4514274B2 JP 2000054005 A JP2000054005 A JP 2000054005A JP 2000054005 A JP2000054005 A JP 2000054005A JP 4514274 B2 JP4514274 B2 JP 4514274B2
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- 239000000919 ceramic Substances 0.000 title claims description 75
- 238000004519 manufacturing process Methods 0.000 title claims description 13
- 239000002002 slurry Substances 0.000 claims description 33
- 239000002994 raw material Substances 0.000 claims description 16
- 238000010304 firing Methods 0.000 claims description 8
- 239000008187 granular material Substances 0.000 claims description 7
- 229920002472 Starch Polymers 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 6
- 235000019698 starch Nutrition 0.000 claims description 6
- 239000008107 starch Substances 0.000 claims description 6
- 238000011010 flushing procedure Methods 0.000 claims description 2
- 239000000463 material Substances 0.000 claims description 2
- 239000011148 porous material Substances 0.000 description 52
- 239000012530 fluid Substances 0.000 description 17
- 239000002245 particle Substances 0.000 description 17
- 239000000843 powder Substances 0.000 description 11
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 10
- 239000012298 atmosphere Substances 0.000 description 9
- 238000005452 bending Methods 0.000 description 9
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- 239000006260 foam Substances 0.000 description 9
- 229910010413 TiO 2 Inorganic materials 0.000 description 8
- 238000004891 communication Methods 0.000 description 8
- 230000001965 increasing effect Effects 0.000 description 8
- 229910052581 Si3N4 Inorganic materials 0.000 description 6
- 239000003054 catalyst Substances 0.000 description 6
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 description 6
- 229910052863 mullite Inorganic materials 0.000 description 6
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 6
- JOYRKODLDBILNP-UHFFFAOYSA-N Ethyl urethane Chemical compound CCOC(N)=O JOYRKODLDBILNP-UHFFFAOYSA-N 0.000 description 5
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 5
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 4
- 229910004298 SiO 2 Inorganic materials 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 4
- 230000003247 decreasing effect Effects 0.000 description 4
- 238000000034 method Methods 0.000 description 4
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- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 239000011230 binding agent Substances 0.000 description 3
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- 238000009826 distribution Methods 0.000 description 3
- 239000000835 fiber Substances 0.000 description 3
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- 239000007789 gas Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000000465 moulding Methods 0.000 description 3
- 239000003960 organic solvent Substances 0.000 description 3
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- 229910052760 oxygen Inorganic materials 0.000 description 3
- 230000035699 permeability Effects 0.000 description 3
- 239000002243 precursor Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- -1 Si 3 N 4 Chemical compound 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 150000004703 alkoxides Chemical class 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
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- 229910052751 metal Inorganic materials 0.000 description 2
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- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 239000012299 nitrogen atmosphere Substances 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 238000007873 sieving Methods 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 238000001694 spray drying Methods 0.000 description 2
- 229920003002 synthetic resin Polymers 0.000 description 2
- 239000000057 synthetic resin Substances 0.000 description 2
- 229910000505 Al2TiO5 Inorganic materials 0.000 description 1
- 229910017109 AlON Inorganic materials 0.000 description 1
- 238000007088 Archimedes method Methods 0.000 description 1
- 239000004604 Blowing Agent Substances 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- NIPNSKYNPDTRPC-UHFFFAOYSA-N N-[2-oxo-2-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)ethyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 NIPNSKYNPDTRPC-UHFFFAOYSA-N 0.000 description 1
- 229910003564 SiAlON Inorganic materials 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 150000004645 aluminates Chemical class 0.000 description 1
- OJMOMXZKOWKUTA-UHFFFAOYSA-N aluminum;borate Chemical compound [Al+3].[O-]B([O-])[O-] OJMOMXZKOWKUTA-UHFFFAOYSA-N 0.000 description 1
- 210000000988 bone and bone Anatomy 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 238000005524 ceramic coating Methods 0.000 description 1
- 239000000084 colloidal system Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 229910052878 cordierite Inorganic materials 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
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- 238000004108 freeze drying Methods 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
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- 229910052602 gypsum Inorganic materials 0.000 description 1
- 239000010440 gypsum Substances 0.000 description 1
- 238000001513 hot isostatic pressing Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 230000011164 ossification Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 239000011505 plaster Substances 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 238000013001 point bending Methods 0.000 description 1
- 238000002459 porosimetry Methods 0.000 description 1
- AABBHSMFGKYLKE-SNAWJCMRSA-N propan-2-yl (e)-but-2-enoate Chemical compound C\C=C\C(=O)OC(C)C AABBHSMFGKYLKE-SNAWJCMRSA-N 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
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- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- RUDFQVOCFDJEEF-UHFFFAOYSA-N yttrium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Y+3].[Y+3] RUDFQVOCFDJEEF-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
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- 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
- C04B38/04—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by dissolving-out added substances
-
- 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
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
- C04B2111/00793—Uses not provided for elsewhere in C04B2111/00 as filters or diaphragms
-
- 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
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
- C04B2111/0081—Uses not provided for elsewhere in C04B2111/00 as catalysts or catalyst carriers
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Filtering Materials (AREA)
- Porous Artificial Stone Or Porous Ceramic Products (AREA)
- Catalysts (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、種々のフィルタや触媒担持体等の流体透過部材や生体代替部材等の構造体の気孔内に物質の出入りがある多孔質セラミック構造体の製造方法に関する。
【０００２】
【従来技術】
従来から、多孔質セラミック構造体は高温での安定性および耐食性に優れることから、断熱材、耐火物や、流体ろ過用フィルタ、触媒担持体等の流体透過部材、さらには人工生体部材等としての応用が期待されている。
【０００３】
かかる多孔質セラミック構造体を作製する方法としては、例えば、特公昭６３−６３２４９号公報では、ハニカム等の円筒管内に炭酸ガスを発生する発泡剤を添加したセラミック原料含有スラリーを充填してこれを発泡、焼成することにより円筒管内に多孔質セラミックスを充填した排ガス浄化用構造体を作製できることが記載されている。
【０００４】
また、特開平１０−１３０００２号公報では、セラミック原料である金属を含有するゾルに圧力を加えノズルから押し出して繊維状とし、これをシート上に堆積させて三次元網目状構造物を作製することが記載されている。
【０００５】
さらに、特開平５−３３０９４１号公報では、セラミック原料粉末を含有するスラリー内にウレタンフォーム等の合成樹脂発泡体を浸漬して前記フォーム表面に被膜を形成した後、これを熱間静水圧プレス（ＨＩＰ）焼成することによって合成樹脂発泡体を焼失させセラミック被膜からなる高強度の多孔質セラミック構造体を作製できることが記載されている。
【０００６】
【発明が解決しようとする課題】
しかしながら、特公昭６３−６３２４９号公報の円筒管内に多孔質セラミックスを充填した構造体では、強度等の特性に異方性があるために単純形状の用途にしか使用できないという問題があり、また、構造体の気孔径を制御することが困難であり、構造体としての機械的強度と高い気孔率とを最適化することができず、また、構造体の気孔間の連通性を制御することが困難であり、フィルタや触媒担持体等の流体透過部材の流体透過特性や人工生体部材内での骨生成特性との透過特性が低下し、充分な特性が得られないという問題があった。
【０００７】
また、特開平１０−１３０００２号公報のセラミック繊維を堆積させた多孔質体では、繊維同士の接触部の結合力が弱いために構造体自体の強度が弱いとともに、気孔径を制御することができないという問題があった。
【０００８】
さらに、特開平５−３３０９４１号公報のウレタンフォームを用いた多孔質構造体では、ウレタンフォームが焼失することによって、骨格となるセラミック被膜は中空体となるために機械的強度が不十分であるという問題があった。
【０００９】
本発明は上記課題を解決するためになされたもので、その目的は、等方的で高い機械的強度および気孔率を有し、かつ気孔間の連通性を高めて高い透過性能を有する多孔質セラミック構造体の製造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】
本発明者等は、多孔質セラミック構造体の骨格構造および気孔構造について検討した結果、骨格部形成用のスラリーまたはゾル内に焼成により焼失する気孔形成用の球状体を添加して成型型内に流し込んだ後、前記気孔形成用の球状体同士が所定の割合に接触するように変形せしめ、これを焼成することによって、中実の骨格部と均一な大きさの気孔を有する多孔質セラミック構造体が作製できるとともに、気孔間の連通性を高めることができることを知見した。
【００１３】
本発明の多孔質セラミック構造体の製造方法は、骨格部を形成するセラミック原料および有機質成分を含有するスラリーまたはゾルを作製する工程と、前記スラリーまたはゾル内に平均径０．０１〜１０ｍｍで、かつ該平均径に対して±３０％以内である割合が９０％以上であり、多孔質セラミックスを形成するセラミック原料と有機質成分とを含有する顆粒からなる球状体を添加する工程と、該球状体を添加した前記スラリーまたはゾルを成形型内に流し込んだ後、前記球状体同士が面接触するように前記球状体を変形させて成形体を作製する工程と、該成形体を加熱して前記有機質成分を焼失させた後、前記骨格部が緻密化する温度で焼成する工程とを具備することを特徴とするものである。
【００１４】
ここで、前記顆粒が澱粉を含有し、該澱粉は加熱により焼失することが望ましい。
【００１５】
また、上記多孔質セラミック構造体は、流体透過部材の一部材として好適に使用できる。
【００１６】
【発明の実施の形態】
本発明の製造方法により得られた多孔質セラミック構造体の一例について、その模式図を図１に示す。図１によれば、多孔質セラミック構造体１は、相対密度が９０％以上、特に９２％以上、さらに９５％以上の緻密質セラミックスからなる骨格部２間に不規則に連通した気孔３が、望ましくは気孔率６０％以上、特に６５％以上、さらに７０％以上形成された構成からなり、また、図１によれば、気孔３内には多孔質セラミックス４が充填されている。
【００１７】
このような多孔質セラミック構造体によれば、骨格部２は三次元網目状セラミックスで、かつ中実体であり、また、骨格部２によって気孔３が形成されており、これによって、構造体１が等方的な特性を有し、単純形状から複雑形状まであらゆる形状の部材に適用できるとともに、機械的特性や透過特性などにおいて異方性を有しないため、透過部材などの構造体としての信頼性が大きく改善される。
【００１８】
また、このような多孔質セラミック構造体によれば、気孔３は平均気孔径が０．０１〜１０ｍｍで、かつ該気孔平均径に対して±３０％以内である割合が９０％以上と均一な気孔径を有することが大きな特徴であり、これによって、気孔径の大きな特定の気孔３に応力集中することがなく構造体１の機械的強度を高めることができることから、構造体１の気孔率を高めることができる結果、構造体１をフィルタや触媒担持体等の流体透過部材として用いた際のフィルタ性能や触媒性能が向上する。
【００１９】
また、このような多孔質セラミック構造体によれば、上記気孔３のうち隣接する気孔３、３間は、連通孔５によって連通されるとともに、連通孔５の平均径が気孔３の平均気孔径の１／４以上であることが大きな特徴であり、これによって流体透過部材等の外部と物質の出入りをする構造体１の物質の透過特性を向上させることができる。
【００２０】
なお、多孔質セラミック構造体における気孔率、気孔径とは破面ＳＥＭ写真によって測定される気孔の画像解析によって求められる値である。また、上記連通孔５の平均径も破面ＳＥＭ写真によって測定される気孔の画像解析によって求められる。
【００２１】
また、気孔３内には多孔質セラミックス４の気孔径を制御できるとともに、構造体１の強度を高める上で、多孔質セラミックス４を充填することが望ましく、また、多孔質セラミックス４の相対密度は、構造体１の気孔率、特に流体透過部材の透過率を高めるために６０％以下、特に４０％以下であることが望ましい。
【００２２】
なお、上記骨格部２および気孔３に充填される多孔質セラミックス４は、Ａｌ2Ｏ3、ＺｒＯ2、ムライト、コージェライト、チタン酸アルミニウム等の酸化物、Ｓｉ3Ｎ4、ＡｌＮ、ＴｉＮ等の窒化物、ＳｉＣ、ＴｉＣ等の炭化物、ＴｉＢ2、ＡｌＢ2、ＺｒＢ2等のホウ化物、ＳｉＡｌＯＮ、ＡｌＯＮ等の酸窒化物、ＴｉＣＮ等の炭窒化物の群から選ばれる少なくとも１種以上を主結晶とする焼結または未焼結のセラミックスが好適に適用できる。
【００２３】
上記多孔質セラミックスの中でも高温での使用によっても反応等が生じず安定した性能を有する酸化物を主体とすることが望ましく、また、多孔質セラミックス内の気孔率を高めるためには、前記多孔質セラミックスがアスペクト比３以上の針状または板状粒子を含有するもの、具体的には、窒化ケイ素、アルミナ、アルミネート、ホウ酸アルミニウム、ムライトの群から選ばれる少なくとも１種を含有することが望ましい。なお、本発明におけるアスペクト比とは、針状または板状結晶粒子の（長手方向の粒径／該粒子の厚み）で表されるものである。
【００２４】
また、上記針状または板状粒子のアスペクト比を高めるためには、窒化ケイ素については、焼結助剤としてＹ2Ｏ3等の希土類元素酸化物を１．５重量％以上含有せしめること、さらに窒化ケイ素原料中の不可避不純物としての酸素をも含めたＳｉＯ2の添加量がＳｉＯ2換算量で１．５重量％以上含有せしめることが望ましいく、また、アルミナについては、ＴｉＯ2、ＭｇＯ、ＳｉＯ2、ＣａＯ等の焼結助剤成分を含有せしめることが望ましい。
【００２５】
特に、骨格部２を形成するセラミックスとして、Ａｌ2Ｏ3やムライトを主体とする場合には、該主結晶相の内部に１μｍ以下のＴｉＯ2等の微粒子を析出分散させることによって骨格体４の強度をさらに高めることができる。
【００２６】
次に、本発明の多孔質セラミック構造体を作製する方法について説明する。
まず、骨格部を形成するための例えば平均粒径０．１〜２μｍのセラミック原料粉末に対して、所望により有機バインダ、分散剤、造粘剤、可塑剤、溶媒等を添加してスラリーを作製するか、または、骨格部を形成する金属酸化物のアルコキシド溶液を加水分解するか、またはコロイド溶液を用いて骨格部用の前駆体ゾルを作製する。
【００２７】
次に、上記スラリーまたは前駆体ゾル内に、平均径、すなわち平均直径０．０１〜１０ｍｍの気孔形成用の球状体を添加、混合する。該球状体としては、構造体の気孔内に充填される多孔質セラミックスの原料を含有する顆粒を用いる。このような球状体は、多孔質セラミックスを形成する、例えば平均粒径０．１〜２μｍのセラミックス原料粉末に対して、所望により有機バインダ、分散剤、溶媒等を添加してスラリーを作製するか、または、多孔質セラミックスを形成するための金属酸化物を含有するアルコキシド溶液を加水分解するか、コロイド溶液を用いて多孔質セラミックス用の前駆体ゾルを作製し、スプレードライ等の公知の造粒方法によって得られた平均気孔径０．０１〜１０ｍｍの顆粒である。この時、上記スラリーまたはゾル内に例えば澱粉等の加熱により焼失する有機物を添加すれば、多孔質セラミックスの気孔率を高めることができる。
【００２８】
本発明によれば、前記気孔の大きさを均一化して骨格体の機械的強度を高めるとともに、後述するスラリー中の球状体の充填率を高めて、気孔の体積比率および気孔間の接触割合を高めるために、図２に示す球状体の直径分布において、前記球状体の直径が前記平均径Ｄ0に対して±３０％以内のＤ1（Ｄ0×０．７）〜Ｄ2（Ｄ0×１．３）である割合が全球状体の９０％以上であるように均一化することが重要であり、このためには前記球状体を前記範囲内となるように２種以上のふるいにて篩別する等の方法を用いることが望ましい。なお、前記球状体としては、楕円体や八面体以上の多面体をも用いることができる。
【００２９】
そして、上記球状体を添加、混合したスラリーまたはゾルを所定形状の成形型内に流し込むが、本発明によれば、構造体の気孔率を高めるために、また後述の球状体の変形性を高めるために、球状体がスラリー表面に突出するような比率に調整することが望ましい。また、前記流し込みの後、成形型に振動を与えて球状体の充填性を高めることもできる。
【００３０】
さらに、上記スラリーを充填した成形型に対して表面から板状体等によって加圧し、前記球状体同士が面接触するように前記成形型を変形させて成形する。なお、上記成形の際に、前記球状体の変形性を高めるため成形体を所定の温度、例えば、５０〜１５０℃に加熱することもできる。
【００３１】
次に、上記成形体を加熱して有機質成分を焼失させた後、骨格部が相対密度９０％以上に緻密化する温度にて焼成することによって多孔質セラミック構造体を作製することができる。
【００３２】
また、ＴｉＯ2等のナノサイズの微粒子をＡｌ2Ｏ3やムライト結晶内に分散させた骨格部を作製するには、焼成中に雰囲気を酸化性雰囲気へ、温度を５０〜３００℃低温へ変化させてＴｉＯ2の主結晶相への固溶量を減少させるか、ＴｉＯ2と等モルのＭｇＯを添加して焼成中に雰囲気を非酸化性雰囲気へ、温度を５０〜３００℃低温へ変化させてＴｉＯ2とＭｇＯのＡｌ2Ｏ3への固溶量を減少させればよい。
【００４２】
また、本発明の製造方法により得られた多孔質セラミックス構造体は、粉塵等の固体や、液体、気体等を分離するフィルタやその支持部材、触媒担持体、金属溶湯等の流体透過部材、または人工骨、人工関節等の生体代替部材として好適に使用可能である。
【００４３】
また、上記用途のうち、例えば、流体透過部材として用いる場合には、平板形状からなり一方の表面から他方の表面、または一方の表面から一方の側面に流体を透過させることができ、また管形状からなり内面側に流した流体を外面へ、または外面側に流した流体を内面へ透過させるものであってもよく、本発明の製造方法により得られた多孔質セラミックス構造体によれば、等方的な機械的特性と流体透過特性を有することからいずれの場合においても高い機械的特性と流体透過特性とを併せ持つ優れた流体透過部材となる。
【００４４】
【実施例】
（参考例１）
平均粒径０．７μｍのアルミナ粉末、平均粒径０．３μｍのアルミナとシリカを重量比７２／２８の比率で混合したムライト原料粉末、及び平均粒径０．７μｍの窒化ケイ素粉末（酸素含有量０．９ｗｔ％）に平均粒径１μｍのイットリア５重量％と平均粒径０．７μｍのアルミナ３重量％を焼結助剤として添加したものそれぞれに対して、有機バインダと、分散剤と、水とを添加してスラリーを作製した。
【００４５】
一方、マイクロトラック法による分析において表１に示す平均径、および該平均径に対して±３０％の範囲内の割合が表１に示す値である（表１では分布と記載）アクリルボールを所望により篩別して準備した。
【００４６】
次に、上述のスラリーに対して前記アクリルボールをスラリー表面から突出するように混合し、これを６０ｍｍφ×２０ｍｍ厚みの石膏型中に流入し、振動させることによりアクリルボールの充填性を高めた。この時、アクリルボールがスラリー乾燥体表面から突出するようにボール量を予め調整した。そして、石膏型の上面にセラミックスの板状体を載置してネジ止めによって表１に示す圧力となるようにかしめた状態で、脱水乾燥した後、５００℃に加熱してアクリル球状体を焼失した。
【００４７】
そして、上記成形体を成形型から取り出して、アルミナとムライトについては大気中にてそれぞれ１６５０℃と１６００℃で、窒化ケイ素については窒素雰囲気中にて１７５０℃で５時間焼成した。
【００４８】
得られた焼結体の骨格部の密度をアルキメデス法により測定した結果、いずれも相対密度９８％以上であった。また、試料の寸法密度を測定し、構造体の気孔率を求めた。また、構造体の断面または破面についてのＳＥＭ写真より一視野における気孔の平均径と、隣接する気孔間の連通孔径、すなわちネック部の直径の平均値を測定した。さらに、ＪＩＳＲ１６０１に基づいて３点曲げ強度を測定した。
【００４９】
さらに上記試料を５０ｍｍφ×１０ｍｍ厚みに加工して円筒状のハウジング内に載置し、一方の表面側から流速１０ｍ／ｓで空気を流して構造体内を透過させた時の圧力損失を圧差計にて測定した。結果は表１に示した。
【００５０】
（参考例２）
参考例１の試料Ｎｏ．１２に対して、ＴｉＯ２を１重量％添加すること、また、焼成を水素雰囲気中１５００℃で５時間焼成した後、大気中で１２００℃にて１０時間アニールする以外は参考例１と同様に多孔質セラミック構造体を作製し、同様に評価した（試料Ｎｏ．１２）。結果は表１に示した。
【００５１】
（比較例）
参考例１の試料Ｎｏ．３の骨格部形成用スラリー内にウレタンフォーム（孔径：０．６ｍｍ）を浸漬して、引き上げ、乾燥することによってフォーム表面に前記スラリーの被膜を形成した後、これを１５００℃で焼成してウレタンフォームを焼失させて多孔質セラミック構造体を作製し、参考例１と同様に評価した（試料Ｎｏ．１３）。結果は表１に示した。
【００５２】
【表１】
表１の結果から明らかなように、平均径が０．０１ｍｍより小さい球状体を用い構造体の気孔径が０．０１ｍｍより小さい試料Ｎｏ．１では、骨格部自体の強度が低下して構造体の曲げ強度が低下するとともに、圧力損失が大きくなった。また、成形型を加圧しない試料Ｎｏ．７では、圧力損失が大きくなった。さらに、平均径が１０ｍｍより大きい球状体を用い構造体の気孔径が１０ｍｍより大きい試料Ｎｏ．６では、構造体の曲げ強度が低下した。また、球状体の平均径に対して±３０％以内の割合が９０％より小さい、すなわち粒径の分布が広い試料Ｎｏ．９では、気孔間の連通性が悪くなり、圧力損失が高く、また、部分的に大きな直径のボールが存在して曲げ強度が低下した。さらに、試料Ｎｏ．１３については、強度が低下した。
【００５４】
これに対して、試料Ｎｏ．２〜５、８、１０〜１２では、いずれも曲げ強度２０ＭＰａ以上、圧力損失２ｋＰａ以下の優れた特性を有するものであった。
【００５５】
（参考例３）
参考例１の試料Ｎｏ．３の構造体を、平均粒径０．７μｍのアルミナ粉末を含有するスラリー内に浸漬して、構造体の気孔内に前記スラリーを充填した後、凍結乾燥処理によって乾燥し、大気中１５００℃で焼成して、試料Ｎｏ．３の気孔内に多孔質セラミックスを充填した試料を作製した。
【００５６】
得られた構造体について、破面ＳＥＭにより気孔率および平均気孔径を測定したところ、充填した多孔質体の相対密度３２％、水銀圧入法による平均気孔径０．０２２ｍｍであった。また、参考例１と同様に曲げ強度と流速１０ｍ／ｓでの圧力損失を測定した結果、曲げ強度３１ＭＰａ、圧力損失１．５８ＭＰａであった。
【００５７】
（実施例１）
参考例３の多孔質セラミックス用のスラリーに澱粉を８５重量％の比率で添加したスラリーをスプレードライによって造粒し、篩別して、平均径１．０ｍｍ、直径が０．７〜１．３ｍｍの範囲内の比率が９２％の顆粒とした。
【００５８】
この顆粒を参考例１のＮｏ．３のアクリルボールに代えて用い、成形型のかしめ圧を０．１ＭＰａとする以外は参考例１と同様に構造体を作製した結果、骨格部の気孔率、すなわち多孔質セラミックスの体積比率が８１％、平均気孔径０．８ｍｍ、連通孔径０．２３ｍｍであり、多孔質セラミックスの相対密度７８％、平均気孔径０．０８ｍｍであった。また、参考例１と同様に曲げ強度と流速１０ｍ／ｓでの圧力損失を測定した結果、曲げ強度３０ＭＰａ、圧力損失１．３５ＭＰａであった。
【００５９】
（参考例４）
表２に示す組成（残部は窒化ケイ素、酸素量０．９〜１．１重量％）の原料粉末に対して、参考例３と同様に有機溶剤を含有する多孔質セラミックス用のスラリーを調製し、これに参考例１の試料Ｎｏ．１１の多孔質セラミック構造体を浸漬して該構造体の気孔内に前記スラリーを充填した後、凍結乾燥処理して、窒素雰囲気中、１８００℃にて５時間焼成した。
【００６０】
また、この試料について、参考例１と同様に評価するとともに、試料破面のＳＥＭ写真を用いてルーゼックス画像処理解析によって、多孔質セラミックスについての結晶の短径および長径の平均値、およびアスペクト比が３以上の粒子の含有比率を測定した。結果は表２に示した。
【００６１】
【表２】
（参考例５）
アスペクト比３、粉末の平均長径が１０μｍのアルミナを３０重量％を含み残部が平均粒径０．７μｍの粉末からなるアルミナ原料に対して、焼結助剤としてＴｉＯ２を１重量％とＭｇ（ＯＨ）２をＭｇＯ換算量で０．５重量％と、ＳｉＯ２を０．３重量％との比率で添加した原料粉末に対して、有機溶剤を含有するスラリーを調製し、これに参考例１の試料Ｎｏ．３の多孔質セラミック構造体を浸漬して該構造体の気孔内に前記スラリーを充填した後、凍結乾燥処理して、大気中、１４００℃にて５時間焼成した。得られた試料について、参考例１と同様に評価するとともに、試料破面のＳＥＭ写真を用いてルーゼックス画像処理解析によって、多孔質セラミックスについての結晶の短径および長径の平均値、およびアスペクト比が３以上の粒子の含有比率を測定した。結果は表３に示した。
【００６３】
（参考例６）
表３に示す組成（残部はアルミナ）の原料粉末に対して、有機溶剤を含有するスラリーを調製し、これに参考例１の試料Ｎｏ．３の多孔質セラミック構造体を浸漬して該構造体の気孔内に前記スラリーを充填した後、凍結乾燥処理して、大気中、表３の条件で５時間焼成した。得られた試料について、参考例１と同様に評価するとともに、試料破面のＳＥＭ写真を用いてルーゼックス画像処理解析によって、多孔質セラミックスについての結晶の短径および長径の平均値、およびアスペクト比が３以上の粒子の含有比率を測定した。また、ＸＲＤ測定の強度比から、９７％以上の結晶相を主結晶相として表３に示した。結果は表３に示した。
【００６４】
【表３】
表２、表３の結果から明らかなように、いずれも高い曲げ強度と高い流体透過特性を有するものであることがわかった。
【００６６】
【発明の効果】
以上詳述したとおり、本発明の多孔質セラミック構造体の製造方法によれば、等方的に高い強度と流体透過特性等の物質の出入特性を高めることができる多孔質セラミック構造体を提供できる。
【００６７】
【図面の簡単な説明】
【図１】 本発明の多孔質セラミック構造体の製造方法により得られた多孔質セラミック構造体の組織構造についての模式図である。
【図２】 本発明の多孔質セラミック構造体の製造方法における球状体直径の分布の一例を示す図である。
【符号の説明】
１ 多孔質セラミック構造体
２ 骨格部
３ 気孔
４ 多孔質セラミックス
５ 連通孔[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a porous ceramic structure in the pores of the various filters and catalyst supports, such as a fluid transmitting member and a biological substitute member like structure of it is out of the material.
[0002]
[Prior art]
Conventionally, porous ceramic structures are excellent in stability and corrosion resistance at high temperatures, so that they can be used as heat-insulating materials, refractories, fluid-permeable members such as filters for fluid filtration, catalyst carriers, and artificial biological members. Application is expected.
[0003]
As a method for producing such a porous ceramic structure, for example, in Japanese Examined Patent Publication No. 63-63249, a ceramic raw material containing slurry added with a blowing agent that generates carbon dioxide gas in a cylindrical tube such as a honeycomb is filled with this. It is described that an exhaust gas purifying structure in which a cylindrical tube is filled with porous ceramics can be produced by foaming and firing.
[0004]
In JP-A-10-130002, pressure is applied to a sol containing a metal, which is a ceramic raw material, and it is extruded from a nozzle to form a fiber, which is then deposited on a sheet to produce a three-dimensional network structure. Is described.
[0005]
Further, in JP-A-5-330941, a synthetic resin foam such as urethane foam is immersed in a slurry containing ceramic raw material powder to form a film on the surface of the foam, which is then subjected to hot isostatic pressing ( It is described that a high-strength porous ceramic structure made of a ceramic coating can be produced by burning out a synthetic resin foam by firing (HIP).
[0006]
[Problems to be solved by the invention]
However, the structure in which a porous ceramic is filled in a cylindrical tube of Japanese Examined Patent Publication No. 63-63249 has a problem that it can only be used for simple shapes due to anisotropy in properties such as strength, It is difficult to control the pore size of the structure, the mechanical strength and high porosity as the structure cannot be optimized, and the communication between the pores of the structure can be controlled. There is a problem that the fluid permeation characteristics of a fluid permeation member such as a filter and a catalyst carrier and the permeation characteristics with the bone formation characteristics in the artificial body member are lowered, and sufficient characteristics cannot be obtained.
[0007]
Further, in the porous body in which ceramic fibers are deposited in JP-A-10-130002, the strength of the structure itself is weak and the pore diameter cannot be controlled because the bonding force between the contact portions of the fibers is weak. There was a problem.
[0008]
Furthermore, in the porous structure using the urethane foam disclosed in Japanese Patent Application Laid-Open No. 5-3094091, the ceramic film that becomes the skeleton becomes a hollow body due to the burning of the urethane foam, so that the mechanical strength is insufficient. There was a problem.
[0009]
The present invention has been made in order to solve the above-mentioned problems, and its object is to provide a porous material having isotropic and high mechanical strength and porosity, and having high permeability by increasing the connectivity between the pores. An object of the present invention is to provide a method for manufacturing a ceramic structure.
[0010]
[Means for Solving the Problems]
As a result of studying the skeletal structure and pore structure of the porous ceramic structure, the present inventors added a spherical body for pore formation that burns down by firing into the slurry or sol for forming the skeleton part, and put it in the mold. After pouring, the porous ceramic structure having a solid skeleton and uniform size pores is deformed so that the spherical bodies for pore formation are brought into contact with each other at a predetermined ratio and fired. It has been found that it is possible to improve the connectivity between pores.
[0013]
The method for producing a porous ceramic structure of the present invention includes a step of producing a slurry or sol containing a ceramic raw material and an organic component forming a skeleton, and an average diameter of 0.01 to 10 mm in the slurry or sol. and a step of adding the ratio is within 30% ± respect to the average diameter Ri der 90%, spheroids ing from granules containing a ceramic raw material and organic component to form a porous ceramic, the after flushing the slurry or sol was added spheroids into the mold, the steps you form a compact said spheres each other by deforming the spherical body so as to surface contact, then heating the molded body And the step of firing at a temperature at which the skeleton portion is densified after the organic component is burned off .
[0014]
Here, it is desirable that the granules contain starch, and the starch is burned off by heating .
[0015]
Moreover, the said porous ceramic structure can be used conveniently as one member of a fluid permeation | transmission member.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a schematic diagram of an example of a porous ceramic structure obtained by the production method of the present invention. According to FIG. 1, the porous ceramic structure 1 has
[0017]
According to such a porous ceramic structure , the
[0018]
In addition, according to such a porous ceramic structure , the
[0019]
In addition, according to such a porous ceramic structure,
[0020]
The porosity and pore diameter in the porous ceramic structure are values obtained by image analysis of pores measured by a fracture surface SEM photograph. Moreover, the average diameter of the communication hole 5 is also obtained by image analysis of pores measured by a fracture surface SEM photograph.
[0021]
In addition, the pore diameter of the porous ceramics 4 can be controlled in the
[0022]
The porous ceramics 4 filled in the
[0023]
Among the porous ceramics, it is desirable that the porous ceramic is mainly composed of an oxide that does not cause a reaction even when used at a high temperature and has stable performance, and in order to increase the porosity in the porous ceramic, It is desirable that the ceramic contains needle-like or plate-like particles having an aspect ratio of 3 or more, specifically, at least one selected from the group consisting of silicon nitride, alumina, aluminate, aluminum borate, and mullite. . In addition, the aspect ratio in the present invention is represented by (the particle size in the longitudinal direction / the thickness of the particles) of needle-like or plate-like crystal particles.
[0024]
In order to increase the aspect ratio of the needle-like or plate-like particles, silicon nitride is allowed to contain 1.5% by weight or more of a rare earth element oxide such as Y 2 O 3 as a sintering aid, the addition amount of SiO 2 that oxygen be included as inevitable impurities in the silicon nitride raw material may be desirable allowed to contain more than 1.5 wt% in terms of SiO 2 amount Ku, also, for alumina,
[0025]
In particular, when Al 2 O 3 or mullite is mainly used as the ceramic forming the
[0026]
Next, a method for producing the porous ceramic structure of the present invention will be described.
First, for example, an organic binder, a dispersant, a thickener, a plasticizer, a solvent, and the like are added to a ceramic raw material powder having an average particle diameter of 0.1 to 2 μm for forming a skeleton, and a slurry is prepared. Alternatively, the alkoxide solution of the metal oxide forming the skeleton is hydrolyzed, or a precursor sol for the skeleton is prepared using a colloid solution.
[0027]
Next, pores for forming pores having an average diameter, that is, an average diameter of 0.01 to 10 mm are added and mixed in the slurry or precursor sol. As the spherical body, a granule containing a raw material of porous ceramics filled in the pores of the structure is used. Such a spherical body forms a porous ceramic, for example, is a slurry prepared by adding an organic binder, a dispersant, a solvent, etc. to a ceramic raw material powder having an average particle diameter of 0.1 to 2 μm as desired. Alternatively, hydrolyzing an alkoxide solution containing a metal oxide for forming porous ceramics or preparing a precursor sol for porous ceramics using a colloidal solution, and known granulation such as spray drying Granules having an average pore diameter of 0.01 to 10 mm obtained by the method. At this time, the porosity of the porous ceramics can be increased by adding, for example, an organic substance that is burned down by heating, such as starch, into the slurry or sol.
[0028]
According to the present invention, the pore size is made uniform to increase the mechanical strength of the skeletal body, and the filling rate of spheres in the slurry to be described later is increased so that the volume ratio of the pores and the contact ratio between the pores are increased. to increase, in the diameter distribution of the spherical body shown in FIG. 2, D 1 (D 0 × 0.7) within 30% ± diameter of the spherical body with respect to the average diameter D 0 ~D 2 (D 0 X1.3) It is important to homogenize so that the ratio is 90% or more of the total spheres. For this purpose, the spheres should be classified into two or more types of sieves so as to be within the above range. It is desirable to use a method such as sieving. As the spherical body, an ellipsoid or an octahedron or higher polyhedron can also be used.
[0029]
Then, the slurry or sol added and mixed with the spherical body is poured into a mold having a predetermined shape. According to the present invention, the deformability of the spherical body described later is increased in order to increase the porosity of the structure. for it is desirable that spherical-shaped body is adjusted to a ratio such as to protrude into the slurry surface. Further, after the pouring, the mold can be vibrated to enhance the filling property of the spherical body.
[0030]
Further, the molding die filled with the slurry is pressurized with a plate-like body or the like from the surface, and the molding die is deformed and molded so that the spherical bodies are in surface contact with each other. In addition, in the case of the said shaping | molding, in order to improve the deformability of the said spherical body, a molded object can also be heated to predetermined temperature, for example, 50-150 degreeC.
[0031]
Then, after they burn out organic component and heating the molded body, it is possible to prepare a porous ceramic structure by baking at a temperature skeletal portion is densified to a relative density of 90% or more.
[0032]
In order to produce a skeleton part in which nano-sized fine particles such as TiO 2 are dispersed in Al 2 O 3 or mullite crystals, the atmosphere is changed to an oxidizing atmosphere and the temperature is changed to a low temperature of 50 to 300 ° C. during firing. or were reduced to the amount of solid solution to TiO 2 in the main crystalline phase is, the atmosphere during firing by the addition of equimolar MgO and TiO 2 to the non-oxidizing atmosphere, the temperature is changed to 50 to 300 ° C. cold Thus, the amount of TiO 2 and MgO dissolved in Al 2 O 3 may be reduced.
[0042]
Further, the porous ceramic structure obtained by the production method of the present invention includes a filter that separates solids such as dust, liquid, gas, and the like, a supporting member thereof, a catalyst carrier, a fluid permeable member such as a molten metal, or the like. It can be suitably used as a biological substitute member such as an artificial bone or an artificial joint.
[0043]
In addition, among the above uses, for example, when used as a fluid permeable member, it has a flat plate shape, and allows fluid to permeate from one surface to the other surface, or from one surface to one side surface. The fluid flowing on the inner surface side may be transmitted to the outer surface, or the fluid flowing on the outer surface side may be transmitted to the inner surface. According to the porous ceramic structure obtained by the manufacturing method of the present invention, etc. In both cases, it has excellent mechanical characteristics and fluid permeation characteristics, so that it has excellent mechanical characteristics and fluid permeation characteristics.
[0044]
【Example】
( Reference Example 1)
Alumina powder having an average particle size of 0.7 μm, mullite raw material powder in which alumina and silica having an average particle size of 0.3 μm are mixed at a weight ratio of 72/28, and silicon nitride powder having an average particle size of 0.7 μm (oxygen content) 0.9 wt%) to which 5% by weight of yttria having an average particle diameter of 1 μm and 3% by weight of alumina having an average particle diameter of 0.7 μm are added as sintering aids, respectively, an organic binder, a dispersant, water Were added to prepare a slurry.
[0045]
On the other hand, in the analysis by the microtrack method, the average diameter shown in Table 1 and the ratio within ± 30% of the average diameter are the values shown in Table 1 (described as distribution in Table 1). And prepared by sieving.
[0046]
Next, the acrylic balls were mixed with the above-mentioned slurry so as to protrude from the surface of the slurry, and the mixture was poured into a gypsum mold having a thickness of 60 mmφ × 20 mm to vibrate, thereby enhancing the fillability of the acrylic balls. At this time, the amount of balls was adjusted in advance so that the acrylic balls protruded from the surface of the slurry dried body. Then, after placing a ceramic plate on the top of the plaster mold and caulking it to the pressure shown in Table 1 by screwing, it was dehydrated and dried, and then heated to 500 ° C. to burn off the acrylic sphere. did.
[0047]
The molded body was taken out from the mold, and alumina and mullite were fired at 1650 ° C. and 1600 ° C. in the air, respectively, and silicon nitride was fired at 1750 ° C. in a nitrogen atmosphere for 5 hours.
[0048]
As a result of measuring the density of the skeleton part of the obtained sintered body by the Archimedes method, the relative density was 98% or more in all cases. In addition, the dimensional density of the sample was measured to determine the porosity of the structure. Further, the average diameter of pores in one field of view and the communication hole diameter between adjacent pores, that is, the average value of the diameter of the neck portion were measured from SEM photographs of the cross section or fracture surface of the structure. Further, the three-point bending strength was measured based on JIS R1601.
[0049]
Further, the sample was processed to a thickness of 50 mmφ × 10 mm and placed in a cylindrical housing, and the pressure loss when the air was passed from one surface side at a flow rate of 10 m / s and permeated through the structure was transferred to a pressure difference meter. Measured. The results are shown in Table 1.
[0050]
( Reference Example 2)
Sample No. of Reference Example 1 12 as in Reference Example 1 except that 1% by weight of TiO 2 is added and baking is performed at 1500 ° C. for 5 hours in a hydrogen atmosphere and then annealed at 1200 ° C. for 10 hours in the atmosphere. A porous ceramic structure was prepared and evaluated in the same manner (Sample No. 12). The results are shown in Table 1.
[0051]
(Comparative example)
Sample No. of Reference Example 1 After forming a film of the slurry on the foam surface by immersing urethane foam (pore diameter: 0.6 mm) in the
[0052]
[Table 1]
As is apparent from the results in Table 1, a spherical body having an average diameter of less than 0.01 mm was used, and the sample No. In No. 1, the strength of the skeleton itself decreased, the bending strength of the structure decreased, and the pressure loss increased. Sample No. which does not pressurize the mold. In No. 7, the pressure loss increased. In addition, a spherical body having an average diameter larger than 10 mm was used, and the structure No. In No. 6, the bending strength of the structure decreased. In addition, a sample No. No. in which the ratio within ± 30% with respect to the average diameter of the spherical body is smaller than 90%, that is, the sample No. In No. 9, the communication between the pores deteriorated, the pressure loss was high, and a ball having a partially large diameter was present, resulting in a decrease in bending strength. Furthermore, sample no. For No. 13, the strength decreased.
[0054]
On the other hand, specimen No. In 2-5, 8, and 10-12, all had excellent characteristics with a bending strength of 20 MPa or more and a pressure loss of 2 kPa or less.
[0055]
( Reference Example 3)
Sample No. of Reference Example 1 3 is immersed in a slurry containing alumina powder having an average particle diameter of 0.7 μm, and the slurry is filled in the pores of the structure, followed by drying by freeze-drying treatment at 1500 ° C. in the atmosphere. After firing, sample no. A sample was prepared by filling the
[0056]
When the porosity and average pore diameter of the obtained structural body were measured by a fracture surface SEM, the relative density of the filled porous body was 32%, and the average pore diameter was 0.022 mm by mercury porosimetry. Moreover, as a result of measuring the bending strength and the pressure loss at a flow rate of 10 m / s as in Reference Example 1, the bending strength was 31 MPa and the pressure loss was 1.58 MPa.
[0057]
(Example 1 )
The slurry in which starch is added to the slurry for porous ceramics of Reference Example 3 at a ratio of 85% by weight is granulated by spray drying and sieved, and the average diameter is 1.0 mm and the diameter is in the range of 0.7 to 1.3 mm. The ratio was 92%.
[0058]
This granule was referred to No. 1 of Reference Example 1. The structure was produced in the same manner as in Reference Example 1 except that it was used instead of the
[0059]
( Reference Example 4 )
A slurry for porous ceramics containing an organic solvent was prepared in the same manner as in Reference Example 3 with respect to the raw material powder having the composition shown in Table 2 (the balance being silicon nitride and an oxygen content of 0.9 to 1.1% by weight). Sample No. 1 of Reference Example 1 was added to this. 11 porous ceramic structures were dipped to fill the pores of the structure with the slurry, freeze-dried, and fired at 1800 ° C. for 5 hours in a nitrogen atmosphere.
[0060]
Further, this sample was evaluated in the same manner as in Reference Example 1, and the average value of the minor axis and the major axis of the crystal and the aspect ratio of the porous ceramic were determined by Luzex image processing analysis using the SEM photograph of the sample fracture surface. The content ratio of three or more particles was measured. The results are shown in Table 2.
[0061]
[Table 2]
( Reference Example 5 )
With respect to an alumina raw material comprising 30% by weight of alumina having an aspect ratio of 3 and an average major axis of powder of 10 μm and the balance being 0.7 μm in average particle size, 1% by weight of TiO 2 as a sintering aid and Mg OH) and 0.5 wt% 2 in terms of MgO amount, the SiO 2 with respect to the raw material powder added in a proportion of 0.3 wt%, the slurry containing the organic solvent was prepared which in reference example 1 Sample No. The porous
[0063]
( Reference Example 6 )
The raw material powder composition (balance alumina) shown in Table 3, the slurry containing the organic solvent to prepare, this sample No. of Reference Example 1 The porous ceramic structure No. 3 was immersed and the slurry was filled in the pores of the structure, then freeze-dried, and fired in the atmosphere for 5 hours under the conditions shown in Table 3. The obtained sample was evaluated in the same manner as in Reference Example 1, and the average value of the minor axis and the major axis of the crystal and the aspect ratio of the porous ceramic were determined by Luzex image processing analysis using the SEM photograph of the sample fracture surface. The content ratio of three or more particles was measured. Further, from the intensity ratio of the XRD measurement, a crystal phase of 97% or more is shown in Table 3 as a main crystal phase. The results are shown in Table 3.
[0064]
[Table 3]
As is apparent from the results of Tables 2 and 3, it was found that both had high bending strength and high fluid permeability.
[0066]
【The invention's effect】
As described above in detail, according to the method for producing a porous ceramic structure of the present invention, it is possible to provide a porous ceramic structure capable of enhancing the entrance and exit characteristics of a substance such as isotropically high strength and fluid permeability. .
[0067]
[Brief description of the drawings]
FIG. 1 is a schematic diagram of the structure of a porous ceramic structure obtained by the method for producing a porous ceramic structure of the present invention.
FIG. 2 is a view showing an example of a spherical body diameter distribution in the method for producing a porous ceramic structure of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Porous
Claims (2)
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| KR101918620B1 (en) * | 2017-06-02 | 2018-11-15 | 안동대학교 산학협력단 | Recovery method of high purity MMA and alumina from crude marble |
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| WO2004080916A1 (en) * | 2003-03-10 | 2004-09-23 | Ngk Insulators, Ltd. | Inorganic porous body and method for producing same |
| JP4805676B2 (en) | 2003-07-25 | 2011-11-02 | 日本碍子株式会社 | Ceramic porous body and method for evaluating permeation performance thereof |
| JP4304276B2 (en) * | 2004-03-31 | 2009-07-29 | 独立行政法人産業技術総合研究所 | Efficient heat insulation method and apparatus for high pressure apparatus |
| JP4095584B2 (en) | 2004-06-15 | 2008-06-04 | 本田技研工業株式会社 | Ceramic molded body and metal matrix composite member |
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| JP2007051033A (en) * | 2005-08-18 | 2007-03-01 | Noritake Co Ltd | Porous ceramic support |
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| JP2011521877A (en) * | 2008-05-30 | 2011-07-28 | コーニング インコーポレイテッド | Low back pressure porous honeycomb and manufacturing method thereof |
| DE102008048614A1 (en) * | 2008-09-23 | 2010-04-01 | H.C. Starck Gmbh | Valve metal and valve metal oxide agglomerate powder and process for their preparation |
| JP5199151B2 (en) * | 2009-03-05 | 2013-05-15 | 三井金属鉱業株式会社 | Ceramic fired body and manufacturing method thereof |
| BR112014006516B8 (en) * | 2011-09-20 | 2022-07-05 | Evonik Roehm Gmbh | REFRACTORY CERAMIC MATERIAL, ITS USE AND ITS PRODUCTION PROCESS |
| WO2013146594A1 (en) * | 2012-03-29 | 2013-10-03 | 株式会社クボタ | Ceramic filter |
| TW201522275A (en) * | 2013-08-23 | 2015-06-16 | Toyo Tanso Co | Porous ceramic and method for producing same |
| JP2015044698A (en) * | 2013-08-27 | 2015-03-12 | 栃木県 | Eucryptite porous body, and method for manufacturing the same |
| CN116751073B (en) * | 2023-08-23 | 2023-10-24 | 天津南极星隔热材料有限公司 | Preparation method of lightweight heat-insulating aluminum borate porous ceramic with multistage pore structure |
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