WO2008026789A1 - Corps poreux à barbes et procédé de fabrication - Google Patents

Corps poreux à barbes et procédé de fabrication Download PDF

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Publication number
WO2008026789A1
WO2008026789A1 PCT/KR2006/003479 KR2006003479W WO2008026789A1 WO 2008026789 A1 WO2008026789 A1 WO 2008026789A1 KR 2006003479 W KR2006003479 W KR 2006003479W WO 2008026789 A1 WO2008026789 A1 WO 2008026789A1
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whiskers
porous body
porous substrate
whiskered
whisker
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PCT/KR2006/003479
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English (en)
Inventor
Jae Hyung Lee
Hyun Wook Ahn
Sun Hee Cho
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Industry-Academic Cooperation Foundation, Yeungnam University
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Priority to PCT/KR2006/003479 priority Critical patent/WO2008026789A1/fr
Publication of WO2008026789A1 publication Critical patent/WO2008026789A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/20—Carbon compounds
    • B01J27/22—Carbides
    • B01J27/224—Silicon carbide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/74—Iron group metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
    • B01J35/56—Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
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    • B01J35/58—Fabrics or filaments
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    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0234—Impregnation and coating simultaneously
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08—Heat treatment
    • B01J37/082—Decomposition and pyrolysis
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    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/62204—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products using waste materials or refuse
    • C04B35/62213—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products using waste materials or refuse using rice material, e.g. bran or hulls or husks
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    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/62227—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products obtaining fibres
    • C04B35/62272—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products obtaining fibres based on non-oxide ceramics
    • C04B35/62277—Fibres based on carbides
    • C04B35/62281—Fibres based on carbides based on silicon carbide
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    • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
    • C04B38/0093—Other features
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    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
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    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
    • C04B41/4596—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with fibrous materials or whiskers
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    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
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    • 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
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/34—Non-metal oxides, non-metal mixed oxides, or salts thereof that form the non-metal oxides upon heating, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3418—Silicon oxide, silicic acids, or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/42—Non metallic elements added as constituents or additives, e.g. sulfur, phosphor, selenium or tellurium
    • C04B2235/428—Silicon
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
    • C04B2235/52—Constituents or additives characterised by their shapes
    • C04B2235/5208—Fibers
    • C04B2235/526—Fibers characterised by the length of the fibers
    • C—CHEMISTRY; METALLURGY
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
    • C04B2235/52—Constituents or additives characterised by their shapes
    • C04B2235/5208—Fibers
    • C04B2235/5264—Fibers characterised by the diameter of the fibers
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
    • C04B2235/52—Constituents or additives characterised by their shapes
    • C04B2235/5276—Whiskers, spindles, needles or pins

Definitions

  • the present invention generally relates to a porous body, and more particularly to a whiskered porous body, wherein whiskers are grown in the pores to maintain high porosity as well as to reduce substantial sizes of the pores.
  • the present invention further relates to a method of manufacturing such a porous body.
  • Porous bodies with variously sized open pores have been applied to numerous fields.
  • they are used as filters for filtering gas or liquid.
  • a vehicular catalyst filter which is used to remove carbon monoxide or nitric oxide from exhaust gas, is manufactured by extruding a ceramic substrate with a large number of linearly arranged holes of several millimeters and then coating a catalyst on the surfaces of the holes.
  • Another carbon-removing filter for use in a diesel vehicle is composed of a great deal of ceramic particles of several tens ⁇ m size. In such a filter, carbon particles are filtered in such a manner so that fine carbon particles among exhaust gas are attached to the surfaces of the pores while the exhaust gas passes through relatively large pores formed between the ceramic particles.
  • Ceramic porous bodies are fabricated by forming ceramic powders through extrusion, uniaxial compression, etc, and then burning the same at a relatively low temperature to bond the same without any contraction.
  • the pore sizes of such a ceramic porous body can be controlled in a range of nano to several tens ⁇ m according to the sizes of the ceramic source particles.
  • the porosity ranges from approximately 20% to approximately 60%. As the size of the pore is smaller, the breathability becomes lower.
  • Said ceramic porous body with the small sized pores is advantageous for filtering the fine particles, but is disadvantageous in terms of high flow resistance.
  • a sponge-micro structured porous body means a porous body having a spongy structure with a porosity of 75% or more. It is discriminated from the porous bodies fabricated by compressing and sintering the powder.
  • the sponge-mi crostructured porous bodies are fabricated using a sponge, the sizes of their pores are as large as hundreds ⁇ m to several mm. They are widely used as filters for filtering molten metal in metal casting, but are not appropriate for use as filters for fine particles.
  • Ceramic filter with higher breathability can be fabricated from ceramic fibers.
  • Such a ceramic filter is similar to an air filter or a water purifier filter composed of organic or chemical fibers. Since most ceramic fibers are expensive and make large pores dues to their relatively large diameters and are compressed by back pressure, it is difficult to maintain high breathability and constant pore sizes.
  • Porous SiC Ceramics (Sumin Zhu, Hong-An Xi, Qin Li, Ruoding Wang) published in J. Am. Ceram. Soc, 88[9], pp. 2619-2621, 2005; and "Pore Structure Modification and Characterization of Porous Alumina Filter with Chemical Vapor Infiltration
  • the present invention is directed to solving the foregoing problems of the prior art. It is an object of the present invention to provide a whiskered porous body and a method of manufacturing the same, wherein porosity is high and pores are small sized by making whiskers grown even at deeper places of the interior of the porous body.
  • whiskers are grown at the interior of a porous body by carbothermal reduction and, in particular, a whisker source is fed in the form of slurry.
  • a method of manufacturing whiskers using carbothermal reduction comprises creating whiskers by high-temperature heat treating source powders containing a whisker source (mainly, oxide powder and carbon compound) under a non-oxidizing gas atmosphere, if necessary, together with a catalyst.
  • a whisker source mainly, oxide powder and carbon compound
  • a catalyst for example, when carbon- containing source powder and silicon-containing source powder or a material containing both of them (e.g., rice bran) are loaded in a graphite crucible and they are heat-treated under an argon gas atmosphere or an argon gas atmosphere mixed with hydrogen gas, Si ingredient and C ingredient among the source react together to thereby create silicon carbide whiskers.
  • a method of growing silicon carbide whiskers on a substrate or an object using carbothermal reduction is disclosed in U.S. Patent Nos. 3,754,076, 4,284,612, 4,637,924 and 4,975,392.
  • slurry which comprises a whisker source and a catalyst for promoting the growth of the whiskers, if necessary, solved together with water or alcohol solvent are infiltrated to the interior of a porous substrate. Thereafter, preventing a whisker source vapor from leaking out of the porous substrate is carried out. Then, whiskers are grown on the surfaces of the pores inside the porous substrate by high-temperature heat treatment under a non-oxidizing gas atmosphere and by carbothermal reduction, thereby manufacturing the whiskered porous body.
  • the surfaces of the pores may be coated with a carbon layer by infiltrating a carbon precursor to the interior of the porous substrate before infiltrating the slurry to the porous substrate.
  • the carbon precursor for coating the surfaces of the pores with the carbon layer may be infiltrated to the interior of the porous substrate as contained in the slurry comprising the whisker source.
  • oxide and non- oxide ceramics such as silicon carbide, silicon nitride, alumina, zirconia, cordierite or the like, or carbon or graphite may be used. Any metal capable of withstanding a whisker-creating temperature can be used.
  • carbon precursor for coating the surfaces of the pores of the interior of the porous substrate with the carbon layer on which the whiskers are readily grown for example, organic substance such as liquid phenol resin, which has a great deal of residual carbon after being burned, may be used. When burned, 40 ⁇ 50% of the liquid phenol resin leaves as carbon.
  • the liquid phenol resin is primarily used to coat the surfaces of the pores of the interior of the porous substrate with the carbon layer on which the whiskers are readily grown. However, it can serve as a carbon source for creating the whiskers.
  • silicon dioxide SiO 2
  • silicon silica gel
  • silicon nitride Si 3 N 4
  • carbon black pitch, tar or the like
  • silicon carbide and silicon dioxide may be used together.
  • Rice bran or rice hulls containing both Si and C may be used as a source of the silicon carbide whiskers.
  • a catalyst may not be needed for causing the creation of the whiskers by means of carbothermal reduction using rice bran or rice hulls. Those sources may be used as a source as properly mixed together.
  • Whiskers of titanium carbide (TiC), titanium nitride (TiN), boron carbide (B 4 C), boron nitride (BN) or mixtures thereof may be grown by substituting the whisker sources with the above- mentioned substances according to types of whiskers to be grown. Further, a fluoride may be fed in order to assist reaction gases of such sources to be created.
  • the catalyst for causing or promoting the growth of the whiskers composed of silicon carbide one or more of metallic powder of iron, nickel, cobalt, tungsten, platinum, magnesium, chrome, titanium, stainless steel, etc., compounds thereof, or glass based on SiO 2 may be used.
  • Such a catalyst may be fed after feeding the whisker sources or may be fed together with the whisker sources as mixed therewith. Further, they may be used as mixed with the carbon precursor for coating the carbon layer.
  • the pores of the porous substrate can be filled with the source slurry by distributing the slurry into the pores of the porous substrate by an ultrasonic homogeniger when the porous substrate is placed in the source slurry.
  • a pressure can be applied so that the slurry can be uniformly distributed up to the interior.
  • the whisker sources As for growing the whiskers uniformly up to the inward deeper places of the porous body, it is important to prevent a vapor of the whisker sources from leaking out of the porous body during heat treatment.
  • the porous substrate When the porous substrate is covered up with the whisker sources during heat treatment, the leak of the vapor of the whisker sources out of the porous body can be prevented.
  • vapor pressures of the whisker sources are set equally throughout inside and outside of the porous body, the leak of the vapor of the whisker sources can be prevented. According to the experiment conducted by the present inventors, when the whisker sources were not disposed sufficiently enough around the porous body, it was found that the very little whiskers were created in the interior of the porous body and were not created nearly in the vicinity of the surface thereof.
  • non-oxidizing gas used for growing the whiskers by carbothermal reduction argon gas, helium gas, hydrogen gas or mixture thereof is used for growing the silicon carbide whiskers.
  • nitrogen gas or nitrogen-containing gas such as ammonia gas and other conditions are maintained equally with the case of growing the silicon carbide whiskers
  • silicon nitride whiskers are created instead of the silicon carbide whiskers or both the silicon carbide whiskers and the silicon nitride whiskers can be created.
  • Heat treatment of the porous substrate with the whisker sources infiltrated thereto is carried out in a container, which is composed of a refractory material such as graphite, ceramics or molybdenum metal, for example, at 125O 0 C to 1800°C (preferably at approximately 1400 0 C). While heat treatment time can vary according to the types and amounts of the sources, the growth of the whiskers is generally completed within 1 hour. By regulating the lengths and diameters of the created whiskers based on the types and amounts of the sources or the time and temperature of the heat treatment, the whiskers may be fully filled in the pores. On the other hand, the whiskers may be created at suitable length on the surfaces of the pores and may not be created in the middle of the pores.
  • a refractory material such as graphite, ceramics or molybdenum metal
  • the whiskered porous body with the whiskers grown therein can be heat-treated under an inert gas atmosphere such as argon gas, nitrogen gas or the like at a suitable temperature according to the substrate (in case of the SiC substrate, at more than 2000 0 C; and in case of the alumina substrate, at more than 1300°C) to enhance the strength of the porous body or the bonding strength between the substrate and the whiskers.
  • an inert gas atmosphere such as argon gas, nitrogen gas or the like
  • the residual carbon can be burned and removed by heat treatment at about 500 0 C under air or oxygen atmosphere.
  • residual silicon oxide source or a catalyst in the whiskered porous body can be removed by acid treatment of fluoric acid or by heat treatment using chloric gas.
  • the whiskered porous body manufactured by the present invention may be used as a catalyst filter or a catalyst material for gas sensors by coating the interiors of the whiskered pores with a catalyst source for a chemical catalyst filter such as platinum, palladium and the like. Further, in case of using the catalyst source for a chemical catalyst filter such as platinum, palladium and the like as the catalyst for creating the whiskers of the present invention and then growing the whiskers, the whiskered porous body can be directly used as a catalyst material without any other additional coating since it already contains a catalyst for filters such as platinum, palladium and the like.
  • Figs. 1 and 2 are photographs taken through an electron microscope, which show a section of a sponge-structured silicon carbide porous substrate before growing whiskers.
  • Figs. 3 and 4 are photographs taken through an electron microscope, which show a section of a silicon carbide whiskered porous body constructed in accordance with one embodiment of the present invention.
  • Figs. 5 and 6 are photographs taken through an electron microscope, which show a section of a silicon carbide whiskered porous body constructed in accordance with a further embodiment of the present invention.
  • Figs. 7 and 8 are photographs taken through an electron microscope, which show a section of a silicon carbide whiskered porous body constructed in accordance with another embodiment of the present invention.
  • Figs. 9 and 10 are photographs taken through an electron microscope, which show a section of a silicon carbide whiskered porous body constructed in accordance with yet another embodiment of the present invention.
  • Figs. 11 and 12 are photographs taken through an electron microscope, which show a section of a silicon carbide whiskered porous body constructed in accordance with still yet another embodiment of the present invention.
  • Figs. 13 and 14 are photographs taken through an electron microscope, which show a section of a silicon carbide whiskered honeycomb porous body constructed in accordance with still yet another embodiment of the present invention.
  • Figs. 15 and 16 are photographs taken through an electron microscope, which show a section of a silicon carbide whiskered porous body constructed in accordance with still yet another embodiment of the present invention.
  • Figs. 17 and 18 are photographs taken through an electron microscope, which show a section of a silicon carbide whiskered codierite honeycomb porous body constructed in accordance with still yet another embodiment of the present invention.
  • Figs. 1 and 2 are photographs of a sponge-structured porous substrate (silicon carbide), which are taken through an electron microscope at 20 magnifications and
  • silicon dioxide powder having mean grain sizes of approximately O.O ⁇ m and iron trichloride hydrate (FeCl 3 .6H 2 O) serving as an iron catalyst were mixed into ethyl alcohol in a weight ratio of 58:42:0.5 (i.e., rice bran : silicon carbide : iron). They were made into slurry by ball-milling for 24 hours with silicon nitride balls. Thereafter, they were dried.
  • the dried mixed powder, liquid phenol resin for coating the carbon layer and ethyl alcohol were mixed by means of an ultrasonic homigenizer in a weight ratio of 1.7:1.5:2.0, thereby making slurry that is infiltrated into a porous substrate.
  • the sponge-structured silicon carbide porous body was placed in the slurry containing the sources and the source slurry was distributed for 2 minutes by means of the ultrasonic homigenizer so that the source slurry was sufficiently infiltrated into the pores of the porous body. Thereafter, the silicon carbide porous body was taken out from the slurry and was dried.
  • the dried porous body was put in a graphite crucible with non-heat-treated rice bran laid on a bottom thereof and was covered up sufficiently with the rice bran and a lid is then closed. Thereafter, heat treatment was carried out in a high-temperature electric furnace, which is heated by graphite heating elements, for 1 hour at 1400 0 C under an argon gas atmosphere.
  • Figs. 3 and 4 are photographs of a section of the silicon carbide whisker porous body, which was manufactured in accordance with the above. Those photographs were taken through an electron microscope at 100 magnifications and 5000 magnifications, respectively. By comparing Figs. 2 and 3 showing the states before and after the creation of the silicon carbide whiskers at the same magnifications, it could be found that the silicon carbide whiskers were fully grown in the interiors of all the pores of the porous body after being processed like this example. The lengths and diameters of the grown whiskers were approximately 1 OO ⁇ m and 0.2 ⁇ m, respectively. The porosity of the sponge-structured whiskered porous body, wherein the whiskers were grown, was 91%.
  • a silicon carbide whiskered porous body was fabricated using the same method as in example 1 except that a sponge-structured porous substrate with lmm- sized pores was used, and that nickel chloride that could produce the same amount of nickel as an amount of iron in example 1 was used as a catalyst, and that powder of SiO 2 and carbon black were filled around the porous body instead of the rice bran.
  • Figs. 5 and 6 are photographs of a section of the silicon carbide whisker porous body, which was fabricated in the above-described manner. Those photographs were taken through an electron microscope at 40 magnifications and 5000 magnifications, respectively.
  • the whiskers were grown fully and uniformly in the interiors of all the pores of the porous body.
  • the lengths of the whiskers were approximately 500 ⁇ m and the diameters of the whiskers were approximately 0.1 ⁇ m.
  • a silicon carbide whiskered porous body was fabricated using the same method as in example 2 except that SiO 2 and carbon black were used in the weight ratio of 65:35 as a whisker source, and that rice bran was filled around the porous body.
  • Figs. 7 and 8 are photographs of a section of the silicon carbide whisker porous body, which was fabricated in the above-described manner. Those photographs were taken through an electron microscope at 80 magnifications and 5000 magnifications, respectively. The whiskers were grown fully and uniformly in the interiors of all the pores of the porous body. A great number of catalyst droplets were observed at the stems of the whiskers. The lengths of the whiskers were approximately 500 ⁇ m and the diameters of the whiskers were approximately 0.1 ⁇ m. [EXAMPLE 4]
  • FIGs. 9 and 10 are photographs of a section of the silicon carbide whisker porous body, which was fabricated in the above-described manner. Those photographs were taken through an electron microscope at 60 magnifications and 5000 magnifications respectively. The whiskers were grown uniformly in the interiors of all the pores of the porous body. The lengths of the whiskers were approximately 500 ⁇ m and the diameters of the whiskers were approximately 0. l ⁇ m. [EXAMPLE 5]
  • a silicon carbide whiskered porous body was fabricated using the same method as in example 1 except that a sponge-structured porous substrate with 0.5mm-sized pores was used, and that powder of SiO 2 , SiC and Si was used as a whisker source in a mole ratio of 1 :2: 1 , and that cobalt was used as a catalyst.
  • Figs. 11 and 12 are photographs of a section of the silicon carbide whisker porous body, which was fabricated in the above-described manner. Those photographs were taken through an electron microscope at 40 magnifications and 5000 magnifications, respectively. The whiskers were grown fully and uniformly in the interiors of all the pores of the porous body. Further, the whiskers were grown straight. The lengths of the whiskers were approximately 200 ⁇ m and the diameters of the whiskers were approximately 0.2 ⁇ m. [EXAMPLE 6]
  • Silicon carbide whiskers were made grown in the pores of a silicon carbide honeycomb using the same method as in example 5 except that a silicon carbide honeycomb for diesel particulate filters, wherein a great number of 1.2 x 1.2mm- sized square pores are linearly arranged, was used as a porous substrate, and that cobalt chloride was used as a catalyst, and that the surfaces of the honeycomb pores were coated with a mixture of liquid phenol resin and ethanol (mixed in a weight ratio of 3:4) before infiltrating a slurry containing both a whisker source and a catalyst .
  • Figs. 13 and 14 are photographs of a section of the honeycomb with the silicon carbide whiskers grown therein, which was fabricated in the above-described manner. Those photographs were taken through an electron microscope at 60 magnifications and 5000 magnifications, respectively. The created whiskers were straight. The diameters of the whiskers were approximately 0.2 ⁇ m. [EXAMPLE 7]
  • Silicon carbide whiskers were made grown in the pores of a cordierite honeycomb using the same method as in example 6 except that a cordierite honeycomb for vehicular exhaust gas purifying filters, wherein a great number of 1.0 x 1.Omm-sized square pores are linearly arranged, was used as a porous substrate.
  • Figs. 15 and 16 are photographs of a section of the honeycomb with the silicon carbide whiskers grown therein, which was fabricated in the above-described manner. Those photographs were taken through an electron microscope at 60 magnifications and 5000 magnifications respectively. The created whiskers were straight. The diameters of the whiskers were 0.1 ⁇ m or less.
  • a silicon carbide whiskered porous body was fabricated using the same method as in example 5 except that palladium, which is used as a catalyst source in catalyst filters, was used as a catalyst for growing whiskers.
  • Figs. 17 and 18 are photographs of a section of the silicon carbide whisker porous body, which was fabricated in the above-described manner. Those photographs were taken through an electron microscope at 40 magnifications and 5000 magnifications, respectively. The whiskers were grown uniformly in the interiors of all the pores of the porous body. Further, the whiskers were grown straight. The lengths of the whiskers were approximately 150 ⁇ m and the diameters of the whiskers were approximately 0.5 ⁇ m. Droplets containing the palladium catalyst were formed not only at the distal ends of the silicon carbide whiskers but also at the stems thereof.
  • a whiskered porous body wherein whiskers are grown fully uniformly or by an appropriate amount even at the deeper places of the porous body. Further, in case whiskers are made grown inside a porous substrate with high porosity such as a sponge-structured porous body as taught by the present invention, a porous body, wherein high porosity is preserved and a specific surface area is large and substantial sizes of the pores become small due to the whiskers, can be manufactured.
  • whiskered porous body is used as a filter, since flow resistance becomes lower due to high porosity and pores are small sized, even fine particles can be effectively filtered off. Also, since carbothermal reduction, which can grow whiskers from inexpensive sources and through simple process compared to conventional chemical vapor infiltration, is employed in manufacturing the whiskered porous body of the present invention, the entire process costs can be reduced and processes can be simplified with regard to manufacturing the whiskered porous body.
  • a catalyst source of a chemical catalyst filter is used as a catalyst for causing or promoting the growth of the whiskers as taught by the present invention
  • a catalyst for a catalyst filter is already contained in the manufactured whiskered porous body, such whiskered porous body can be utilized as a catalyst material without the need for additionally coating a catalyst for a chemical filter.

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Abstract

La présente invention concerne un corps poreux à barbes, les barbes étant développées dans les pores du corps poreux. L'invention concerne également un procédé de fabrication dudit corps poreux. Les barbes d'un corps poreux à barbes de l'état antérieur de la technique n'étaient pas formées au plus profond du corps poreux céramique. La présente invention permet de résoudre un tel problème. Le corps poreux à barbes de la présente invention est produit par infiltration d'une bouillie contenant une source de barbes dans un corps poreux et croissance de barbes à l'intérieur du corps poreux dans une atmosphère de gaz non oxydant par réduction carbothermale. Conformément à la présente invention, les barbes se développent de façon uniforme, même à l'intérieur du corps poreux.
PCT/KR2006/003479 2006-09-01 2006-09-01 Corps poreux à barbes et procédé de fabrication WO2008026789A1 (fr)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112176412A (zh) * 2020-09-29 2021-01-05 陕西科技大学 一种原位自生弥散分布碳化物晶须预制体的制备方法
CN112661531A (zh) * 2021-01-08 2021-04-16 武汉科技大学 氮化硅晶须增强方镁石-尖晶石-碳过滤器及其制备方法
CN112794727A (zh) * 2021-01-08 2021-05-14 武汉科技大学 一种氮化硅晶须增强镁碳多孔陶瓷过滤器及其制备方法
CN115368161A (zh) * 2022-05-14 2022-11-22 西北工业大学 多级结构的氮化硅泡沫陶瓷及通过渗硅氮化原位生长晶须或纳米线结合cvi工艺制备方法

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US4284612A (en) * 1980-01-28 1981-08-18 Great Lakes Carbon Corporation Preparation of SiC whiskers
US4637924A (en) * 1981-12-16 1987-01-20 Atlantic Richfield Company Continuous silicon carbide whisker production
US6390304B1 (en) * 1997-06-02 2002-05-21 Hitco Carbon Composites, Inc. High performance filters comprising inorganic fibers having inorganic fiber whiskers grown thereon
KR20040082529A (ko) * 2003-03-19 2004-09-30 한국기계연구원 비표면적이 큰 다공성 재료의 제조방법

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4284612A (en) * 1980-01-28 1981-08-18 Great Lakes Carbon Corporation Preparation of SiC whiskers
US4637924A (en) * 1981-12-16 1987-01-20 Atlantic Richfield Company Continuous silicon carbide whisker production
US6390304B1 (en) * 1997-06-02 2002-05-21 Hitco Carbon Composites, Inc. High performance filters comprising inorganic fibers having inorganic fiber whiskers grown thereon
KR20040082529A (ko) * 2003-03-19 2004-09-30 한국기계연구원 비표면적이 큰 다공성 재료의 제조방법

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112176412A (zh) * 2020-09-29 2021-01-05 陕西科技大学 一种原位自生弥散分布碳化物晶须预制体的制备方法
CN112661531A (zh) * 2021-01-08 2021-04-16 武汉科技大学 氮化硅晶须增强方镁石-尖晶石-碳过滤器及其制备方法
CN112794727A (zh) * 2021-01-08 2021-05-14 武汉科技大学 一种氮化硅晶须增强镁碳多孔陶瓷过滤器及其制备方法
CN112661531B (zh) * 2021-01-08 2023-03-10 武汉科技大学 氮化硅晶须增强方镁石-尖晶石-碳过滤器及其制备方法
CN115368161A (zh) * 2022-05-14 2022-11-22 西北工业大学 多级结构的氮化硅泡沫陶瓷及通过渗硅氮化原位生长晶须或纳米线结合cvi工艺制备方法
CN115368161B (zh) * 2022-05-14 2023-10-13 西北工业大学 多级结构的氮化硅泡沫陶瓷及通过渗硅氮化原位生长晶须或纳米线结合cvi工艺制备方法

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