WO1991000850A1 - Ceramic bodies of controlled porosity and process for making same - Google Patents
Ceramic bodies of controlled porosity and process for making same Download PDFInfo
- Publication number
- WO1991000850A1 WO1991000850A1 PCT/US1990/003690 US9003690W WO9100850A1 WO 1991000850 A1 WO1991000850 A1 WO 1991000850A1 US 9003690 W US9003690 W US 9003690W WO 9100850 A1 WO9100850 A1 WO 9100850A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- ceramic body
- ceramic
- fibers
- layers
- resin
- Prior art date
Links
- 239000000919 ceramic Substances 0.000 title claims abstract description 57
- 238000000034 method Methods 0.000 title claims description 24
- 239000000835 fiber Substances 0.000 claims abstract description 39
- 229920005989 resin Polymers 0.000 claims abstract description 27
- 239000011347 resin Substances 0.000 claims abstract description 27
- 239000011148 porous material Substances 0.000 claims abstract description 22
- 239000007788 liquid Substances 0.000 claims abstract description 9
- 229910010293 ceramic material Inorganic materials 0.000 claims abstract description 8
- 238000005245 sintering Methods 0.000 claims description 17
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 12
- 239000000463 material Substances 0.000 claims description 12
- 229910002804 graphite Inorganic materials 0.000 claims description 10
- 239000010439 graphite Substances 0.000 claims description 10
- 239000002002 slurry Substances 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 229920005992 thermoplastic resin Polymers 0.000 claims description 3
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 2
- 229920000742 Cotton Polymers 0.000 claims description 2
- 229920004934 Dacron® Polymers 0.000 claims description 2
- 229910052796 boron Inorganic materials 0.000 claims description 2
- 239000005020 polyethylene terephthalate Substances 0.000 claims description 2
- 229920001187 thermosetting polymer Polymers 0.000 claims description 2
- 238000012876 topography Methods 0.000 claims description 2
- 229920000642 polymer Polymers 0.000 claims 2
- 229920002430 Fibre-reinforced plastic Polymers 0.000 claims 1
- 229910052799 carbon Inorganic materials 0.000 claims 1
- 239000011151 fibre-reinforced plastic Substances 0.000 claims 1
- 239000011159 matrix material Substances 0.000 claims 1
- 239000000203 mixture Substances 0.000 claims 1
- 230000003647 oxidation Effects 0.000 claims 1
- 238000007254 oxidation reaction Methods 0.000 claims 1
- 230000037361 pathway Effects 0.000 claims 1
- 238000007493 shaping process Methods 0.000 claims 1
- 239000000969 carrier Substances 0.000 abstract description 5
- 238000000576 coating method Methods 0.000 abstract description 5
- 239000011248 coating agent Substances 0.000 abstract description 3
- 239000000843 powder Substances 0.000 description 24
- 239000012700 ceramic precursor Substances 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 4
- 239000004925 Acrylic resin Substances 0.000 description 3
- 229920001778 nylon Polymers 0.000 description 3
- 229920000049 Carbon (fiber) Polymers 0.000 description 2
- 239000004677 Nylon Substances 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 239000004917 carbon fiber Substances 0.000 description 2
- 239000000701 coagulant Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000002243 precursor Substances 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910002113 barium titanate Inorganic materials 0.000 description 1
- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000009770 conventional sintering Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 239000002657 fibrous material Substances 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 239000012634 fragment Substances 0.000 description 1
- LNEPOXFFQSENCJ-UHFFFAOYSA-N haloperidol Chemical compound C1CC(O)(C=2C=CC(Cl)=CC=2)CCN1CCCC(=O)C1=CC=C(F)C=C1 LNEPOXFFQSENCJ-UHFFFAOYSA-N 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 229920001225 polyester resin Polymers 0.000 description 1
- 239000004645 polyester resin Substances 0.000 description 1
- 229920005749 polyurethane resin Polymers 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000011342 resin composition Substances 0.000 description 1
- 239000012260 resinous material Substances 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- -1 silk Polymers 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 239000004416 thermosoftening plastic Substances 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
- C04B38/06—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by burning-out added substances by burning natural expanding materials or by sublimating or melting out added substances
- C04B38/063—Preparing or treating the raw materials individually or as batches
-
- 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
- C04B2111/00612—Uses not provided for elsewhere in C04B2111/00 as one or more layers of a layered structure
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S264/00—Plastic and nonmetallic article shaping or treating: processes
- Y10S264/19—Inorganic fiber
Definitions
- This invention pertains to the manufacture of sintered, ceramic bodies having oriented, controlled porosity. Particularly, multi-layered ceramic bodies, having oriented porosity, on a micron scale, are provided.
- Porous, sintered ceramic bodies are used in a variety of applications. Significant applications include insulating bodies, heat exchange devices, filters for high temperature applications, etc.
- the dominant commercial method for the manufacture of such materials is the extrusion of a ceramic greenstock, through a die with small blockages, which correspond to holes formed in the greenstock. The greenstock is subsequently fired to sinter the ceramic material. Using this process, it is difficult to control the exact orientation, diameter and ultimate form of the pores in the ceramic. Additionally, the extruded greenstock is susceptible to extensive deformation or molding, and must be directly sintered into a ceramic body. Finally, extremely small, micron size pores are not achievable using this process.
- U.S. Patent 2,875,501 discloses the use of heat destructible fiber cores, which, upon sintering, define the oriented porosity in the ceramic body.
- yarns preferably of nylon are drawn through a liquid coagulating agent, which may include a PVA suspension, and then subsequently passed through a dispersion of ceramic precursor, which may be barium titanate.
- the PVA coated on the nylon yarn adheres the titanate particles to the fiber.
- a plurality of yarns similarly passed through the ceramic precursor are assembled, and the mass is subsequently, fired, to sinter the ceramic. In the process, the fiber, and the PVA are destroyed.
- U.S. Patents 2,919,483 and 3,112,184 disclose similar processes, the '184 patent using a carrier sheet, which may be deformed.
- a common problem to the processes of these patents is the fact that the material, prior to sintering, has no inherent strength, and cannot be molded, handled, or otherwise easily assembled.
- the carrier sheet of U.S. Patent 3,112,184 provides for some flexibility, and provides an opportunity to make multi-layered articles, the film itself is the fugitive carrier, and does not permit the formation of small pores, particularly pores in the micron range.
- unidirectional tape so coated can be subjected to mild heating, below sintering temperature, to partially cure the resin. It is particularly preferred to cure the resin to a "B" stage, such that the resulting body can be easily deformed.
- a plurality of pieces can be laid up and/or molded to any desired form (a preform) .
- the stacked preforms are sintered at conventional sintering temperatures, so as to produce a ceramic body.
- the tape, prepared from fibrous materials, such as graphite or other carbon fibers are destroyed, together with the partially cured resin.
- the result is a ceramic body, which may be comprised of a plurality of layers, provided with small-dimensioned continuous pores, which need not be linear and may define a tortuous path, and may be differentially oriented, in various layers, to provide a ceramic body.
- the body may be employed, if provided with non-Linear pores, as an ultra-high temperature microporous filter, if provided with differing orientations in a plurality of layers, as a heat-exchanging substrate for integrated circuit devices, and other high temperature applications.
- the ceramic bodies of controlled porosity are prepared by coating a fugitive carrier of small dimension, such as graphite-fibers, with-a curable resin and a ceramic precursor powder.
- the coating process may be preferably effected by pulling the fibers, preferably in the form of a unidirectional tape, through a slurry comprised of a resin bath with ceramic precursor powder distributed therein, or alternatively by first coating the fiber with the resin and subsequently dredging the coated fiber in the ceramic powder.
- the coating method is not critical, a preferred embodiment being simply towing or drawing a tape of graphite fibers through a slurry of liquid resin and ceramic powder.
- the resin employed in the invention can be virtually any resin compatible with the ceramic powder, and not destructive or toxic when oxidized and destroyed during sintering. Due to their ease of processing, and relative low cost, ther oset resins such as epoxy resins, polyester resins, polyurethane resins, etc. may be used.
- thermoplastic resin If the application involves exposing the unsintered, preliminarily cured body to extremely high temperatures, it may be desirable to use a ' thermoplastic resin. None in the processing prohibits its use. However, the higher temperatures, and more difficult processing, generally associated with such resins may make them, for general purposes, less suitable alternatives.
- the basic requirements of the resin are that it be coatable onto the carrier, in a liquid state, and be curable to a B stage, that is, a moldable or drapable state.
- One preferred embodiment involves the use of an acrylate resin.
- thermoplastic resins offer unique advantages. Specifically, layers of the greenstock can be stacked one upon the other to form a block, and the block then deformed at a temperature above the softening point of the thermoplastic, but below the sintering temperature of the ceramic. Thus, parts with various shapes, curves, or bends can be prepared. Though similar forms may be layered up using thermosetting systems, further deformation after curing would not be possible. By this process, it is also possible to stack partially cured layers together and heat the layers under pressure at a temperature below the sintering temperature to form a block, which block can then be machined to a desired shape prior to sintering.
- the ceramic powder material employed as the precursor of the ceramic body can be virtually any suitable ceramic powder.
- powder material is A1 2 0 3 , although other suitable materials are known.
- suitable materials are recited in U.S. Patent 3,112,184. This ceramic powder need only be compatible with the resin, in its liquid and preliminarily cured state.
- the fiber is coated with the curable resin and ceramic powder simultaneously, by towing a unidirectional tape of the fibers through-a slurry comprised of the resin and powder.
- the ratio of resin to powder will vary depending on the particular components selected. In general, the limit on the content of ceramic powder will be the ability to cure the resin to a state which provides moldability or drapability, but retains integrity of the preform.
- the minimum ceramic powder concentration will of course be that which provides a ceramic body upon sintering. In general, on a volume basis, if a resin/powder slurry is employed, the powder will constitute from 15-50 percent, by volume, of the slurry.
- the resin is staged, by mild heating, to form a preform, or similar body.
- these materials may be stored, and transported, and shaped, molded, or combined in layers, to provide any desired shape.
- the carrier body such as a graphite fiber
- the preform may be laid up on a tooling mold, corresponding to the desired path, and the body subsequently sintered, leaving a continuous, but non-linear pore through the ceramic body.
- a plurality of partially cured layers may be stacked together, and the resulting multi-layer product subsequently Sintered.
- a plurality of layers may be stacked, and cured by heat and pressure below the sintering temperature t'o form a single block.
- the block can then be machined to the desired shape, and sintered.
- unidirectional tapes or similar carriers are employed, the orientation of the fibers in each layer can be altered, giving a multi-layered product, with continuous pores passing in different directions within the ceramic body.
- a preferred example of such an embodiment is one wherein alternating layers are laid at orientations 90° from the adjacent layer, providing an optimum heat-exchange device.
- the resulting device should be distinguished from that addressed in, e.g., U.S. Patent 3,112,184, which employs, as a carrier, a sheet or film, which provides only a single passageway per layer, resulting in inferior heat-exchange properties.
- the carrier can be virtually any small dimensioned material which is resistant to the mild heating needed to preliminarily cure the resin but is destroyed upon sintering.
- U.S. Patent 2,875,501 discloses the use of nylon fibers. Such fibers are undesirable, in view of the relatively large dimension that is the minimum that may be achieved in the preparation of such fibers.
- a preferred fiber is a graphite fiber, which can be provided with micron sized diameters and yet is well known to be compatible with ceramic sintering, disappearing from the ceramic body without ill effects or side reactions.
- Other suitable carriers would include fibers prepared from similar materials, which are commonly drawable or spinnable to fine dimensions, and include such organic fibers as dacron, silk, cotton, and the like.
- Non-organic yarns such as boron yarns, can also be used. It should be noted that in all cases, the final pore diameter will be less than the corresponding fiber diameter due to shrinkage of the ceramic material during firing. Generally, the shrinkage factor will be from 10-50% dependent upon the initial green density.
- a unidirectional tape (36 tows) of graphite fiber (filament diameter approximately 7 microns) was drawn through a slurry containing 75 percent by volume acrylate resin and 25 percent A1 2 0 3 powder (0.5 micron) .
- the tows were impregnated and the acrylate resin was cured by mild heating, up to about 350°F.
- the resulting sheets were stacked and fired in an oxygen containing atmosphere at 1400°C, for a period of about 2 hours.
- the graphite fibers burned off, leaving holes (passages) smaller than the diameter of the original fibers due to shrinkage of the ceramic during sintering.
- the resultant holes were 3.5 microns in diameter, 50% of the original.
- multiple layers can be provided, in aligned fashion, and sintered to provide a catalyst support. With such a support it may also be advantageous to -8 - use textured or staple yarns or fibers as the support in order to increase the total surface area.
- the sheets are layered in alternating 0°-90° orientation. To prepare a ceramic body for filter applications, the layers are placed on a tool having a non-linear topography, and sintered thereon.
- the prepared device consists solely of the ceramic, with continuous pores provided therethrough.
Abstract
A ceramic body of controlled porosity is formed by coating unidirectional fiber carriers with a hardenable liquid resin bearing powdered ceramic material, which resin is subsequently cured, hardened, or cooled to provide a green body which may be assembled with similar layers, in a desired shape, and subsequently sintered, to form a ceramic body having continuous pores corresponding to the position of the fibers.
Description
Description
Ceramic Bodies of Controlled Porosity and Process for Making Same
Technical Field This invention pertains to the manufacture of sintered, ceramic bodies having oriented, controlled porosity. Particularly, multi-layered ceramic bodies, having oriented porosity, on a micron scale, are provided. Background Art
Porous, sintered ceramic bodies are used in a variety of applications. Significant applications include insulating bodies, heat exchange devices, filters for high temperature applications, etc. The dominant commercial method for the manufacture of such materials is the extrusion of a ceramic greenstock, through a die with small blockages, which correspond to holes formed in the greenstock. The greenstock is subsequently fired to sinter the ceramic material. Using this process, it is difficult to control the exact orientation, diameter and ultimate form of the pores in the ceramic. Additionally, the extruded greenstock is susceptible to extensive deformation or molding, and must be directly sintered into a ceramic body. Finally, extremely small, micron size pores are not achievable using this process.
Alternative processes are known in the art. Thus, U.S. Patent 2,875,501 discloses the use of heat destructible fiber cores, which, upon sintering, define the oriented porosity in the ceramic body. In this patent, yarns preferably of nylon are drawn through a liquid coagulating agent, which may include a PVA suspension, and then subsequently passed through a dispersion of ceramic precursor, which may be barium titanate. The PVA coated on the nylon yarn adheres the titanate particles to the fiber. A plurality of yarns similarly passed through the ceramic precursor are assembled, and the mass is subsequently, fired, to sinter the ceramic. In the process, the fiber, and the PVA are destroyed. The result is a ceramic body
having longitudinally oriented continuous holes, or passages, which makes an ideal insulator for conductive material placed in the passages. U.S. Patents 2,919,483 and 3,112,184 disclose similar processes, the '184 patent using a carrier sheet, which may be deformed. A common problem to the processes of these patents is the fact that the material, prior to sintering, has no inherent strength, and cannot be molded, handled, or otherwise easily assembled. While the carrier sheet of U.S. Patent 3,112,184 provides for some flexibility, and provides an opportunity to make multi-layered articles, the film itself is the fugitive carrier, and does not permit the formation of small pores, particularly pores in the micron range.
A similar process is addressed by Japanese Patent Publication 297762/48 which teaches the use of a carbon fiber provided with a small amount of binder, such as PVA, dredged in a ceramic raw material powder, which is subsequently fired to form a porous ceramic plate. Alternative processes include premolding a ceramic pcwder, provided with cavities, and filling the cavities with a graphite powder product, the premolded material being subsequently compressed and sintered, whereupon the graphite is destroyed, resulting in cavities in the ceramic. Taken as a whole, the art fails to teach a process whereby a ceramic body may be produced, with continuous, small dimension pores, which can' be molded into a variety of shapes, or combined with a plurality of layers, in any desired orientation. This is particularly due to the fact that those methods that employ carriers for the ceramic powder, which are subsequently destroyed upon sintering, merely adhere the ceramic powder to the carrier via the use of a coagulating agent, such as PVA, which does not give the resulting, unfired precursor any integrity or body strength.
Disclosure of the Invention The above-identified drawbacks of the prior art, and other objectives, are met by towing a plurality of fibers of small, micron dimension, through a curable liquid resin composition, the coated fiber being provided with ceramic precursor powder, such as AI2O3. The alumina powder is preferably provided in the liquid resin itself, converting the liquid to a slurry. Alternatively, it may also be provided by drawing the coated fiber through a bed of the powder material. A plurality of fibers, such as a
"unidirectional tape" so coated can be subjected to mild heating, below sintering temperature, to partially cure the resin. It is particularly preferred to cure the resin to a "B" stage, such that the resulting body can be easily deformed. A plurality of pieces can be laid up and/or molded to any desired form (a preform) . Once prepared, the stacked preforms are sintered at conventional sintering temperatures, so as to produce a ceramic body. In the sintering process, the tape, prepared from fibrous materials, such as graphite or other carbon fibers are destroyed, together with the partially cured resin. The result is a ceramic body, which may be comprised of a plurality of layers, provided with small-dimensioned continuous pores, which need not be linear and may define a tortuous path, and may be differentially oriented, in various layers, to provide a ceramic body. The body may be employed, if provided with non-Linear pores, as an ultra-high temperature microporous filter, if provided with differing orientations in a plurality of layers, as a heat-exchanging substrate for integrated circuit devices, and other high temperature applications.
Brief Description of the Invention The ceramic bodies of controlled porosity are prepared by coating a fugitive carrier of small dimension, such as graphite-fibers, with-a curable resin and a ceramic precursor powder. The coating process may be preferably effected by pulling the fibers, preferably in the form of a unidirectional tape, through a slurry comprised of a resin bath with ceramic precursor powder distributed therein, or alternatively by first coating the fiber with the resin and subsequently dredging the coated fiber in the ceramic powder. The coating method is not critical, a preferred embodiment being simply towing or drawing a tape of graphite fibers through a slurry of liquid resin and ceramic powder. The resin employed in the invention can be virtually any resin compatible with the ceramic powder, and not destructive or toxic when oxidized and destroyed during sintering. Due to their ease of processing, and relative low cost, ther oset resins such as epoxy resins, polyester resins, polyurethane resins, etc. may be used. If the application involves exposing the unsintered, preliminarily cured body to extremely high temperatures, it may be desirable to use a 'thermoplastic resin. Nothing in the processing prohibits its use. However, the higher temperatures, and more difficult processing, generally associated with such resins may make them, for general purposes, less suitable alternatives. The basic requirements of the resin are that it be coatable onto the carrier, in a liquid state, and be curable to a B stage, that is, a moldable or drapable state. One preferred embodiment involves the use of an acrylate resin.
If the application warrants the cost, the use-of thermoplastic resins offers unique advantages. Specifically, layers of the greenstock can be stacked one upon the other to form a block, and the block then deformed at a temperature above the softening point of the thermoplastic, but below the sintering temperature of the ceramic. Thus,
parts with various shapes, curves, or bends can be prepared. Though similar forms may be layered up using thermosetting systems, further deformation after curing would not be possible. By this process, it is also possible to stack partially cured layers together and heat the layers under pressure at a temperature below the sintering temperature to form a block, which block can then be machined to a desired shape prior to sintering. Similarly, the ceramic powder material employed as the precursor of the ceramic body can be virtually any suitable ceramic powder. One ubiquitous, and therefore particular preferred, powder material is A1203, although other suitable materials are known. A variety of suitable materials are recited in U.S. Patent 3,112,184. This ceramic powder need only be compatible with the resin, in its liquid and preliminarily cured state.
In preferred embodiments, the fiber is coated with the curable resin and ceramic powder simultaneously, by towing a unidirectional tape of the fibers through-a slurry comprised of the resin and powder. The ratio of resin to powder will vary depending on the particular components selected. In general, the limit on the content of ceramic powder will be the ability to cure the resin to a state which provides moldability or drapability, but retains integrity of the preform. The minimum ceramic powder concentration will of course be that which provides a ceramic body upon sintering. In general, on a volume basis, if a resin/powder slurry is employed, the powder will constitute from 15-50 percent, by volume, of the slurry. Once the fiber is coated with the resin in which are embedded, or on which are adhered, ceramic powder particles, the resin is staged, by mild heating, to form a preform, or similar body. As is familiar to those skilled in the art, these materials may be stored, and transported, and shaped, molded, or combined in layers, to provide any desired shape. It should be noted that the carrier body,
such as a graphite fiber, remains present in the body, and in fact, lends the body substantial strength. Thus, if a tortuous path is desired for the pores of the ceramic body, the preform may be laid up on a tooling mold, corresponding to the desired path, and the body subsequently sintered, leaving a continuous, but non-linear pore through the ceramic body. Additionally, as is common in the prepreg art, a plurality of partially cured layers may be stacked together, and the resulting multi-layer product subsequently Sintered.
Alternatively, a plurality of layers may be stacked, and cured by heat and pressure below the sintering temperature t'o form a single block. The block can then be machined to the desired shape, and sintered. Where unidirectional tapes or similar carriers are employed, the orientation of the fibers in each layer can be altered, giving a multi-layered product, with continuous pores passing in different directions within the ceramic body. A preferred example of such an embodiment is one wherein alternating layers are laid at orientations 90° from the adjacent layer, providing an optimum heat-exchange device. The resulting device should be distinguished from that addressed in, e.g., U.S. Patent 3,112,184, which employs, as a carrier, a sheet or film, which provides only a single passageway per layer, resulting in inferior heat-exchange properties.
As noted, the carrier can be virtually any small dimensioned material which is resistant to the mild heating needed to preliminarily cure the resin but is destroyed upon sintering. U.S. Patent 2,875,501 discloses the use of nylon fibers. Such fibers are undesirable, in view of the relatively large dimension that is the minimum that may be achieved in the preparation of such fibers. A preferred fiber is a graphite fiber, which can be provided with micron sized diameters and yet is well known to be compatible with ceramic sintering, disappearing from the ceramic body without ill effects or side reactions. Other
suitable carriers would include fibers prepared from similar materials, which are commonly drawable or spinnable to fine dimensions, and include such organic fibers as dacron, silk, cotton, and the like. Certain high temperature resinous materials, which can be drawn to small dimension, can also be employed. Non-organic yarns, such as boron yarns, can also be used. It should be noted that in all cases, the final pore diameter will be less than the corresponding fiber diameter due to shrinkage of the ceramic material during firing. Generally, the shrinkage factor will be from 10-50% dependent upon the initial green density.
Of further note is the fact that reference has been made to carriers which are continuous in nature. This is not intended to distinguish between "continuous" fibers and fibers prepared,from spun staple fragments. Rather, it is necessary, for the practice of the invention, to have a carrier which is continuous in length, such that a continuous passage is provided in the final ceramic body.
EXAMPLE
To prepare a ceramic body of controlled porosity, a unidirectional tape (36 tows) of graphite fiber (filament diameter approximately 7 microns) was drawn through a slurry containing 75 percent by volume acrylate resin and 25 percent A1203 powder (0.5 micron) . The tows were impregnated and the acrylate resin was cured by mild heating, up to about 350°F. The resulting sheets were stacked and fired in an oxygen containing atmosphere at 1400°C, for a period of about 2 hours. The graphite fibers burned off, leaving holes (passages) smaller than the diameter of the original fibers due to shrinkage of the ceramic during sintering. In this example, the resultant holes were 3.5 microns in diameter, 50% of the original. Alternatively, multiple layers can be provided, in aligned fashion, and sintered to provide a catalyst support. With such a support it may also be advantageous to
-8 - use textured or staple yarns or fibers as the support in order to increase the total surface area. For a heat-exchange device, the sheets are layered in alternating 0°-90° orientation. To prepare a ceramic body for filter applications, the layers are placed on a tool having a non-linear topography, and sintered thereon.
In all cases, upon sintering, the prepared device consists solely of the ceramic, with continuous pores provided therethrough. Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.
Claims
1. A process for manufacturing a ceramic body of controlled porosity, comprising:
(1) impregnating a plurality of fibers which volatilize upon oxidation with a slurry comprised of a liquid polymer with powdered ceramic material dispersed therethrough,
(2) hardening said polymer to provide a layer of fiber-reinforced polymer matrix with powdered ceramic material therein,
(3) repeating steps (1) and (2) to provide a plurality of said layers,
(4) assembling said layers in a predetermined order and shaping said layers as necessary to the desired shape, and
(5) sintering the assembled layers to provide a ceramic body with continuous pores provided therethrough.
2. The process of Claim 1, wherein said assembled layers are consolidated, by heat and/or pressure, and shaped or machined as desired to the final shape, prior to sintering.
3. The process of Claim 1, wherein the fibers of any one layer are oriented in the same direction, and the fibers in any layer in the assembly are oriented at an angle other than 0° with respect to the adjacent layers.
4. The process of Claim 1, wherein said fibers have an average filament diameter of less than about 15 microns.
5. The process of Claim 1, wherein said assembly is formed on a tool having a non-linear topography.
6. The process of Claim 1, wherein said resin is a thermosetting resin and said fiber is comprised of graphite.
7. The process of Claim 1, wherein said resin is a thermoplastic resin.
8. The process of Claim 1, wherein said fibers are comprised of oxidizable material selected from the group consisting of graphite, non-graphite carbon, dacron, silk, cotton, boron and mixtures thereof.
9. The process of Claim 1, wherein-said fiber has an average filament diameter of less than 10 microns.
10. A ceramic body of controlled porosity, comprised of sintered ceramic material, said ceramic body comprising at least two substantially planar layers of continuous pores therethrough, the pores of said first layer being in a direction other than 0° to the direction of the pores of said second layer.
11. The ceramic body of Claim 10, wherein said continuous pores have an average diameter of less than 15 microns.
12. The ceramic body of Claim 10, wherein said continuous pores have a non-linear pathway.
13. A ceramic body of controlled porosity, comprised of sintered ceramic material, said ceramic body comprising continuous pores therethrough having an average diameter of less than about 10 microns.
14. A ceramic body of controlled porosity, comprised of sintered ceramic material, said ceramic body comprising continuous pores therethrough, said pores having a non-linear path.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP90911261A EP0484386B1 (en) | 1989-07-07 | 1990-07-05 | Ceramic bodies of controlled porosity and process for making same |
DE69023910T DE69023910T2 (en) | 1989-07-07 | 1990-07-05 | CERAMIC BODY WITH CONTROLLED POROSITY AND METHOD FOR THE PRODUCTION THEREOF. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US377,085 | 1989-07-07 | ||
US07/377,085 US5017522A (en) | 1989-07-07 | 1989-07-07 | Ceramic bodies of controlled porosity and process for making same |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1991000850A1 true WO1991000850A1 (en) | 1991-01-24 |
Family
ID=23487706
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1990/003690 WO1991000850A1 (en) | 1989-07-07 | 1990-07-05 | Ceramic bodies of controlled porosity and process for making same |
Country Status (8)
Country | Link |
---|---|
US (1) | US5017522A (en) |
EP (1) | EP0484386B1 (en) |
JP (1) | JPH05500353A (en) |
AT (1) | ATE130832T1 (en) |
DE (1) | DE69023910T2 (en) |
DK (1) | DK0484386T3 (en) |
ES (1) | ES2081998T3 (en) |
WO (1) | WO1991000850A1 (en) |
Families Citing this family (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2766029B2 (en) * | 1990-03-12 | 1998-06-18 | 日本碍子株式会社 | Ceramic green sheet material, electrochemical device, and method of manufacturing the same |
CA2074200A1 (en) * | 1991-08-20 | 1993-02-21 | Robert G. Smith | High temperature ceramic composite |
US5849375A (en) * | 1996-07-17 | 1998-12-15 | Minnesota Mining & Manufacturing Company | Candle filter |
US5780126A (en) * | 1996-07-17 | 1998-07-14 | Minnesota Mining & Manufacturing | Filter material |
US5989736A (en) * | 1997-05-30 | 1999-11-23 | Unifrax Corporation | Carbon fiber and ceramic fiber paper composites and uses therefor |
JP3455776B2 (en) * | 2000-09-19 | 2003-10-14 | 独立行政法人産業技術総合研究所 | Manufacturing method of hollow ceramic fiber aggregate using unidirectionally oriented organic fiber as a mold by electrostatic method |
FR2852003B1 (en) * | 2003-03-04 | 2005-05-27 | Snecma Propulsion Solide | PROCESS FOR PRODUCING A MULTIPERFORATED PART IN CERAMIC MATRIX COMPOSITE MATERIAL |
CA2483231C (en) * | 2004-09-30 | 2011-11-29 | Aceram Technologies Inc. | Ceramic armor system with diamond coating |
GB201009851D0 (en) * | 2010-06-14 | 2010-07-21 | Hexcel Composites Ltd | Improvements in composite materials |
DE102011009397A1 (en) | 2011-01-25 | 2012-07-26 | Basf Se | Composite foam, useful for soundproofing, comprises first foam layer comprising polysulfone foam and second foam layer comprising melamine-formaldehyde foam |
JP6185391B2 (en) * | 2011-12-28 | 2017-08-23 | 太盛工業株式会社 | Porous sintered body and method for producing porous sintered body |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2875501A (en) * | 1953-03-18 | 1959-03-03 | Clevite Corp | Forming electromechanically sensitive ceramic bodies |
US2919483A (en) * | 1955-03-21 | 1960-01-05 | Clevite Corp | Method of forming ceramic capacitors |
US3112184A (en) * | 1958-09-08 | 1963-11-26 | Corning Glass Works | Method of making ceramic articles |
JPS6036362A (en) * | 1983-08-05 | 1985-02-25 | 東京窯業株式会社 | Air permeable refractories |
US4794046A (en) * | 1986-06-16 | 1988-12-27 | Kureha Kagaku Kogyo Kabushiki Kaisha | Implant material with continuous and two-dimensional pores and process for producing the same |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4070514A (en) * | 1973-06-05 | 1978-01-24 | The United States Of America As Represented By The United States Department Of Energy | Method of fabricating graphite for use as a skeletal prosthesis and product thereof |
-
1989
- 1989-07-07 US US07/377,085 patent/US5017522A/en not_active Expired - Fee Related
-
1990
- 1990-07-05 JP JP2510729A patent/JPH05500353A/en active Pending
- 1990-07-05 DK DK90911261.7T patent/DK0484386T3/en active
- 1990-07-05 EP EP90911261A patent/EP0484386B1/en not_active Expired - Lifetime
- 1990-07-05 AT AT90911261T patent/ATE130832T1/en not_active IP Right Cessation
- 1990-07-05 DE DE69023910T patent/DE69023910T2/en not_active Expired - Fee Related
- 1990-07-05 WO PCT/US1990/003690 patent/WO1991000850A1/en active IP Right Grant
- 1990-07-05 ES ES90911261T patent/ES2081998T3/en not_active Expired - Lifetime
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2875501A (en) * | 1953-03-18 | 1959-03-03 | Clevite Corp | Forming electromechanically sensitive ceramic bodies |
US2919483A (en) * | 1955-03-21 | 1960-01-05 | Clevite Corp | Method of forming ceramic capacitors |
US3112184A (en) * | 1958-09-08 | 1963-11-26 | Corning Glass Works | Method of making ceramic articles |
JPS6036362A (en) * | 1983-08-05 | 1985-02-25 | 東京窯業株式会社 | Air permeable refractories |
US4794046A (en) * | 1986-06-16 | 1988-12-27 | Kureha Kagaku Kogyo Kabushiki Kaisha | Implant material with continuous and two-dimensional pores and process for producing the same |
Also Published As
Publication number | Publication date |
---|---|
EP0484386A1 (en) | 1992-05-13 |
DE69023910D1 (en) | 1996-01-11 |
ATE130832T1 (en) | 1995-12-15 |
DE69023910T2 (en) | 1996-07-25 |
ES2081998T3 (en) | 1996-03-16 |
EP0484386B1 (en) | 1995-11-29 |
DK0484386T3 (en) | 1996-03-11 |
EP0484386A4 (en) | 1992-06-24 |
US5017522A (en) | 1991-05-21 |
JPH05500353A (en) | 1993-01-28 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP0484386B1 (en) | Ceramic bodies of controlled porosity and process for making same | |
US4396663A (en) | Carbon composite article and method of making same | |
US4412854A (en) | Method of producing fiber reinforced glass matrix composite articles of complex shape | |
US4741873A (en) | Method for forming rigid composite preforms | |
US5589115A (en) | Method for making fiber-reinforced ceramic matrix composite | |
US4983451A (en) | Carbon fiber-reinforced carbon composite material and process for producing the same | |
US4518704A (en) | Activated carbon formed body and method of producing the same | |
US5041321A (en) | Fiberformed ceramic insulation and method | |
US7198739B2 (en) | Manufacture of thick preform composites via multiple pre-shaped fabric mat layers | |
EP0179137B1 (en) | Method for forming composite articles of complex shapes | |
US6472058B2 (en) | Fiber-composite material and method for producing the same | |
JP2002534352A5 (en) | ||
GB2163736A (en) | Graphite fiber mold | |
US5134016A (en) | Fiber reinforced porous sheets | |
WO1998043809A1 (en) | Carbon-carbon parts having filamentized composite fiber substrates and methods of producing the same | |
WO2013009534A1 (en) | Composite materials, bodies and nuclear fuels including metal oxide and silicon carbide and methods of forming same | |
CA2012240C (en) | Fiber reinforced ceramic matrix composite member and method for making | |
CN113149683A (en) | Carbon or carbon ceramic composite material short fiber preform, product and preparation method thereof | |
US6277313B1 (en) | Combination continuous woven-fiber and discontinuous ceramic-fiber structure | |
CA1161214A (en) | Carbon composite article and method of making same | |
JPS63252981A (en) | Ceramic-macromolecule composite formed article and manufacture | |
WO2006127002A1 (en) | Manufacture of thick preform composites via multiple pre-shaped fabric mat layers | |
KR100242963B1 (en) | Carbon-carbon composites for friction product and manufacturing method thereof | |
CA2122169A1 (en) | Method of preparing an air-permeable molded body | |
JPH02257093A (en) | Production of nuclear fuel body and overcoated and coated fuel particle |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AK | Designated states |
Kind code of ref document: A1 Designated state(s): JP |
|
AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): AT BE CH DE DK ES FR GB IT LU NL SE |
|
WWE | Wipo information: entry into national phase |
Ref document number: 1990911261 Country of ref document: EP |
|
WWP | Wipo information: published in national office |
Ref document number: 1990911261 Country of ref document: EP |
|
WWG | Wipo information: grant in national office |
Ref document number: 1990911261 Country of ref document: EP |