IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0856495
(1999-12-03)
|
우선권정보 |
DE-0057591 (1998-12-14) |
국제출원번호 |
PCT//EP99/09479
(2001-09-24)
|
§371/§102 date |
20010924
(20010924)
|
국제공개번호 |
WO00//35558
(2000-06-22)
|
발명자
/ 주소 |
- Adler, J?rg
- Lenk, Reinhard
- Richter, Hans-J?rgen
|
출원인 / 주소 |
- Fraunhofer-Gesellschaft zur Forderung der Angewandten Forschung e.V.
|
대리인 / 주소 |
|
인용정보 |
피인용 횟수 :
1 인용 특허 :
10 |
초록
▼
The invention relates to the area of ceramics and to ceramic multilayer filters, such as used for separating gases. The invention provides ceramic multilayer filters which are more economical to produce. To this end, the inventive ceramic multilayer filters include at least two layers of different p
The invention relates to the area of ceramics and to ceramic multilayer filters, such as used for separating gases. The invention provides ceramic multilayer filters which are more economical to produce. To this end, the inventive ceramic multilayer filters include at least two layers of different particle size, the particle surfaces of all of the ceramic particles being completely or partially perfused with a material and spot and/or surface joints being formed between particles. The invention also provides a method for producing ceramic multilayer filters of this type, according to which slips are produced from at least two ceramic powders of different particle size, the particles of the ceramic powders being perfused with a material or a material in powder form being added to the ceramic slips. One or more layers are formed from the slips and then dried. At least two layers are placed one above the other and/or joined to each other and together are subjected to a temperature increase.
대표청구항
▼
1. A ceramic multi-layer filter comprising:at least two layers, said at least two layers comprising the same or different ceramic materials, and a different particle size of ceramic particles in said at least two layers;one of said at least two layers is a support layer and at least one other layer
1. A ceramic multi-layer filter comprising:at least two layers, said at least two layers comprising the same or different ceramic materials, and a different particle size of ceramic particles in said at least two layers;one of said at least two layers is a support layer and at least one other layer of said at least two layers is present as a layer with ceramic material with a smaller particle size;particle surfaces of all ceramic particles in each of said at least two layers, during formation of said at least two layers, are wet entirely or partially with at least one material which wets the surfaces of the ceramic particles and has the same or approximately the same thermal coefficient of expansion as the ceramic particles, and the particle size, particle morphology and particle composition/crystal structure of the ceramic particles is not altered or only slightly altered with about ?1% shrinkage of the ceramic multi-layer filter, and in which at least one of spot and surface connections are formed between the particles by said at least one material;the at least one material that wets the surfaces of the ceramic particles and forms the at least one of spot and surface connections between the ceramic particles is a borosilicate glass, an aluminum borosilicate glass or a lithium aluminum silicate glass; andpore volume and pore size between the ceramic particles is reduced by the material only slightly or only partially but not by more than 50%.2. The ceramic multi-layer filter according to claim 1, wherein, when more than two layers are present on the support layer, the particle size of the ceramic particles decreases in a direction going away from the support.3. The ceramic multi-layer filter according to claim 1, wherein said at least two layers comprise layers of the same ceramic material.4. The ceramic multi-layer filter according to claim 3, wherein the ceramic material is silicon carbide or aluminum oxide.5. The ceramic multi-layer filter according to claim 1, wherein the ceramic material in all layers of the filter and the material which wets the surfaces of the ceramic particles, have a same composition in all layers of the filter.6. The ceramic multi-layer filter according to claim 1, wherein the quantity of material, which wets the surface of the ceramic particles and forms the at least one of spot and surface connections between the ceramic particles, is selected in terms of size in such a way that the pore volume and the pore size between the particles is reduced only slightly by the material.7. The ceramic multi-layer filter according to claim 6, wherein the quantity of material, which wets the surface of the ceramic particles and forms the at least one of spot and surface connections between the ceramic particles, is selected in terms of size in such a way that the pore volume and the pore size between the particles is reduced by not more than 10%.8. The ceramic multi-layer filter according to claim 1, wherein the ceramic particles of at least two layers differentiate from one another in a ratio of 1:5 to 1:10 in terms of their average particle size.9. The ceramic multi-layer filter according to claim 1, wherein the particles of the support layer have an average particle size of 20 to 50 μm.10. A process for producing a ceramic multi-layer filter, said ceramic multi-layer filter comprising:at least two layers, said at least two layers comprising the same or different ceramic materials, and a different particle size of ceramic particles in said at least two layers;one of said at least two layers is a support layer and at least one other layer of said at least two layers is present as a layer with ceramic material with a smaller particle size;particle surfaces of all ceramic particles in each of said at least two layers, during formation of said at least two layers, are wet entirely or partially with at least one material which wets the surfaces of the ceramic particles and has the same or approximately the same thermal coefficient of expansion as the ceramic particles, and the particle size, particle morphology and particle composition/crystal structure of the ceramic particles is not altered or only slightly altered with about ?1% shrinkage of the ceramic multi-layer filter, and in which at least one of spot and surface connections are formed between the particles by said at least one material;the at least one material that wets the surfaces of the ceramic particles and forms the at least one of spot and surface connections between the ceramic particles is a borosilicate glass an aluminum borosilicate glass or a lithium aluminum silicate glass; andpore volume and pore size between the ceramic particles is reduced by the material only slightly or only partially but not by more than 50%;said process comprising:providing at least two ceramic slurries containing at least two ceramic powders of the same or different composition but different particle sizes,wetting particles of the ceramic powders with a material having the same or approximately the same thermal coefficient of expansion as the ceramic particles, and which does not or only slightly alters the particle size, particle morphology and particle composition/crystal structure of the ceramic powder and which forms at least one of spot and surface connections in the case of a temperature change between the particles, where the material is only added in a quantity that coats the ceramic particles so that the pore quantity and pore size between the particles is reduced by the material only slightly or only partially but not more than 50%;forming at least one layer from said at least two slurries;partially or completely drying the formed layer;forming at least one other layer on the formed and dried layer comprising ceramic particles with a smaller particle size than the already formed and dried layer; andjointly subjecting the formed and dried layer and the at least one other layer to a temperature increase to form the at least one of spot or surface connection between the ceramic particles by the material.11. The process according to claim 10, wherein the at least two ceramic slurries contain forming and sintering auxiliary agents.12. The process according to claim 10, wherein the material comprises a material that is added to the ceramic slurries in powdered form, and the material wets the surface of the ceramic particles when subjected to a temperature increase.13. The process according to claim 10, wherein the material forms a liquid phase during increasing temperature.14. The process according to claim 13, wherein the liquid phase has a high surface tension.15. The process according to claim 10, wherein the material has liquid phase which partially or completely crystallizes during cooling.16. The process according to claim 10, wherein the material comprises a pulverized material that is homogeneously distributed in the at least two ceramic slurries, and, after drying, is distributed homogeneously on the surface of the ceramic particles.17. The process according to claim 10, in which the ceramic particles are wet with the material before manufacturing the ceramic slurry.18. The process according to claim 17, in which the ceramic particles are wet with the material using a chemical method.19. The process according to claim 18, wherein the chemical method comprises co-precipitation.20. The process according to claim 10, wherein the temperature increase is performed under air.21. The process according to claim 10, wherein the temperature is increased to a range between 700° C. and 1200° C.22. The process according to claim 10, wherein the ceramic powders comprise closely fractionated abrasive powders.23. The ceramic multi-layer filter according to claim 1, wherein the particle size, particle morphology and particle composition/crystal structure of the ceramic particles is not altered or only slightly altered includes no shrinkage of the ceramic multi-layer filter.24. The ceramic multi-layer filter according to claim 1, wherein the at least two layers have the same shrinkage.25. The process according to claim 10, wherein the particle size, particle morphology and particle composition/crystal structure of the ceramic particles is not altered or only slightly altered includes no shrinkage of the ceramic multi-layer filter.26. The process according to claim 10, wherein the at least two layers have the same shrinkage.
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