Reticulated pore formers for ceramic articles

• US 20080022644A1
• Filed: 07/28/2006
• Published: 01/31/2008
• Est. Priority Date: 07/28/2006
• Status: Abandoned Application

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: DeRosa, Michael Edward
• Application Number:
  US11/495,205
• Publication Number:
  US 20080022644A1
• Time in Patent Office: Days
• US Class Current: 55/523
• CPC Class Codes: C04B 2111/00793 as filters or diaphragms
• CPC Class Codes: C04B 2111/0081 as catalysts or catalyst carriers
• CPC Class Codes: C04B 2235/3217 Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• CPC Class Codes: C04B 2235/3418 Silicon oxide, silicic acids or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint
• CPC Class Codes: C04B 2235/3445 Magnesium silicates, e.g. forsterite
• CPC Class Codes: C04B 2235/349 Clays, e.g. bentonites, smectites such as montmorillonite, vermiculites or kaolines, e.g. illite, talc or sepiolite
• CPC Class Codes: C04B 2235/6562 Heating rate
• CPC Class Codes: C04B 2235/6565 Cooling rate
• CPC Class Codes: C04B 35/00 Shaped ceramic products characterised by their composition porous ceramic products C04B38/00; ceramic articles characterised by particular shape, see the relevant classes, e.g. linings for casting ladles, tundishes, cups or the like B22D41/02; ceramic substrates for microelectronic semi-conductors H01L23/15; Ceramics compositions containing free metal bonded to carbides, diamond, oxides, borides, nitrides, silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides or sulfides other than as macroscopic reinforcing agents C22C; shaping of ceramics B28B; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products chemical preparation of powders of inorganic compounds C01; infiltration of sintered ceramic preforms with molten metal C04B41/51
• CPC Class Codes: C04B 35/195 Alkaline earth aluminosilicates, e.g. cordierite or anorthite
• CPC Class Codes: C04B 35/62655 Drying, e.g. freeze-drying, spray-drying, microwave or supercritical drying
• CPC Class Codes: C04B 38/0006 Honeycomb structures from one or more corrugated sheets by winding or stacking C04B38/0083
• CPC Class Codes: C04B 38/0615 the burned-out substance being a monolitic element having approximately the same dimensions as the final article, e.g. a porous polyurethane sheet or a prepreg obtained by bonding together resin particles C04B38/0022 takes precedence

Abstract

The present invention relates to reticulated pore formers and ceramic articles including reticulated pore structures. The pore former of the present invention provides open pores having an interconnected generally three-dimensional structure and are useful in the manufacture of porous ceramic articles, such as honeycomb diesel particulate filters and catalyzed filters. The reticulated pore formers of the present invention provide controlled pore size and reticulated channel morphology in the finished ceramic articles. The pore size and the length of the pore channel may be controlled by using the desired foam structure and size. The pore formers may be mixed into a ceramic batch and extruded through a forming die resulting in a ceramic article that has semi-continuous reticulated channels throughout the entire body after firing to remove the pore former. The pore formers of the present invention are flexible and highly elastic, which inhibits rupture of the particle during the extrusion process. The use of reticulated pore formers enables the manufacture of highly permeable ceramic filters with controlled pore size distribution.

Claims

1. A porous ceramic article, comprising:

a ceramic matrix; and

a plurality of pores having a reticulated shape.

2. The porous ceramic article of claim 1, wherein said pores have a generally triangular cross section.

3. The porous ceramic article of claim 1, wherein said reticulated shape is a portion of a generally dodecahedron shape.

4. The porous ceramic article of claim 1, wherein said reticulated shape includes generally dodecahedronal shapes.

5. The porous ceramic article of claim 1, wherein said reticulated shape comprises:

at least three channels; and

at least two nodes positioned between said channels, wherein at least two of said channels lie substantially in a common plane.

6. The porous ceramic article of claim 1, wherein said ceramic matrix is selected from the group consisting of cordierite, aluminum titanate, silicon carbide, mullite, silicon nitride and other porous refractory materials.

7. A pore former, comprising:

a first strut having first and second ends;

a node at one of said ends of said first strut; and

a second strut coupled to said node and positioned at an obtuse angle to said first strut.

8. A pore former of claim 7 wherein said pore former is a three dimensional open skeletal structured polymer foam made of polyester urethane or polyether urethane.

9. A pore former of claim 8 wherein said pore former is created by making fragments of pore former by first reducing a temperature of the polymer foam below a glass transition temperature of the foam to make it brittle, then shredding, grating, grinding, pulping, chopping or milling to create a distribution of pore former fragments.

10. The pore former of claim 9, wherein the pore former fragments are separated using screens to obtain fragment sizes between about 250 microns (60 mesh screen) and about 1900 microns (10 mesh screen).

11. The pore former of claim 7, further comprising:

a second node; and

a third strut.

12. The pore former of claim 7, further comprising:

a second node coupled to said second strut, opposite said first node; and

a third strut coupled to said second node, said third strut lying outside said plain.

13. The pore former of claim 7, wherein said pore former is in the shape of a dodecahedron.

14. The pore former of claim 7, wherein said struts have a generally triangular cross-sectional shape.

15. The pore former of claim 7, further comprising PPI between 40 and 110.

16. The pore former of claim 15, further comprising PPI between 80 and 110.

17. A ceramic green body, comprising:

a powdered ceramic material precursor;

a liquid;

an organic binder; and

a pore former having a reticulated shape.

18. The ceramic green body of claim 17, wherein said reticulated shape is a generally a complete skeletal dodecahedron shape or portion of one or more than one complete dodecahedron shapes.

19. A method of manufacturing a ceramic body, comprising the steps of:

forming a plasticized batch including a reticulated foam pore former, and

extruding said batch to form a green body article.

20. The method of claim 19, further comprising the steps of:

extruding said batch to form a honeycomb green body article.