Porous ceramic material, filter, and articles
The present disclosure relates to porous ceramic materials and porous ceramic articles, including honeycomb structure bodies and porous ceramic filters comprised of plugged honeycomb bodies. In various embodiments, a particulate filter is disclosed herein, such as suitable as a gasoline particulate filter (GPF) for use with a gasoline engine and treating its exhaust, and/or such as a diesel particulate filter (DPF) suitable for use with a diesel engine and treating its exhaust.
1. A particulate filter comprising a honeycomb structure comprised of a matrix of walls comprised of at least one porous ceramic wall, wherein the porous ceramic wall is comprised primarily of cordierite,
wherein the porous ceramic wall comprises a microstructure comprising:
average bulk porosity >60% as measured by mercury porosimetry,
14.7 μm<d50<16.0 μm,
d10>9.0 μm,
df=(d50−d10)/d50<0.45,
d90<37 μm; and
a minimum porosity as measured by x-ray tomography at any point from a surface of the porous ceramic wall perpendicularly into the porous ceramic wall to within 15 μm of the surface of the porous ceramic wall is at least 90% of an average porosity of the middle 30% of the porous ceramic wall.
2. The filter of claim 1 wherein 15.0 μm<d50<16.0 μm.
3. The filter of claim 1 wherein db=(d90−d50)/d50<1.70.
4. The filter of claim 1 wherein the porous ceramic wall has a surface porosity as measured by x-ray tomography that is within 10% of the average bulk porosity at a midpoint of the porous ceramic wall.
5. The filter of claim 1 wherein the average bulk porosity as measured by mercury porosimetry is between 63 and 68%, inclusive.
6. The filter of claim 1 wherein the porous ceramic wall has a surface porosity as measured by x-ray tomography that differs from the average bulk porosity at midpoint of the porous ceramic wall by less than 10%.
7. The filter of claim 1 wherein the porous ceramic wall has a surface porosity as measured by x-ray tomography that differs from the average bulk porosity at a midpoint of the porous ceramic wall by less than 5%.
8. The filter of claim 1 wherein the filter is a washcoat-loaded filter which further comprises a washcoat material disposed at least partially within the porous ceramic wall.
9. The filter of claim 8 wherein the washcoat-loaded filter has a CTE which is within 10% of a bare porous ceramic wall.
10. The filter of claim 1 wherein the porous ceramic wall has a wall thickness >40 μm.
11. The filter of claim 1 wherein the porous ceramic wall has a wall thickness of from 40-500 μm.
12. The filter of claim 1 wherein the porous ceramic wall has a wall thickness <500 μm.
13. The filter of claim 1 wherein a modulus of rupture (MOR) of the filter is >180 psi.
14. The filter of claim 1 wherein a modulus of rupture (MOR) of the filter is >200 psi.
15. The filter of claim 1 wherein the porous ceramic wall comprises a primary crystalline constituent of greater than 85% cordierite.
16. The filter of claim 15 wherein the porous ceramic wall further comprises one or more minor crystalline phases constituting less than 15%.
17. The filter of claim 16 wherein the minor crystalline phases are selected from the group consisting of spinel, sapphirine, mullite, and combinations thereof.
18. The filter of claim 1 wherein the filter comprises an isostatic compressive strength (ISO) of greater than 10 bar.
19. The filter of claim 1 wherein a thickness of the porous ceramic walls increases with decreasing distance to an outer periphery of the filter.
20. The filter of claim 19 wherein:
the filter comprises a plurality of cells defined by the matrix of walls;
the thickness of the porous ceramic walls increases from 5 cells from an outer periphery of the filter to a maximum wall thickness at the periphery of the filter.