Narrow pore size distribution aluminum titanate body and method for making same
First Claim
1. A ceramic body, comprising:
- a phase of aluminum titanate and a narrow pore size distribution as characterized by the relation (d50−
d10)/d50 being less than 0.50,a coefficient of thermal expansion (RT-1000°
C.) Less than 15×
10−
7 C−
1,a porosity of at least 38% by volume, andat least 0.10% by weight of a metal oxide for a metal selected from the group consisting of bismuth, calcium, yttrium, lanthanides and combinations thereof.
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Abstract
This invention relates to an aluminum titanate body having a narrow pore size distribution as characterized by the relation (d50−d10)/d50 being less than 0.50 corresponding to a high degree of interconnected porosity. The body also preferably exhibits a low coefficient of thermal expansion of less than 15×10−7 C−1, high porosity of at least 38% by volume, and at least 0.10% by weight metal oxide, the metal being either yttrium, calcium, bismuth, a lanthanide metal or combinations of thereof. MOR is preferably at least 450 psi. Median pore diameter is preferably at least 8 microns. The inventive ceramic body is particularly useful as a wall-flow filter for a diesel exhaust. A method of fabrication is provided where the sintering temperature is preferably between 1375°-1550° C.
94 Citations
41 Claims
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1. A ceramic body, comprising:
-
a phase of aluminum titanate and a narrow pore size distribution as characterized by the relation (d50−
d10)/d50 being less than 0.50,a coefficient of thermal expansion (RT-1000°
C.) Less than 15×
10−
7 C−
1,a porosity of at least 38% by volume, and at least 0.10% by weight of a metal oxide for a metal selected from the group consisting of bismuth, calcium, yttrium, lanthanides and combinations thereof. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 38)
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21. A method for making an aluminum titanate ceramic body, comprising the steps of:
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providing a mixture of inorganic raw materials comprising an alumina source, a silica source, and a titanium dioxide source, in combination with a source of a metal oxide as a sintering additive in an amount of at least 0.10% by weight super-addition, the source corresponding to an oxide of a metal selected from the group of metals consisting of bismuth, calcium, yttrium, lanthanides and combinations thereof, shaping the mixture into a body; and sintering the body to a temperature of between 1375°
C. to 1550°
C. for a period of between 1 hour to 15 hours, thereby forming a phase of aluminum titanate and a narrow pore size distribution as characterized by the relation (d50−
d10)/d50 being less than 0.50;wherein a weighted average of median particle diameters of the inorganic raw materials, D50, is at least 6 microns to form a median pore size, d50, in the aluminum titanate ceramic body after sintering of at least 8 microns. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 39, 41)
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33. A ceramic body, comprising:
-
a phase of aluminum titanate and a narrow pore size distribution as characterized by the relation (d50−
d10)/d50 being less than 0.25,a coefficient of thermal expansion (RT-1000°
C.) less than 10×
10−
7 C−
1, anda porosity of between 45-60% by volume. - View Dependent Claims (34, 35, 36, 37, 40)
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Specification