Narrow pore size distribution aluminum titanate body and method for making same

a technology of aluminum titanate and pore microstructure, which is applied in the field of narrow pore size distribution of aluminum titanate ceramic bodies, can solve the problems of relatively high cost of silicon carbide, inability to obtain well-interconnected pore microstructures, and inability to meet the requirements of high temperature operation, and achieve high degree of interconnected porosity

Inactive Publication Date: 2007-09-20
MERKEL GREGORY A
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the relatively low volumetric heat capacity (approximately 2.8 J cm−3° C.−1 at 800 K) and low thermal conductivity of cordierite can result in unacceptably high temperatures during operation when the filters are regenerated under certain conditions.
Further, obtaining a well-interconnected pore microstructure in cordierite filters, in combination with low porosity required for high thermal mass, has been a challenge.
However, silicon carbide is relatively expensive.
Furthermore, the high coefficient of thermal expansion requires silicon carbide filters to be fabricated as cement-bonded segments, adding to manufacturing cost and raising concerns about their long-term thermo-mechanical durability.
However, in the manufacture of AT and MAT bodies, high sintering temperatures greater than 1600° C. are often required to achieve sufficient grain growth for microcracking and low thermal expansion.
Such high heating temperatures add cost to manufacturing and final product.
Nonetheless, such methods often result in a strong sensitivity of the physical properties, including CTE, porosity, or pore size, to the firing temperature, which is undesirable for manufacturability.
Also, desired properties for DPF use are not expected to be achieved.

Method used

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  • Narrow pore size distribution aluminum titanate body and method for making same
  • Narrow pore size distribution aluminum titanate body and method for making same
  • Narrow pore size distribution aluminum titanate body and method for making same

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[0037] The invention is further illustrated with the following non-limiting examples. Inventive and comparative samples are prepared by admixing the inorganic raw materials, metal oxide additives, and pore-forming agents with 4 to 6 wt % methyl cellulose binder, 0.15 wt % triethanol amine, 1% tall oil, and 14 to 18 wt % water. The mixture is plasticized in a stainless steel muller and extruded as 5 / 16-inch diameter rod and 1-inch, 2-inch, or 5.7-inch diameter honeycomb. Parts are dried and then fired in a gas or electric kiln at 14000 to 1500° C. and held for 4 to 10 hours.

[0038] After firing, the porosities of the samples are characterized by mercury porosimetry, the CTEs measured by dilatometry, and the modulus of rupture (MOR) by the four-point method on 5 / 16-in diameter rods. MOR values are reported in pounds per square inch (psi). Some samples are also crushed and their crystalline phases identified by powder x-ray diffractometry. Pore diameters (d10, d50 and d90) are in micro...

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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.

Description

RELATED APPLICATIONS [0001] The present invention is a continuation of U.S. patent application Ser. No. 11 / 193,123 to G. Merkel filed Jul. 28, 2005 entitled “Narrow Pore Size Distribution Aluminum Titanate Body and Method for Making Same,” which is a continuation-in-part application of U.S. patent application Ser. No. 10 / 902,381 to G. Merkel filed Jul. 29, 2004 and entitled “Mullite-Aluminum Titanate Body And Method For Making Same,” now abandoned.FIELD OF THE INVENTION [0002] The present invention relates to an aluminum titanate ceramic body that has improved properties for use in high temperature applications and a method for making the same. BACKGROUND OF THE INVENTION [0003] Porous refractory ceramics have long been used as particulate filters in hot gas or corrosive environments such as advanced coal-based gas turbine cycles, municipal and industrial waste incinerators, and diesel or natural-gas engine exhaust systems. For such applications, ceramic particulate filters must pos...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B01D46/00
CPCB01D46/2429B01D46/244B01D46/2444B01D2046/2433B01D2046/2437B01D2046/2496B01D2279/30C04B35/185C04B35/478C04B35/6263C04B35/632C04B38/0006C04B2111/00129C04B2111/00793C04B2235/3205C04B2235/3208C04B2235/3213C04B2235/3217C04B2235/3218C04B2235/322C04B2235/3222C04B2235/3224C04B2235/3225C04B2235/3227C04B2235/3229C04B2235/3231C04B2235/3232C04B2235/3236C04B2235/3244C04B2235/3251C04B2235/3256C04B2235/3258C04B2235/3284C04B2235/3286C04B2235/3293C04B2235/3298C04B2235/3409C04B2235/3418C04B2235/3454C04B2235/3463C04B2235/349C04B2235/445C04B2235/5436C04B2235/5445C04B2235/656C04B2235/6567C04B2235/77C04B2235/80C04B2235/96C04B2235/9607F01N3/022F01N2330/06F01N2330/14Y02T10/20Y10S55/05Y10S264/48Y10S55/30Y10S55/10C04B38/0074C04B38/0009C04B38/0051C04B38/0054Y02T10/12B01D46/24492B01D46/24491B01D46/2498B01D46/24494
Inventor MERKEL, GREGORY A.
Owner MERKEL GREGORY A
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