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High temperature tolerant ceramic composites having porous interphases

United States Patent

May 3, 2005
View the Complete Patent at the US Patent & Trademark Office
In general, this invention relates to a ceramic composite exhibiting enhanced toughness and decreased brittleness, and to a process of preparing the ceramic composite. The ceramic composite comprises a first matrix that includes a first ceramic material, preferably selected from the group including alumina (Al.sub.2 O.sub.3), mullite (3Al.sub.2 O.sub.3.2SiO.sub.2), yttrium aluminate garnet (YAG), yttria stabilized zirconia (YSZ), celsian (BaAl.sub.2 Si.sub.2 O.sub.8) and nickel aluminate (NiAl.sub.2 O.sub.4). The ceramic composite also includes a porous interphase region that includes a substantially non-sinterable material. The non-sinterable material can be selected to include, for example, alumina platelets. The platelets lie in random 3-D orientation and provide a debonding mechanism, which is independent of temperature in chemically compatible matrices. The non-sinterable material induces constrained sintering of a ceramic powder resulting in permanent porosity in the interphase region. For high temperature properties, addition of a sinterable ceramic powder to the non-sinterable material provides sufficiently weak debonding interphases. The ceramic composite can be provided in a variety of forms including a laminate, a fibrous monolith, and a fiber-reinforced ceramic matrix. In the laminated systems, intimate mixing of strong versus tough microstructures were tailored by alternating various matrix-to-interphase thickness ratios to provide the bimodal laminate.
Kriven; Waltraud M. (Champaign, IL), Lee; Sang-Jin (Chonnam, KR)
The Board of Trustees of the University (Urbana, IL)
10/ 145,845
May 14, 2002
GOVERNMENT RIGHTS The U.S. Government has paid-up rights in this invention and the right in limited circumstances to require the Patent Owner to license others on reasonable terms as provided by the terms of Contract No. ANL-981932401 awarded by the Department of Energy.