Ceramic body of zirconium dioxide (ZrO.sub.2) and method for its preparation
First Claim
1. In a ceramic body of zirconium dioxide or zirconium dioxide containing aluminum oxide, the improvement comprising said ceramic bodybeing partially stabilized with 0.5 to 5 mole-% of yttrium oxide, 5 to 15 mole-% magnesium oxide, calcium oxide, 5 to 15 mole-% cerium oxide, 5 to 15 mole-% of one or more rare earth dioxides or 5 to 15 mole-% of a combination thereof;
- being 30 to 100% in the tetragonal lattice modification; and
having, in the surface region, a content of yttrium oxide, cerium dioxide, magnesium oxide, calcium oxide or rare earth oxide that is 2 to 20 mole-% higher than the average content in said ceramic body, such that the body is covered with a thin layer of a more highly stabilized tetragonal lattice form or one predominantly in the cubic lattice form.
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Abstract
A ceramic body of zirconium dioxide containing, if desired, aluminum oxide,nd partially stabilized with yttrium oxide and/or one or more rare earth oxides (e.g., cerium dioxide) and/or magnesium oxide and/or calcium oxide is partially stabilized with 0.5 to 5 mole-% of yttrium oxide and/or 5 to 12 mole-% of magnesium oxide and/or calcium oxide and/or cerium dioxide or one or more rare earth oxides, is 30 to 100% in the tetragonal lattice modification and has in the surface region a content of yttrium oxide, cerium dioxide, magnesium oxide, calcium oxide or rare earth oxide that is 1 to 20 mole-% higher than the average content, such that the body is coated with a thin, PSZ-like layer in a more highly stabilized tetragonal or with a layer that is predominantly in the cubic lattice form. For preparation, the surface of an already sintered or only presolidified compact of partially stabilized zirconium oxide is brought into intimate contact with yttrium oxide, cerium dioxide, magnesium oxide, calcium oxide and/or another rare earth powder or a zirconium dioxide powder containing at least 12 mole-% of yttrium oxide and/or other stabilizer oxides, and then annealed at 1000° to 1600° C. until a more highly stabilized tetragonal or predominantly cubic surface layer of 0.1 to 200 micrometers thickness and 2 to 20 mole-% higher content of yttrium oxide, cerium dioxide, magnesium oxide, calcium oxide or rare earth oxide has formed.
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Citations
13 Claims
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1. In a ceramic body of zirconium dioxide or zirconium dioxide containing aluminum oxide, the improvement comprising said ceramic body
being partially stabilized with 0.5 to 5 mole-% of yttrium oxide, 5 to 15 mole-% magnesium oxide, calcium oxide, 5 to 15 mole-% cerium oxide, 5 to 15 mole-% of one or more rare earth dioxides or 5 to 15 mole-% of a combination thereof; -
being 30 to 100% in the tetragonal lattice modification; and having, in the surface region, a content of yttrium oxide, cerium dioxide, magnesium oxide, calcium oxide or rare earth oxide that is 2 to 20 mole-% higher than the average content in said ceramic body, such that the body is covered with a thin layer of a more highly stabilized tetragonal lattice form or one predominantly in the cubic lattice form. - View Dependent Claims (2)
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3. A method for the preparation of a ceramic body which is partially stabilized with 0.5 to 5 mole-% of yttrium oxide, 5 to 15 mole-% of magnesium oxide, calcium oxide and/or cerium oxide or one or more rare earth dioxides;
- is 30 to 100% in the tetragonal lattice modification; and
has in the surface region a content of yttrium oxide, cerium dioxide, magnesium oxide, calcium oxide or rare earth oxide that is 2 to 20 mole-% higher than the average content, such that the body is covered with a thin layer of a more highly stabilized tetragonal lattice form of one predominantly in the cubic lattice form, comprising the steps ofplacing the surface of an already sintered or only presolidified compact of partially stabilized zirconium dioxide in intimate contact with yttrium oxide, cerium dioxide, magnesium oxide, calcium oxide and/or other rare earth powder, or a zirconium dioxide powder containing at least 12 mole-% yttrium oxide and/or other stabilizer oxides, and then annealing said sintered or presolidified compact at 1000°
to 1600°
C., to form a more highly stabilized tetragonal or mainly cubic surface layer of 0.1 to 200 micrometers thickness having a 2 to 20 mole-% higher content of yttrium oxide, cerium dioxide, magnesium oxide, calcium oxide or rare earth oxide than the average content in the ceramic body. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
- is 30 to 100% in the tetragonal lattice modification; and
Specification