Zirconia ceramics and a method of producing the same
AssigneeNGK Insulators, Ltd.
InventorsTadashi Otagiri, Tetsuo Watanabe, Syunzo Mase
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Abstract
Zirconia ceramics consisting mainly of ZrO.sub.2 and Y.sub.2 O.sub.3 in a molar ratio of Y.sub.2 O.sub.3 /ZrO.sub.2 of 2/98.about.7/93 and consisting of crystal grains having a mixed phase consisting essentially of tetragonal phase and cubic phase or having a phase consisting essentially of tetragonal phase, the average size of the crystal grains being not larger than 2 .mu.m, has a high strength and shows little deterioration of strength due to the lapse of time, and is suitable as a solid electrolyte for oxygen concentration cells, machine parts for internal combustion engines, thermistors, cutting tools and other industrial materials.
Claims6
Zirconia ceramics consisting essentially of ZrO.sub.2 and Y.sub.2 O.sub.3 in a molar ratio of Y.sub.2 O.sub.3 /ZrO.sub.2 of 2/98.about.7/93, and consisting of crystal grains having a mixed phase consisting essentially of tetragonal phase and cubic phase or having a phase consisting essentially of tetragonal phase, the average size of said crystal grains being not larger than 2 .mu.m.
A method of producing zirconia ceramics consisting of crystal grains having a mixed phase consisting essentially of tetragonal phase and cubic phase or having a phase consisting essentially of tetragonal phase, said crystal grains having an average grain size of not larger than 2 .mu.m, wherein a mixture of zirconium oxide and an yttrium compound in a molar ratio, calculated as oxide, of Y.sub.2 O.sub.3 /ZrO.sub.2 of 2/98.about.7/93 is molded into a molded article, and the molded article is fired at a temperature within the range of 1,000.degree..about.1,550.degree. C., wherein said zirconium oxide has a crystallite size of not larger than 700 A.
A method of producing zirconia ceramics consisting of crystal grains having a mixed phase consisting essentially of tetragonal phase and cubic phase or having a phase consisting essentially of tetragonal phase, said crystal grains having an average grain size of not larger than 2 .mu.m, wherein a mixture of zirconium oxide and an yttrium compound in a molar ratio, calculated as oxides, of Y.sub.2 O.sub.3 /ZrO.sub.2 of 2/98.about.7/93 is molded into a molded article, and the molded article is fired at a temperature within the range of 1,000.degree..about.1,500.degree. C., wherein said zirconium oxide is amorphous.
Dependencies are inferred from the claim text.