Stevens, Davis, Miller & Mosher
Zirconia ceramics and a method of producing the same
 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. 
NGK Insulators, Ltd.
Y F Y C H G F
Y02P F05C Y02E C04B H01M G01N F02F
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Tadashi Tetsuo Syunzo
Otagiri Watanabe Mase