Patent ID: 6905993

Claim:
A zirconia based sintered body excellent in durability, characterized in that in Y 2 O 3 -toughened zirconia based sintered body, (a) ZrO 2 contained therein is mainly composed of tetragonal ZrO 2 , and the sintered body contains Y 2 O 3 as a secondary component and further SiO 2 and Al 2 O 3 as a third component; (b) the sintered body has a molar ratio of Y 2 O 3 /ZrO 2 in the range of 1.5/98.5 to 4/96; (c) the sintered body has a SiO 2 content of 0.05 to 2.5 wt %; (d) the sintered body has a Al 2 O 3 content of 0.05 to 3.0 wt %; (e) the sintered body has an average crystal grain diameter of 0.7 μm or less; (f) SiO 2 (wt %)×average crystal grain diameter (μm) takes a value ranging from 0.03 to 0.5; (g) the sintered body contains at least one oxide of Na 2 O, K 2 O, CaO and Fe 2 O 3 as an impurity and a weight ratio of SiO 2 /(total amount of the impurity) is 5 or more; and (h) the sintered body has a bulk density of 5.70 g/cm 3 or more.