Patent ID: 7928028

Claim:
A ZrO 2 —Al 2 O 3 composite ceramic material comprising a ZrO 2 phase containing 10 to 12 mol % of CeO 2 as a stabilizer and composed of 90 vol % or more of tetragonal ZrO 2 , and an Al 2 O 3 phase, wherein an amount of said Al 2 O 3 phase in the composite ceramic material is in a range of 40 to 70 vol %, Al 2 O 3 grains each having a fine ZrO 2 grain therein are dispersed in the composite ceramic material, some of the Al 2 O 3 grains each having the fine ZrO 2 grain therein are trapped within ZrO 2 grains to form composite grains, a first dispersion ratio defined as a ratio of the number of the Al 2 O 3 grains each having the fine ZrO 2 grain therein relative to the number of the entire Al 2 O 3 grains dispersed in the composite ceramic material is 50% or more, and a second dispersion ratio defined as a ratio of the number of the Al 2 O 3 grains of said composite grains relative to the number of the entire Al 2 O 3 grains dispersed in the composite ceramic material is 0.3% or more.