A ZrO 2 —Al 2 O 3 composite ceramic material is provided, which is excellent in mechanical strength and toughness, and has the capability of preventing low temperature degradation. This ceramic material includes a first phase of ZrO 2 grains having an average grain size of 0.1 to 0.8 μm, and containing 10 to 12 mol % of CeO 2 and 0.005 mol % to less than 0.5 mol % of Y 2 O 3 , and a second phase of Al 2 O 3 grains having an average grain size of 0.1 to 0.5 μm. The ZrO 2 grains is composed of 90 vol % or more of tetragonal ZrO 2 , and a content of the second phase in the composite ceramic material is in a range of 20 to 60 vol %, and preferably 30 to 50 vol %.
1. A ZrO 2 —Al 2 O 3 composite ceramic material comprising:
a first phase of ZrO 2 grains having an average grain size of 0.1 to 0.8 μm, and comprising 10 to 12 mol % of CeO 2 and 0.005 mol % to 0.17 mol % of Y 2 O 3 , said ZrO 2 grains composed of 90 vol % or more of tetragonal ZrO 2 ; and
a second phase of Al 2 O 3 grains having an average grain size of 0.1 to 0.5 μm, a content of said second phase in the composite ceramic material being in a range of 20 to 60 vol %.
2. The composite ceramic material as set forth in claim 1 , wherein a content of said second phase in the composite ceramic material is in a range of 30 to 50 vol %.
3. The composite ceramic material as set forth in claim 1 , wherein a ratio of the number of said Al 2 O 3 grains dispersed within said ZrO 2 grains relative to the number of the entire Al 2 O 3 grains dispersed in the composite ceramic material is 0.02 or more.
4. The composite ceramic material as set forth in claim 1 , wherein a ratio of the number of said ZrO 2 grains that are two or more times larger than the average grain size of said first phase relative to the number of the entire ZrO 2 grains dispersed in the composite ceramic material is 0.10 or less.
5. A ZrO 2 —Al 2 O 3 composite ceramic material as claimed in claim 1 , wherein said first phase comprises 10 to 12 mol % of CeO 2 and 0.005 mol % to 0.100 mol % of Y 2 O 3 .
6. A ZrO 2 —Al 2 O 3 composite ceramic material as claimed in claim 1 , wherein said first phase comprises 10 to 12 mol % of CeO 2 and 0.005 mol % to 0.070 mol % of Y 2 O 3 .
7. A ZrO 2 —Al 2 O3 composite ceramic material as claimed in claim 1 , wherein said first phase comprises 10 to 12 mol % of CeO 2 and 0.005 mol % to 0.030 mol % of Y 2 O 3 .
8. A ZrO 2 —Al 2 O 3 composite ceramic material as claimed in claim 1 , wherein said ZrO 2 grains are composed of more than 95 vol % of tetragonal ZrO 2 with a balance of monoclinic ZrO 2 .
9. A ZrO 2 —Al 2 O 3 composite ceramic material as claimed in claim 2 , wherein said ZrO 2 grains are composed of more than 95 vol % of tetragonal ZrO 2 with a balance of monoclinic ZrO 2 .
10. A ZrO 2 —Al 2 O 3 composite ceramic material as claimed in claim 3 , wherein said ZrO 2 grains are composed of more than 95 vol % of tetragonal ZrO 2 with a balance of monoclinic ZrO 2 .
11. A ZrO 2 —Al 2 O 3 composite ceramic material as claimed in claim 4 , wherein said ZrO 2 grains are composed of more than 95 vol % of tetragonal ZrO 2 with a balance of monoclinic ZrO 2 .
12. A ZrO 2 —Al 2 O 3 composite ceramic material as claimed in claim 5 , wherein said ZrO 2 grains are composed of more than 95 vol % of tetragonal ZrO 2 with a balance of monoclinic ZrO 2 .
13. A ZrO 2 —Al 2 O 3 composite ceramic material as claimed in claim 6 , wherein said ZrO 2 grains are composed of more than 95 vol % of tetragonal ZrO 2 with a balance of monoclinic ZrO 2 .
14. A ZrO 2 —Al 2 O 3 composite ceramic material as claimed in claim 7 , wherein said ZrO 2 grains are composed of more than 95 vol % of tetragonal ZrO 2 with a balance of monoclinic ZrO 2 .
15. A ZrO 2 —Al 2 O 3 composite ceramic material as set forth in claim 1 , wherein a content of said second phase in the composite ceramic material is in a range of 30 to 50 vol %, wherein said Al 2 O 3 grains have an average grain size of 0.26 to 0.40 μm, wherein said ZrO 2 grains are composed of more than 95 vol % of tetragonal ZrO 2 with a balance of monoclinic ZrO 2 , and wherein said ZrO 2 grains have an average grain size of 0.27 to 0.73 μm.
16. A ZrO 2 —Al 2 O 3 composite ceramic material as set forth in claim 3 , wherein a content of said second phase in the composite ceramic material is in a range of 30 to 50 vol %, wherein said Al 2 O 3 grains have an average grain size of 0.26 to 0.40 μm, wherein said ZrO 2 grains are composed of more than 95 vol % of tetragonal ZrO 2 with a balance of monoclinic ZrO 2 , and wherein said ZrO 2 grains have an average grain size of 0.27 to 0.73 μm.
17. A ZrO 2 —Al 2 O 3 composite ceramic material as set forth in claim 4 , wherein a content of said second phase in the composite ceramic material is in a range of 30 to 50 vol %, wherein said Al 2 O 3 grains have an average grain size of 0.26 to 0.40 μm, wherein said ZrO 2 grains are composed of more than 95 vol % of tetragonal ZrO 2 with a balance of monoclinic ZrO 2 , and wherein said ZrO 2 grains have an average grain size of 0.27 to 0.73 μm.
18. A ZrO 2 —Al 2 O 3 composite ceramic material as set forth in claim 5 , wherein a content of said second phase in the composite ceramic material is in a range of 30 to 50 vol %, wherein said Al 2 O 3 grains have an average grain size of 0.26 to 0.40 μm, wherein said ZrO 2 grains are composed of more than 95 vol % of tetragonal ZrO 2 with a balance of monoclinic ZrO 2 , and wherein said ZrO 2 grains have an average grain size of 0.27 to 0.73 μm.
19. A ZrO 2 —Al 2 O 3 composite ceramic material as set forth in claim 6 , wherein a content of said second phase in the composite ceramic material is in a range of 30 to 50 vol %, wherein said Al 2 O 3 grains have an average grain size of 0.26 to 0.40 μm, wherein said ZrO 2 grains are composed of more than 95 vol % of tetragonal ZrO 2 with a balance of monoclinic ZrO 2 , and wherein said ZrO 2 grains have an average grain size of 0.27 to 0.73 μm.
20. A ZrO 2 —Al 2 O3 composite ceramic material as set forth in claim 7 , wherein a content of said second phase in the composite ceramic material is in a range of 30 to 50 vol %, wherein said Al 2 O 3 grains have an average grain size of 0.26 to 0.40 μm, wherein said ZrO 2 grains are composed of more than 95 vol % of tetragonal ZrO 2 with a balance of monoclinic ZrO 2 , and wherein said ZrO 2 grains have an average grain size of 0.27 to 0.73 μm.