| 摘要 |
The invention consists of zirconia base with high hydrothermal stability which: (a) consists essentially of at least 40 weight % of partially stabilized zirconia of the ZrO2-Y2O3-CeO2 system wherein the proportion of ZrO2, Y2O3, and CeO2 is within the range defined by the line connecting points F, G, L, M, N and K in a ternary diagram (ZrO2, YO1.5, CeO2), the vertices of said points being given by the following molar % of ZrO2, YO1.5, and CeO2, respectively: F (88, 10, 2), G (89, 10, 1), L (93.5, 4, 2.5), M (93, 2, 5), N (88, 1, 11), and K (86, 1,13), and 3 to 60 weight % of at least one of Al2O3, MgO.Al2O3, spinel and mullite, and (b) has a mean crystal grain size not exceeding 2 micrometers and a bending strength of at least 100 kgf/mm2, said ZrO2 containing a minimum of 50 volume % tetragonal crystal structure and a maximum of 5 volume % monoclinic crystal structure when tested in steam of 180 DEG C. and 10 atm for 10 hours. The monoclinic crystal structure does not exceed 5 volume % when tested in an atmosphere of 300 DEG C. for 3000 hours. These zirconia base ceramics are stable in the presence of moisture under low temperatures of approximately 200 DEG -400 DEG C. |
