Patent number: 4820666
Abstract: 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 ZrO.sub.2 -Y.sub.2 O.sub.3 -CeO.sub.2 system wherein the proportion of ZrO.sub.2, Y.sub.2 O.sub.3, and CeO.sub.2 is within the range defined by the line connecting points F, G, L, M, N and K in a ternary diagram (ZrO.sub.2, YO.sub.1.5, CeO.sub.2), the vertices of said points being given by the following molar % of ZrO.sub.2, YO.sub.1.5, and CeO.sub.2, respectively:F (88, 10, 2),G (89, 10, 1),L (93.5, 4, 2.5),M (93, 2, 5),N (88, 1, 11), andK (86, 1,13),and 3 to 60 weight % of at least one of Al.sub.2 O.sub.3, MgO.Al.sub.2 O.sub.3, spinel and mullite, and(b) has a mean crystal grain size not exceeding 2 micrometers and a bending strength of at least 100 kgf/mm.sup.2, said ZrO.sub.2 containing a minimum of 50 volume % tetragonal crystal structure and a maximum of 5 volume % monoclinic crystal structure when tested in steam of 180.degree. C.
Type:
Grant
Filed:
March 21, 1986
Date of Patent:
April 11, 1989
Assignee:
Noritake Co., Limited
Inventors:
Masanori Hirano, Hiroshi Inada