US4820666A — Zirconia base ceramics

Claim 1

Independent Claim 192 words

Zirconia base ceramics which: (a) consist essentially of at least 40 weight % of paritally stabilized zirconia of the ZrO 2 -Y 2 O 3 -CeO 2 system wherein the proportion of ZrO 2 , Y 2 O 3 and CeO 2 is within the range defined by the line connecting points F, G, L, M, N, and K in a ternary diagram (ZrO 2 , YO 1 .5, CeO 2 ), the vertices of said points being given by the following molar % of ZrO 2 , YO 1 .5 and CeO 2 , 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 Al 2 O 3 , and (b) has a mean crystal grain size not exceeding 2 micrometers and a bending strength of at least 100 kgf/mm 2 , said ZrO 2 containing a minimum of 50 vol % tetragonal crystal structure and a maximum of 5 vol % monoclinic crystal structure when tested in steam of 180° C. and 10 atm for 10 hours.

Claim 2

Dependent Claim 192 words

Zirconia base ceramics which: (a) consist essentially of at least 40 weight % of paritally stabilized zirconia of the ZrO 2 -Y 2 O 3 -CeO 2 system wherein the proportion of ZrO 2 , Y 2 O 3 and CeO 2 is within the range defined by the line connecting points F, G, L, M, N, and K in a ternary diagram (ZrO 2 , YO 1 .5, CeO 2 ), the vertices of said points being given by the following molar % of ZrO 2 , YO 1 .5 and CeO 2 , 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 Al 2 O 3 , and (b) has a mean crystal grain size not exceeding 2 micrometers and a bending strength of at least 100 kgf/mm 2 , said ZrO 2 containing a minimum of 50 vol % tetragonal crystal structure and a maximum of 5 vol % monoclinic crystal structure when tested in steam of 180° C. and 10 atm for 10 hours.

Claim 3

Dependent Claim 32 words

Zirconia base ceramics as defined in claim 1, which has quantity of said monoclinic crystal structure not exceeding 5 vol % when tested in an atmosphere of 300° C. for 3000 hours.

Claim 4

Dependent Claim 22 words

Zirconia base ceramics as defined in claim 1, wherein the amount of Al 2 O 3 is 5 to 50 weight %.

Claim 5

Dependent Claim 22 words

Zirconia base ceramics as defined in claim 3, wherein the amount of Al 2 O 3 is 15 to 35 weight %.

Claim 6

Dependent Claim 192 words

Zirconia base ceramics which: (a) consists essentially of at least 40 weight % of partially stabilized zirconia of the ZrO 2 -Y 2 O 3 -CeO 2 system wherein the proportion of ZrO 2 , Y 2 O 3 and CeO 2 is within the range defined by the line connecting points F, G, L, M, N and K in a ternary diagram (ZrO 2 , YO 1 .5, CeO 2 ), the vertices of said points being given by the following molar % of ZrO 2 , YO 1 .5 and CeO 2 , 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 MgO.Al 2 O 3 spinel, and (b) has a means crystal grain size not exceeding 2 micromenters and a bending strength of a least 100 kgf/mm 2 , said ZrO 2 containing a minimum of 50 vol % tetragonal crystal structure and a maximum of 5 vol % monoclinic crystal structure when tested in steam of 180° C. and 10 atm for 10 hours.

Claim 7

Dependent Claim 192 words

Zirconia base ceramics which: (a) consists essentially of at least 40 weight % of partially stabilized zirconia of the ZrO 2 -Y 2 O 3 -CeO 2 system wherein the proportion of ZrO 2 , Y 2 O 3 and CeO 2 is within the range defined by the line connecting points F, G, L, M, N and K in a ternary diagram (ZrO 2 , YO 1 .5, CeO 2 ), the vertices of said points being given by the following molar % of ZrO 2 , YO 1 .5 and CeO 2 , 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 MgO.Al 2 O 3 spinel, and (b) has a means crystal grain size not exceeding 2 micromenters and a bending strength of a least 100 kgf/mm 2 , said ZrO 2 containing a minimum of 50 vol % tetragonal crystal structure and a maximum of 5 vol % monoclinic crystal structure when tested in steam of 180° C. and 10 atm for 10 hours.

Claim 8

Dependent Claim 33 words

Zirconia base ceramics as defined in claim 5, which have a quantity of said monoclinic crystal structure not exceeding 5 vol % when tested in an atmosphere of 300° C. for 3000 hours.

Claim 9

Dependent Claim 31 words

Zirconia base ceramics as defined in claim 10, which have a quantity of said monoclinic crystal structure not exceeding 30 vol % when tested in a sulfuric solution for 100 hours.

Claim 10

Dependent Claim 23 words

Zirconia base ceramics as defined in claim 5, wherein the amount of MgO.Al 2 O 3 spinel is 5 to 50 weight %.

Claim 11

Dependent Claim 23 words

Zirconia base ceramics as defined in claim 8, wherein the amount of MgO.Al 2 O 3 spinel is 15 to 35 weight %.

Claim 12

Dependent Claim 26 words

Zirconia base ceramics as defined in claim 5, wherein a part of the MgO.Al 2 O 3 spinel is replaced by Al 2 O 3 .

Claim 13

Dependent Claim 188 words

Zirconia base ceramics which: (a) consists essentially of at least 40 weight % of patially stabilized zirconia of the ZrO 2 -Y 2 O 3 -CeO 2 system wherein the proportion of ZrO 2 , Y 2 O 3 and CeO 2 is within the range defined by the line connecting points F, G, L, M, N and K in a ternary diagram (ZrO 2 , YO 1 .5, CeO 2 ), the vertices of said points being given by the following molar % of ZrO 2 , YO 1 .5 and CeO 2 , 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 mullite, and (b) has a mean crystal grain size not exceeding 2 micrometers and a bending strength of at least 100 kgf/mm 2 , said ZrO 2 containing a minimum of 50 vol % tetragonal crystal structure and a maximum of 5 vol % monoclinic crystal structure when tested in steam of 180° C. and 10 atm for 10 hours.

Claim 14

Dependent Claim 188 words

Zirconia base ceramics which: (a) consists essentially of at least 40 weight % of patially stabilized zirconia of the ZrO 2 -Y 2 O 3 -CeO 2 system wherein the proportion of ZrO 2 , Y 2 O 3 and CeO 2 is within the range defined by the line connecting points F, G, L, M, N and K in a ternary diagram (ZrO 2 , YO 1 .5, CeO 2 ), the vertices of said points being given by the following molar % of ZrO 2 , YO 1 .5 and CeO 2 , 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 mullite, and (b) has a mean crystal grain size not exceeding 2 micrometers and a bending strength of at least 100 kgf/mm 2 , said ZrO 2 containing a minimum of 50 vol % tetragonal crystal structure and a maximum of 5 vol % monoclinic crystal structure when tested in steam of 180° C. and 10 atm for 10 hours.

Claim 15

Dependent Claim 33 words

Zirconia base ceramics as defined in claim 11, which have a quantity of said monoclinic crystal structure not exceeding 5 vol % when tested in an atmosphere of 300° C. for 3000 hours.

Claim 16

Dependent Claim 19 words

Zirconia base ceramics as defined in claim 11, wherein the amount of mullite is 5 to 50 weight %.

Claim 17

Dependent Claim 19 words

Zirconia base ceramics as defined in claim 13, wherein the amount of mullite is 15 to 35 weight %.

Claim 18

Dependent Claim 22 words

Zirconia base ceramics as defined in claim 11, wherein the bending strength at 500° C. is at least 50 kgf/mm 2 .

Claim 19

Dependent Claim 34 words

Zirconia base ceramics as defined in claim 11, wherein the mullite amount is at least 10 weight % and the coefficient of the linear thermal expansion is 1×10 -5 ° C. -1 or less.

Claim 20

Dependent Claim 22 words

Zirconia base ceramics as defined in claim 11, wherein a part of the mullite is replaced by Al 2 O 3 .

Claim 21

Dependent Claim 212 words

Zirconia base ceramics which: (a) consists essentially of at least 40 weight % of partially stabilized zirconia of the ZrO 2 -Y 2 O 3 -CeO 2 system wherein the proportion of ZrO 2 , Y 2 O 3 and CeO 2 is within the range defined by the line connecting points F, G, L, M, N and K in a ternary diagram (ZrO 2 , YO 1 .5, CeO 2 ), the vertices of said points being given by the following molar % of ZrO 2 , YO 1 .5, and CeO 2 , 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 5 to 60 weight % of the sum of MgO.Al 2 O 3 spinel and mullite, provided that any one of the spinel and mullite is 3 weight % or more, and (b) has a mean crystal grain size not exceeding 2 micrometers and a bending strength of at least 100 kgf/mm 2 , said ZrO 2 containing a minimum of 50 vol % tetragnal crystal structure and a maximum of 5 vol % monoclinic crystal structure when tested in steam of 180° C. and 10 atm for 10 hours.

Claim 22

Dependent Claim 212 words

Zirconia base ceramics which: (a) consists essentially of at least 40 weight % of partially stabilized zirconia of the ZrO 2 -Y 2 O 3 -CeO 2 system wherein the proportion of ZrO 2 , Y 2 O 3 and CeO 2 is within the range defined by the line connecting points F, G, L, M, N and K in a ternary diagram (ZrO 2 , YO 1 .5, CeO 2 ), the vertices of said points being given by the following molar % of ZrO 2 , YO 1 .5, and CeO 2 , 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 5 to 60 weight % of the sum of MgO.Al 2 O 3 spinel and mullite, provided that any one of the spinel and mullite is 3 weight % or more, and (b) has a mean crystal grain size not exceeding 2 micrometers and a bending strength of at least 100 kgf/mm 2 , said ZrO 2 containing a minimum of 50 vol % tetragnal crystal structure and a maximum of 5 vol % monoclinic crystal structure when tested in steam of 180° C. and 10 atm for 10 hours.

Claim 23

Dependent Claim 33 words

Zirconia base ceramics as defined in claim 18, which have a quantity of said monoclinic crystal structure not exceeding 5 vol % when tested in an atmosphere of 300° C. for 3000 hours.

Claim 24

Dependent Claim 26 words

Zirconia base ceramics as defined in claim 18, wherein the sum of the MgO.Al 2 O 3 spinel and mullite is 50 weight % or less.

Claim 25

Dependent Claim 26 words

Zirconia base ceramics as defined in claim 20, wherein the sum of the MgO.Al 2 O 3 spinel and mullite is 15 to 35 weight %

Claim 26

Dependent Claim 19 words

Zirconia base ceramics as defined in claim 16, wherein the amount of mullite is at least 10 weight %.

Claim 27

Dependent Claim 22 words

Zironia base ceramics as defined in claim 20, wherein the bending strength at 500° C. is at least 60 kgf/mm 2 .

Claim 28

Dependent Claim 28 words

Zirconia base ceramics as defined in claim 20, wherein the coefficient of linear thermal expansion between 25° and 1000° C. is 1×10 -5 ° C. -1 or less.

Claim 29

Dependent Claim 24 words

Zirconia base ceramics as defined in claim 18, wherein the amount of the MgO.Al 2 O 3 spinel is at least 10 weight %.

Claim 30

Dependent Claim 24 words

Zirconia base ceramics according to claims 1, 5, or 18, wherein ZrO 2 does not exceed 92% in the ternary diagram of FIG. 1.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1992-04-10	1992-10-10	1993-04-11	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1996-04-10	1996-10-10	1997-04-11	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2000-04-10	2000-10-10	2001-04-11	$7700.00	Window Closed / Lapsed

Zirconia base ceramics

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