US4886768A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Toughened ceramics
Assignee: BOARD OF REGENTS ACTING FOR AND ON BEHALF OF UNIVERSITY OF MICHIGAN A CORP OF MI
•
Filing: 1987-11-13
•
Granted: 1989-12-12
•
Expires: 2007-11-13
Abstract
Abstract Novel partially stabilized zirconia ceramic compositions exhibiting improved toughness comprising: a major component consisting of ZrO2, a minor stabilizing component Y2O3 and an effective amount of a toughening agent (e.g., Ta2O5). The toughness of the tetragonal zirconia polycrystal (e.g., 96% ZrO2, 3 mole % Y2O3) can be increased nearly three-fold by replacing 1% of the ZrO2 with Ta2O5. Empirical equations based on ratios of fundamental lattice parameters (e.g. c/a) quantitatively relating to the stability/instability of tetragonal zirconia oxide are disclosed and used in a novel method for improving the toughness of the ceramic compositions.
Inventors
- 👤 Tseng-Ying Tien
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 21:15
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/48; C04B35/486
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
87 words
A ceramic composition consisting essentially of: a major component consisting of ZrO 2 present at about 93 to 97.5 mole precent, a minor stabilizing component selected from the group consisting of Y 2 O 3 , MgO, Sc 2 O 3 , IN 2 O 3 and rare earth oxides present at about 2 to about 4 mole percent; and a toughening agent selected from the group consisting of Ta 2 O 5 and Nb 2 O 5 present at about 0.5 to about 3 mole percent.
Claim 2
Dependent Claim
87 words
A ceramic composition consisting essentially of: a major component consisting of ZrO 2 present at about 93 to 97.5 mole precent, a minor stabilizing component selected from the group consisting of Y 2 O 3 , MgO, Sc 2 O 3 , IN 2 O 3 and rare earth oxides present at about 2 to about 4 mole percent; and a toughening agent selected from the group consisting of Ta 2 O 5 and Nb 2 O 5 present at about 0.5 to about 3 mole percent.
Claim 3
Dependent Claim
16 words
A ceramic composition of claim 1 wherein the stabilizing component is Y 2 O 3 .
Claim 4
Dependent Claim
16 words
A ceramic composition of claim 1 wherein the toughening agent is Ta 2 O 5 .
Claim 5
Dependent Claim
16 words
A ceramic composition of claim 2 wherein the toughening agent is Ta 2 O 5 .
Claim 6
Dependent Claim
53 words
A ceramic composition consisting essentially of ZrO 2 , Y 2 O 3 and Ta 2 O 5 wherein for every mole of ZrO 2 there is present from about 0.01 to about 0.04 moles of Y 2 O 3 and from about 0.005 to 3 moles of Ta 2 O 5 .
Claim 7
Dependent Claim
53 words
A ceramic composition consisting essentially of ZrO 2 , Y 2 O 3 and Ta 2 O 5 wherein for every mole of ZrO 2 there is present from about 0.01 to about 0.04 moles of Y 2 O 3 and from about 0.005 to 3 moles of Ta 2 O 5 .
Claim 8
Dependent Claim
46 words
A ceramic composition of claim 5 wherein the Y 2 O 3 is present at about 0.03 moles for every mole of ZrO 2 and the Ta 2 O 5 is present at about 0.01 to about 0.015 moles for every mole of ZrO 2 .
Claim 9
Dependent Claim
113 words
In a method for preparing a partially stabilized zirconia wherein a major component of ZrO 2 present at about 93 to 97.5 mole percent is stabilized by adding a minor component of a stabilizing agent selected from the group consisting of Y 2 O 3 , MgO, Sc 2 O 3 , In 2 O 3 and rare earth oxides present at about 2 to 4 mole percent, to form a mixture and sintering said mixture, the improvement comprising the steps of adding about 0.5 to about 3 mole percent of a toughening agent selected from the group consisting of Ta 2 O 5 , Nb 2 O 5 and HfO 2 .
Claim 10
Dependent Claim
113 words
In a method for preparing a partially stabilized zirconia wherein a major component of ZrO 2 present at about 93 to 97.5 mole percent is stabilized by adding a minor component of a stabilizing agent selected from the group consisting of Y 2 O 3 , MgO, Sc 2 O 3 , In 2 O 3 and rare earth oxides present at about 2 to 4 mole percent, to form a mixture and sintering said mixture, the improvement comprising the steps of adding about 0.5 to about 3 mole percent of a toughening agent selected from the group consisting of Ta 2 O 5 , Nb 2 O 5 and HfO 2 .
Claim 11
Dependent Claim
25 words
The improved method of claim 7 wherein the stabilizing agent is Y 2 O 3 and the toughening agent is Ta 2 O 5 .
Claim 12
Independent Claim
41 words
A method of improving the ease of transformability of the t→m phase in stabilizing t-ZrO 2 polycrystal comprising the step of adding an amount of a transition metal oxide sufficient to cause the ratio of the lattice parameters c/a to increase.
Claim 13
Independent Claim
41 words
A method of improving the ease of transformability of the t→m phase in stabilizing t-ZrO 2 polycrystal comprising the step of adding an amount of a transition metal oxide sufficient to cause the ratio of the lattice parameters c/a to increase.
References Cited (Backward Citations)
US3634113A
Cited
SU525642A1
Cited
US4598053A
Cited
US4053321A
Cited
US4421861A
Cited
US4406699A
Cited
US4507394A
Cited
JPS59152266A
Cited
US4520114A
Cited
US4621936A
Cited
US4533647A
Cited
US4627892A
Cited
EP0199459A2
Cited
JPS61242954A
Cited
JPS61242955A
Cited
JPH06246959A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-12-11 | 1993-06-12 | 1993-12-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-12-11 | 1997-06-12 | 1997-12-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-12-11 | 2001-06-12 | 2001-12-12 | $7700.00 | Window Closed / Lapsed |