US3706583A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermal shock resistant hafnia ceramic material
Assignee: National Aeronautics and Space Administration
•
Filing: 1971-10-14
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Granted: 1972-12-19
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Expires: 1991-10-14
Abstract
Abstract Ceramic hafnia artefacts having high thermal shock resistance are provided by incorporating tungsten or molybdenum particles in a yttria-, magnesia-, or calcia-stabilized hafnia matrix. The mix is sintered by hot pressing to form the ceramic article which has a high fracture strength relative to its elastic modulus and thus has an improved thermal shock resistance. The hafnia is preferably stabilized to about 50 percent and the tungsten or molybdenum particles are preferably elongate, having a length/thickness ratio of at least 2/1. Tungsten or molybdenum wire pieces are suitable.
Inventors
- 👤 Lynn D Lineback
- 👤 Charles R Manning
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 09:15
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/71; C04B35/74; C04B35/76; C04B35/01; C04B35/46; C04B35/48; C04B35/50; Y; Y10; Y10S; Y10S264/00; Y10S264/36
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
24 words
A ceramic artefact according to claim 1 wherein the metal is tungsten and the amount of tungsten is from 5 to 24 weight percent.
Claim 2
Dependent Claim
24 words
A ceramic artefact according to claim 1 wherein the metal is tungsten and the amount of tungsten is from 10 to 20 weight percent.
Claim 3
Dependent Claim
23 words
A ceramic artefact according to claim 1 wherein the hafnia is stabilized to a value of from about 40 percent to 100 percent.
Claim 4
Dependent Claim
24 words
A ceramic artefact according to claim 4 wherein the hafnia is stabilized to a value of from about 40 percent to about 60 percent.
Claim 5
Dependent Claim
19 words
A ceramic artefact according to Claim 5 wherein the hafnia is stabilized to a value of about 50 percent.
Claim 6
Dependent Claim
16 words
A ceramic artefact according to claim 1 having a theoretical density of at least 70 percent.
Claim 7
Dependent Claim
31 words
A ceramic artefact according to claim 1 wherein said metal particles are elongate pieces having a thickness of up to about 0.05 inches and a length/thickness ratio of at least 2/1.
Claim 8
Dependent Claim
26 words
A ceramic artefact according to claim 8 wherein the metal is tungsten and said pieces are wire pieces having a diameter/length ratio of at least 5/1.
Claim 9
Dependent Claim
16 words
A ceramic artefact according to claim 1 having a density at least 70 percent of theoretical.
Claim 10
Dependent Claim
66 words
A ceramic artefact according to claim 1 wherein: the hafnia is stabilized to a value of from about 40 to 60 percent; said artefact has a theoretical density of at least 70 percent; said particles are elongate tungsten wire pieces having a length/diameter ratio of at least 5/1; and tungsten is present in an amount of from about 3 percent to about 12 percent by weight.
Claim 11
Independent Claim
77 words
A method of making a ceramic article having high resistance to thermal shock comprising the steps of providing a mixture of particles of yttria- magnesia- or calcia-stabilized hafnia and from 2 to o 30 percent by weight of tungsten of a metal selected from the group consisting of tungsten and molybdenum, and hot pressing the mixture at a sintering temperature and at a pressure sufficient to produce an article of at least 70 percent of theoretical density.
Claim 12
Dependent Claim
19 words
A method according to claim 12 wherein the mixture is hot pressed at a temperature of at least 1,800*C.
Claim 13
Dependent Claim
20 words
A method according to claim 13 wherein the mixture is hot pressed at a pressure of at least 2,000 psi.
Claim 14
Dependent Claim
19 words
A method according to claim 12 wherein the hafnia particles have a particle size of less than 100 mesh.
Claim 15
Dependent Claim
22 words
A method according to claim 15 wherein the hafnia is stabilized to a value of from about 40 percent to 100 percent.
Claim 16
Dependent Claim
35 words
A method according to claim 15 wherein the metal is tungsten and said tungsten particles are elongate pieces having a thickness of up to about 0.05 inches and a length/thickness ratio of at least 2/1.
Claim 17
Dependent Claim
20 words
A method according to claim 17 wherein said pieces are wire pieces having a length/diameter ratio of at least 5/1.
References Cited (Backward Citations)
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US3526485A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-12-19 | 1976-06-19 | 1976-12-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-19 | 1980-06-19 | 1980-12-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-19 | 1984-06-19 | 1984-12-19 | $7700.00 | Window Closed / Lapsed |