US3907949A
Expired / Lapsed
US
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Method of making tubular polycrystalline oxide body with tapered ends
Assignee: Philips North America LLC
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Filing: 1972-11-08
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Granted: 1975-09-23
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Expires: 1992-11-08
Abstract
Abstract A single piece open ended polycrystalline oxide body having a generally tubular configuration with a smaller internal diameter at its ends than the internal diameter adjacent its mid-portion. The body is produced by isostatic pressing of prepared small uniform spherical agglomerates of the oxide powder in a urethane outer mold carrying a preshaped low melting point metal mandrel. The mandrel is removed after pressing by melting and the remaining oxide body is then sintered in a hydrogen atmosphere at high temperature to produce the polycrystalline structure.
Inventors
- 👤 William G Carlson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:06
CPC Classifications
B; B29; B29C; B29C43/00; B29C43/02; B29C43/10; B28; B28B; B28B3/00; B28B3/003; B28B7/00; B28B7/34; B28B7/342; C; C04; C04B; C04B35/00; C04B35/622; C04B35/626; C04B35/63; C04B35/638; H; H01; H01J; H01J5/00; H01J5/02; H01J9/00; H01J9/24; H01J9/245; H01J9/247; B29C43/32; B29C43/36; B29C43/3642; B29C2043/3652; B29K; B29K2303/00; B29K2303/04; B29K2303/06; B29L; B29L2023/00; Y; Y10; Y10S; Y10S264/00; Y10S264/44; Y10S425/00; Y10S425/012
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
209 words
The method of making a tubular polycrystalline oxide body having tapered ends comprising the steps of; forming an aqueous slurry which principally comprises alumina, water and a fugitive binder feeding the slurry into a spray dryer to form larger uniform spherical agglomerates from the smaller oxide particles, placing the spray dried spherical agglomerates into a mold having a low melting point preshaped metal mandrel centrally thereof, said preshaped mandrel having end portions of smaller diameter than the central portion thereof and a melting point below 350*C, mechanically vibrating the mold for several minutes to uniformly fill the cavity, within said mold about said mandrel, isostatically pressing said spherical agglomerates at a predetermined pressure of about 9,000 psi, removing the pressed oxide body containing the mandrel from the mold and heating the body in a non-oxidizing atmosphere while in a near vertical orientation to thereby melt said mandrel and permit said mandrel metal to flow from said body, presintering the oxide body at a first predetermined temperature for a first predeterMined time to remove the remaining binder and partially sinter said envelope, and finally sintering the body at a second predetermined temperature in hydrogen for a second predetermined time to thereby produce a translucent polycrystalline oxide body with tapered ends.
Claim 2
Independent Claim
209 words
The method of making a tubular polycrystalline oxide body having tapered ends comprising the steps of; forming an aqueous slurry which principally comprises alumina, water and a fugitive binder feeding the slurry into a spray dryer to form larger uniform spherical agglomerates from the smaller oxide particles, placing the spray dried spherical agglomerates into a mold having a low melting point preshaped metal mandrel centrally thereof, said preshaped mandrel having end portions of smaller diameter than the central portion thereof and a melting point below 350*C, mechanically vibrating the mold for several minutes to uniformly fill the cavity, within said mold about said mandrel, isostatically pressing said spherical agglomerates at a predetermined pressure of about 9,000 psi, removing the pressed oxide body containing the mandrel from the mold and heating the body in a non-oxidizing atmosphere while in a near vertical orientation to thereby melt said mandrel and permit said mandrel metal to flow from said body, presintering the oxide body at a first predetermined temperature for a first predeterMined time to remove the remaining binder and partially sinter said envelope, and finally sintering the body at a second predetermined temperature in hydrogen for a second predetermined time to thereby produce a translucent polycrystalline oxide body with tapered ends.
Claim 3
Dependent Claim
45 words
The method of making a tubular polycrystalline oxide body according to claim 1 wherein said aqueous slurry principally comprises about 100 parts by weight of Al2O3 and 180 parts by weight of water in addition to a predetermined amount of a fugitive binder and MgO.
Claim 4
Dependent Claim
47 words
The method of making a tubular polycrystalline oxide body according to claim 1 wherein said non-oxidizing atmosphere principally comprises nitrogen and said oxide body is heated to a temperature only slightly higher than the melting point of said mandrel to remove the mandrel from within said body.
Claim 5
Dependent Claim
30 words
The method of making a tubular polycrystalline oxide body according to claim 1 wherein said first predetermined temperature is about 1,000*C and said first predetermined time is about 1 hour.
Claim 6
Dependent Claim
37 words
The method of making a tubular polycrystalline oxide body according to claim 1 wherein said second predetermined temperature is between about 1,700* to 1,800*C and said second predetermined time is from between about 2 to 24 hours.
Claim 7
Dependent Claim
45 words
The method of making a tubular polycrystalline oxide body according to claim 1 wherein said first predetermined temperature is about 1,000*C, said first predetermined time is about 1 hour, said second predetermined temperature is about 1,700*C and said second predetermined time is about 16 hours.
Claim 8
Independent Claim
146 words
THE METHOD OF MAKING A TUBULAR POLYCRYSTALLINE ALUMINA BODY HAVING END PORTIONS OF SMALLER INTERNAL AND EXTERNAL DIAMETER THAN THE MID PORTION THEREOF COMPRISING THE STEPS OF: DISPOSING A PRESHAPED MANDREL HAVING END PORTIONS OF SMALLER DIAMETER THAN THE CENTRAL PORTION AND FORMED OF A METAL HAVING A MELTING POINT BELOW 350*C, CENTRALLY OF AN OUTER MOLD FORM, FILLING SAID MOLD FROM ABOUT SAID MANDREL WITH ALUMINA PARTICLES OF PREDETERMINED SIZE, VIBRATING SAID MOLD FORM FOR SEVERAL MINUTES TO UNIFORMITY FILL THE SPACE BETWEEN THE MOLD FORM AND SAID MANDREL WITH ALUMINA PARTICLES, ISOSTACTICALLY PRESSING SAID PARTICLES AT A PREDETERMINED PRESSURE OF ABOUT 9,000 PSI REMOVING THE PRESSED ALUMINA BODY CONTAINING THE MANDREL FROM THE MOLD AND HEATING THE BODY IN A NON-OXIDIZING ATMOSPHERE WHILE IN A NEAR VERTICAL ORIENTATATION TO THEREBY MELT SAID MANDREL AND PERMIT SAID MANDREL METAL TO FLOW FROM SAID BODY, AND
Claim 9
Independent Claim
146 words
THE METHOD OF MAKING A TUBULAR POLYCRYSTALLINE ALUMINA BODY HAVING END PORTIONS OF SMALLER INTERNAL AND EXTERNAL DIAMETER THAN THE MID PORTION THEREOF COMPRISING THE STEPS OF: DISPOSING A PRESHAPED MANDREL HAVING END PORTIONS OF SMALLER DIAMETER THAN THE CENTRAL PORTION AND FORMED OF A METAL HAVING A MELTING POINT BELOW 350*C, CENTRALLY OF AN OUTER MOLD FORM, FILLING SAID MOLD FROM ABOUT SAID MANDREL WITH ALUMINA PARTICLES OF PREDETERMINED SIZE, VIBRATING SAID MOLD FORM FOR SEVERAL MINUTES TO UNIFORMITY FILL THE SPACE BETWEEN THE MOLD FORM AND SAID MANDREL WITH ALUMINA PARTICLES, ISOSTACTICALLY PRESSING SAID PARTICLES AT A PREDETERMINED PRESSURE OF ABOUT 9,000 PSI REMOVING THE PRESSED ALUMINA BODY CONTAINING THE MANDREL FROM THE MOLD AND HEATING THE BODY IN A NON-OXIDIZING ATMOSPHERE WHILE IN A NEAR VERTICAL ORIENTATATION TO THEREBY MELT SAID MANDREL AND PERMIT SAID MANDREL METAL TO FLOW FROM SAID BODY, AND
Claim 10
Dependent Claim
26 words
The method of claim 7 wherein said preshaped mandrel principally comprises a low melting point metal selected from the groups consisting of bismuth, lead and tin.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-22 | 1979-03-24 | 1979-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-22 | 1983-03-24 | 1983-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-22 | 1987-03-24 | 1987-09-23 | $7700.00 | Window Closed / Lapsed |