Patent US3853973A successfully refreshed from Google Patents.
US3853973A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Isostatic hot-pressing process for manufacturing dense sintered articles
Assignee: US Philips Corp
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Filing: 1972-12-21
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Granted: 1974-12-10
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Expires: 1992-12-21
Abstract
Abstract A method of making highly-dense polycrystalline bodies, e.g., video recording heads by sintering in an inert gas atmosphere having a pressure greater than atmospheric, i.e., 25 to 30 kg/cm2 at the sintering temperature.
Inventors
- 👤 K Hardtl
- 👤 H Knufer
- 👤 A Stuijts
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 12:21
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/26
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
113 words
IN THE METHOD OF FORMING A POLYCRYSTALLINE BODY HAVING A DENSITY GREATER THAN 98 PERCENT OFF THE THEORETICAL DENSITY THEREOF IN WHICH PARTICULATE POLYCRYSTALLINE MATERIAL IS COMPACTED AND SINTERED TO FORM A COHERENT DENSE BODY, THE OM: PROVEMENT COMPRISING: A. INTRODUCING LATTICE DEFECTS INTO SAID PARTICULATE POLYCRYSTALLINE MATERIAL, B. COMPACTING SAID PARTICULATE POLYCRYSTALLINE MATERIAL INTO A BODY; AND C. EXPOSING SAID COMPACTED BODY DIRECTLY AND ON ALL SIDES TO AN INERT GAS AT A PRESSURE OFF FROM 25 TO 300KG/CM2 WHILE HEATING SAID BODY TO A TEMPERATURE OF ABOUT 300*C FOR A TIME SUFFICIENT TO SINTER AND INCREASE THE DENSITY OF SAID BODY TO BETWEEN 98 AND 100 PERCENT OF THE THEORETICAL DENSITY.
Claim 2
Dependent Claim
113 words
IN THE METHOD OF FORMING A POLYCRYSTALLINE BODY HAVING A DENSITY GREATER THAN 98 PERCENT OFF THE THEORETICAL DENSITY THEREOF IN WHICH PARTICULATE POLYCRYSTALLINE MATERIAL IS COMPACTED AND SINTERED TO FORM A COHERENT DENSE BODY, THE OM: PROVEMENT COMPRISING: A. INTRODUCING LATTICE DEFECTS INTO SAID PARTICULATE POLYCRYSTALLINE MATERIAL, B. COMPACTING SAID PARTICULATE POLYCRYSTALLINE MATERIAL INTO A BODY; AND C. EXPOSING SAID COMPACTED BODY DIRECTLY AND ON ALL SIDES TO AN INERT GAS AT A PRESSURE OFF FROM 25 TO 300KG/CM2 WHILE HEATING SAID BODY TO A TEMPERATURE OF ABOUT 300*C FOR A TIME SUFFICIENT TO SINTER AND INCREASE THE DENSITY OF SAID BODY TO BETWEEN 98 AND 100 PERCENT OF THE THEORETICAL DENSITY.
Claim 3
Dependent Claim
17 words
A method as claimed in claim 1, wherein the gas pressure is from 50 to 200 kg/sqcm.
Claim 4
Dependent Claim
26 words
A method as claimed in claim 1 wherein the polycrystalline body consists of a material selected from the group consisting of a ceramic material and cermet.
Claim 5
Dependent Claim
37 words
A method as claimed in claim 3, wherein the ceramic material is selected from the group consisting of ceramic materials whose crystals have the perowskite structure, ceramic materials whose crystals have the spinel structure, and ceramic ferrite.
Claim 6
Dependent Claim
31 words
A method as claimed in claim 4, wherein the ceramic material is ceramic ferrite and the gas has an oxygen content such that the oxygen content of the ferrite remains unchanged.
References Cited (Backward Citations)
US3458927A
Cited
US3383737A
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US3455682A
Cited
US3469976A
Cited
US3622313A
Cited
US3606286A
Cited
US3562371A
Cited
US3725094A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-09 | 1978-06-10 | 1978-12-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-09 | 1982-06-10 | 1982-12-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-09 | 1986-06-10 | 1986-12-10 | $7700.00 | Window Closed / Lapsed |