US3892835A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of manufacturing hot pressed ceramic material based on silicon nitride
Assignee: ZF International UK Ltd
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Filing: 1973-03-30
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Granted: 1975-07-01
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Expires: 1993-03-30
Abstract
Abstract In manufacturing a hot pressed ceramic material based on silicon nitride, the ceramic material is introduced into a die cavity defined within a graphite die. There is provided between the ceramic material and the walls of the die cavity a further material which, at the elevated temperature of the hot pressing process, forms a substantially non-porous continuous barrier layer at or near the surface of the ceramic material so that reaction between the ceramic material and the graphite die is substantially prevented.
Inventors
- 👤 Martin Richard Holdsworth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:23
CPC Classifications
C; C04; C04B; C04B33/00; C04B33/32; C04B33/326; B; B28; B28B; B28B3/00; B28B3/02; B28B3/025; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/593; C04B35/597
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
110 words
A METHOD OF MANUFACTURING HOT PRESSED CERAMIC MATERIAL BASED ON SILICON NITRIDE, COMPRISING THE STEPS OF STRATING WITH A GRAPHITE DIE DEFINING A DIE CAVITY FOR RECEIVING THE CERAMIC MATERIAL TO BE HOT PRESSED, INTRODUCING THE CERAMIC MATERIAL INTO THE DIE CAVITY, PROVIDING A COMPOUND OF ALUMINA OR A COMPOUND OF ALUMINIUM WHICH DECOMPOSES TO ALUMINA AT ELEVATED TEMPERATURES BETWEEN SAID CERAMIC MATERIAL AND THE WALLS OF THE DIE CAVITY, HEATING THE CERAMIC MATERIAL TO AN ELEVATED TEMPERATURE AND SIMULTANEOUSLY APPLYING PRESSURE TO SAID CERAMIC MATERIAL TO HOT PRESS THE MATERIAL SAID COMPOUND OF ALUMINA OR A COMPOUND OF ALUMINIUM WHICH DECOMPOSES TO ALUMINA AT ELEVATED TEMPERATURES REACTING WITH THE
Claim 2
Independent Claim
110 words
A METHOD OF MANUFACTURING HOT PRESSED CERAMIC MATERIAL BASED ON SILICON NITRIDE, COMPRISING THE STEPS OF STRATING WITH A GRAPHITE DIE DEFINING A DIE CAVITY FOR RECEIVING THE CERAMIC MATERIAL TO BE HOT PRESSED, INTRODUCING THE CERAMIC MATERIAL INTO THE DIE CAVITY, PROVIDING A COMPOUND OF ALUMINA OR A COMPOUND OF ALUMINIUM WHICH DECOMPOSES TO ALUMINA AT ELEVATED TEMPERATURES BETWEEN SAID CERAMIC MATERIAL AND THE WALLS OF THE DIE CAVITY, HEATING THE CERAMIC MATERIAL TO AN ELEVATED TEMPERATURE AND SIMULTANEOUSLY APPLYING PRESSURE TO SAID CERAMIC MATERIAL TO HOT PRESS THE MATERIAL SAID COMPOUND OF ALUMINA OR A COMPOUND OF ALUMINIUM WHICH DECOMPOSES TO ALUMINA AT ELEVATED TEMPERATURES REACTING WITH THE
Claim 3
Dependent Claim
20 words
A method as claimed in claim 1 wherein the ceramic material introduced into the die cavity includes free silicon nitride.
Claim 4
Dependent Claim
43 words
A method as claimed in claim 1 wherein the ceramic material is introduced into the die cavity as a preform and said further material is provided as a coating on the surface of the preform presented to the walls of the die cavity.
Claim 5
Dependent Claim
38 words
A method as claimed in claim 1 wherein the ceramic material is introduced into the die cavity as a powder and said further material is provided on the walls of the die cavity presented to said ceramic material.
Claim 6
Dependent Claim
24 words
A method as claimed in claim 3 wherein the walls of the die cavity presented to the preform are coated with a release agent.
Claim 7
Dependent Claim
24 words
A method as claimed in claim 4 wherein a release agent is interposed between said further material and the walls of the die cavity.
Claim 8
Dependent Claim
14 words
A method as claimed in claim 5 wherein the release agent is boron nitride.
Claim 9
Dependent Claim
14 words
A method as claimed in claim 6 wherein the release agent is boron nitride.
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) | 1978-06-30 | 1978-12-30 | 1979-07-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-30 | 1982-12-30 | 1983-07-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-30 | 1986-12-30 | 1987-07-01 | $7700.00 | Window Closed / Lapsed |