US3940509A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Semi-conducting materials and a method for the manufacture thereof
Assignee: Universal Oil Products Co
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Filing: 1973-12-19
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Granted: 1976-02-24
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Expires: 1993-12-19
Abstract
Abstract Semi-conducting materials which may be used in preparing resistors may be prepared by treating a refractory oxide with a pyrolyzable organic compound at an elevated temperature and thereafter further treating the resultant semi-conducting pyropolymeric inorganic refractory oxide composite material at an elevated temperature with subsequently controlled cooling rate to provide a material which possesses a lower resistivity and a controllable temperature coefficient of resistance over a wide range.
Inventors
- 👤 Karl J. Youtsey
- 👤 William C. Holt, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 15:41
CPC Classifications
H; H01; H01C; H01C7/00; H01C7/04; H01B; H01B1/00; H01C7/02; H01C7/022
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
128 words
A method of manufacturing a semi-conducting pyropolymeric inorganic refractory oxide material which comprises heating a refractory oxide in an oxygen-free atmosphere with a pyrolyzable organic compound at a temperature in the range of from about 400° to about 800°C. for a sufficient time to form a mono-layer of carbonaceous pyropolymer on the surface of said refractory oxide, thereafter further heating the resultant semiconducting pyropolymeric inorganic refractory oxide material in an inert atmosphere at a temperature higher than the firstmentioned temperature and in the range of from about 700° to about 1200°C. for a sufficient time to form a semi-conducting pyropolymeric inorganic refractory oxide material having a temperature coefficient of resistance in a range of from about +20,000 to about -20,000 ppm/°C., and cooling and recovering the last-named material.
Claim 2
Independent Claim
128 words
A method of manufacturing a semi-conducting pyropolymeric inorganic refractory oxide material which comprises heating a refractory oxide in an oxygen-free atmosphere with a pyrolyzable organic compound at a temperature in the range of from about 400° to about 800°C. for a sufficient time to form a mono-layer of carbonaceous pyropolymer on the surface of said refractory oxide, thereafter further heating the resultant semiconducting pyropolymeric inorganic refractory oxide material in an inert atmosphere at a temperature higher than the firstmentioned temperature and in the range of from about 700° to about 1200°C. for a sufficient time to form a semi-conducting pyropolymeric inorganic refractory oxide material having a temperature coefficient of resistance in a range of from about +20,000 to about -20,000 ppm/°C., and cooling and recovering the last-named material.
Claim 3
Dependent Claim
39 words
A method of manufacturing a semi-conducting pyropolymeric inorganic refractory oxide material as set forth in claim 1 in which said material has a temperature coefficient of resistance in a range of from about +25 to about -25 ppm/° C.
Claim 4
Dependent Claim
37 words
A method of manufacturing a semi-conducting pyropolymeric inorganic refractory oxide material as set forth in claim 1 in which said material possesses a resistivity in the range of from about 10.sup. -2 to about 10 8 ohm-centimeters.
Claim 5
Dependent Claim
34 words
A method of manufacturing a semi-conducting pyropolymeric inorganic refractory oxide material as set forth in claim 1 in which said refractory oxide is a platinum containing gamma-alumina and said pyrolyzable organic compound is cyclohexane.
Claim 6
Dependent Claim
31 words
A method of manufacturing a semi-conducting pyropolymeric inorganic refractory oxide material as set forth in claim 1 in which said refractory oxide is gamma-alumina and said pyrolyzable organic compound is benzene.
Claim 7
Dependent Claim
31 words
A method of manufacturing a semi-conducting pyropolymeric inorganic refractory oxide material as set forth in claim 1 in which said refractory oxide is gamma-alumina and said pyrolyzable organic compound is dextrose.
Claim 8
Dependent Claim
31 words
A method of manufacturing a semi-conducting pyropolymeric inorganic refractory oxide material as set forth in claim 1 in which said refractory oxide is silica-alumina and said pyrolyzable organic compound is toluene.
Claim 9
Dependent Claim
31 words
A method of manufacturing a semi-conducting pyropolymeric inorganic refractory oxide material as set forth in claim 1 in which said refractory oxide is silica-alumina and said pyrolyzable organic compound is n-pentane.
Claim 10
Dependent Claim
25 words
A method as set forth in claim 1 in which said organic compound is passed over said refractory oxide material in an oxygen-free carrier gas.
Claim 11
Dependent Claim
17 words
A method as set forth in claim 9 in which said carrier gas comprises nitrogen or hydrogen.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-02-23 | 1979-08-25 | 1980-02-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-02-23 | 1983-08-25 | 1984-02-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-02-23 | 1987-08-25 | 1988-02-24 | $7700.00 | Window Closed / Lapsed |