Patent US4502929A successfully refreshed from Google Patents.
US4502929A
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US
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Corrosion protection method
Assignee: Tyco International Ltd Bermuda
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Filing: 1982-07-29
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Granted: 1985-03-05
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Expires: 2002-07-29
Abstract
Abstract Methods of preventing corrosion in which current flows between the to-be-protected substrate and a distributed electrode whose electrochemically active surface is provided by an element which is composed of a conductive polymer and which is at least 500 microns thick. In one embodiment, the electrode is a flexible strip comprising a highly conductive core, e.g. of copper, and a conductive polymer element surrounding the core. In another embodiment, the electrode is a conductive polymer layer which conforms to the surface of the substrate but is separated from it by a layer of insulation.
Inventors
- 👤 Ray F. Stewart
- 👤 Michael Masia
- 👤 Albert B. Macknick
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 22:05
CPC Classifications
C; C23; C23F; C23F13/00; C23F13/02; F; F16; F16L; F16L58/00
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
137 words
A method of cathodically protecting an elongate, electrically conductive substrate which is buried in soil, which method comprises establishing a potential difference between the substrate as cathode and a distributed elongate anode which is buried in the soil adjacent to the substrate and spaced apart from the substrate by soil, the anode comprising a flexible strip comprising (1) a continuous elongate flexible metal core which has a resistance at 23° C. of less than 0.03 ohm/meter; and (2) an elongate element which (i) is in electrical contact with the core; (ii) is composed of a conductive polymer having an elongation of at least 10% and a resistivity at 23° of 0.1 to 10 3 ohm.cm; (iii) provides substantially the whole of the electrochemically active surface of the flexible strip; and (iv) is at least 500 microns thick.
Claim 2
Independent Claim
137 words
A method of cathodically protecting an elongate, electrically conductive substrate which is buried in soil, which method comprises establishing a potential difference between the substrate as cathode and a distributed elongate anode which is buried in the soil adjacent to the substrate and spaced apart from the substrate by soil, the anode comprising a flexible strip comprising (1) a continuous elongate flexible metal core which has a resistance at 23° C. of less than 0.03 ohm/meter; and (2) an elongate element which (i) is in electrical contact with the core; (ii) is composed of a conductive polymer having an elongation of at least 10% and a resistivity at 23° of 0.1 to 10 3 ohm.cm; (iii) provides substantially the whole of the electrochemically active surface of the flexible strip; and (iv) is at least 500 microns thick.
Claim 3
Dependent Claim
17 words
A method according to claim 1 wherein the conductive polymer element is at least 1000 microns thick.
Claim 4
Dependent Claim
29 words
A method according to claim 1 wherein the anode has Quasi-Tafel Constant of at least 300 millivolts/decade over a current density range of 1 to 500 microamps/cm 2 .
Claim 5
Dependent Claim
17 words
A method according to claim 3 wherein the anode has a Quasi-Tafel Constant of at least 400.
Claim 6
Dependent Claim
17 words
A method according to claim 4 wherein the anode has a Quasi-Tafel Constant of at least 500.
Claim 7
Dependent Claim
18 words
A method according to claim 1 wherein the conductive polymer has a resistivity of 1 to 100 ohm.cm.
Claim 8
Dependent Claim
19 words
A method according to claim 1 wherein the conductive polymer contains carbon black or graphite as a conductive filler.
Claim 9
Dependent Claim
22 words
A method according to claim 1 wherein the conductive polymer will pass a current density of at least 10 milliamps/cm 2 .
Claim 10
Dependent Claim
41 words
A method according to claim 1 wherein the anode is in the form of a flexible strip which has a constant cross-section along its length and which consists essentially of the metallic core and the conductive polymer element surrounding the core.
Claim 11
Dependent Claim
58 words
A method according to claim 1 wherein the ratio b+D/a+D is less than 2, where b is the largest distance from the substrate to the electrode, a is the smallest distance from the substrate to the electrode, and D is the largest dimension of the substrate in a plane at right angles to the axis of the electrode.
Claim 12
Dependent Claim
17 words
A method according to claim 10 wherein the substrate is a metal pipe having a diameter D.
Claim 13
Independent Claim
141 words
A method of cathodically protecting metal reinforcing bars encased in a mass of concrete, which method comprises establishing a potential difference between the reinforcing bars as cathode and a distributed anode which lies within the mass of concrete adjacent to the reinforcing bars and spaced apart from the reinforcing bars by concrete, the anode comprising a flexible strip comprising (1) a continuous elongate flexible metal core which has a resistance at 23° C. of less than 0.03 ohm/meter; and (2) an elongate element which (i) is in electrical contact with the core; (ii) is composed of a conductive polymer having an elongation of at least 10% and a resistivity at 23° C. of 0.1 to 10 3 ohm.cm; (iii) provides substantially the whole of the electrochemically active outer surface of the flexible strip; and (iv) is at least 500 microns thick.
Claim 14
Independent Claim
141 words
A method of cathodically protecting metal reinforcing bars encased in a mass of concrete, which method comprises establishing a potential difference between the reinforcing bars as cathode and a distributed anode which lies within the mass of concrete adjacent to the reinforcing bars and spaced apart from the reinforcing bars by concrete, the anode comprising a flexible strip comprising (1) a continuous elongate flexible metal core which has a resistance at 23° C. of less than 0.03 ohm/meter; and (2) an elongate element which (i) is in electrical contact with the core; (ii) is composed of a conductive polymer having an elongation of at least 10% and a resistivity at 23° C. of 0.1 to 10 3 ohm.cm; (iii) provides substantially the whole of the electrochemically active outer surface of the flexible strip; and (iv) is at least 500 microns thick.
Claim 15
Dependent Claim
30 words
A method according to claim 12 wherein the electrode has a Quasi-Tafel Constant of at least 300 millivolts/decade over a current density range of 1 to 500 microamps/cm 2 .
Claim 16
Dependent Claim
17 words
A method according to claim 13 wherein the electrode has a Quasi-Tafel Constant of at least 400.
Claim 17
Dependent Claim
30 words
A method according to claim 12 wherein the conductive polymer has a resistivity of 1 to 100 ohm.cm and the conductive polymer contains carbon black or graphite as conductive filler.
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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) | 1988-03-04 | 1988-09-03 | 1989-03-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-03-04 | 1992-09-03 | 1993-03-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-03-04 | 1996-09-03 | 1997-03-05 | $7700.00 | Window Closed / Lapsed |