EP0067679A1
Expired / Lapsed
EP
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Corrosion protection system
Assignee: Raychem Corp
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Filing: 1982-06-11
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Granted: —
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Expires: 2002-06-11
Abstract
Abstract Methods of preventing corrosion in which current flows between the to-be-protected substrate and a distributed electrode whose electrochemically active surface 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, eg. 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
- 👤 Brian A. Macknick
- 👤 Ray F. Stewart
- 👤 Michael Masia
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 08:44
CPC Classifications
F; F16; F16L; F16L58/00; C; C23; C23F; C23F13/00; C23F13/02
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
65 words
A method of protecting an elongate, electrically conductive substrate from corrosion, which method comprises establishing a potential difference between the substrate and a spaced-apart electrode, characterised in that the electrode is a distributed electrode whose electrochemically active outer surface is provided by an element which is composed of a conductive polymer and which is at least 500 microns thick, preferably at least 1000 microns thick.
Claim 2
Independent Claim
65 words
A method of protecting an elongate, electrically conductive substrate from corrosion, which method comprises establishing a potential difference between the substrate and a spaced-apart electrode, characterised in that the electrode is a distributed electrode whose electrochemically active outer surface is provided by an element which is composed of a conductive polymer and which is at least 500 microns thick, preferably at least 1000 microns thick.
Claim 3
Dependent Claim
39 words
A method according to Claim 1 characterised in that the electrode has Quasi-Tafel Constant of at least 300, preferably at least 400, particularly at least 500, millivolts/decade over a current density range of 1 to 500 microamps/cm 2 .
Claim 4
Dependent Claim
36 words
A method according to Claim 1-or 2 characterised in that the conductive polymer has a resistivity at 23°C of 0.1 to 10 3 ohms.cm, preferably 1 to 100 ohm.cm, and an elongation of at least 10%.
Claim 5
Dependent Claim
21 words
A method according to Claim 3 characterised in that the conductive filler in the conductive polymer is carbon black or graphite.
Claim 6
Independent Claim
36 words
A method according to any one of the preceding claims characterised in that the electrode is in the form of a flexible strip which comprises a metallic core and a conductive polymer element surrounding the core.
Claim 7
Independent Claim
36 words
A method according to any one of claims 1 to 4 characterised in that the electrode is in the form of a layer of conductive polymer which is secured to an insulating layer on the substrate.
Claim 8
Dependent Claim
25 words
A method according to Claim 6 characterised in that the conductive polymer has been recovered against the substrate, preferably by heating a cross-linked heat-recoverable article.
Claim 9
Dependent Claim
129 words
A flexible electrode suitable for use in an impressed current corrosion protection system, characterised by comprising (1) a continuous, elongate flexible core which is composed of a material having a resistivity at 23°C of less than 5 x 10 -4 ohm.cm, preferably less tahn 3 x 10 -5 ohm.cm, and which has a resistance at 23°C of less than 0.03 ohm/meter, preferably less than 0.003 ohm/meter; and preferably having a resistivity at 23°C of 0.1 to 10 3 ohm.cm. (2) an element which (i) is in electrical contact with the core; (ii) is composed of a conductive polymer having an elongation of at least 10%; (iii) provides substantially the whole of the electrochemically active outer surface of the electrode; and (iv) has a thickness of at least 500 microns.
Claim 10
Dependent Claim
129 words
A flexible electrode suitable for use in an impressed current corrosion protection system, characterised by comprising (1) a continuous, elongate flexible core which is composed of a material having a resistivity at 23°C of less than 5 x 10 -4 ohm.cm, preferably less tahn 3 x 10 -5 ohm.cm, and which has a resistance at 23°C of less than 0.03 ohm/meter, preferably less than 0.003 ohm/meter; and preferably having a resistivity at 23°C of 0.1 to 10 3 ohm.cm. (2) an element which (i) is in electrical contact with the core; (ii) is composed of a conductive polymer having an elongation of at least 10%; (iii) provides substantially the whole of the electrochemically active outer surface of the electrode; and (iv) has a thickness of at least 500 microns.
Claim 11
Dependent Claim
38 words
An electrode according to Claim 13 characterised by having a Quasi-Tafel Constant of at least 300, preferably at least 400, particularly at least 500, millivolts/ decade over a current density range of 1 to 500 microamps/cm 2 .
Claim 12
Dependent Claim
39 words
An electrode according to Claim 8 or 9 characterised by comprising an insulating shield which is permeable to electrolytes and which prevents physical contact between the conductive polymer element and a flat surface on which the electrode is placed.
References Cited (Backward Citations)
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