Dacco Sci, Inc.

Guy D Davis

Chester M Dacres

Lorrie A Krebs

A portable and nondestructive adhesive tape corrosion sensor which is utilized under actual field or laboratory conditions in detecting coating and substrate degradation using Electrochemical Impedance Spectroscopy (EIS) of coated or uncoated metal structures has been developed. The invention allows for broad applicability, flexibility in utilizing the sensor in various environments without structural compromise and the ability to inspect and evaluate corrosion of the actual structure, regardless of the size, shape, composition, or orientation of the structure. The electrodes may be removed once a measurement is made or remain in the original fixed position so that subsequent measurements may be made with the same electrode. The nondestructive sensor apparatus is comprised of a pressure-sensitive adhesive tape that consists of a conductive film or foil and conductive adhesive overlapping another pressure-sensitive adhesive tape that consists of a conductive film or foil and non-conductive adhesive. The conductive tape serves as the sensing element or device. The non-conductive tape serves as the lead between the sensing element and the point of measurement. In an alternative configuration, the tape with the conductive adhesive may be used alone, acting as both sensor electrodes and the lead to the point of measurement. The metal structure or other substrate being sensed or evaluated for degradation serves as the working electrode. This two electrode sensing device is responsive to water uptake, incubation, and corrosion by measuring differences in impedance spectra. The invention can readily detect, quantify and monitor coating and metal degradation from its earliest stages, well before any visual indication of corrosion appears, under both laboratory and field conditions.

Adhesive tape sensor for detecting and evaluating coating and substrate degradation utilizing electrochemical processes

A hand-held or permanently attached corrosion sensor is described that uses electrochemical impedance spectroscopy (EIS, also known as AC impedance) to detect coating and structural degradation caused by excessive moisture uptake of coated and uncoated composite laminations or honeycomb or adhesively bonded structures. The hand-held sensor is pressed against the surface of the structure or specimen to be inspected. Alternatively, the sensor electrode may be permanently or temporarily attached. An EIS spectrum can then be obtained in the field or under arbitrary conditions and the degree of moisture uptake or coating or material degradation can be determined from the resultant spectrum. There are no restrictions on the configuration of the structure being inspected. The area of detection is controlled by controlling the extent and degree of wetness of the surface. A dry surface will provide a localized measurement; a wet surface will allow inspection of the wetted area.

In-situ electrochemical-based moisture sensor for detecting moisture in composite and bonded structures

A hand-held and flexible corrosion sensor is described that uses electrochemical impedance spectroscopy (EIS, also known as AC impedance) to detect coating degradation and corrosion of coated and uncoated metals. The hand-held and flexible corrosion sensor is pressed against the surface of the structure of specimen to be inspected, and may be either straight in structural configuration in the form of a pen or bent in a curved or angled manner to achieve better access to the structure. An EIS spectrum can than be obtained in the field or under arbitrary conditions and the degree of coating or material degradation can be determined from the resultant spectrum. There are no restrictions on the configuration of the structure being inspected. The area of detection is controlled by moderating the extent and degree of wetness of the surface. A dry surface will provide a localized measurement; a wet surface will allow inspection of the wetted area.

Portable, hand-held, in-situ electrochemical sensor for evaluating

A method for the early detection of electrochemical corrosion and coating degradation utilizing an inexpensive, in situ electrochemical metallic sensor for sensing coating and material degradation, particularly for materials such as aluminum 2024-T3, 7075, 6061, cold rolled steel samples, and coated metal structures such as automobiles, bridges, aircraft, and ships has been developed. The sensor utilizes AC Impedance or Electrochemical impedance spectroscopy (EIS) to acquire a precise, low-frequency impedance signature and is comprised of conductive ink deposited on a coating in the shape of the outline of a quadrilateral or other configuration. The resulting apparatus is comprised of a coated, metallic coupon used as a sensor, while a metallic grid electrode is deposited onto the steel coupon, thereby eliminating the need for a remote or counter electrode (i.e., reduction from a traditional, three-electrode system to a two-electrode system). Relying on the relatively lower impedance of the metallic grid electrode versus the coated metal, the electrodes are able to demonstrate a lower, interfacial impedance than the three-electrode testing system. This two-electrode approach eliminates the need for an electrolyte use in conventional, three-electrode AC Impedance testing and enables in-situ analyses of metallic and/or coating systems.

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Baltimore, MD, United States of America

Guy D Davis