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

• US 6,328,878 B1
• Filed: 08/11/1999
• Issued: 12/11/2001
• Est. Priority Date: 08/11/1999
• Status: Expired due to Fees

• Current Assignee: Dacco SCI, Inc.
• Original Assignee: Dacco SCI, Inc.
• Inventors: Krebs, Lorrie A., Davis, Guy D., Dacres, Chester M.
• Primary Examiner(s): Warden, Sr., Robert J.
• Assistant Examiner(s): Olsen, Kaj K.
• Application Number:
  US09/372,074
• Time in Patent Office: 853 Days
• Field of Search: 324/693, 324/700, 324/707, 324/713, 324/722, 324/71.2, 205/776.5, 205/777, 205/791.5, 204/404, 422/53
• US Class Current: 205/776.5
• CPC Class Codes: G01N 17/02 Electrochemical measuring systems for weathering, corrosion or corrosion-protection measurement

Abstract

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.

Claims

1. A method for the determination of coating or substrate degradation of a material caused by electrochemical corrosion comprising the steps of:

providing a first adhesive tape element, said first adhesive tape element comprising a first conductive foil and a conductive pressure-sensitive adhesive applied to said first conductive foil;

providing a second adhesive tape element, said second adhesive tape element comprising a second conductive foil and a non-conductive, pressure sensitive adhesive applied to said second conductive foil;

applying said second adhesive tape element to the coating or substrate;

applying said first adhesive tape element to the coating or substrate in a manner that said first and second adhesive tape elements partially overlap each other thereby allowing first adhesive tape element to function as a detection electrode and said second adhesive tape element to function as an electrical lead for said detection electrode;

measuring an electrochemical impedance spectrum between the detection electrode and the material being monitored, said material thereby functioning as a working electrode; and

determining the degradation of the coating or substrate from said measured electrochemical impedance spectrum.

2. An apparatus for the determination of coating or substrate degradation of a material caused by electrochemical corrosion, said apparatus comprising:

a first adhesive tape element comprising a first conductive foil and a conductive pressure-sensitive adhesive applied to said first conductive foil;

a second adhesive tape element comprising a second conductive foil and a non-conductive pressure sensitive applied to said second conductive foil;

said first and second adhesive tape elements are arranged on the coating or substrate in a manner that they partially overlap each other with the first adhesive element placed over the second adhesive element allowing the first adhesive tape element to function as a detection electrode and the second adhesive tape element to function as an electrical lead for said detection electrode;

means for measuring an electrochemical impedance spectrum across the detection electrode and the material, said material thereby functioning as the working electrode; and

means for determining the coating or substrate degradation based on said measured electrochemical impedance spectrum.