Portable, Non-destructive, Surface/Coating Integrity Verification

Background

Coating integrity is typically measured in a lab using a procedure requiring removal of some of the coating material and then measurement of impedance via liquid electrolyte in glass cells that are clamped onto flat metal coupons. This method is time‑intensive, has a time lag due to the need for a full lab, and requires taking a sample of the surface material.

To better serve the needs of the industry, this new method of measuring surface impedance allows for field testing using portable, widely available standard equipment without the need to extract a sample. The use of electrostatic gel pads as the measurement device allows for curved and delicate surfaces to be tested. After establishing a baseline when a coating is first applied, subsequent measurements detect increases in the permeability of coatings, serving as an early-warning scheme to prevent corrosion of the underlying metal.

Technology Overview

Hydrogels are versatile materials that are both flexible and conductive, making them a natural choice for surface electrodes. A conductive anionic hydrogel is used as a portable electrolyte solution for Electrochemical Impedance Spectroscopy characterization of the barrier properties of protective coatings. Using standard and portable equipment, our hydrogels can measure the impedance of a coated substrate, yielding measurements similar to those from standard liquid cells, but without the hassle, time, or cost of lab‑based testing.

Benefits

• Removes the need to extract a sample of the coating for submission to a lab.
• Removes the need for an on‑site lab.
• Reduces the time of measurement (essentially instant results).
• Enables field workers to take measurements more often for critical components/infrastructure.
• Keeps results “in house” by removing need for 3rd party labs.

Applications

Electrochemical Impedance Spectroscopy is a proven method for measuring surface properties; however, current applications of this technology are limited to rigid planar surfaces. Conductive hydrogel leads developed may open new avenues of application in the field of metrology, allowing for measurement of non-planar surfaces, which may be useful in the coatings production, characterization, and analysis industries.

In addition, many industries would benefit from having the ability to self‑measure (instantly, and on‑site) the integrity of their surface coatings on an as‑needed basis:

• Commercial Building
• Municipal Infrastructure
• Photovoltaic (Solar) Cell/Collector
• Fine Art Preservation (metal statues and historic objects)
• Critical Infrastructure (oil and gas pipelines, oil rigs, railroads)
• Marine Vessels
• Military Equipment
• Commercial Airline Equipment Maintenance