Microwave Detection of Corrosion Under Paint

Corrosion under paint (CUP) is detectable by telltale electrochemical activity, but direct detection of CUP via nondestructive evaluation (NDE) methods is not commercially available. As corrosion forms, ferric oxides are created which have dielectric properties quite distinct from uncorroded areas. Microwave NDE methods sense these changes in dielectric properties to detect CUP. In a recent TRI/Austin - Colorado State University (CSU) initiative for CUP detection, microwaves were found to be extremely sensitive to corrosion, capable of mapping the corroded area, and able to determine the thickness of the remaining paint layer. This innovative approach to detecting CUP is ready for transition from the laboratory to a fielded NDE device. CSU's microwave NDE model will be used to develop optimal waveguide probe configurations for CUP detection. Using frequency and probe stand-off distance as parameters for optimizing CUP detection the design, development and test of a laboratory level microwave CUP system will be completed in Phase I. Data collected will be used in the notional design of a CUP NDE system for Naval ships. Microwave devices are small and easily operated by enlisted personnel, and offer an innovative means of assessing CUP in Navy and commercial applications.