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Microwave Detection of Corrosion Under Paint (CUP). Chris R. Coughlin TRI/Austin, Inc. U.S. Navy & Industry Corrosion Technology Information Exchange July 16-20, 2001. Team Members. Russell Austin TRI/Austin, Inc. Chris Coughlin TRI/Austin, Inc. Reza Zoughi Applied Microwave NDT Lab
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Microwave Detection ofCorrosion Under Paint (CUP) Chris R. Coughlin TRI/Austin, Inc. U.S. Navy & Industry Corrosion Technology Information Exchange July 16-20, 2001
Team Members Russell Austin TRI/Austin, Inc. Chris Coughlin TRI/Austin, Inc. Reza Zoughi Applied Microwave NDT Lab Colorado State University
Outline • Introduction • Microwave Technology • Technical Approach • Results of the Effort • Future Directions • Conclusions
Introduction • Corrosion is a serious issue • Safety • Total Cost of Ownership (TCO) • Military: Service Readiness • Many corrosion-inhibiting systems are used • Insulation • Appliqués • Paints • Problem: inhibiting systems inhibit early detection
Introduction, cont... • Corrosion Under Paint (CUP) is normally only detected when the paint blisters or peels • TRI/Austin in cooperation with Dr. Reza Zoughi has developed a prototypical method of early CUP detection based on microwave technology • works on steel and aluminum substrates
Microwave Technology • Premise: • Metals reflect microwaves • Dielectrics alter the microwave • Analogous to capacitors and inductors in electrical circuits • Important Properties: • Permittivity • Loss Factor • Paint and corrosion have very different dielectric properties, which are very different again from the base metal’s properties • Microwaves can distinguish CUP
Microwave Technology, cont... Typical Dielectric Properties MaterialPerm.Loss Metal — Paint 3.0 -0.1 Red Rust 8.1 -1.0 Black Rust 11.2 -1.8 Water 80.0 -80.0
Microwave Technology, cont... • Prototype system illustrated at right • low power requirements (5 VDC) • small size (hand-held) • rapid inspections • can detect CUP for aluminum or steel substrate
Steel Plates Placed in Salt Fog Chamber After corroding, rust sandblasted away, leaving circle of corrosion on plate Plates primed and painted Scanned with microwave equipment Technical Approach
Initial Bare plates placed in corrosion chamber Corrosion sandblasted into circular shape Plate primed & painted Microwave scan provided result to the right Shows corroded area clearly Results
Advanced Primed & painted plates placed in corrosion chamber Microwave scan provided result to the right Shows widespread corrosion except at corners where plate was supported in corrosion chamber Results, cont...
Results, cont... Rust Thickness Note - Low Stand-Off Sensitivity
Future Directions • Status: Proof of Concept complete • Next step: secure additional funding and develop interest towards commercial deployment • Initial commercial design specs: • Dimensions: 5” tall by 2” wide by 2” thick • Weight: Approximately 5 ounces (140 grams) including battery • Completely cordless (hand-held unit) • Battery provides for 9 hours continuous use • Estimated final consumer cost: less than $1000.00
Future Directions, cont... • Commercial system uses 3 LED’s to report level of CUP • Green: No CUP detected • Yellow: Minor CUP • Red: Severe CUP detected • Can optionally include a “jack” to connect to a multi-meter or a PC • Usage concept-picture a “stud finder” on wheels
Conclusions • Prototypical device for early CUP detection for both aluminum and steel has been demonstrated • Small (handheld) • Low power (battery) • Fast • Further Information: • Visit us online at http://www.tri-austin.com • Specific information on CUP and related projects available at http://www.tri-austin.com/austin/nde.htm
Conclusions, cont... • Visit our sister site for NTIAC, the DoD’s Nondestructive Testing Information Analysis Center at http://www.ntiac.com • Searching NTIAC.com for “corrosion under paint” brings up 136 hits • The old fashioned way: TRI/Austin, Inc. 9063 Bee Caves Road Austin TX 78733-6201 1.512.263.2101 or toll-free 1.800.973.3266 • Questions?