Microwave Detection ofMicrowave Detection ofCorrosion Under Paint (CUP)Corrosion Under Paint (CUP)
Chris R. CoughlinChris R. Coughlin
TRI/Austin, Inc.TRI/Austin, Inc.U.S. Navy & Industry Corrosion Technology Information U.S. Navy & Industry Corrosion Technology Information
ExchangeExchange
July 16-20, 2001July 16-20, 2001
Team MembersTeam Members
Russell AustinRussell Austin
TRI/Austin, Inc.TRI/Austin, Inc.
Chris CoughlinChris Coughlin
TRI/Austin, Inc.TRI/Austin, Inc.
Reza ZoughiReza ZoughiApplied Microwave NDT LabApplied Microwave NDT Lab
Colorado State UniversityColorado State University
OutlineOutline
• IntroductionIntroduction• Microwave TechnologyMicrowave Technology• Technical ApproachTechnical Approach• Results of the EffortResults of the Effort• Future DirectionsFuture Directions• ConclusionsConclusions
IntroductionIntroduction
• Corrosion is a serious issueCorrosion is a serious issue– SafetySafety– Total Cost of Ownership (TCO)Total Cost of Ownership (TCO)– Military: Service ReadinessMilitary: Service Readiness
• Many corrosion-inhibiting systems are usedMany corrosion-inhibiting systems are used– InsulationInsulation– AppliquésAppliqués– PaintsPaints
• Problem: inhibiting systems inhibit early detectionProblem: inhibiting systems inhibit early detection
Introduction, cont...Introduction, cont...
• Corrosion Under Paint (CUP) is normally Corrosion Under Paint (CUP) is normally only detected when the paint blisters or only detected when the paint blisters or peelspeels
• TRI/Austin in cooperation with Dr. Reza TRI/Austin in cooperation with Dr. Reza Zoughi has developed a prototypical method Zoughi has developed a prototypical method of early CUP detection based on microwave of early CUP detection based on microwave technologytechnology– works on steel and aluminum substratesworks on steel and aluminum substrates
Microwave TechnologyMicrowave Technology
• Premise:Premise:– Metals reflect microwavesMetals reflect microwaves– Dielectrics alter the microwaveDielectrics alter the microwave
• Analogous to capacitors and inductors in electrical circuitsAnalogous to capacitors and inductors in electrical circuits• Important Properties:Important Properties:
– PermittivityPermittivity
– Loss FactorLoss Factor
– Paint and corrosion have very different dielectric Paint and corrosion have very different dielectric properties, which are very different again from the base properties, which are very different again from the base metal’s propertiesmetal’s properties
• Microwaves can distinguish CUPMicrowaves can distinguish CUP
Microwave Technology, cont...Microwave Technology, cont...
Typical Dielectric PropertiesTypical Dielectric Properties
MaterialMaterial Perm.Perm. LossLossMetalMetal — — PaintPaint 3.03.0 -0.1-0.1
Red RustRed Rust 8.18.1 -1.0-1.0
Black RustBlack Rust 11.211.2 -1.8-1.8
WaterWater 80.080.0 -80.0 -80.0
Microwave Technology, cont...Microwave Technology, cont...
• Prototype system Prototype system illustrated at rightillustrated at right– low power requirements low power requirements
(5 VDC)(5 VDC)– small size (hand-held)small size (hand-held)– rapid inspectionsrapid inspections– can detect CUP for can detect CUP for
aluminum or steel aluminum or steel substratesubstrate
Technical ApproachTechnical Approach
• Steel Plates Placed in Steel Plates Placed in Salt Fog ChamberSalt Fog Chamber– After corroding, rust After corroding, rust
sandblasted away, sandblasted away, leaving circle of leaving circle of corrosion on platecorrosion on plate
– Plates primed and Plates primed and painted painted
– Scanned with Scanned with microwave equipmentmicrowave equipment
ResultsResults• Initial Initial
– Bare plates placed in Bare plates placed in corrosion chambercorrosion chamber
– Corrosion sandblasted Corrosion sandblasted into circular shapeinto circular shape
– Plate primed & painted Plate primed & painted – Microwave scan provided Microwave scan provided
result to the rightresult to the right• Shows corroded area Shows corroded area
clearlyclearly
Results, cont...Results, cont...• AdvancedAdvanced
– Primed & painted plates Primed & painted plates placed in corrosion placed in corrosion chamberchamber
– Microwave scan provided Microwave scan provided result to the rightresult to the right
• Shows widespread Shows widespread corrosion except at corners corrosion except at corners where plate was supported where plate was supported in corrosion chamberin corrosion chamber
Results, cont...Results, cont...
Rust ThicknessRust Thickness
Note - Low Stand-Off Sensitivity
Future DirectionsFuture Directions
• Status: Proof of Concept completeStatus: Proof of Concept complete– Next step: secure additional funding and develop Next step: secure additional funding and develop
interest towards commercial deploymentinterest towards commercial deployment
• Initial commercial design specs:Initial commercial design specs:– Dimensions: 5” tall by 2” wide by 2” thickDimensions: 5” tall by 2” wide by 2” thick– Weight: Approximately 5 ounces (140 grams) including Weight: Approximately 5 ounces (140 grams) including
batterybattery– Completely cordless (hand-held unit)Completely cordless (hand-held unit)– Battery provides for 9 hours continuous useBattery provides for 9 hours continuous use– Estimated final consumer cost: less than $1000.00Estimated final consumer cost: less than $1000.00
Future Directions, cont...Future Directions, cont...
• Commercial system uses 3 LED’s Commercial system uses 3 LED’s to report level of CUPto report level of CUP– Green: No CUP detectedGreen: No CUP detected– Yellow: Minor CUPYellow: Minor CUP– Red: Severe CUP detectedRed: Severe CUP detected– Can optionally include a “jack” to Can optionally include a “jack” to
connect to a multi-meter or a PCconnect to a multi-meter or a PC
• Usage concept-picture a “stud Usage concept-picture a “stud finder” on wheelsfinder” on wheels
ConclusionsConclusions
• Prototypical device for early CUP detection for Prototypical device for early CUP detection for both aluminum and steel has been demonstratedboth aluminum and steel has been demonstrated– Small (handheld)Small (handheld)– Low power (battery)Low power (battery)– FastFast
• Further Information:Further Information:– Visit us online at http://www.tri-austin.comVisit us online at http://www.tri-austin.com
• Specific information on CUP and related projects available at Specific information on CUP and related projects available at http://www.tri-austin.com/austin/nde.htmhttp://www.tri-austin.com/austin/nde.htm
Conclusions, cont...Conclusions, cont...– Visit our sister site for NTIAC, the DoD’s Visit our sister site for NTIAC, the DoD’s
Nondestructive Testing Information Analysis Center at Nondestructive Testing Information Analysis Center at http://www.ntiac.comhttp://www.ntiac.com
• Searching NTIAC.com for “corrosion under paint” brings up Searching NTIAC.com for “corrosion under paint” brings up 136 hits136 hits
– The old fashioned way:The old fashioned way:TRI/Austin, Inc.TRI/Austin, Inc.
9063 Bee Caves Road9063 Bee Caves Road
Austin TX 78733-6201Austin TX 78733-6201
1.512.263.2101 or toll-free 1.800.973.32661.512.263.2101 or toll-free 1.800.973.3266
• Questions?Questions?
