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NDT of HVOF Coatings

NDT of HVOF Coatings. John Sauer Sauer Engineering HCAT Toronto September 25 th , 2002. NDT. Outline Where have we been?? Where are we going??. NDT. Where have we been ? Chrome plating Common usage of magnetic particle and fluorescent penetrant

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NDT of HVOF Coatings

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  1. NDT of HVOF Coatings John Sauer Sauer Engineering HCAT Toronto September 25th, 2002

  2. NDT • Outline • Where have we been?? • Where are we going??

  3. NDT • Where have we been? Chrome plating • Common usage of magnetic particle and fluorescent penetrant • Recent inclusion of Barkhausen inspection on critical components • Some applications require stripping of chrome regardless of condition-no NDT issues

  4. NDT • What are we looking for?? • Chrome is already cracked so we are not looking for “plating defects” • Looking for substrate defects or “grinding burn” via Barkhausen

  5. NDT • What do we see?? • Recent studies by AFRL and Boeing St.Louis say that any defects under .250” ( that size may be larger) cannot be found with common methods • Barkhausen can detect burn but cracks??

  6. NDT • Hill AFB • Estimate that ~ 50 % of the parts that come in for repair with chrome are not stripped and put back into service • Question • Are .250” defects OK from a damage tolerance standpoint?? • What size defect do we really need to find??

  7. NDT • Where are we going?? HVOF Coatings • A positive aspect of HVOF is the possibility that the coating may not require stripping thru multiple repair cycles • However, this highlights the issue: • What is happening in and under the coating??

  8. NDT • What are we looking for?? • Cracks/defects in coating • Delaminations • Substrate cracks/defects • Size of substrate defects • Must be in the .250” critical size range since we must be better or EQUAL to chrome 

  9. NDT • What do we see?? • Limited work shows varied forms of ultrasonic are the “best methods for seeing smaller defects down to ~.050”

  10. NDT • How do we get there?? • Define the requirements • Understand the applications • Assess production feasibility

  11. NDT What are we looking for?? • Size • Location • How does that vary from application to application? • What is the production feasibility for use of the technique on a reliable basis in the field?

  12. NDT • Research has shown some ideas on the horizon might be: • JENTEK's MWMTM-Array sensor to involving eddy-current technology • EWI suggests either eddy current or USI C scan • GEAE suggests Pulsed Eddy Current (PEC) • Naval Center has performed work on corrosion under paints using • Real time Ultrasound Imaging • Thermal Imaging • Near Field Microwave Imaging

  13. NDT • JENTEK's MWMTM-Array sensor technology can be used to develop surface-mountable eddy-current sensors that can be modified for difficult-to-access locations on complex configurations • Work has been performed on coatings for Gas Turbine Industry and WCCo

  14. NDT • Ultrasonic inspection by EWI (similar to AFRL) Ultrasonic C-Scan Image of a Coated Sample

  15. NDT • GEAE suggests Pulsed Eddy Current (PEC) • Most existing Eddy current inspections use single frequency excitation • Uses a current pulse in a drive coil to transmit transient electromagnetic flux into the structure • Advantages of this are the presence of wide range of frequency components in the exciting field • Work would be performed by GE's Global Research Center (GRC)

  16. NDT • Naval Center has performed work with on corrosion under paints using • Real time Ultrasound Imaging • Basis is patented two dimensional piezo microelectric array to generate real time C-scan • Thermal Imaging • Active Thermography-External source for heat -use IR camera • Sonic Thermography-high amplitude sonic waves cause frictional heat-use IR camera • Near Field Microwave Imaging • Rely on rlection properties of metallic surfaces using open ended microwave probes

  17. NDT • Cannot resolve this issue today • Significant issue for both HCAT/PEWG • Subcommittee being formed with Chuck Alford(PEWG) and John Sauer (HCAT) as co-chairs to pool resources and address issue

  18. NDT • Any one interested please see Chuck or myself during this meeting • Possible side discussion tonite if people are interested

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