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 –Recent inclusion of Barkhausen inspection on critical components –Some applications require stripping of chrome regardless of condition-no NDT issues

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

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??

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??

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??

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

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

NDT How do we get there?? –Define the requirements –Understand the applications –Assess production feasibility

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?

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

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

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

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)

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

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

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