> Boro Djordjevic, CNDE associate director, presented his view of the future developments in NDE that we can look forward to in the next century. Not only will existing instrumentations be improved with increased capability provided by smaller computers with tremendous expanded memory capacity, but new nondestructive testing instruments will be developed permitting measurements to be made of material properties which were not previously possible. There will also be an increase in the application of nondestructive techniques to nondestructive materials characterization for materials process control. Boro cited the example of a recently developed system for process control of tape placement for manufacture of graphite/epoxy cylinders that used laser generation/air-coupled detection to verify the adhesion of a new layer of tape to the previously placed ones. He also described several other NDE
demonstrated that carbonized tulip poplar (Lifiodendron tulipifera) was 30% stronger than the precursor wood, and a carbon/polymer composite was 250% stronger than the precursor wood.
Among the characterization tools used in this study, nondestructive techniques played an integral role. In particular, x-ray radiography was shown to be instrumental in the evaluation of polymer infiltration and ceramic conversion uniformity. Ultrasonic evaluation provided insight into the effects of thermal treatment on carbonized wood characteristics. While these techniques were performed ex-situ, it is anticipated that in future work real-time nondestructive monitoring of critical process parameters will speed the development of this unique materials manufacturing approach. As a first demonstration of this tech nology, Johns Hopkins University and Rotordynamics-Seal Research (RSR), a small business located in North Highlands, California, recently completed a Phase I STTR (small business technology transfer) project, where it was demonstrated that a net shape silicon carbide race could be produced from carbonized wood. This silicon carbide race was successfully tested with a silicon nitride ball bearing by RSR. The Phase 2 follow-on contract has been approved pending matching funding where further optimization of the processing and testing of the bearing system will be done. |
Published in:
CNDE Summer 1998 Newsletter.
Presentations of the Twelfth CNDE Annual Spring Meeting
Center for Nondestructive Evaluation at The Johns Hopkins University
http://www.cnde.com
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