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Integrated Diagnostics and Process Maps
Thermal spray industry is beginning to see wide spread implementation of sophisticated process diagnostic sensors. However, a robust connection between process input parameters and resulting coating properties has yet to be achieved beyond the laboratory scale.
To address this, CTSR has developed protocols in which various commercially available tools are implemented to monitor the spray process. Parallels between results from each sensor are then derived providing greater insight into individual data as well as the overall process dynamics.
In addition, process diagnostics are compared with on-line and off-line property measurements with the goal of connecting starting conditions with resulting coating behavior. Such an approach provides confidence in measured outcomes.
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CTSR’s integrated diagnostics and in-situ coating property measurement facility
for rapid development of process maps |
Process Maps and the Issues of Reliability
Process Maps provide a robust means for design and improved reliability by systematically comparing torch parameters to particle state and subsequently to coating behavior. Research has shown that powder particle in-flight temperature and velocity directly affect coating build-up, microstructure and architecture which in turn influence the overall properties. Accordingly, CTSR has developed first order process maps that link particle temperature and velocity to starting input parameters. The reliability of this data has been specifically assessed via devoted process reproducibility experiments. Second order process maps are being developed to build the next link, between process and properties. Extensive data has been compiled on thermal conductivity and elastic modulus, two critical properties for thermal barrier coatings. Similar strategies have also been applied to HVOF sprayed metallic alloys and cemented carbides.
The overall goal of this thrust is to provide industry with a more quantitative and reliability methodology for design, optimization and production of thermal spray coatings.
Second Order Process Maps
-link in-flight particle state with coating properties. Shown here is a contour plot of thermal conductivity as a function of average particle temperature and velocity. This allows industry to tailor spray conditions to intended design and performance criteria |
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In-situ Substrate Curvature Measurements
provide quantitative information on residual stresses and in-plane mechanical properties. Shown here is the effect of starting powder morphology on the non-linear compliance of YSZ coatings.
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Indentation Stress-Strain Curves
provide quantitative information of metallic coating elastic and plastic mechanical behaviour. Shown here are results comparing effects of spray torch., and between material systems |
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Cyclic Indentation Testing
gives insight into fatigue and wear progression by detecting individual damage events under repeated loading. Shown here are results for hard face coatings over a range of compositions.
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