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| Abstract No.: |
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Scheduled at:
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Wednesday, June 04, 2008, Room 08 2:40 PM
Diagnostics and Sensors 2
Modern process diagnostics offer a lot of possibilities for gaining data for both quality control and process knowledge. The recorded data is the base for process models and enhances the process knowledge
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| Title: |
Spreading of plasma sprayed molybdenum on grit-blasted glass
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| Authors: |
Andre McDonald* / Department of Mechanical Engineering -
University of Alberta, Canada
Christian Moreau/ Industrial Materials Institute - NRC, Canada
Sanjeev Chandra/ University of Toronto, Canada
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| Abstract: |
Plasma-sprayed, molten molybdenum particles (~55 µm diameter) were photographed during impact on grit-blasted glass surfaces that were maintained at either room temperature or at 350oC. Droplets approaching the surface were sensed using a photodetector and after a known delay, a fast charge-coupled device (CCD) camera was triggered to capture time-integrated images of the spreading splat from behind the glass. A rapid two-color pyrometer was used to collect the thermal radiation from the spreading droplets to follow the evolution of their temperature and calculate the splat cooling rates. It was found that as the surface roughness increased, the maximum spread diameters of the molten molybdenum droplets decreased, while the splat cooling rates increased. Impact on non-heated and heated roughened glass with similar roughness values produced splats with approximately the same maximum spread diameters, skewed morphologies, and cooling rates. On smooth glass, the splat morphologies were circular, with larger maximum spread diameters and smaller cooling rates on non-heated smooth glass. An established model was used to estimate the splat-substrate thermal contact resistances. On highly roughened glass, the thermal contact resistance decreased as the glass roughness increased, suggesting that splat-substrate contact was improved as the molten metal penetrated the spaces between the large asperities.
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