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7379 |
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Wednesday, May 04, 2022, Hall G1 2:00 PM HVOF / HVAF Spraying I |
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The characteristics of in-flight Ti-6Al-4V particles and coatings manufactured by inner-diameter high velocity air-fuel (ID-HVAF) process |
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Peyman Khamsepour* / Concordia University, Canada Jorg Oberste-Berghaus / National Research Council of Canada, Canada Maniya Aghasibeig/ National Research Council of Canada, Canada Christian Moreau/ Concordia University, Canada Ali Dolatabadi/ University of Toronto, Canada |
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High velocity air-fuel (HVAF) technique is a combustion process that allows solid-state deposition of metallic particles while minimizing oxidation and decomposition. Although HVAF and cold spray share the similarity of solid-state particle deposition, a slightly higher temperature of HVAF may allow further particle softening and thus more deformation at impact. This study aims to enhance Ti-6Al-4V particle deformation and, therefore, the density of as-sprayed samples by utilizing an inner-diameter (ID) HVAF gun. The ID gun is considered a scaled-down version of standard HVAF with a narrower jet, beneficial for near net shape manufacturing. To explore the potential of the ID gun as a solid-state deposition process, the effect of spraying parameters including spray distance, fuel pressure, and nozzle length on in-flight particle characteristics and as-fabricated coating attributes such as porosity, oxygen content, and hardness were investigated. Using in-flight particle diagnostics is challenging as some fine particles are heated at high temperatures due to titanium's exothermic solid oxidation reaction, while other particles are too cold to be detected from their thermal emission. However, the DPV Evolution diagnostic system was successfully employed to discriminate the non-emitting solid particles from the burning ones. Accurate measurement of the in-flight particle characteristics is essential inputs to validate simulation work for the HVAF deposition of Ti-6Al-4V. |