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| Abstract No.: |
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| Title: |
A numerical model for combustion and expansion in HVOF and suspension flame spraying
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| Authors: |
Esther Dongmo* / Universität Stuttgart, Institut für Fertigungstechnologie keramischer Bauteile, IFKB / Institute for Manufacturing Technologies of Ceramic Components and Composites, Germany
Martin Wenzelburger / Universität Stuttgart, Institute for Manufacturing Technologies of Ceramic Components and Composites, Germany
Rainer Gadow/ Universität Stuttgart, Institute for Manufacturing Technologies of Ceramic Components and Composites, Germany
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| Abstract: |
Nano structured coatings applied by supersonic flame spray processes show a better bonding mechanism, superior hardness and better wear resistance compared to coatings with micron scale structure. However, handling and particle feeding of nano scale spray powders is difficult due to their large surface area and easy agglomeration, but also health risks. Therefore, nano structured oxide ceramic powders are mixed with organic solvents in order to form liquid suspensions that are suitable to improve the particle feeding properties.
Recent attempts to understand the momentum and heat transfer mechanisms between flame and particles in HVOF and suspension flame spraying led to measurement of the in-flight particle properties and computational modeling of the processes. In this work, modeling and simulation of the HVOF spraying process as a two phase model and the HVSFS process as a three phase model is applied in order to analyze thermal and mass flow processes for an optimization of the spray particle properties and the final properties of the coatings themselves. Simulation results are given for particle tracking (combustion chamber to substrate surface) during the spray process. Thereby, particle properties are sensitive to a large number of process parameters as well as the particle diameter. Numerical results are validated by experimental diagnosis of particle properties with the SprayWatch® system and by the analysis of experimental coatings.
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