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2075 |
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Wednesday, May 05, 2010, Olivia Room 9:40 AM Modeling and Simulation 1 |
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Homogenization of coating properties in atmospheric plasma spraying ? current results of a DFG- (German Research Foundation) Funded Research Group |
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Jens Prehm* / Institute of Materials Science,
Leibniz Universitaet Hannover, Germany Friedrich-Wilhelm Bach / Institute of Materials Science, Leibniz Universitaet Hannover, Germany Kai Möhwald/ Institute of Materials Science, Leibniz Universitaet Hannover, Germany Kirsten Bobzin/ Surface Engineering Institute, RWTH Aachen University, Germany Nazlim Bagcivan/ Surface Engineering Institute, RWTH Aachen University, Germany Ivica Petkoviæ/ Surface Engineering Institute, RWTH Aachen University, Germany Jochen Schein/ Lab for Plasma Technology, Universitaet der Bundeswehr Muenchen, Germany José-Luis Marqués/ Lab for Plasma Technology, Universitaet der Bundeswehr Muenchen, Germany Stephan Zimmermann/ Lab for Plasma Technology, Universitaet der Bundeswehr Muenchen, Germany |
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In the area of atmospheric plasma spraying, newly-developed triple-cathode technologies offer the potential to homogenize the coating properties with respect to porosity and residual stresses. Focused on numerical simulation, combined with advanced diagnostics, the goal of this research group is to adjust these properties systematically. A numerical model that couples fluid dynamic, electro-magnetic and thermal phenomena for a 3-cathode torch was developed to investigate the plasma and the dynamic electric arc behavior inside the torch. With help of self-developed computer tomography equipment, which is based on emission spectroscopy, combined with the solution of the Saha equation in thermodynamical equilibrium, it is now possible to reconstruct the 3-dimensional temperature distribution close to the torch outlet. This measurement allows us to confirm the torch numerical modeling. Coating formation is simulated by coupled computational fluid dynamics (CFD) and FEM simulation, so that fluid structure interaction is taken into account. This innovative approach has the advantage to predict residual stresses which occur during cooling and moreover the shrinking effects can be considered. By simulation of the individual regions, in combination with experimental results, which also include the particle velocity, diameter and surface temperature, the corresponding process parameters can be obtained for the desired coating properties. |