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2810 |
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Tuesday, September 27, 2011, Saal B2.1 4:25 PM Cold Spraying 2 |
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Application of parameter selection maps in cold spraying |
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Hamid Assadi* / Tarbiat Modares University, Iran Frank Gärtner / Helmut Schmidt University, Germany Tobias Schmidt/ Helmut Schmidt University, Germany Horst Richter/ Dartmouth College, USA Jan-Oliver Kliemann/ Helmut Schmidt University, Germany Kurt Binder/ Helmut Schmidt University, Germany Thomas Klassen/ Helmut Schmidt University, Germany Heinrich Kreye/ Helmut Schmidt University, Germany |
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What would be the most appropriate parameters, namely, gas temperature and gas pressure, for cold spraying of a given feedstock material? This question is the focus of the present contribution. Initially, it is shown that main coating characteristics can be described as a unique function of a dimensionless parameter, defined as the ratio of particle velocity to critical velocity. Subsequently, these velocities and the respective ratio are worked out and expressed explicitly in terms of key process and material parameters, such as gas temperature and particle size. In this way, final properties of cold-sprayed deposits are linked directly to primary cold-spray parameters. Moreover, it is shown that the window of deposition, as well as the relationship between final properties of the deposit and the spraying conditions, can be incorporated conveniently into simple 2-D diagrams, showing contours of the velocity ratio on the plane of the selected primary parameters. Based on these diagrams, primary process parameters related to a given coating property can be identified and selected, without a need to refer to intermediate variables such as particle velocity. The paper includes examples of the application of these maps for cold spraying of copper. |