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2078 |
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Tuesday, May 04, 2010, Hullet Room 10:00 AM Cold Spraying 3 |
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Residual stresses in cold sprayed coatings |
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Frank Gärtner* / Helmut Schmidt University of the Federal Armed Forces, Germany Hamid Assadi / Tarbiat Modarres University, Iran Tobias Schmidt/ Helmut Schmidt University, Germany Kurt Binder/ Helmut Schmidt University, Germany Thomas Klassen/ Helmut Schmidt University, Germany |
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In cold spraying, particles impact the substrate in the solid state. Thus, no volume changes due to solidification and only limited thermal shrinkage have to be considered. By the high kinetic energy upon impact and the subsequent deformation of spray particles and previously deposited spray layers, compressive stress should be prominent in cold sprayed coatings. With respect to coating performance in technical applications, more details about the origin of residual stresses and individual stress levels are essentially needed. For the example of Copper, Titanium and Niobium as spray materials, residual stresses of cold sprayed coatings are investigated by X-ray diffraction. The amount of compressive stresses in the coatings depends on the type of spray material and the individually varied spray conditions. Moreover, stress profiles over coating depth reveal a non uniform stress distribution. These results are discussed under viewpoints of thermal and mechanical distortion to obtain more information to which extend stresses can be influenced by certain spray conditions. The knowledge concerning stress development is beneficial to estimate and to optimize the lifetime of coated components. |