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1271 |
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Tuesday, June 03, 2008, Auditorium 2 10:10 AM Gasturbines 1 Coatings for mobile and stationary turbines, protection against wear, high temperature corrosion and thermal stresses, clearance control coatings for a better efficiency |
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Deposition mechanism of cold sprayed MCrAlY coatings focused on nanostructure |
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Yuji Ichikawa* / Tohoku University, Japan Takamichi Miyazaki / Tohoku Univeristy, Japan Kazuhiro Ogawa/ Tohoku Univeristy, Japan Michel Jeandin/ Ecole des Mines de Paris, France Tetsuo Shoji/ Tohoku Univeristy, Japan |
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Thermal-sprayed (i.e. low pressure plasma spray or high velocity oxygen fuel spray) MCrAlY coatings are widely used for land-based gas turbine applications against high-temperature oxidation and hot corrosion. However, due to requirement for further improvement of turbine efficiency, dense and stable coatings are necessary. The cold spray makes it possible to increase coating density, due to high velocity particle impacts during spraying. Many researchers have discussed critical velocity as most important factor of deposition mechanism of cold-sprayed coating. However, the dominant parameter of critical velocity has not been completely understood. This study considered that the dominant factor of deposition was plastic deformation of deposited particle. There is native oxide on the sur-face of particles and substrate. After plastic deforma-tion of particle and substrate, the native oxide break down, and then nascent surface can be created and contact of them causes to begin deposition. The critical deposit condition was studied by particle observation and FEM approaches. From the results of these inves-tigations, it is thought that the dominant factor of the deposition is substrate maximum plastic strain of sub-strate. |