|
4700 |
|
Effect of nozzle material on cold spray process performance |
|
Samuel Leblanc-Robert* / University of Ottawa, Canada Daniel MacDonald / University of Ottawa, Canada Rubén Fernández/ University of Ottawa, Canada A. Farjam/ University of Ottawa, Canada Bertrand Jodoin/ University of Ottawa, Ontario |
|
In cold gas dynamic spraying, the gas nature, stagnation pressure and temperature, and the standoff distance are known to be the main parameters that affect the deposition efficiency, deposition rate, and coating quality. This investigation attempts to elucidate the effect of nozzle material on the resulting cold spray Al7075 coatings. Through experimentation using polymer, copper, steel, and ceramic nozzles, it is shown that the nozzle material has a substantial effect on the spray process deposition efficiency. It is shown through particle velocity measurements that the deposition efficiency increases with lower particle velocities, which seems contradictory with common knowledge in cold spray. However, the increased performance is attributed to higher particle impact temperatures. It is proposed that this is related to the thermal diffusivity of the nozzle material, as a higher thermal diffusivity will transfer more heat to the particle during particle/wall interactions. |