The effect of nozzle design on plasma jet behavior, particle motion, and coating properties
- Univ. of Minnesota, Minneapolis, MN (United States)
In a plasma spray torch, vortexed arc gas flow is used to stabilize the cathode arc attachment and continuously move the anode arc spot reducing the specific anode heat load. When spray powder is introduced into the swirling plasma jet, it is immediately dragged off the torch axis leading to non-uniform particle heating and consequently asymmetric coating properties across the spray pattern. Particle heating is also influenced by the large scale instabilities of the plasma jet due to the anode arc root motion. In an effort to create uniform particle heating and coating properties with vortexed arc gas flow, the torch anode nozzle has been modified to include gas flow inlets downstream of the anode arc attachment point. These gas flow inlets oppose the primary arc gas vortex and allow control of the particle trajectory. The properties of coatings formed with the modified anode nozzle are compared to those obtained with the standard anode. Particle trajectories as well as luminous plasma jet geometry and fluctuations are determined using high speed videography and computerized image analysis for both anode configurations. The results of this study shows improved spray pattern and higher deposition efficiencies.
- OSTI ID:
- 160468
- Report Number(s):
- CONF-940684--; ISBN 0-87170-509-5
- Country of Publication:
- United States
- Language:
- English
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