| Abstract: |
Using suspensions in thermal plasma coating processes has become popular nowadays. Fine ceramic powders can be used to create stable suspensions in fluids like water or ethanol. These suspensions are injected into a plasma jet. The heat from plasma will evaporate the carrier fluid and eventually melt the solid content. The suspension droplets go through several breakups before evaporation is complete. A detailed understanding of how these parameters affect the properties of the deposited coating is of great importance.
Physical properties of the suspension, operating conditions of the plasma torch, along with injection parameters, i.e., position, angle, and speed, play an important role on how efficiently the fluid is evaporated and final molten drops reach the surface. In the current work, a numerical study of suspension plasma spraying is presented. Atomization processes, evaporation of the fluid phase, and melting of the solid phase are included in the model. Detailed attention has also been given to the changes in physical properties of the suspension mixture as the liquid phase is evaporating. These include phenomena such as shell formation, changes in heat transfer properties, and changes in viscosity and surface tension. Utilizing this improved model, several test cases have been studied to better evaluate effect of parameters on the final deposited surface.
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