Development of Low Power Plasma Spray Process Using Atmospheric Pressure Microwave Plasma

Abstract In this study, atmospheric pressure microwave plasma spraying is evaluated as a potential coating process for heat susceptible materials. The work was carried out using an experimental setup consisting of a 2.45 GHz microwave generator and a modified plasma torch. To characterize the spraying process, investigators measured plasma temperature, plume shape, and particle velocities for different gas flow rates, nozzle diameters, and spray distances and correlated the results with the flattening behavior of particles as captured in SEM images. Spray trials were then conducted to optimize the deposition of hard chrome on carbon-fiber reinforced polymer substrates and TiO2 powder on stainless steel. In both cases, the coatings were successfully applied; the former by decreasing the nozzle diameter, the latter by reducing heat input to spray particles.