Measurements of size and velocity characteristics in plasma spraying process using PDA

Phase doppler anemometry (PDA) has been considered a powerful technique to study in-flight powder behavior in plasma spraying process, since it can simultaneously and non-intrusively measure the velocity and the distributions of particle sizes. In order to enhance measurement accuracy in its application to plasma spraying process, properties of the light scattered from the spherical metal particles was studied and analyzed in detail with the aid of Mie theory. The optimum optical settings used in the Dual Mode PDA system (58N81 DualPDA Dantec Measurement Technology) for this process are discussed in this article. Measurements at 5cm and 10cm below the SG-100 (Miller) plasma gun were obtained and illustrated in this article. In this study, only one particle injection port was used. It was observed that there was a correlation between particle size and velocity inside plasma spray as well as a correlation existed between particle size and RJVIS velocity. Two flux concentration peaks were also found to exist at the cross section 10cm below the nozzle.