In-Flight Analysis of Particles in Plasma Spraying

In-flight behavior of particles is a key factor that affects the quality of coating. There are some problems such as jet instability and poor coating quality in practical application process. This study focused on internal and external flow characteristics of supersonic plasma spray gun based on the analysis of plasma spraying multi-physical fields. Drag, thermophoretic, and pressure-gradient forces were considered. Flow field calculation and particle analysis were separated. The flow field calculation results were used as the initial conditions of particle computation. Heating and acceleration behavior of particles in the flow field were analyzed. In-flight particles were monitored by Spray Watch and compared with calculated values. Results show that particle velocity and temperature reach the maximum at 80–100 mm away from the nozzle exit. Particles in supersonic plasma spraying are more likely to refine near the nozzle exit, which conforms to experimental observations. The velocity calculation of particles with small diameter is consistent with the measurements.