Numerical analysis of flame and particle behavior in an HVOF thermal spray process

Abstract

In this study, a kerosene-fueled high-velocity thermal spraying model is used to examine the flame and particle behavior in a thermal spray process. The gas flow characteristics (including temperature, velocity, and pressure), mass fraction of the gas components, and the particle characteristics (including the particle temperature, velocity, and in-flight trajectory) are successfully simulated. Besides, the effects of particle diameter, particle shape, and particle injection velocity on the particle behavior in the spraying flame are also investigated. The optimal particle size range is found to be between 20 and 40μm. In this case, most of the particles are located towards the center of the gun and are in a semi-solid state before impacting the substrate. When the shape factor falls from 1 to 0.6, the non-spherical particles gain more momentum and less heat than spherical particles in the process owing to their higher drag coefficient and shorter dwell time within the flame flow. A comprehensive consideration of the injection velocity on the spray particle dynamics revealed that the optimal particle injection velocity should be greater than 5m/s but no more than 20m/s.