Liquid metal atomization using de Laval nozzle is an established technique for producing fine (< 100 μm) metal powders for a lot of industrial applications. This process offers a variety of advantages as spherical morphology or low consumption of inert gas for example. Despite its widespread uses, however, the relationships among gas dynamics melt nozzle and de Laval nozzle diameters, processing parameters, and particle size remain defined. As a result, efforts to reduce powder costs by improving particle size control and energy efficiency remain hindered. Then, the optimization of this process is a great challenge. This experimental study examines the atomizing spray behavior depending on the process parameters. Experiments were conducted on copper (at 99.9%). Particle Image Velocimetry technique was implemented in the atomization chamber and measurements were performed to characterize in velocity the atomized droplets. The PIV system was placed in such a way that the atomization zone, comprised between 50 and 110 mm downstream the de Laval nozzle exit, can be monitored by the camera. The evolutions of the particle velocity and particle sizes were finally analyzed versus the working conditions.

In this investigation, particle image velocimetry (PIV) diagnostics were employed to analyze the spray produced by a two-fluid atomizer as used in suspension plasma spraying (SPS). This led to a change in the design of the atomizing nozzle in order to achieve a high-speed spray with narrow distributions in droplet size. The resultant spray was characterized and the diagnostic was adapted accordingly. Various suspensions of YSZ powders were then injected into the plasma under different conditions and particle velocities were determined and correlated with the coating morphologies obtained.