Effect of Convergent-Divergent Nozzle on Fine Particle Velocity in Low-Pressure Induction Plasma Jet in Plasma-Assisted Aerosol Deposition

Plasma-assisted aerosol deposition (PAD) is a new ceramic coating technology that utilizes a low-pressure induction plasma jet to accelerate particles toward the substrate and form a coating. This plasma jet was generated by a radio frequency (RF) inductively coupled plasma torch under reduced pressure. Although the particle velocity was expected to directly influence the phenomena of particle collision, adhesion, and coating formation, it has not been investigated systematically. Thus, we aimed to clarify the velocity of particles accelerated by a subsonic or supersonic low-pressure induction plasma jet using a convergent-divergent (C-D) nozzle. The particles’ velocity colliding with the substrate was measured using a time-of-flight method. The effects of the C-D nozzle, input RF power, and carrier gas flow rate on the particle velocity were investigated for alumina and yttria-stabilized zirconia particles. The use of the C-D nozzle increased the particle velocity, significantly, while the input RF power was an insensitive parameter for the particle velocity. This study implies the introduction of the C-D nozzle is effective on the particle acceleration in PAD.