The reactive evaporation phenomenon of a silicon particle treated by a RF thermal plasma torch results from two phase changes (Solid→Liquid→ Vapour) and from chemical reactions at high temperatures.
The aim of this experimental study is to follow on-line the mass transfer between silicon particles and plasma during a thermal R.F. plasma treatment. The gas temperature surrounding the particles during their trajectories in the jet is well known, by two modelling approaches, as well as the gas velocity VG. The different chemical compositions and gas flows are controlled and composed of pure Ar or Ar+H2. The technique used (Laser Doppler Metrology) gives the velocity of the particles VPart., which allows the calculation of their residence time (τ) in a high temperature gradient plasma.
This paper is focused on the fitting between experimental data and two models which allows the evaluation of the thermal plasma treatment Activity (A). Both brings complementary arguments which explain the chemical and thermal history of the particles during their treatment.