The phenomenon of particle vaporization in a dc plasma jets is difficult to control. It depends on thermal properties of plasma-forming gas, the plasma jet's length and diameter, the size and trajectory of injected particles. The vaporization of particles is detrimental to the deposition
efficiency and may affect the coating quality. in plasma spraying, however, it could be desired in other plasma processes (for example : selective evaporation for metals purification and plasma assisted chemical vapor deposition process).
To have a better understanding of particle vaporization under plasma spraying conditions, and especially the effect of vapor issuing from particles on. coating formation, the vaporization of metallic powders was investigated using an absorption spectroscopic technique which allows
determination of metal vapor concentration within the plasma jet and its plume.
Several absorption lines have been utilized in real time mode in this technique to determine the metallic gas density surrounding a single evaporating in flight particle and the geometry of its vapor
cloud. Results on iron powders injected in different plasma gas mixtures are reported.