The Role of Nucleation and Growth in Plasma Spray-Physical Vapor Deposition

Plasma spray-physical vapor deposition (PS-PVD) is a novel coating process based on plasma spraying. In contrast to conventional methods, deposition takes place not only from liquid splats but also from nano-sized clusters and from the vapor phase. This offers new opportunities to obtain advanced microstructures and thus to comply with growing demands on modern functional coatings.

In this work, the role of nucleation and growth of feedstock material during flight in the plasma jet is investigated. The formation of nano-sized primary particles from supersaturated vapors is calculated based on the kinetic nucleation theory. Their growth by condensation and the formation of secondary particles by coagulation is further studied. As the deposited microstructures are significantly dependent on such mechanisms, process conditions can be designed to obtain specific characteristics. These theoretical considerations are compared with experimental results.