Numerical and Experimental Investigation of Two-Phase Plasma Jet during Deposition of Coatings

Abstract

Atmospheric pressure plasma spraying is widely used to produce various coatings, especially hard ceramic coatings for wear and corrosion protection and thermal barrier function, porous catalytic coatings for environment control and protection, hydrophobic coatings, etc. The plasma spraying process uses a DC electric arc to generate a jet of high temperature ionized plasma gas, which acts as the spraying heat source. The sprayed material, in powder form, is carried into the plasma jet where it is heated, partially or fully melted and propelled towards the substrate. The properties of the produced coating are dependent on the feedstock material, the thermal spray process and application parameters, and post treatment of the coating. However, the influence of flow and particle temperature and velocity on coatings characteristics, its adherence to the substrate, reproducibility of its properties and quality is not clearly established [Fouchais et al., 2006]. Generally, to correlate coating properties to flow parameters and particle in-flight characteristics experimental procedure is used. To monitoring the whole plasma spraying process (plasma jet generation, powder injection, formation of the coating) same techniques, as plasma computer tomography (PCT), particle shape imaging (PST), particle flux imaging (PFI) [Landes, 2006] are used. Such techniques are expensive and complicate for use in industry. Numerical investigations of plasma spray process generally is focused on investigation of heat transfer between plasma jet and surface [Garbero et al., 2006], substrate temperature influence on coatings morphology, adhesion, chemical processes between substrate material and deposited material [Yeh, 2006, Kersten et al., 2001]. In this paper, by means of Jets&Poudres software [Delluc et al., 2003], a numerical simulation of interaction of plasma jet and dispersed particles was investigated. Simulation results were compared with experimental data.