Plasma-particle interactions in plasma spraying systems

Three Dimensional Modeling of the Plasma Spray Process

“…In Recent years, 3D modeling work concerning the effects of transverse gas injection from a single injection port on the plasma jet characteristics and the trajectories of injected particles attracted increasing interest (Ref [44][45][46][47][48][49][50][51][52]. The common feature of most of these papers is that assumed 2D temperature and velocity distributions at the outlet of the torch nozzle (or the inlet of the plasma jet region) are employed as boundary conditions for 3D modeling of heat transfer, flow patterns, and particle behavior in the jet region, i.e., only the effect of the carrier gas injection on the 3D characteristics of the plasma jet is included in the modeling work (Ref [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43]. Using velocity and temperature profiles obtained from modeling of DC arc plasma torches as the starting conditions of plasma jets (Ref 4,53) depends strongly on the ability to model plasma torches.…”

“…The 3D heat transfer and flow patterns, as well as the ionization-recombination process, inside a thermal plasma torch also have significant effects on the characteristics of the thermal plasma jet issuing from the exit of the plasma torch and, for example, on the quality of the coatings obtained by plasma spray. Over the past few decades, many papers have been devoted to modeling of the DC arc plasma spray process or to the study of spray-related basic processes based on 2D (axi-symmetrical) assumption with neglecting the effects of the transverse injection of the cold carrier gas on the jet flow field and on particle behavior ( Ref 4,[26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43]. But experimental results showed that even a small amount of carrier gas (5% of the main flow) transverse injection, as well as the particles used as the tracers in LDV measurements, may induce a deflection of the plasma jet with a deflection angle as great as 5°, and this 3D effect must be taken into account in the interpretation of the LDV data ( Ref 35).…”

3-D time-dependent modelling of the plasma spray process. Part 1: flow modelling

“…The modelling of this deposition process has received considerable attention during the last years and various models have been proposed in the literature [3][4][5][6][7][8] they adopt practically the same methodology for the calculation of the turbulent plasma jet and particle behaviour, very little deal with transient phenomena as plasma formation in the nozzle [9][10][11] and flow fluctuations. This paper presents a tri-dimensional and time-dependent model of the jet formation and mixing with the surrounding atmosphere.…”

Particle in-flight behavior and its influence on the microstructure and mechanical properties of plasma-sprayed Al2O3 coatings

“…It is suggested the momentum transferred from the plasma gas to the particles shows high dependence on the mass of the injected particle. 18 Thus, the coarser (heavier) particles attain a lower velocity as compared with the finer ones. The similar trend of the in-flight temperature variation with the particle size is illustrated in Fig.…”