Capturing the Influence of Jet Fluctuations on Particles in Plasma Spraying

Abstract

Instabilities and fluctuations of the plasma jet in a thermal spray process can have a significant influence on the particle in-flight temperatures and velocities, affecting the properties of resulting plasma-sprayed coatings. Presented in this paper is a novel method for capturing the effects particles are exposed to in the plasma spraying process. High-speed camera images of a plasma jet generated by a cascaded three-cathode plasma generator (TriplexPro-210) were recorded for varying operating conditions. The images are processed using the inverse Abel transform. This transformation accounts for the fact that the images represent a 2D projection of the 3D jet and generates more accurate intensity values that the sprayed particles would experience. These images are then combined with particle tracks resulting from CFD simulations of the plasma jet to match the particles path with the recorded plasma jet. This new method allows a precise description of the plasma intensity experienced by individual particles with a high temporal resolution. The results show a high sensitivity of the method, even detecting the influence on the particles of the plasma jet originating from the cascaded triple arc plasma generator, which is considered as rather stable.

Experimental study on the life and performance of an improved DC arc plasma torch

“…A large number of numerical modelings [22,[26][27][28][29] and experimental studies [30][31][32][33][34] have been performed to analyze the mechanisms of anode erosion, and propose the methods to inhibit the anode erosion. The modeling found that the arc usually attached on the anode surface in the diffusive or constricted forms.…”

Influence of Plasma Torch Power on the Plasma Jet Properties and Microstructure of Alumina Coatings

“…This work introduces a visualization method to analyze plasma-sprayed particles' movement using high-speed video camera footage. In previous works, other authors analyzed flame spray pyrolysis [23], and plasma jet instabilities and fluctuations [24,25], observed using high-speed cameras; the results of a single particle motion are still lacking in the scientific literature.…”

Effect of a Spatially Fluctuating Heating of Particles in a Plasma Spray Process

“…The properties of the coatings produced in the plasma spray process are affected by factors such as the plasma torch operation, the state of the generated plasma jet, the properties of the injected powder, and the placement of the substrate [4][5][6][7][8][9][10][11][12][13]. In order to improve the quality and productivity of functional coatings, many studies have been carried out over the past few decades.…”