Three Dimensional Modeling of the Plasma Spray Process

Abstract

Results of simulations of three-dimensional (3D) temperature and flow fields inside and outside of a DC arc plasma torch in steady state are presented with transverse particle and carrier gas injection into the plasma jet. The results show that an increase of the gas flow rate at constant current moves the anode arc root further downstream leading to higher enthalpy and velocity at the exit of the torch anode, and stronger mixing effects in the jet region. An increase of the arc current with constant gas flow rate shortens the arc, but increases the enthalpy and velocity at the exit of the torch nozzle, and leads to longer jets. 3D features of the plasma jet due to the 3D starting conditions at the torch exit and, in particular, due to the transverse carrier gas and particle injection, as well as 3D trajectories and heating histories of sprayed particles are also discussed.

Thermal Plasma Synthesis of Nano-Sized Powders

“…With the injection ports at torch exit, which is conventionally used for plasma spray coating applications, however, it is hard for this type of DC torch to enable most of the injected precursors to be fully evaporated during their flight of plasma flame. As reported in other papers [30][31][32], there are many trajectories far from full evaporation of injected metal precursors in this case. Although smaller particles are relatively easily evaporated, some parts of the precursors injected into the plasma flame can be still reproduced without full evaporation due to their ineffective trajectories [33].…”

Three-dimensional simulation of an argon–hydrogen DC non-transferred arc plasma torch

“…Simulation works on plasma arc inside the torch were firstly studied by using two-dimensional (2D) [1][2][3][4][5][6][7] and then extended to three-dimensional (3D) models [8][9][10][11][12][13][14][15][16][17]. For 2D models, the anode arc attachment was calculated based on axisymmetric assumption, which normally leads to the unrealistic result.…”

“…In general, the position of the arc-root attachment in a DC plasma torch can be determined by the Steenbeck's minimum principle (to seek the minimum arc voltage) [2,8,15] or the principle of minimum entropy production (to seek the minimum entropy production) [13].…”

Influence of Alumina Addition to Aluminum Fins for Compact Heat Exchangers Produced by Cold Spray Additive Manufacturing

“…The schematic of a plasma gun is shown in This figure shows the working gas path through the narrow passage between the cathode and the anode, where the electric arc produces the plasma plume [26][27]. The injected particles are accelerated and heated up to their melting temperature by the plasma gas, typically argon, until the particles hit the substrate and form the coating [26][27]. The high temperature produced by the plasma torch allows for the possibility of using a broad range of coating materials as long as the material does not decompose or sublimate as the melting point is achieved [28].…”

“…The high temperature produced by the plasma torch allows for the possibility of using a broad range of coating materials as long as the material does not decompose or sublimate as the melting point is achieved [28]. However, numerous items affect the deposition efficiency of this method, such as nozzle geometry, particle size, velocity, temperature and working gas flow rate [26], [27], [29]. It is notable that the time it takes for the in-flight particles to reach their melting point from the injection point is one the most important factors in deposition efficiency [27].…”