Swirling Effects in Atmospheric Plasma Spraying Process: Experiments and Simulation

Israel Martínez-Villegas,John Mckelliget,Carlos A Poblano-Salas,Haideé Ruiz-Luna,Alma G Mora-García,Juan Muñoz-Saldaña,Gerardo Trápaga-Martínez

doi:10.3390/coatings10040388

Abstract

Experimental evidence of swirling effects in 3D trajectories of in-flight particles is presented based on static and dynamic footprints analysis as a function of stand-off distance of Al2O3 deposited employing a Metco-9MB torch. Swirling effects were validated with a proprietary computational fluid dynamics (CFD) code that considers an argon-hydrogen plasma stream, in-flight particles trajectories, both creating the spray cone, and particle impact to form a footprint on a fixed substrate located at different distances up to 120 mm. Static and dynamic footprints showed that swirl produces a slight deviation of individual particle trajectories and thus footprint rotation, which may affect coating characteristics.

Highlights

Among the different types of plasmas, atmospheric plasma spraying (APS) is one of the main thermal spray processes that has been widely used for the deposition of ceramic or metallic materials [1,2]
The size distribution of the powder and in-flight particles as measured measured by the DPV-Evolution system can be described by d10 = 11 μm, d50 = 22.8 μm and d90 = 37 μm by the DPV-Evolution system can be described by d10 = 11 μm, d50 = 22.8 μm and d90 = 37 μm and and d10 = 13 μm, d50 = 20.4 μm and d90 = 31 μm, respectively (Figure 1a)
Swirl simultaneously reduces the tendency of turbulence effects such as vortex other types of spraying systems, e.g., even modifying the powder injection system [29] or by changing formation in plasma jet and produces a slight deviation of individual particle trajectories identified the characteristics of the feeding material such as in suspension or solution plasma spraying [30,31]

Summary

Introduction

Among the different types of plasmas, atmospheric plasma spraying (APS) is one of the main thermal spray processes that has been widely used for the deposition of ceramic or metallic materials [1,2]. Powder feeding is externally injected into the plasma torch at atmospheric pressure. Under these conditions, the plasma jet and in some cases material characteristics can be affected by the contact with oxygen from ambient air, because it may alter chemical compositions of plasma species, cool the thermal plasma flame, and reduce the jet velocity. The original design of the Metco 9MB plasma torch is based on a plasma cutting system for metals and was modified for coating deposition adding an external powder injection system and changing the internal gas flow to generate swirling in a de

Methods

Results

Conclusion