Drag on a metallic or nonmetallic particle exposed to a rarefied plasma flow

Chen, Xi; Chen, Xiaoming

doi:10.1007/bf01083674

Cited by 38 publications

(5 citation statements)

References 7 publications

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“…Therefore, the velocity, time of flight and evaporation of the particles were calculated with the approach proposed by Chen et al for particles processed in plasma jet under rarefied plasma conditions [19][20][21][22][23][24]. It makes it possible to calculate the drag force exerted by the plasma jet on the powder particles, and the plasma-particle heat transfer [12,25].…”

Section: Particle Dynamics and Heatingmentioning

confidence: 99%

“…It makes it possible to calculate the drag force exerted by the plasma jet on the powder particles, and the plasma-particle heat transfer [12,25]. The calculations were based on the following assumptions drawn from [12,[19][20][21][22][23][24][25]:…”

Section: Particle Dynamics and Heatingmentioning

confidence: 99%

“…where v is the gas velocity and x the distance traveled from the particle since the injection point. Chen et al showed that under the assumptions listed above, the drag coefficient, C D , can be expressed as [20,23]:…”

Section: Particle Dynamics and Heatingmentioning

confidence: 99%

“…Mauer et al [12,18] explained that the models used for investigating the acceleration and heating of particles under atmospheric plasma conditions could not be applied in the free molecular flow that prevails in the torch nozzle. Using the model proposed by Chen for particles injected in a rarefied plasma flow [19][20][21][22][23][24], Mauer [12] concluded that "the feedstock treatment along the very first trajectory segment between injector and jet expansion plays a key role". He found that with an Ar (35 slm)-He (60 slm) plasma jet at a net power of 60 kW, YSZ particles up to 0.92 µ m in diameter could be evaporated in the torch nozzle while with an Ar (100 slm)/H2 (10 slm) plasma jet only particles up to 0.55 µ m in diameter could be evaporated.…”

Section: Introductionmentioning

confidence: 99%

“…To determine the size of the particles that can be evaporated in the whole PS-PVD process (in the torch nozzle and deposition chamber) operated with different plasma gas mixtures (Ar-H 2 and Ar-He) at torch net powers higher than 40 KW, this study used a CFD approach combined with a model of particle dynamics and evaporation. The latter model used the Chen approach [19][20][21][22][23][24] to calculate the heat transfer to a particle exposed to a rarefied plasma flow.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Analysis of the Interactions between Plasma Jet and Powder Particles in PS-PVD Conditions

et al. 2021

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Plasma spray-physical vapor deposition (PS-PVD) refers to a very low-pressure (~100 Pa) deposition process in which a powder is injected in a high-enthalpy plasma jet, and mostly vaporized and recondensed onto a substrate to form a coating with a specific microstructure (e.g., columnar). A key issue is the selection of the powder particle size that could be evaporated under specific spray conditions. Powder evaporation takes place, first, in the plasma torch between the injection location and nozzle exit and, then, in the deposition chamber from the nozzle exit to the substrate location. This work aims to calculate the size of the particles that can be evaporated in both stages of the process. It deals with an yttria-stabilized zirconia powder and two commercial plasma torches operated at different arc powers with gas mixtures of argon and helium or argon and hydrogen. First, it used computational fluid dynamics simulations to calculate the velocity and temperature fields of the plasma jets under very low-pressure plasma conditions. Then, it estimated the evaporation of the particles injected in both plasma jets assuming an isothermal evaporation process coupled with momentum and heat transfer plasma-particle models in a rarefied plasma. The calculations showed that, for different powers of the Ar–H2 and the Ar–He operating conditions of this study, the heat flux from the plasma jet to particles inside the torch is much higher than that transferred in the deposition chamber while the specific enthalpy transferred to particles is comparable. The argon-helium mixture is more efficient than the argon-hydrogen mixture to evaporate the particles. Particles less than 2 μm in diameter could be fully evaporated in the Ar–He plasma jet while they should be less than 1 µm in diameter in the Ar–H2 plasma jet.

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