Numerical Simulation of Plasma Jet Characteristics under Very Low-Pressure Plasma Spray Conditions
Plasma spray-physical vapor deposition (PS-PVD) is an emerging technology for the deposition of uniform and large area coatings. As the characteristics of plasma jet are difficult to measure in the whole chamber, computational fluid dynamics (CFD) simulations could predict the plasma jet temperature...
Main Authors: | , , , |
---|---|
Format: | Article |
Language: | English |
Published: |
MDPI AG
2021-06-01
|
Series: | Coatings |
Subjects: | |
Online Access: | https://www.mdpi.com/2079-6412/11/6/726 |
id |
doaj-8ebe428590564a6faf172d5326504d3a |
---|---|
record_format |
Article |
spelling |
doaj-8ebe428590564a6faf172d5326504d3a2021-07-01T00:23:35ZengMDPI AGCoatings2079-64122021-06-011172672610.3390/coatings11060726Numerical Simulation of Plasma Jet Characteristics under Very Low-Pressure Plasma Spray ConditionsTao Zhang0Gilles Mariaux1Armelle Vardelle2Chang-Jiu Li3State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaInstitute for Research on Ceramics (IRCER), CNRS-University of Limoges, 87068 Limoges, FranceInstitute for Research on Ceramics (IRCER), CNRS-University of Limoges, 87068 Limoges, FranceState Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaPlasma spray-physical vapor deposition (PS-PVD) is an emerging technology for the deposition of uniform and large area coatings. As the characteristics of plasma jet are difficult to measure in the whole chamber, computational fluid dynamics (CFD) simulations could predict the plasma jet temperature, velocity and pressure fields. However, as PS-PVD is generally operated at pressures below 500 Pa, a question rises about the validity of the CFD predictions that are based on the continuum assumption. This study dealt with CFD simulations for a PS-PVD system operated either with an argon-hydrogen plasma jet at low-power (<50 kW) or with an argon-helium plasma jet at high-power (≥50 kW). The effect of the net arc power and chamber pressure on the plasma jet characteristics and local gradient Knudsen number (Kn) was systematically investigated. The Kn was found to be lower than 0.2, except in the region corresponding to the first expansion shock wave. The peak value in this region decreased rapidly with an increase in the arc net power and the width of this region decreased with an increase in the deposition chamber pressure. Based on the results of the study, the local Knudsen number was introduced for detecting conditions where the continuum approach is valid under PS-PVD conditions for the first time and the CFD simulations could be reasonably used to determine a process parameter window under the conditions of this study.https://www.mdpi.com/2079-6412/11/6/726plasma sprayingvery low-pressurePS-PVDCFDshock wavegradient-length local Knudsen number |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Tao Zhang Gilles Mariaux Armelle Vardelle Chang-Jiu Li |
spellingShingle |
Tao Zhang Gilles Mariaux Armelle Vardelle Chang-Jiu Li Numerical Simulation of Plasma Jet Characteristics under Very Low-Pressure Plasma Spray Conditions Coatings plasma spraying very low-pressure PS-PVD CFD shock wave gradient-length local Knudsen number |
author_facet |
Tao Zhang Gilles Mariaux Armelle Vardelle Chang-Jiu Li |
author_sort |
Tao Zhang |
title |
Numerical Simulation of Plasma Jet Characteristics under Very Low-Pressure Plasma Spray Conditions |
title_short |
Numerical Simulation of Plasma Jet Characteristics under Very Low-Pressure Plasma Spray Conditions |
title_full |
Numerical Simulation of Plasma Jet Characteristics under Very Low-Pressure Plasma Spray Conditions |
title_fullStr |
Numerical Simulation of Plasma Jet Characteristics under Very Low-Pressure Plasma Spray Conditions |
title_full_unstemmed |
Numerical Simulation of Plasma Jet Characteristics under Very Low-Pressure Plasma Spray Conditions |
title_sort |
numerical simulation of plasma jet characteristics under very low-pressure plasma spray conditions |
publisher |
MDPI AG |
series |
Coatings |
issn |
2079-6412 |
publishDate |
2021-06-01 |
description |
Plasma spray-physical vapor deposition (PS-PVD) is an emerging technology for the deposition of uniform and large area coatings. As the characteristics of plasma jet are difficult to measure in the whole chamber, computational fluid dynamics (CFD) simulations could predict the plasma jet temperature, velocity and pressure fields. However, as PS-PVD is generally operated at pressures below 500 Pa, a question rises about the validity of the CFD predictions that are based on the continuum assumption. This study dealt with CFD simulations for a PS-PVD system operated either with an argon-hydrogen plasma jet at low-power (<50 kW) or with an argon-helium plasma jet at high-power (≥50 kW). The effect of the net arc power and chamber pressure on the plasma jet characteristics and local gradient Knudsen number (Kn) was systematically investigated. The Kn was found to be lower than 0.2, except in the region corresponding to the first expansion shock wave. The peak value in this region decreased rapidly with an increase in the arc net power and the width of this region decreased with an increase in the deposition chamber pressure. Based on the results of the study, the local Knudsen number was introduced for detecting conditions where the continuum approach is valid under PS-PVD conditions for the first time and the CFD simulations could be reasonably used to determine a process parameter window under the conditions of this study. |
topic |
plasma spraying very low-pressure PS-PVD CFD shock wave gradient-length local Knudsen number |
url |
https://www.mdpi.com/2079-6412/11/6/726 |
work_keys_str_mv |
AT taozhang numericalsimulationofplasmajetcharacteristicsunderverylowpressureplasmasprayconditions AT gillesmariaux numericalsimulationofplasmajetcharacteristicsunderverylowpressureplasmasprayconditions AT armellevardelle numericalsimulationofplasmajetcharacteristicsunderverylowpressureplasmasprayconditions AT changjiuli numericalsimulationofplasmajetcharacteristicsunderverylowpressureplasmasprayconditions |
_version_ |
1721348755967442944 |