Modeling and Parametric Analysis of Plasma Spray Particle State Distribution for Deposition Rate Control

2008 ◽  
Author(s):  
Donald Wroblewski ◽  
Onomitra Ghosh ◽  
Annie Lum ◽  
David Willoughby ◽  
Michael VanHout ◽  
...  
Keyword(s):  
Deposition Rate ◽  
Plasma Spray ◽  
Gas Flow ◽  
Particle Temperature ◽  
Turbulent Shear ◽  
Injection Velocity ◽  
Particle Model ◽  
Particle State ◽  
Zone Model ◽  
Spatial Gradients

Plasma spray for depositing thermal barrier coatings features large distributions of particle states that result in significant variations in coating quality. These variations arise from distributions of particle sizes, large spatial gradients of plasma thermal-fluid fields, and temporal variations of the arc and jet. This paper describes a simplified approach for studying how particle state distributions are influenced by torch conditions and powder distributions, and the implications for deposition rate monitoring and control. The approach combines a simplified jet model with a more detailed particle model. The important fluid-thermal spatial gradients in the plasma jet are captured using a three zone model: a core region, modeled by growth of a turbulent shear layer around a laminar core, a transition region and a similarity region. Plasma-particle momentum and thermal interactions, particle phase transitions, internal particle temperature gradients, and collapse of in-flight hollow particles have been modeled using a multi-lumped particle model. Effects of distributions of particle size, particle morphology, injection velocity, and carrier gas flow were studied for YSZ spray in an Ar-He plasma. The results provide guidance on sensor design and operation and on approaches for plume location control.

Process Maps for Plasma Spray Part I: Plasma-Particle Interactions

2000 ◽  
Author(s):  
D.L. Gilmore ◽  
R.A. Neiser ◽  
Y. Wan ◽  
S. Sampath
Keyword(s):  
Plasma Spray ◽  
Gas Flow ◽  
Operating Conditions ◽  
Injection Velocity ◽  
Microstructural Development ◽  
Spray Parameters ◽  
Particle Interactions ◽  
Plasma Particle ◽  
Particle Injection ◽  
Process Maps

Abstract This is the first paper of a two part series based on an integrated study carried out at Sandia National Laboratories and the State University of New York at Stony Brook. The aim of the study is to develop a more fundamental understanding of plasma-particle interactions, droplet-substrate interactions, deposit formation dynamics and microstructural development as well as final deposit properties. The purpose is to create models that can be used to link processing to performance. Process maps have been developed for air plasma spray of molybdenum. Experimental work was done to investigate the importance of such spray parameters as gun current, auxiliary gas flow, and powder carrier gas flow. In-flight particle diameters, temperatures, and velocities were measured in various areas of the spray plume. Samples were produced for analysis of microstructures and properties. An empirical model was developed, relating the input parameters to the in-flight particle characteristics. Multi-dimensional numerical simulations of the plasma gas flow field and in-flight particles under different operating conditions were also performed. In addition to the parameters which were experimentally investigated, the effect of particle injection velocity was also considered. The simulation results were found to be in good general agreement with the experimental data.

More on the Influence of Injector Geometry and Carrier Gas Flow Rate on Spray Pattern and Particle Temperature

2000 ◽  
Author(s):  
J.R. Fincke ◽  
W.D. Swank ◽  
D.C. Haggard
Keyword(s):  
Gas Flow ◽  
Particle Temperature ◽  
Gas Jet ◽  
Injection Velocity ◽  
Minor Effect ◽  
Gas Bubble ◽  
Particle Injection ◽  
Spray Pattern ◽  
Carrier Gas ◽  
Cold Gas

Abstract Recently it has been suggested that the carrier gas jet interaction with the plasma can have a large effect on the resulting particle temperature. The postulated interaction is through deflection of the main plasma jet and by delaying the heating of particles by the formation of a "cold" gas bubble. We have examined the effect of the gas jet itself on the temperature of the particles by attempting to artificially form a cold gas bubble using a separate, closely oriented gas jet. The effect of the "twin" co-flowing jet was evaluated by measuring its effect on the mean and standard deviation of the particle injection velocity and the resulting spray pattern and particle temperature. Additionally we have used alternative carrier gases with similar density but with specific heats that are higher than argon by a factor of two. A measurable but minor effect on particle temperature is observed.

Plasma Spraying of Functionally Graded Materials: Measured and Simulated Results

2000 ◽  
Author(s):  
J.R. Fincke ◽  
R.L. Williamson ◽  
C.H. Chang
Keyword(s):  
Functionally Graded Materials ◽  
Gas Flow ◽  
Particle Temperature ◽  
Computer Code ◽  
Functionally Graded ◽  
Turbulent Dispersion ◽  
Particle Model ◽  
Graded Materials ◽  
Measured Velocity ◽  
Discrete Particle Model

Abstract Thermal spray processing of functionally graded materials requires that the spray patterns of different particle types coincide at impact and that each particle type arrives with the appropriate temperature and degree of melting. Measurements of particle velocity, temperature, and size along with spray pattern characteristics have been obtained for co-injected NiCrAlY and zirconia powder. The plasma and particle flow fields were also simulated with a pseudo 3-D model using the LAVA computer code. The model assumes that the gas flow is axisymmetric while the particles are treated in a fully 3-D manner. A stochastic discrete-particle model that includes turbulent dispersion dictates particle behavior. The simulation produced reasonably accurate velocities and particle trajectories, although, particle temperature is consistently over predicted. Comparisons between the calculated and measured velocity and temperature statistical distributions and calculated molten fractions are discussed.

An Investigation of Particle Injection and Resulting In-Flight Particle Behavior During Air Plasma Spraying

2006 ◽  
Author(s):  
W. Zhang ◽  
V. Srinivasan ◽  
L. L. Zheng ◽  
S. Sampath
Keyword(s):  
Gas Flow ◽  
Process Parameter ◽  
Diagnostic Tools ◽  
Particle State ◽  
Plasma Diagnostic ◽  
Air Plasma ◽  
Particle Injection ◽  
Carrier Gas ◽  
Particle Behavior ◽  
Particle Characteristics

In this article we present our studies on the role of particle injection on the in-flight particle characteristics in an external orthogonally injected air plasma spray system. The influence of carrier gas on the in-flight particle state has been investigated, experimentally and using simulation, for Yttria Stabilized Zirconia (YSZ) thermal spray powder processed in an Ar-H2 plasma. Diagnostic tools such as IPP and SPT have been used to measure the plume characteristics and ensemble temperature while DPV-2000 has been used to measure the distributions of individual particle characteristics such as temperature, velocity and size, at the point of the maximum particle flux and at various points (square grid) in the plume cross-section. Three-dimensional simulations have been performed for the cases presented in the experiments. Specifically, the effects of carrier gas flow rate on the in-flight particle characteristics were studied at multiple stand-off distances. Simulation results agree well with the experimental observation that the particle velocity and temperature will increase with the plume angle and then decrease after reaching a maxima for a given process parameter combination and stand-off distance. This maxima has been observed at the same plume angle for different process parameter combinations. The results of this study are currently being used to 'optimize' the particle injection and trajectory, which enables better understanding of the influence of plasma forming and stabilizing parameters (gas flows and arc current) on the in-flight particle behavior.

Modeling and Visualization of Plasma Spray Process for Depositing Functionally Graded Materials

1999 ◽  
Author(s):  
Y. P. Wan ◽  
V. Gupta ◽  
H. Zhang ◽  
A. Varshney ◽  
S. Sampath ◽  
...  
Keyword(s):  
Functionally Graded Materials ◽  
Plasma Spray ◽  
System Development ◽  
Particle Interaction ◽  
Functionally Graded ◽  
Powder Injection ◽  
Injection Velocity ◽  
Multivariate System ◽  
Graded Materials ◽  
Spray Process

Abstract Recently, several models have been developed to simulate the plasma spraying process. The present paper extends our previous model (Wan et al., 1999a) to the plasma spray system of two-component materials with two different feed nozzles. It accounts for plasma-particle interaction, particle heating/melting/evaporation and solidification on the substrate. A special visualization algorithm has been developed to demonstrate the effects of various parameters on particle conditions while in flight, growth of functionally graded materials and distribution of the two components in the coating. Visualization of thermal processes is a challenging task if it has to be used for materials design and system development. It requires special schemes for data management in a multivariate system that includes at least velocity, temperature and species in four co-ordinates (space and time). Our effort is focused on developing a visualization scheme which goes far beyond the process animation and can be ultimately used for virtual prototyping of the processes, an area that needs special research efforts. Simulation and visualization have been performed for spraying of zirconia and NiCrAlY powders, with many combinations of powder injection features, e.g., number of nozzles, nozzle location and injection velocity. The fluctuation of the voltage is also simulated and animated to show its effect on both plasma gas and particle behavior. The optimized operating parameters are deduced from the distribution of these two materials in the coating layer. Issues related to visualization are also discussed.

scholarly journals Numerical Simulations of Molten Breakup Behaviors of a de Laval-Type Nozzle, and the Effects of Atomization Parameters on Particle Size Distribution

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1027
Author(s):  
Lianghui Xu ◽  
Xianglin Zhou ◽  
Jinghao Li ◽  
Yunfei Hu ◽  
Hang Qi ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Gas Flow ◽  
Nozzle Geometry ◽  
Particle Model ◽  
Process Conditions ◽  
Operating Pressure ◽  
Gas Temperature ◽  
Tracking Model

In this work, an atomizer with a de Laval-type nozzle is designed and studied by commercial computational fluid dynamics (CFD) software, and the secondary breakup process during atomization is simulated by two-way coupling and the discrete particle model (DPM) using the Euler-Lagrange method. The simulation result demonstrates that the gas flow patterns greatly change with the introduction of liquid droplets, which clearly indicates that the mass loading effect is quite significant as a result of the gas-droplet interactions. An hourglass shape of the cloud of disintegrating molten metal particles is observed by using a stochastic tracking model. Finally, this simulation approach is used for the quantitative evaluation of the effects of altering the atomizing process conditions (gas-to-melt ratio, operating pressure P, and operating gas temperature T) and nozzle geometry (protrusion length h, half-taper angle α, and gas slit nozzle diameter D) on the particle size distribution of the powders produced.

Variation of thin film deposition rate on SS 314 with the variation of gas flow rate using CVD

2011 ◽  
Vol 63 (6) ◽  
pp. 433-439 ◽  
Author(s):  
Mohammad Asaduzzaman Chowdhury ◽  
Dewan Muhammad Nuruzzaman ◽  
Khaled Khalil ◽  
Mohammad Lutfar Rahaman
Keyword(s):  
Thin Film ◽  
Deposition Rate ◽  
Flow Rate ◽  
Gas Flow ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Gas Flow Rate ◽  
Film Deposition Rate

Emission spectra study of plasma enhanced chemical vapor deposition of intrinsic, n+, and p+ amorphous silicon thin films

2013 ◽  
Vol 1536 ◽  
pp. 133-138
Author(s):  
I-Syuan Lee ◽  
Yue Kuo
Keyword(s):  
Deposition Rate ◽  
Gas Flow ◽  
Emission Spectra ◽  
Chemical Vapor ◽  
Critical Factor ◽  
Optical Emission ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Silicon Thin Films ◽  
Deposition Processes

ABSTRACTThe PECVD intrinsic, n+, and p+ a-Si:H thin film deposition processes have been studied by the optical emission spectroscope to monitor the plasma phase chemistry. Process parameters, such as the plasma power, pressure, and gas flow rate, were correlated to SiH*, Hα*, and Hβ* optical intensities. For all films, the deposition rate increases with the increase of the SiH* intensity. For the doped films, the Hα*/SiH* ratio is a critical factor affecting the resistivity. The existence of PH3 or B2H6 in the feed stream enhances the deposition rate. Changes of the free radicals intensities can be used to explain variation of film characteristics under different deposition conditions.

Wide Bandgap Fluorinated Silicon-Carbide-Nitride Films Using NF3

1991 ◽  
Vol 219 ◽  
Author(s):  
H. C. Goh ◽  
S. M. Tan ◽  
H. A. Naseem ◽  
S. S. Ang ◽  
W. D. Brown
Keyword(s):  
Silicon Carbide ◽  
Refractive Index ◽  
Carbon Content ◽  
Power Density ◽  
Deposition Rate ◽  
Gas Flow ◽  
Substantial Reduction ◽  
Wide Bandgap ◽  
Amorphous Hydrogenated Silicon ◽  
Stainless Steel Reactor

ABSTRACTAmorphous hydrogenated silicon carbide has been studied extensively because of its properties as a wide bandgap material. However, a large amount of methane is needed to deposit the material. Also, the high carbon content of these films poses some problems. The addition of NF3 to the gas stream results in wide bandgap films with a substantial reduction in the required CH4 flow for deposition. Amorphous SiCx Ny :H:F films were prepared using rf glow discharge decomposition of silane, methane, and nitrogen trifluoride in a parallel-plate stainless steel reactor. Gas flow rate and power density were varied. For a gas mixture containing 6% NF3 and 78% CH4, FTIR measurements reveal a reduction in C-H peak heights at 2960 cm-1 and 2880 cm-1 with respect to the Si-H peak at 2080 cm-1 indicating a smaller carbon content in the film. The C-H peaks shift to higher wavenumbers with increasing NF3. The use of NF3 increases the bandgap from 2.6 to 3.14 eV while reducing the refractive index from 2.12. to 1.87. A maximum deposition rate of 625 A/min was achieved. This should be compared to the very low deposition rate of 18 A/min for comparable bandgap Si-C films deposited using 97% methane in silane. Increasing the deposition power density resulted in a larger bandgap and a smaller refractive index.

Numerical Analysis on the Performance of the Solid Solar Particle Receiver With the Influence of Aerowindow

2008 ◽  
Author(s):  
Zhuoqi Chen ◽  
Yitung Chen ◽  
Taide Tan
Keyword(s):  
Solid Particle ◽  
Particle Temperature ◽  
Research Work ◽  
Three Dimensional ◽  
Fluid Phase ◽  
Injection Velocity ◽  
Average Particle ◽  
Three Dimensional Model ◽  
Particle Radiation ◽  
Solar Particle

In this research work, a three dimensional model of the solid solar particle receiver (SPR) with the influence of aerowindow is analyzed. The free-falling down particles will form a solid particle curtain and be directly heated up by the reflected concentrating solar energy which passes through the aperture of the cavity. The mass, momentum and energy exchange between the solid particle phase and gas fluid phase are simulated by the two-way coupling Euler-Lagrange method. A discrete ordinate radiative transfer method has been applied to study the coupling of radiative heat transfer and the falling particle curtain. The realizable κ-ε model is used in the investigation of turbulence flow. In order to predict the performance of the SPR, the aerodynamic behavior of the particles and thermal interaction, which include particle-particle radiation, particle-wall radiation, particle-air convection, and air-wall convection are analyzed and demonstrated in this work. All the investigation on the simulation model is focusing on optimizing the performance of the SPR. The parametric studies of the performance of the SPR with aerowindow are investigated under the different working conditions, such as air injection velocity, particle mass flow rate, and the efficiency of the SPR and exit average particle temperature are compared upon these conditions.

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