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.

The Influence of Injector Geometry and Carrier Gas Flow Rate on Spray Pattern

1997 ◽  
Author(s):  
J.R. Fincke ◽  
W.D. Swank ◽  
D.C. Haggard
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Functionally Graded ◽  
Injection Velocity ◽  
Average Particle ◽  
Gas Flow Rate ◽  
Particle Injection ◽  
Spray Pattern ◽  
Carrier Gas ◽  
Carrier Gas Flow

Abstract The performance (particle velocity and velocity distribution) of a typical injector, and the resulting particle spray pattern for metallic (NiCrAlY) and ceramic (ZrO2) particles are examined as a function of carrier gas flow rate and the effect of varying the geometry immediately upstream of the injector. Injector performance is also examined for a 1:1 mixture of ceramic and metallic particles such as is used in the spraying of functionally graded materials. The upstream geometries tested included a 90° "tee," a 90° elbow, and a straight entrance. The elbow geometry was tested in both "up" and "down" orientation to determine the influence of gravity. The upstream geometry can alter the average particle injection velocity by 10-15% influencing both the spray pattern trajectory and width.

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.

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.

The Effects of Optimized Nozzle-Substrate Distance on Cold Gas Dynamic Spray (CGDS) Process

2010 ◽  
Author(s):  
Yi-Hsin Yen ◽  
Sung-Cheng Wong ◽  
Tien-Chien Jen ◽  
Qinghua Chen ◽  
Quan Liao
Keyword(s):  
Particle Size ◽  
Gas Flow ◽  
Aluminum Substrate ◽  
Coating Quality ◽  
Carrier Gas ◽  
Substrate Distance ◽  
Gas Dynamic ◽  
Cold Gas Dynamic Spray ◽  
Gas Dynamic Spray ◽  
Cold Gas

This paper presents research that is focused on the particle coating quality of Cold Gas Dynamic Spray (CGDS) process. The coating quality is affected by several different factors, namely the carrier gas species, nozzle-substrate distance, nozzle inlet pressure and the coating particle size. The intent of this research is to use numerical simulations to predict the coating quality and to find the optimized nozzle-substrate distance and particle size in CGDS process by tuning the factor of nozzle-substrate distance and the coating particle size. Air was chosen as the carrier gas to accelerate copper (Cu) particles, which have diameters ranging from 2–50μm.. There are two main target factors, the nozzle-substrate distance and particle size, which are going to affect the coating quality in this study. In the first part, 14 sets of nozzle-substrate distance models ranging from 2.5mm to 100 mm were setup to study the air velocity, density, temperature and pressure contour through the De-Laval nozzle to the aluminum substrate. In the second part, 49 sets of different particle sizes ranging from 2–50μm in diameter were computed. The particle’s impact velocities on the aluminum substrate were applied to 12 different nozzle-substrate distance models. The bow shock wave, a high pressure gradient region, formed in front of the aluminum substrate, makes the copper particles decelerate in front of the substrate. The results showed that the gas flow velocity contours was affected by different nozzle-substrate distances, which caused different particle accelerating characteristics.

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.

Fabrication of Rheological Material by Rotating Gas Bubble Stirring

2011 ◽  
Vol 239-242 ◽  
pp. 1573-1576 ◽  
Author(s):  
Lei Zhang ◽  
Xuan Pu Dong ◽  
Wen Jun Wang ◽  
Rong Ma ◽  
Ke Li ◽  
...  
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Rotation Speed ◽  
Gas Bubble ◽  
Gas Flow Rate ◽  
Control Functions ◽  
Stirring Effect ◽  
Strong Convection ◽  
Semi Solid ◽  
Flow Rate Control

A rotating gas bubble stirring technique with specially designed equipment has been developed for the production of light alloy semi-solid slurry. The equipment was specially designed to have temperature, rotation speed and gas flow rate control functions. An Al-Si aluminum alloy was applied as the experimental material. The results showed that large volume of semi-solid slurry could be achieved with the actual stirring temperature of 4 °C to 20 °C below the liquidus temperature of the alloy, and the rotation speed of 195 r/min, and the gas flow rate of 2 L/min. A strong convection and weak stirring effect which was induced by the rotating gas bubbles in the melt was founded responsible for the formation of the semi-solid slurry.

scholarly journals О газоструйном методе осаждения наноструктурных пленок серебра

2019 ◽  
Vol 89 (6) ◽  
pp. 830
Author(s):  
Н.Ю. Быков ◽  
А.И. Сафонов ◽  
Д.В. Лещев ◽  
С.В. Старинский ◽  
А.В. Булгаков
Keyword(s):  
Substrate Surface ◽  
Supersonic Jet ◽  
Direct Simulation Monte Carlo ◽  
Gas Jet ◽  
Silver Clusters ◽  
Silicon Substrates ◽  
Silver Nanostructures ◽  
Carrier Gas ◽  
Silver Vapor ◽  
Background Gas

AbstractThe synthesis of thin silver films by the gas-jet deposition method is experimentally and theoretically studied. When the metal is deposited onto silicon substrates from a supersonic jet of silver vapor with a helium carrier gas, nanostructured films with a 3−30 nm size of nanostructures are obtained for a 1230−1380 K range of jet source temperatures. The data on Ag–He gas-jet dynamics when it is expanded into vacuum (velocity, temperature, concentration, flux of particles onto a substrate) depending on parameters at the source (vapor temperature, flow rate of a carrier gas) are obtained by the method of direct simulation Monte Carlo. The range of optimal helium flow rates, when the efficiency of a gas-jet source is maximal, is determined. It is established that the presence of a background gas in a deposition chamber at pressure higher than 1 Pa decreases the flow of particles onto a substrate, and a simple way of its evaluation is proposed. Conditions for formation of silver clusters in the jet are determined by using the simulation. It is shown that for experimental deposition regimes there are no clusters in the jet, and the observed silver nanostructures are formed on the substrate surface.

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