D.C. Plasma Spraying: Effect of Arc root Fluctuations on Particle Behavior in the Plasma Jet

1999 ◽  
Vol 3 (2-3) ◽  
pp. 235-254 ◽  
Author(s):  
B. Dussoubs ◽  
G. Mariaux ◽  
Armelle Vardelle ◽  
Michel Vardelle ◽  
Pierre Fauchais
Keyword(s):  
Plasma Spraying ◽  
Plasma Jet ◽  
Particle Behavior ◽  
Arc Root

Numerical Study on Plasma Jet and Particle Behavior in Multi-arc Plasma Spraying

2017 ◽  
Vol 26 (5) ◽  
pp. 811-830 ◽  
Author(s):  
K. Bobzin ◽  
M. Öte ◽  
J. Schein ◽  
S. Zimmermann
Keyword(s):  
Plasma Spraying ◽  
Numerical Study ◽  
Plasma Jet ◽  
Arc Plasma ◽  
Particle Behavior

scholarly journals High-Speed Video Analysis of the Process Stability in Plasma Spraying

2021 ◽  
Author(s):  
K. Bobzin ◽  
M. Öte ◽  
M. A. Knoch ◽  
I. Alkhasli ◽  
H. Heinemann
Keyword(s):  
Plasma Spraying ◽  
High Speed ◽  
Plasma Jet ◽  
Plasma Jets ◽  
Time Dependent ◽  
Acquisition Time ◽  
Fast Fourier Transformation ◽  
Frequency Spectra ◽  
Dependent Signal ◽  
The Stability

AbstractIn plasma spraying, instabilities and fluctuations of the plasma jet have a significant influence on the particle in-flight temperatures and velocities, thus affecting the coating properties. This work introduces a new method to analyze the stability of plasma jets using high-speed videography. An approach is presented, which digitally examines the images to determine the size of the plasma jet core. By correlating this jet size with the acquisition time, a time-dependent signal of the plasma jet size is generated. In order to evaluate the stability of the plasma jet, this signal is analyzed by calculating its coefficient of variation cv. The method is validated by measuring the known difference in stability between a single-cathode and a cascaded multi-cathode plasma generator. For this purpose, a design of experiment, covering a variety of parameters, is conducted. To identify the cause of the plasma jet fluctuations, the frequency spectra are obtained and subsequently interpreted by means of the fast Fourier transformation. To quantify the significance of the fluctuations on the particle in-flight properties, a new single numerical parameter is introduced. This parameter is based on the fraction of the time-dependent signal of the plasma jet in the relevant frequency range.

Plasma Spraying Using Ar-He-H2 Gas Mixtures

1998 ◽  
Author(s):  
S. Janisson ◽  
A. Vardelle ◽  
J.F. Coudert ◽  
B. Pateyron ◽  
P. Fauchais ◽  
...  
Keyword(s):  
Plasma Spraying ◽  
Gas Flow ◽  
Plasma Jet ◽  
Gas Mixtures ◽  
Gas Velocity ◽  
Gas Flow Rate ◽  
Static Behavior ◽  
Operating Variables ◽  
Arc Current ◽  
Plasma Guns

Abstract In D.C. plasma guns used for plasma spraying, the properties of the plasma forming-gas control, to a great extent, the characteristics of the plasma jet and the momentum, heat and mass transfer to the particles injected in the flow. This paper deals with mixtures of argon, helium and hydrogen and the effect of the volume composition of these mixtures on the dynamic and static behavior of the plasma jet. Both were investigated from the measurements of arc voltage and gas velocity. Correlations between these parameters and the operating variables (arc current, gas flow rate, gas mixture composition) were established from a dimensional analysis. The results were supported by the calculation of the thermodynamic and transport properties of the ternary gas mixtures used in this study.

scholarly journals The Influence of Anode Inner Contour on Atmospheric DC Plasma Spraying Process

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Kui Wen ◽  
Min Liu ◽  
Kesong Zhou ◽  
Xuezhang Liu ◽  
Renzhong Huang ◽  
...  
Keyword(s):  
Plasma Spraying ◽  
Thermal Efficiency ◽  
Plasma Jet ◽  
Measured Temperature ◽  
Arc Voltage ◽  
Cylindrical Nozzle ◽  
Jet Characteristics ◽  
Plasma Spraying Process ◽  
Spraying Process ◽  
Plasma Jet Characteristics

In thermal plasma spraying process, anode nozzle is one of the most important components of plasma torch. Its inner contour controls the characteristics of plasma arc/jet, determining the motion and heating behaviors of the in-flight particles and hence influencing the coating quality. In this study, the effects of anode inner contour, standard cylindrical nozzle, and cone-shaped Laval nozzle with conical shape diverging exit (CSL nozzle) on the arc voltage, net power, thermal efficiency, plasma jet characteristics, in-flight particle behaviors, and coating properties have been systematically investigated under atmospheric plasma spraying conditions. The results show that the cylindrical nozzle has a higher arc voltage, net power, and thermal efficiency, as well as the higher plasma temperature and velocity at the torch exit, while the CSL nozzle has a higher measured temperature of plasma jet. The variation trends of the plasma jet characteristics for the two nozzles are comparable under various spraying parameters. The in-flight particle with smaller velocity of CSL nozzle has a higher measured temperature and melting fraction. As a result, the coating density and adhesive strength of CSL nozzle are lower than those of cylindrical nozzle, but the deposition efficiency is greatly improved.

scholarly journals Structural Changes of Hydroxylapatite during Plasma Spraying: Raman and NMR Spectroscopy Results

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 987
Author(s):  
Robert B. Heimann
Keyword(s):  
Plasma Spraying ◽  
Structural Changes ◽  
Plasma Jet ◽  
Biological Properties ◽  
Atmospheric Plasma Spraying ◽  
Atmospheric Plasma ◽  
Decomposition Reactions ◽  
Laser Raman ◽  
Hot Plasma ◽  
Crystallographic Symmetry

Functional osseoconductive coatings based on hydroxylapatite (HAp) and applied preferentially by atmospheric plasma spraying to medical implant surfaces are a mainstay of modern implantology. During contact with the hot plasma jet, HAp particles melt incongruently and undergo complex dehydration and decomposition reactions that alter their phase composition and crystallographic symmetry, and thus, the physical and biological properties of the coatings. Surface analytical methods such as laser-Raman and nuclear magnetic resonance (NMR) spectroscopies are useful tools to assess the structural changes of HAp imposed by heat treatment during their flight along the hot plasma jet. In this contribution, the controversial information is highlighted on the existence or non-existence of oxyapatite, i.e., fully dehydrated HAp as a thermodynamically stable compound.

Capturing the Influence of Jet Fluctuations on Particles in Plasma Spraying

2021 ◽  
Author(s):  
K. Bobzin ◽  
H. Heinemann ◽  
A. O‘Brien
Keyword(s):  
Plasma Spraying ◽  
High Speed ◽  
High Sensitivity ◽  
Plasma Jet ◽  
Plasma Generator ◽  
Operating Conditions ◽  
High Temporal Resolution ◽  
Cathode Plasma ◽  
Novel Method ◽  
Plasma Sprayed

Abstract Instabilities and fluctuations of the plasma jet can have a significant influence on the particle in-flight temperatures and velocities, thus affecting the properties of plasma sprayed coatings. Presented in this paper is a novel method for capturing the effects particles are exposed to in the plasma spraying process. High-speed camera images of a plasma jet generated by a cascaded three cathode plasma generator (TriplexPro-210) are recorded for varying operating conditions. The images are processed using the inverse Abel transform. This transformation accounts for the fact that the images represent a 2-D projection and generates correct intensity values of the plasma jet images. These images are then combined with particle tracks resulting from CFD simulations of the plasma jet to match the particles path with the recorded plasma jet. This new method allows a precise description of the plasma intensity experienced by individual particles with a high temporal resolution. The results show a high sensitivity of the method, it can even detect the influence of the plasma jet originating from the cascaded triple arc plasma generator, which is considered as rather stable, on the particles.

Integrated Simulation of the Atmospheric Plasma Spraying Process

1998 ◽  
Author(s):  
S. Kundas ◽  
A. Kuzmenkov ◽  
E. Lugscheider ◽  
U. Eritt
Keyword(s):  
Plasma Spraying ◽  
Experimental Verification ◽  
Computer Experiments ◽  
Plasma Jet ◽  
Atmospheric Plasma Spraying ◽  
Atmospheric Plasma ◽  
Temperature Dependent ◽  
Integrated Simulation ◽  
Plasma Spraying Process ◽  
Spraying Process

Abstract The main purpose of this work is the development of mathematical and computer models for the integrated simulation of all stages of the atmospheric plasma spraying process (APS) with temperature dependent thermophysical and mechanical properties of the used materials and gases and experimental verification of the simulated results. The following mathematical models of APS were created: particle heating and movement in the plasma jet; coating structure formation; heat transfer and residual stresses in the coating-substrate system. The computer realization of these models enables us to model all stages of APS (integrated or separately). Databases of coating, substrate and plasma-gas substances include the temperature dependent properties. The model of APS is divided in 3 parts, which are connected by continuous data interface. Two dimensional approximation of plasma-gas velocity and temperature in the free plasma jet was used for computation of particle velocity, trajectory and temperature. This information was created with a special Graphic program module and included in database. Computer experiments for plasma spraying of Ah03 and ZrO2+8%Y2O3 in Ar/H2 plasma were carried out. The experimental verification of developed models with High-Velocity-Pyrometry (HVP) and Laser-Doppler- Anemometry (LDA) have shown the satisfactory precision of simulated results.

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