Role of Atmosphere During Plasma Processing for Application to Plasma Spraying of Aluminum Onto Polyethyleneterephtalate (PET)

1998 ◽  
Author(s):  
H. Hubert ◽  
F. Blein ◽  
A. Freslon ◽  
M. Jeandin ◽  
C. Le Paven ◽  
...  
Keyword(s):  
Plasma Spraying ◽  
Detrimental Effect ◽  
Plasma Processing ◽  
Plasma Jet ◽  
Tensile Tests ◽  
Polymeric Substrates ◽  
The Impact ◽  
Plasma Spraying Process ◽  
Spraying Process

Abstract Polymeric substrates have to be severely cooled during the plasma spraying process to limit detrimental effect due to the high heating flow from the plasma jet. The « Atmosphere and Temperature Controlled process » (ATC, patented by CEA) was used to maintain the substrates near room temperature. However, the PET substrates might undergo some superficial modifications which could result from the plasma jet heating and particle heating at the impact. This paper deals with a study of chemical modifications in PET as a function of surrounding atmospheres during plasma processing. Aluminum coating adhesion was determined using tensile tests.

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.

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.

The Investigation of the Zirconium Silicate Coatings Prepared by APS

2011 ◽  
Vol 686 ◽  
pp. 678-685
Author(s):  
Yan Bo Liu ◽  
Quan Sheng Wang ◽  
Zhuang Ma ◽  
Zhong Du ◽  
Juan Liu
Keyword(s):  
Plasma Spraying ◽  
Design Method ◽  
Orthogonal Design ◽  
Functional Coatings ◽  
Zirconium Silicate ◽  
Spraying Parameters ◽  
Orthogonal Design Method ◽  
The Impact ◽  
Plasma Spraying Process ◽  
Spraying Process

The zirconium silicate can be deposited as functional coatings which will be used at high temperature because of its high melting point and low thermal conductivity. It can also prevent the oxygen of the environment through the coatings and react with the substrate. In this paper, plasma spraying technology was selected to prepare the coatings of zirconium silicate. The orthogonal design method was used to optimize the parameter of plasma spraying process. The content of zirconium silicate in the coatings was checked by XRD because of the decomposition of the zirconium silicate at 1711K.The bond strength and porosity of the coatings were also measured after the optimizing of the plasma spraying parameters in this paper. According the impact on the porosity, the factors of the process can be ordered as follows: spraying distance, current, primary gases and secondary gases. And the order of spraying factors according the impact on the content of zirconium silicate in the coatings was showed as follows: spraying distance, secondary gas, primary gas and current.

Pupil with Obsessive-Compulsive Disorder

2017 ◽  
Vol 7 (2) ◽  
pp. 7-25
Author(s):  
Karolina Diallo
Keyword(s):  
Obsessive Compulsive Disorder ◽  
School Performance ◽  
School Environment ◽  
Detrimental Effect ◽  
Obsessive Compulsive ◽  
Compulsive Disorder ◽  
The Past ◽  
And Performance ◽  
The Impact

Pupil with Obsessive-Compulsive Disorder. Over the past twenty years childhood OCD has received more attention than any other anxiety disorder that occurs in the childhood. The increasing interest and research in this area have led to increasing number of diagnoses of OCD in children and adolescents, which affects both specialists and teachers. Depending on the severity of symptoms OCD has a detrimental effect upon child's school performance, which can lead almost to the impossibility to concentrate on school and associated duties. This article is devoted to the obsessive-compulsive disorder and its specifics in children, focusing on the impact of this disorder on behaviour, experience and performance of the child in the school environment. It mentions how important is the role of the teacher in whose class the pupil with this diagnosis is and it points out that it is necessary to increase teachers' competence to identify children with OCD symptoms, to take the disease into the account, to adapt the course of teaching and to introduce such measures that could help children reduce the anxiety and maintain (or increase) the school performance within and in accordance with the school regulations and curriculum.

Improvement of Solution Type Plasma Spraying Process

2005 ◽  
Vol 502 ◽  
pp. 505-510 ◽  
Author(s):  
Masami Futamata ◽  
Xiaohui Gai ◽  
Toyokazu Mizumoto ◽  
Kimio Nakanishi
Keyword(s):  
Mechanical Properties ◽  
Plasma Spraying ◽  
Hollow Cathode ◽  
Thermal History ◽  
Thermal Spraying ◽  
Physical And Mechanical Properties ◽  
Good Reproducibility ◽  
Solution Type ◽  
Plasma Spraying Process ◽  
Spraying Process

To fabricate thermal spraying coatings with good reproducibility, it is necessary to improve the process of the equalization of both thermal history and impacting behavior of the particles. In this study, the characteristics of the solution type plasma spraying using the hollow-cathode type torch are investigated. The physical and mechanical properties that are different from usual thermal spraying coatings are described. By using solutions including metal ingredients in a state of ion, colloid or sol, thinner coating that cannot be made by conventional plasma spraying methods is formed on various substrates. The coatings are uniform in appearance.

Mathematical Modeling of a Free Plasma Jet Discharging into Air and Comparison with Probe Measurements

1997 ◽  
Author(s):  
R. Bolot ◽  
M. Imbert ◽  
C. Coddet
Keyword(s):  
Local Thermodynamic Equilibrium ◽  
Argon Plasma ◽  
Plasma Jet ◽  
Equilibrium Composition ◽  
Physical Phenomena ◽  
Plasma Spraying Process ◽  
Spraying Process ◽  
Free Plasma ◽  
Argon Plasma Jet ◽  
Probe Measurements

Abstract Plasma spraying process modeling is useful to understand physical phenomena and to decrease the number of experiments. In this paper, a study of the external plasma jet is proposed: the PHOENICS™ CFD code was used with a 2D axisymmetrical geometry and a standard K-ε turbulence model. In a first step, thermodynamic and transport properties were calculated from chemical equilibrium composition, thermodynamic derivatives and kinetic theory of gases. Local Thermodynamic Equilibrium (LTE) was assumed for both plasma and surrounding gases. The proposed numerical results were computed for comparison with temperature measurements realized by Brossa and Pfender in the case of an argon plasma jet discharging into air, using enthalpy probes. The predictions were found reasonably accurate. The influence of the surrounding gas nature was also verified as the validity of the parabolic assumption.

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