Influence of Plasma Gas (Spral 22, Ar/H2) and Impurities (O2, H2O) on the Electrode Lifetime During Spraying

1998 ◽  
Author(s):  
V. Gourlaouen ◽  
F. Remy ◽  
J.M. Leger ◽  
J. Sattonnet
Keyword(s):  
Plasma Spraying ◽  
Spare Parts ◽  
Coating Properties ◽  
Voltage Versus ◽  
Plasma Spraying Process ◽  
Good Coating ◽  
Spraying Process

Abstract The plasma spraying electrodes are spare parts playing an important role in the process. In order to ensure good coating properties, they have to be frequently replaced. The purpose of this work was to evaluate the electrode lifetime and to study its evolution for different plasma gas (Ar/H2 mixture or SPRAL22) and impurity levels (oxygen and humidity). For these experiments, a PTF4 torch was used. The evolution of the voltage versus time was recorded during spraying. The time elapsed for a 5V drop was taken as the electrode lifetime. Experiments pointed out that the SPRAL22 led to an increase of lifetime by a factor 3 to 4. The evolution of the voltage versus time was also carried out for an Ar/H2 mixture with different oxygen and humidity contents. These impurities were systematically analysed during the tests. The electrode lifetime was strongly affected by both elements. This emphasized the importance of the gas purity in the plasma spraying process.

Correlations Between In-Flight Particle Concentrations and Coating Properties in Atmospheric Plasma Spraying of Alumina

1996 ◽  
Author(s):  
T. Lehtinen ◽  
J. Knuuttila ◽  
J. Vattulainen ◽  
T. Mäntylä ◽  
R. Hernberg
Keyword(s):  
Plasma Spraying ◽  
Powder Particle ◽  
Particle Concentration ◽  
Ccd Camera ◽  
Atmospheric Plasma Spraying ◽  
Atmospheric Plasma ◽  
Electrode Wear ◽  
Coating Properties ◽  
Plasma Spraying Process ◽  
Spraying Process

Abstract The plasma spraying process is controlled by various parameters that have an influence on powder particle velocities, temperatures and trajectories just before impact to the substrate. In order to fully utilize the thermal and kinetic energy of the plasma it is important to obtain information from these powder particle properties. In this work an intensified CCD camera has been used to detect in-flight particles in an atmospheric plasma spraying process. Plasma spraying was performed using fused and crushed AI2O3 powder. The powder carrier gas flow rate was varied during the spraying experiments. All the other deposition parameters were kept constant. Coatings produced using relatively new spraygun electrodes are compared with ones produced later with the same electrodes when they were worn out. The particle concentration is determined on a relative scale by the fraction of the area of a CCD camera frame covered by particle images. Further investigations necessary to clearify the relationship between the measured relative particle concentration and the true particle concentration are identified. The coatings are analyzed for wear resistance, degree of melting, deposition efficiency, hardness and porosity. The dependence of these coating properties on the relative particle concentration and the effect of electrode wear on the relative particle concentration are studied.

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.

A Numerical Study of Suspension Injection in Plasma-Spraying Process

2013 ◽  
Vol 23 (1-2) ◽  
pp. 3-13 ◽  
Author(s):  
F. Jabbari ◽  
M. Jadidi ◽  
R. Wuthrich ◽  
A. Dolatabadi
Keyword(s):  
Plasma Spraying ◽  
Numerical Study ◽  
Plasma Spraying Process ◽  
Spraying Process

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.

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