In-Flight Particle Characteristics of Plasma-Sprayed Dense Yttria Stabilized Zirconia

1998 ◽  
Author(s):  
L. Leblanc ◽  
C. Moreau
Keyword(s):  
Monitoring System ◽  
Particle Temperature ◽  
Deposition Efficiency ◽  
The State ◽  
Spray Parameters ◽  
Zirconia Powder ◽  
Integrated Optical ◽  
Coating Characteristics ◽  
Coating Microstructure ◽  
Plasma Sprayed

Abstract The influence of input spray parameters on the state of plasma-sprayed zirconia powder is studied. The particle temperature, velocity and diameter are measured using an integrated optical monitoring system. The monitoring system allows the investigation of the particles behavior in the spray jet. The collected information is correlated to coating characteristics such as deposition efficiency, microstructure and thermal diffusivity. Results show that, by monitoring the state of sprayed particles, a better understanding of the coating microstructure and properties can be achieved.

The Role of Different Atmospheric Plasma Spray Parameters on Microstructure of Abradable AlSi-Polyester Coatings

2017 ◽  
Vol 270 ◽  
pp. 224-229
Author(s):  
David Jech ◽  
Ladislav Čelko ◽  
Pavel Komarov ◽  
Jindřich Ziegelheim ◽  
Zdeněk Česánek ◽  
...  
Keyword(s):  
Deposition Efficiency ◽  
Atmospheric Plasma ◽  
Spray Parameters ◽  
Technological Parameters ◽  
Coating Microstructure ◽  
Two Parameters ◽  
Plasma Sprayed ◽  
Abradable Coatings ◽  
And Control

One of the approaches to increase the thermic efficiency of aerospace engines is the application of abradable coatings enabling minimization and control of the clearance between the stator and the rotating blades tips. The main purpose of this contribution is to define the role of different technological parameters utilized for atmospheric plasma spraying of AlSi-polyester coating on its resulting microstructure. Deposition of abradable coatings on the real engine parts is mostly dependent on spraying stand-off distance and on spraying angle. These two parameters influence not only the coating microstructure but also the deposition efficiency itself, which is directly connected with economical aspects of the coating production. The set of experimental samples with atmospheric plasma sprayed Ni-based bond coat and two in chemical composition same initial powders delivered from different powder manufacturers were used to spray thick AlSi-polymer top coats with different spraying stand-off distances and angles. Subsequently some of the samples were also heat treated to burn-out the polymer phase from the coating microstructure. The Rockwell HR15Y hardness was measured on all samples and the microstructure and coating thickness were evaluated by means of light microscopy and image analysis methods.

Simultaneous Independent Measurement of Splat Diameter and Cooling Time during Impact on a Substrate of Plasma Sprayed Molybdenum Particles

1997 ◽  
Author(s):  
P. Gougeon ◽  
C. Moreau
Keyword(s):  
High Speed ◽  
Thermal Emission ◽  
Particle Temperature ◽  
Cooling Time ◽  
Spray Parameters ◽  
Coating Structure ◽  
Molten Droplets ◽  
Plasma Sprayed ◽  
The Impact ◽  
Molybdenum Particles

Abstract In thermal spray processes, the coating structure is the result of flattening and cooling of molten droplets on the substrate. The study of the cooling time and evolution of the splat size during impact is then of the highest importance to understand the influence of the spray parameters and substrate characteristics on the coating structure. Measurement of particle temperature during impact requires the use of a high-speed 2-color pyrometer to collect the thermal emission of the particle during flattening. Simultaneous measurement of the splat size with this pyrometer is difficult since the size of the particle can change as it cools down. To measure the splat size independently, a new measurement technique has been developed. In this technique the splat size is measured from the attenuation of the radiation of a laser beam illuminating the particle during impact. Results are presented for plasma sprayed molybdenum particles impacting on a glass substrate at room temperature. It is shown that the molybdenum splat reaches its maximum extent about 2 microseconds after the impact. In this work, we show that this increase of the splat surface is followed by a phase during which the splat size decreases significantly during 2 to 3 microseconds.

Particle Velocity and Temperature influences on the Microstructure of Plasma Sprayed Nickel

1996 ◽  
Author(s):  
R.N. Wright ◽  
J.R. Fincke ◽  
W.D. Swank ◽  
D.C. Haggard
Keyword(s):  
Relative Density ◽  
Particle Velocity ◽  
Particle Temperature ◽  
Deposition Efficiency ◽  
Nickel Coatings ◽  
Higher Temperature ◽  
Velocity Changes ◽  
Particle Velocities ◽  
Lower Temperature ◽  
Plasma Sprayed

Abstract The variation in microstructure of high power plasma sprayed nickel coatings deposited with particle velocities ranging from 150 to 425 m/s and nominal particle temperatures of 1650 or 2050°C has been characterized. The relative density of coatings produced at the higher temperature is above 99.5% of theoretical regardless of the particle velocity; at the lower particle temperature the relative density is found to increase with increasing particle velocity. The fraction of unmelted particles is also found to increase with increasing velocity at the lower temperature. The relative deposition efficiency is approximately twice as high for the lower temperature particles compared to the high temperature, and for both temperatures the deposition efficiency decreases substantially with increasing velocity. Changes in the morphology of individual splats with changes in particle characteristics are also described.

Tungsten Carbide-Cobalt Coatings for Industrial Applications

2000 ◽  
Author(s):  
M. Dorfman ◽  
J. DeFalco ◽  
J. Karthikeyan
Keyword(s):  
Surface Roughness ◽  
Wear Resistance ◽  
Tungsten Carbide ◽  
Gas Flow ◽  
Deposition Efficiency ◽  
Industrial Applications ◽  
Spray Parameters ◽  
Coating Characteristics ◽  
Steel Substrates

Abstract This paper compares the coating characteristics of two HVOF processes: air-cooled converging-nozzle Diamond Jet (DJ) spraying and Hybrid 2600 air/water-cooled converging/diverging technology. WC-Co coatings were deposited on steel substrates using different combinations of spray parameters, gas flow ratios, and cooling gas types. The coatings were then examined and tested to determine the extent to which microstructure, hardness, surface roughness, wear resistance, and deposition efficiency can be controlled. In addition to investigating process relationships, the paper also addresses the issues of practicality and cost.

Investigation of the Long-Term Stability of Plasma Spraying by Monitoring Characteristics of the Sprayed Particles

1997 ◽  
Author(s):  
L. Leblanc ◽  
P. Gougeon ◽  
C. Moreau
Keyword(s):  
Plasma Spraying ◽  
Particle State ◽  
Electrode Wear ◽  
Spray Parameters ◽  
Long Term Stability ◽  
Long Term Experiment ◽  
On Line ◽  
Coating Microstructure ◽  
Plasma Sprayed

Abstract In plasma spraying temperature and velocity of the sprayed particles are among the most important parameters influencing the microstructure and properties of the deposited coatings. However, the sprayed particle state is influenced by uncontrollable parameters such as the wear state of the electrodes. In order to investigate the influence of the electrode wear state on sprayed particles, a long-term experiment was conducted during which on-line measurements of plasma sprayed yttria-zirconia powder were performed. Results show that even though input parameters were kept constant during the experiment the state of the sprayed particle changed significantly and coatings prepared at different spraying times have different microstructures and can have different properties. However, by changing some input spray parameters it was possible to retrieve the initial sprayed particle state and coating microstructure.

Plasma Sprayed Alumina-Titania Coatings

1992 ◽  
Vol 271 ◽  
Author(s):  
T. J. Steeper ◽  
A. J. Rotolico ◽  
J. E. Nerz ◽  
W. L. Riggs ◽  
D. J. Varacalle ◽  
...  
Keyword(s):  
Dielectric Strength ◽  
Deposition Efficiency ◽  
Hydraulic Testing ◽  
Fractional Factorial ◽  
Operating Parameters ◽  
Spray Parameters ◽  
Air Plasma ◽  
X Ray Diffraction ◽  
Plasma Sprayed ◽  
Titania Coatings

ABSTRACTThis paper presents an experimental study of the air plasma spraying (APS) of alumina-titania powder using argon-hydrogen working gases. This powder system is being used in the fabrication of heater tubes that emulate nuclear fuel tubes for use in thermal-hydraulic testing. Experiments were conducted using a Taguchi fractional-factorial design parametric study. Operating parameters were varied around the typical spray parameters in a systematic design of experiments in order to display the range of plasma processing conditions and their effect on the resultant coatings. The coatings were characterized by hardness and electrical tests, surface profilometry, image analysis, optical metallography, and x-ray diffraction. Coating qualities are discussed with respect to dielectric strength, hardness, porosity, surface roughness, deposition efficiency, and microstructure. Attempts are made to correlate the features of the coatings with the changes in operating parameters.

Correlation between Particle Temperature and Velocity and the Structure of Plasma Sprayed Zirconia Coatings

1996 ◽  
Author(s):  
M. Prystay ◽  
P. Gougeon ◽  
C. Moreau
Keyword(s):  
Thermal Diffusivity ◽  
Size Distribution ◽  
Particle Temperature ◽  
Total Porosity ◽  
Crack Size ◽  
Optical Monitoring ◽  
Coating Properties ◽  
Coating Structure ◽  
Integrated Optical ◽  
Plasma Sprayed

Abstract The correlation between particle temperature and velocity and the structure of plasma sprayed zirconia coatings is studied to determine which parameter most strongly influences the coating structure. The particle temperature and velocity are measured using an integrated optical monitoring system positioned normal to the spraying axis. The total porosity, angular crack distribution, crack size distribution and thermal diffusivity are correlated with the particle temperature and velocity. Results show that the temperature of the sprayed particles has a larger effect on the coating properties than the velocity in the conditions investigated.

Effect of In-Flight Particle Characteristics on the Properties of Plasma Sprayed Nicraly & NiCoCrALY

1998 ◽  
Author(s):  
L. Pejryd ◽  
J. Wigren ◽  
P. Gougeon ◽  
C. Moreau
Keyword(s):  
Bond Coat ◽  
Dominant Role ◽  
Diagnostic System ◽  
Gas Flows ◽  
Spray Parameters ◽  
Particle Properties ◽  
Spraying Parameters ◽  
On Line ◽  
Coating Microstructure ◽  
Plasma Sprayed

Abstract Plasma sprayed bondcoats of MCrAIY type play a dominant role for the life of thermal barrier coatings. During service an oxide is formed between the bond and top coat, also internally and between the bond coat and the substrate. This oxide growth has to be minimised to improve the coating's life. Apart from the powder chemistry, the coating microstructure is the major factor governing the oxidation in a given environment. It is known that the coating microstructure and the coating strength are strongly related to the plasma spraying parameters. In this work, the effects of the in flight particle properties on the adhesion/cohesion and on the microstructure of a NiCrAIY & NiCoCrAIY bond coat are investigated. The relation between the particle velocity and temperature, as measured with the DPV 2000 particle diagnostic system, and the coating properties are very important. Relatively small changes of spray parameters (arc current, gas flows, ..) lead to significant changes on the sprayed particles and finally also in the coating microstructure. On the other hand, the same particle properties, although sprayed with different guns, produces coatings with similar properties. Through on-line control of the particle states it is expected that the quality of plasma sprayed MCrAIY's coatings can be significantly improved.

Predicting the Deposition Efficiency of Plasma Sprayed Alumina Coatings on AZ31B Magnesium Alloy by Response Surface Methodology

2018 ◽  
Vol 877 ◽  
pp. 66-81
Author(s):  
D. Thirumalaikumarasamy ◽  
V. Balasubramanian ◽  
S. Sree Sabari ◽  
R. Rajesh ◽  
Medha R. Elayidom
Keyword(s):  
Response Surface Methodology ◽  
Magnesium Alloy ◽  
Response Surface ◽  
Plasma Spray ◽  
Deposition Efficiency ◽  
Spray Parameters ◽  
Empirical Relationships ◽  
Alumina Coatings ◽  
Az31b Magnesium Alloy ◽  
Plasma Sprayed

Plasma sprayed ceramic coatings are successfully employed in many industrial applications, where high wear and corrosion resistance with thermal insulation are needed. Plasma spray parameters such as power, stand-off distance and powder feed rate have significant influence on coating characteristics like deposition efficiency. This paper presents the use of statistical techniques specially response surface methodology (RSM), analysis of variance, and regression analysis to develop empirical relationships to predict deposition efficiency of plasma sprayed alumina coatings on AZ31B magnesium alloy. The developed empirical relationships can be efficiently used to predict deposition efficiency of plasma sprayed alumina coatings at 95% confidence level. Response graphs and contour plots were constructed to identify the optimum plasma spray parameters to attain maximum deposition efficiency in alumina coatings. Further, correlating the spray parameters with coating properties permits the identification of characteristics regime to achieve desired quality of coatings.

Investigation of the Silicon Loss in APS MoSi2 under Typical Spray Conditions

1996 ◽  
Author(s):  
K.J. Hollis ◽  
A. Bartlett ◽  
R.G. Castro ◽  
R.A. Neiser
Keyword(s):  
Particle Trajectory ◽  
Particle Temperature ◽  
Sem Analysis ◽  
Empirical Models ◽  
Spray Parameters ◽  
X Ray Diffraction ◽  
Temperature Oxidation ◽  
X Ray ◽  
Plasma Sprayed ◽  
Oxidation And Corrosion

Abstract MoSi2 provides good high temperature oxidation and corrosion resistance. However, the lower silicides such as MosSis do not provide such resistance. In this study, atmosphereic plasma sprayed (APS) MoSi2 particle temperatures and velocities were measured under various torch conditions chosen to span the majority of typically utilized spray parameters. Empirical models of particle temperature and velocity were computed from the data. Three spray conditions were chosen to produce high, medium and low particle temperatures and velocities. Coatings produced under these spray conditions were characterized by profile tracing, quantitative x-ray diffraction, and SEM analysis. The Mo5Si3 level in the coatings ranged from 5% to 8% while the Mo5Si3 level in the starting powder was 0.6%. Particle size, particle trajectory, and torch parameters were found to be important factors in the Si loss process when APS depositing MoSi2.

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