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.

scholarly journals Вплив діаметру частинок порошку нікелю на їх швидкість і температуру при холодному газодинамічному напилюванні

2021 ◽  
pp. 110-116
Author(s):  
Олександр Володимирович Шорінов ◽  
Сергій Олександрович Поливяний
Keyword(s):  
Particle Velocity ◽  
High Speed ◽  
Gas Flow ◽  
Particle Temperature ◽  
Cold Gas Dynamic Spraying ◽  
Optimal Size ◽  
Properties Of Coatings ◽  
Powder Particles ◽  
The Impact ◽  
Nozzle Inlet

To deposit coatings in cold gas-dynamic spraying (CS), a high-speed gas flow is used to accelerate and heat particles. Therefore, first of all, it is necessary to consider the general laws of the gas flow and the movement of particles in the flow, as well as its interaction with the substrate. Due to the CS process depends primarily on the particle velocity, it is important to understand the effect of the process parameters (pressure and temperature at the nozzle inlet), the characteristics of the powder particles (material density, shape, and size), and the geometry of the nozzle. The gas velocity limits the particle velocity that can be achieved with the CS process. Utilization of high gas pressure, long nozzles, and small particles lead to the fact that the particles move at a velocity close to the velocity of the gas, which can be increased by using gases with low molecular weight, as well as heating it. As a result of the analysis of theoretical and experimental methods for studying the cold spraying process, it was found that for coating formation velocity of powder particles needs to obtain a certain value (critical velocity), which depends on particle temperature at the impact, and density of the particle material. Numerical simulation of gas dynamics of a two-phase flow in CS nozzle and at the outlet from it for the range of air temperatures from 573 K to 873 K and constant pressure of 1,0 MPa has been carried out. The influence of the diameter of nickel powder particles on their temperature and velocity at impact was investigated. Numerical simulations were performed for a range of particle diameters from 5 to 30 μm. In the future, the results obtained can be used to find the optimal size of the powder particles under certain spraying conditions, to calculate the critical particle velocity, and also to develop the window of deposition. This will make it possible to select the optimal parameters of the gas flow at the nozzle inlet (pressure and temperature), which are guaranteed to ensure the adhesion of particles to the substrate and the formation of coatings. Also, the results obtained can be used to predict the properties of coatings, as well as to achieve maximum deposition efficiency of the CS process.

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.

scholarly journals Comparative Assessment of Spray Behavior, Combustion and Engine Performance of ABE-Biodiesel/Diesel as Fuel in DI Diesel Engine

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6521
Author(s):  
Sattar Jabbar Murad Algayyim ◽  
Andrew P. Wandel
Keyword(s):  
Diesel Engine ◽  
High Speed ◽  
Engine Performance ◽  
Combustion Efficiency ◽  
Green Energy ◽  
Spray Parameters ◽  
Gas Temperature ◽  
Performance And Emission ◽  
The Impact ◽  
Ci Engines

This study investigates the impact of an acetone-butanol-ethanol (ABE) mixture on spray parameters, engine performance and emission levels of neat cottonseed biodiesel and neat diesel blends. The spray test was carried out using a high-speed camera, and the engine test was conducted on a variable compression diesel engine. Adding an ABE blend can increase the spray penetration of both neat biodiesel and diesel due to the low viscosity and surface tension, thereby enhancing the vaporization rate and combustion efficiency. A maximum in-cylinder pressure value was recorded for the ABE-diesel blend. The brake power (BP) of all ABE blends was slightly reduced due to the low heating values of ABE blends. Exhaust gas temperature (EGT), nitrogen oxides (NOx) and carbon monoxide (CO) emissions were also reduced with the addition of the ABE blend to neat diesel and biodiesel by 14–17%, 11–13% and 25–54%, respectively, compared to neat diesel. Unburnt hydrocarbon (UHC) emissions were reduced with the addition of ABE to diesel by 13%, while UHC emissions were increased with the addition of ABE to biodiesel blend by 25–34% compared to neat diesel. It can be concluded that the ABE mixture is a good additive blend to neat diesel rather than neat biodiesel for improving diesel properties by using green energy for compression ignition (CI) engines with no or minor modifications.

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.

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.

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

Case study: Prediction and field tests of railway noise and effects of a low-height noise barrier

2020 ◽  
Vol 68 (4) ◽  
pp. 303-314
Author(s):  
Yuna Park ◽  
Hyo-In Koh ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
...  
Keyword(s):  
High Speed ◽  
Field Tests ◽  
Residential Areas ◽  
Railway Systems ◽  
Railway Noise ◽  
Sound Levels ◽  
Noise Barrier ◽  
The Difference ◽  
Reduction Effect ◽  
The Impact

Railway noise is calculated to predict the impact of new or reconstructed railway tracks on nearby residential areas. The results are used to prepare adequate counter- measures, and the calculation results are directly related to the cost of the action plans. The calculated values were used to produce noise maps for each area of inter- est. The Schall 03 2012 is one of the most frequently used methods for the production of noise maps. The latest version was released in 2012 and uses various input para- meters associated with the latest rail vehicles and track systems in Germany. This version has not been sufficiently used in South Korea, and there is a lack of standard guidelines and a precise manual for Korean railway systems. Thus, it is not clear what input parameters will match specific local cases. This study investigates the modeling procedure for Korean railway systems and the differences between calcu- lated railway sound levels and measured values obtained using the Schall 03 2012 model. Depending on the location of sound receivers, the difference between the cal- culated and measured values was within approximately 4 dB for various train types. In the case of high-speed trains, the value was approximately 7 dB. A noise-reducing measure was also modeled. The noise reduction effect of a low-height noise barrier system was predicted and evaluated for operating railway sites within the frame- work of a national research project in Korea. The comparison of calculated and measured values showed differences within 2.5 dB.

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