Effect of Increase in Entrance Convergent Section Length of Gun Nozzle on HVOF Thermal Spray Process and its Application to Nozzle Design for Cold Gas-Dynamic Spray Method

2000 ◽  
Author(s):  
K. Sakaki ◽  
Y. Shimizu
Keyword(s):  
Gas Flow ◽  
Experimental Studies ◽  
Deposition Efficiency ◽  
Cold Gas Dynamic Spraying ◽  
Nozzle Geometry ◽  
Nozzle Design ◽  
Hvof Spraying ◽  
Combustion Gas ◽  
Gas Dynamic ◽  
Cold Gas

Abstract Nozzle geometry has a profound effect on HVOF spraying, influencing combustion gas dynamics as well as particle behavior. Nozzle dimensions are also important in cold gas-dynamic spraying (CGDS), particularly the length of the nozzle which affects gas flow temperature and speed. In this study, numerical simulations and experiments were conducted to determine how the length of the entrance convergent section of gun nozzles affects HVOF spraying. Process changes that occur inside the nozzle (as predicted by simulation) were correlated with coating properties. An Al2O3-TiO2 powder was used for the experimental studies. Changes in nozzle length had a significant impact on deposition efficiency, microstructure, hardness, and particle velocity. These relationships (as measured and calculated) were then applied to the nozzle design for the CGDS method.

Numerical Modelling for Oblique Impacts With Ductile Material Particle Erosion During Cold Gas Dynamic Spray

2020 ◽  
Author(s):  
Sunday Temitope Oyinbo ◽  
Tien-Chien Jen ◽  
Samson A. Aasa
Keyword(s):  
Contact Angle ◽  
Numerical Modelling ◽  
Gas Flow ◽  
Deposition Efficiency ◽  
Ductile Material ◽  
Material Particle ◽  
Gas Dynamic ◽  
Cold Gas Dynamic Spray ◽  
Gas Dynamic Spray ◽  
Cold Gas

Abstract Another key parameter that affects the coating deposition efficiency of cold gas dynamic spray technology is the contact angle. The particle tangential sliding on the substrate at impact is due to the gas flow bow shock at a supersonic velocity which is liable for the erosion at the surface of the substrate. This study presented a finite element approach of a numerical model to investigate the profile of the deformed sprayed particles under the condition of oblique impact and the erosion mechanism for solid particle impact on ductile material during Cold Gas Dynamic spray. In the numerical modelling of cold gas dynamic spray (CGDS) by a Lagrangian approach that was developed, oblique erodent particle on the substrate at controlled contact angle (10°–90°), velocity (500 m/s) and friction coefficient (0.3) was simulated. It was discovered that in the substrate, the crater depth decreases as well as the area of contact between the substrate and the deformed particles when the contact angle increases at the same impacting conditions. The material removal and crack formation mechanism were also simulated successfully by the accumulation of residual strain that resulted in the dynamic detachment of material elements at the surface as they fail.

Corrosion resistant protective coating of the Zr–Nb–Sn system obtained by high speed cold gas dynamic spraying

2021 ◽  
pp. 90-96
Author(s):  
T. I. Bobkova ◽  
R. Yu. Bystrov ◽  
A. F. Vasilev ◽  
E. A. Samodelkin ◽  
B. V. Farmakovsky
Keyword(s):  
High Speed ◽  
Alloy Composition ◽  
Experimental Studies ◽  
Cold Gas Dynamic Spraying ◽  
Precision Engineering ◽  
Corrosion Resistant ◽  
Gas Dynamic ◽  
Corrosion Resistant Coatings ◽  
Practical Recommendations ◽  
Cold Gas

The article presents the results of experimental studies on the creation of an optimal alloy composition of the Zr–Nb–Sn system for obtaining corrosion-resistant coatings using the technology of supersonic cold gas-dynamic spraying. Practical recommendations are given on the use of the developed coating in precision engineering products.

scholarly journals КЕРУВАННЯ ЕФЕКТИВНІСТЮ ПРОЦЕСУ ХОЛОДНОГО НАПИЛЮВАННЯ ЗАХИСНО-ВІДНОВЛЮВАЛЬНИХ ПОКРИТТІВ НА МАГНІЄВІ СПЛАВИ

2018 ◽  
pp. 66-73
Author(s):  
Александр Владимирович Шоринов ◽  
Сергей Евгеньевич Маркович
Keyword(s):  
Powder Mixture ◽  
Total Pressure ◽  
Cold Spraying ◽  
Deposition Efficiency ◽  
Cold Gas Dynamic Spraying ◽  
Stagnation Temperature ◽  
Working Pressure ◽  
Local Flow ◽  
Gas Dynamic ◽  
Cold Gas

The crucial task of developing the technology of low pressure cold gas–dynamic spraying and its wide application in the aviation, automotive and other industries is the possibility of obtaining coatings with given properties and deposition efficiency as great as practicable. To do this requires it is necessary to study the effect of complex parameters on coating deposition.An important characteristic of cold gas–dynamic spraying is deposition efficiency – the ratio of weight increment of the sample (weight of the coating) to the weight of powder used to produce the coating. Dependence of the deposition efficiency on the parameters of cold spraying, such as gas stagnation temperature and total pressure, material, shape and size of the powder particles, stand–of–distance, etc., allows a deeper understanding of the nature of the cold gas–dynamic spraying process, and as a consequence, to establish how these parameters effect on coating properties.The effect of stagnation temperature, total pressure and stand–of–distance on the cold spraying coating deposition efficiency on magnesium alloy utilized powder mixture based on aluminum was established. As a result of the deposition efficiency calculation, the optimal sputtering parameters ensuring the maximum deposition efficiency were established. It is shown that changing of the stagnation temperature has the greatest effect on the efficiency of coating formation. Stand–of–distance is the second most influential parameter, and the change in working pressure has the least effect. It is shown that with increasing temperature, the particle velocities increase during the deposition process, since the local speed of sound in the nozzle depends on the local flow temperature.The obtained results are the basis for the development of technological recommendations and processes for the formation of protective and restorative coatings on aeronautical part made of magnesium alloys during maintenance, repair and overhaul. Further optimization of the geometry of the nozzle, the composition of the powder mixture and the particle size is necessary to obtain deposition efficiency as great as practicable.

Effect of a conical separation region on cold gas-dynamic spraying

2012 ◽  
Vol 53 (6) ◽  
pp. 948-953 ◽  
Author(s):  
A. P. Alkhimov ◽  
V. F. Kosarev ◽  
S. V. Klinkov ◽  
A. A. Sova
Keyword(s):  
Cold Gas Dynamic Spraying ◽  
Separation Region ◽  
Gas Dynamic ◽  
Cold Gas

Effects of Gun Nozzle Geometry on High Velocity Oxygen-Fuel (HVOF) Thermal Spraying Process

1998 ◽  
Author(s):  
K. Sakaki ◽  
Y. Shimizu ◽  
Y. Gouda ◽  
A. Devasenapathi
Keyword(s):  
Numerical Simulation ◽  
Experimental Studies ◽  
Thermal Spraying ◽  
Deposition Efficiency ◽  
Divergence Angle ◽  
Nozzle Geometry ◽  
Oxide Content ◽  
Hvof Thermal Spraying ◽  
Throat Diameter ◽  
Spraying Process

Abstract Effect of nozzle geometry (such as throat diameter of a barrel nozzle, exit diameter and exit divergence angle of a divergent nozzle) on HVOF thermal spraying process (thermodynamical behavior of combustion gas and spray particles) was investigated by numerical simulation and experiments with Jet KoteTM II system. The process changes inside the nozzle as obtained by numerical simulation studies were related to the coating properties. A NiCrAIY alloy powder was used for the experimental studies. While the throat diameter of the barrel nozzle was found to have only a slight effect on the microstructure, hardness, oxygen content and deposition efficiency of the coatings, the change in divergent section length (rather than exit diameter and exit divergence angle) had a significant effect. With increase in divergent section length of the nozzle, the amount of oxide content of the NiCrAIY coatings decreased and the deposition efficiency increased significantly. Also, with increase in the exit diameter of the divergent nozzle, the gas temperature and the degree of melting of the particle decreased. On the other hand the calculated particle velocity showed a slight increase while the gas velocity increased significantly.

CoNiCrAlY microstructural changes induced during Cold Gas Dynamic Spraying

2008 ◽  
Vol 203 (3-4) ◽  
pp. 364-371 ◽  
Author(s):  
P. Richer ◽  
A. Zúñiga ◽  
M. Yandouzi ◽  
B. Jodoin
Keyword(s):  
Cold Gas Dynamic Spraying ◽  
Microstructural Changes ◽  
Gas Dynamic ◽  
Cold Gas

scholarly journals Simulation of Thermoplastic Powder Cold Spraying

2021 ◽  
Vol 14 (6) ◽  
pp. 726-734
Author(s):  
Tatyana A. Brusentseva ◽  
◽  
Vladislav S. Shikalov ◽  
Sergei M. Lavruk ◽  
Vasily M. Fomin
Keyword(s):  
Gas Flow ◽  
Experimental Studies ◽  
Cold Spraying ◽  
Deposition Efficiency ◽  
Powder Materials ◽  
Stagnation Temperature ◽  
Computational Domain ◽  
Ansys Fluent ◽  
Process Gas ◽  
Spray Method

The work is devoted to the deposition of composite powder materials by cold spray method. As a spraying material, a thermoplastic compound «WAY» for marking the roadway was used. An asphalt concrete was used as a substrate. As a result of experimental studies, the dependence of the deposition efficiency on the stagnation temperature of the working air in the ejector nozzle was obtained. The ANSYS Fluent package was used for evaluative modeling of the cold spraying process. Gas flow patterns were obtained in the computational domain without particles and taking into account the interaction of the flow with particles. The trajectory of the particles was calculated for various spraying parameters

scholarly journals Improving the performance of the air-cooling unit in the cooling system of a radar

2021 ◽  
Vol 2057 (1) ◽  
pp. 012004
Author(s):  
Yu A Borisov ◽  
V V Volkov-Muzilev ◽  
D A Kalashnikov ◽  
H S Khalife
Keyword(s):  
Heat Exchanger ◽  
Gas Flow ◽  
Cooling System ◽  
Experimental Studies ◽  
Air Cooling ◽  
Axial Fan ◽  
Gas Dynamic ◽  
Cooling Unit ◽  
Calculation Results ◽  
Axial Fans

Abstract The article discusses the issues of reducing the size of the cooling unit of the antenna of a radar station by improving the gas-dynamic processes occurring in the air-cooling unit. The results of the experimental studies of the gas flow in a plate-fin heat exchanger, being blown by one axial fan are presented. The feasibility of changing the number of axial fans for organizing a more uniform flow around the heat-exchange surfaces has been determined by calculation and theoretical methods. The calculation results are confirmed by experimental studies of the air flow in the segment of the heat exchanger, which is provided by a smaller fan.

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