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.

An Attempt to Improve the Deposition Efficiency of AI2O3 Coating by HVOF Spraying

2000 ◽  
Author(s):  
Y. Shimizu ◽  
K. Sugiura ◽  
K. Sakaki ◽  
A. Devasanapathi
Keyword(s):  
Hardness Test ◽  
Deposition Efficiency ◽  
Nozzle Geometry ◽  
Hvof Spraying ◽  
Fuel Gas ◽  
Dense Microstructure ◽  
Alumina Particles ◽  
Coating Characteristics ◽  
Nozzle Geometries ◽  
Spraying Process

Abstract High Velocity Oxy-Fuel (HVOF) method using propylene as a fuel gas was employed to spray alumina particles. In order to improve the coating characteristics such as the deposition efficiency and the hardness, three HVOF gun nozzles of varying geometry were designed and tested experimentally. The spraying process was also simulated numerically for each of the nozzle geometries to understand their effectiveness in influencing the velocity and temperature of the sprayed particles. The coating was characterized using optical and scanning electron microscopy (SEM), micro-vickers hardness test and X-ray diffractometry (XRD). Results showed that with the use of a convergent and divergent type gun nozzle, similar to that of a Laval nozzle, the extent of melting of the alumina particles could be increased. This was exhibited by an increase in the deposition efficiency to the extent of 45%. However, the sharp changes in the convergent and divergent nozzle geometry, resulted in fusion and agglomeration of alumina particles leading to spitting during the spraying process. The results clearly showed that alumina coatings of excellent hardness in the range of 920-1290 HV, with a relatively dense microstructure could be obtained in HVOF method irrespective of the gun nozzle geometry, provided the spraying parameters are properly controlled.

Application of Acoustic Emission for Monitoring the HVOF Thermal Spraying Process

2006 ◽  
pp. 291-298
Author(s):  
Nadimul Haque Faisal ◽  
John A. Steel ◽  
R. Ahmed ◽  
R.L. Reuben ◽  
G. Heaton ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Thermal Spraying ◽  
Hvof Thermal Spraying ◽  
Spraying Process

scholarly journals Corrosion Resistance of HastelloyC Coatings Formed by an Improved HVOF Thermal Spraying Process

2003 ◽  
Vol 44 (2) ◽  
pp. 253-258 ◽  
Author(s):  
Jin Kawakita ◽  
Seiji Kuroda ◽  
Takeshi Fukushima ◽  
Toshiaki Kodama
Keyword(s):  
Corrosion Resistance ◽  
Thermal Spraying ◽  
Hvof Thermal Spraying ◽  
Spraying Process

scholarly journals Influence of HVOF deposition thickness on adhesion strength of WC–CrC–Ni coatings

2019 ◽  
Vol 44 (1) ◽  
pp. 33-41
Author(s):  
Alin Constantin Murariu ◽  
Ion Aurel Perianu
Keyword(s):  
Stainless Steel ◽  
Structural Steel ◽  
Adhesion Strength ◽  
Thermal Stresses ◽  
Thermal Spraying ◽  
Experimental Program ◽  
304L Stainless Steel ◽  
Hvof Thermal Spraying ◽  
Deposition Thickness ◽  
Spraying Process

In this paper, adhesion strength of WC–CrC–Ni coatings obtained by HVOF thermal spraying process of WOKA7504 powder has been studied in correlation with deposition thickness, chemical and structural properties. Besides the parameters strictly related to the process, deposition thickness was found to be the most significant factor affecting the adhesion strength. In the frame of experimental program 304L stainless steel and S235JR structural steel were used as substrate. Mechanical tests, SEM and EDX analysis, have been performed in order to assess structural and mechanical properties, phase composition of the deposited layers. Maximum average adhesion strength has been experimentally found of 23.4 N/mm2 for stainless steel and of 35.8 N/mm2 for structural steel, for a deposition thickness of 220 µm, achieved in two layers. Once the coatings’ thickness increases, the adhesion strength decreases constantly and over thickness of 400 to 650 µm, the existing coating imperfections and elongated carbides placed in the interlayer interface area could fail due to the thermal stresses during the HVOF thermal spraying process, since they are brittle stress concentrators and thus leading tocracking of coatings at small loads, since the coating layershave high hardness of 990 to 1151 HV 1.

Tribological and microstructural behaviour in coatings applied using GTAW and HVOF (thermal spraying process) and used to recover AISI/SAE D2 grade tool steels

2018 ◽  
Vol 32 (10) ◽  
pp. 660-666
Author(s):  
Carlos Alberto Guevara Chávez ◽  
Jorge Leobardo Acevedo Dávila ◽  
Pedro Hernandez Gutierrez ◽  
Jose Jorge Ruiz Mondragon ◽  
Patricia del Carmen Zambrano-Robledo
Keyword(s):  
Thermal Spraying ◽  
Tool Steels ◽  
Hvof Thermal Spraying ◽  
Spraying Process

Novel photocatalytic TiO2 coatings produced by HVOF thermal spraying process

2010 ◽  
Vol 64 (10) ◽  
pp. 1173-1175 ◽  
Author(s):  
Maryamossadat Bozorgtabar ◽  
Mohammadreza Rahimipour ◽  
Mehdi Salehi
Keyword(s):  
Thermal Spraying ◽  
Hvof Thermal Spraying ◽  
Tio2 Coatings ◽  
Spraying Process ◽  
Photocatalytic Tio2
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