Development of long laminar plasma jet on thermal spraying process: Microstructures of zirconia coatings

The paper presents a pretreatment of the substrate material prior to the thermal spraying process. The ultrasonic finishing method allowed creation of a rolling topography comprising alternating projections and cavities, compressive stress, and increase of the number of defects on the surface. Optical profilometry and metallographic analysis allowed detecting of adhesion zones which form a strong physicochemical bond at the interface between the coating and the substrate material. This interfacial adhesion should provide a firm adhesion strength in end products.

Download Full-text

Improvement of Solution Type Plasma Spraying Process

Materials Science Forum ◽

10.4028/www.scientific.net/msf.502.505 ◽

2005 ◽

Vol 502 ◽

pp. 505-510 ◽

Cited By ~ 2

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.

Download Full-text

In-situ heating effect of laminar plasma jet during Mo coatings deposition

Materials Letters ◽

10.1016/j.matlet.2021.130743 ◽

2021 ◽

Vol 305 ◽

pp. 130743

Author(s):

Hui-Yu Zhang ◽

Sen-Hui Liu ◽

Chang-Jiu Li ◽

Cheng-Xin Li

Keyword(s):

Plasma Jet ◽

Heating Effect ◽

Laminar Plasma Jet ◽

In Situ Heating

Download Full-text

Peculiarities of the Structure and Phase Composition of Hydroxy Apatite Coatings Sprayed by Laminar Plasma Jet and Treated by Electron Beam

Thermal Spray 1996: Proceedings from the National Thermal Spray Conference ◽

10.31399/asm.cp.itsc1996p0445 ◽

1996 ◽

Author(s):

V.A. Klimenov ◽

Yu. F. Ivanov ◽

A.V. Karlov ◽

V.V. Trophimov ◽

L.B. Bataeva

Keyword(s):

Electron Beam ◽

Phase Composition ◽

Thermal Spraying ◽

Medical Problem ◽

Cyclic Strength ◽

Titanium Implants ◽

Hydroxy Apatite ◽

Laminar Plasma Jet ◽

Scientific Technical ◽

Titanium Substrates

Abstract The covering of titanium implants by means gas-thermal spraying of hydroxyapatite powders is an actual scientific, technical and medical problem. Application of hydroxyapatite for these purposes is more preferable. However, the problem of its structural and cyclic strength under conditions of bioenvironment response determines of application areas of such coatings and reliability of them usage. Structure and phase composition of hydroxyapatite coating under plasma spraying on titanium substrates and their changing, caused as conditions of forming coating on its increasing, so and conditions of spraying an laminar and turbulent plasma streem were studied. Exact belief about the crystalline structure and phase composition of coating is obtained by methods electronic microscopy and X-ray analysis. Changing of coating structure after sintering in the vacuum and electron beam melting in the vacuum is discussed.

Download Full-text

Mathematical Modeling of a Free Plasma Jet Discharging into Air and Comparison with Probe Measurements

Thermal Spray 1997: Proceedings from the United Thermal Spray Conference ◽

10.31399/asm.cp.itsc1997p0549 ◽

1997 ◽

Author(s):

R. Bolot ◽

M. Imbert ◽

C. Coddet

Keyword(s):

Local Thermodynamic Equilibrium ◽

Argon Plasma ◽

Plasma Jet ◽

Equilibrium Composition ◽

Physical Phenomena ◽

Plasma Spraying Process ◽

Spraying Process ◽

Free Plasma ◽

Argon Plasma Jet ◽

Probe Measurements

Abstract Plasma spraying process modeling is useful to understand physical phenomena and to decrease the number of experiments. In this paper, a study of the external plasma jet is proposed: the PHOENICS™ CFD code was used with a 2D axisymmetrical geometry and a standard K-ε turbulence model. In a first step, thermodynamic and transport properties were calculated from chemical equilibrium composition, thermodynamic derivatives and kinetic theory of gases. Local Thermodynamic Equilibrium (LTE) was assumed for both plasma and surrounding gases. The proposed numerical results were computed for comparison with temperature measurements realized by Brossa and Pfender in the case of an argon plasma jet discharging into air, using enthalpy probes. The predictions were found reasonably accurate. The influence of the surrounding gas nature was also verified as the validity of the parabolic assumption.

Download Full-text

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

Thermal Spray 1998: Proceedings from the International Thermal Spray Conference ◽

10.31399/asm.cp.itsc1998p0445 ◽

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.

Download Full-text