Synthesis of thick photocatalytic titania surface layers by solution plasma spraying and subsequent treatment by pulsed laminar plasma jet

AbstractIn plasma spraying, instabilities and fluctuations of the plasma jet have a significant influence on the particle in-flight temperatures and velocities, thus affecting the coating properties. This work introduces a new method to analyze the stability of plasma jets using high-speed videography. An approach is presented, which digitally examines the images to determine the size of the plasma jet core. By correlating this jet size with the acquisition time, a time-dependent signal of the plasma jet size is generated. In order to evaluate the stability of the plasma jet, this signal is analyzed by calculating its coefficient of variation cv. The method is validated by measuring the known difference in stability between a single-cathode and a cascaded multi-cathode plasma generator. For this purpose, a design of experiment, covering a variety of parameters, is conducted. To identify the cause of the plasma jet fluctuations, the frequency spectra are obtained and subsequently interpreted by means of the fast Fourier transformation. To quantify the significance of the fluctuations on the particle in-flight properties, a new single numerical parameter is introduced. This parameter is based on the fraction of the time-dependent signal of the plasma jet in the relevant frequency range.

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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

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Plasma Spraying Using Ar-He-H2 Gas Mixtures

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

10.31399/asm.cp.itsc1998p0803 ◽

1998 ◽

Author(s):

S. Janisson ◽

A. Vardelle ◽

J.F. Coudert ◽

B. Pateyron ◽

P. Fauchais ◽

...

Keyword(s):

Plasma Spraying ◽

Gas Flow ◽

Plasma Jet ◽

Gas Mixtures ◽

Gas Velocity ◽

Gas Flow Rate ◽

Static Behavior ◽

Operating Variables ◽

Arc Current ◽

Plasma Guns

Abstract In D.C. plasma guns used for plasma spraying, the properties of the plasma forming-gas control, to a great extent, the characteristics of the plasma jet and the momentum, heat and mass transfer to the particles injected in the flow. This paper deals with mixtures of argon, helium and hydrogen and the effect of the volume composition of these mixtures on the dynamic and static behavior of the plasma jet. Both were investigated from the measurements of arc voltage and gas velocity. Correlations between these parameters and the operating variables (arc current, gas flow rate, gas mixture composition) were established from a dimensional analysis. The results were supported by the calculation of the thermodynamic and transport properties of the ternary gas mixtures used in this study.

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The Influence of Anode Inner Contour on Atmospheric DC Plasma Spraying Process

Advances in Materials Science and Engineering ◽

10.1155/2017/2084363 ◽

2017 ◽

Vol 2017 ◽

pp. 1-12 ◽

Cited By ~ 1

Author(s):

Kui Wen ◽

Min Liu ◽

Kesong Zhou ◽

Xuezhang Liu ◽

Renzhong Huang ◽

...

Keyword(s):

Plasma Spraying ◽

Thermal Efficiency ◽

Plasma Jet ◽

Measured Temperature ◽

Arc Voltage ◽

Cylindrical Nozzle ◽

Jet Characteristics ◽

Plasma Spraying Process ◽

Spraying Process ◽

Plasma Jet Characteristics

In thermal plasma spraying process, anode nozzle is one of the most important components of plasma torch. Its inner contour controls the characteristics of plasma arc/jet, determining the motion and heating behaviors of the in-flight particles and hence influencing the coating quality. In this study, the effects of anode inner contour, standard cylindrical nozzle, and cone-shaped Laval nozzle with conical shape diverging exit (CSL nozzle) on the arc voltage, net power, thermal efficiency, plasma jet characteristics, in-flight particle behaviors, and coating properties have been systematically investigated under atmospheric plasma spraying conditions. The results show that the cylindrical nozzle has a higher arc voltage, net power, and thermal efficiency, as well as the higher plasma temperature and velocity at the torch exit, while the CSL nozzle has a higher measured temperature of plasma jet. The variation trends of the plasma jet characteristics for the two nozzles are comparable under various spraying parameters. The in-flight particle with smaller velocity of CSL nozzle has a higher measured temperature and melting fraction. As a result, the coating density and adhesive strength of CSL nozzle are lower than those of cylindrical nozzle, but the deposition efficiency is greatly improved.

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Determining the heat flux distribution of laminar plasma jet impinging upon a flat surface: An indirect method using surface transformation hardening

International Journal of Heat and Mass Transfer ◽

10.1016/j.ijheatmasstransfer.2017.11.050 ◽

2018 ◽

Vol 118 ◽

pp. 879-889 ◽

Cited By ~ 5

Author(s):

Yong Xiang ◽

Deping Yu ◽

Fangyuan Liu ◽

Cheng Lv ◽

Jin Yao

Keyword(s):

Heat Flux ◽

Indirect Method ◽

Flux Distribution ◽

Flat Surface ◽

Plasma Jet ◽

Heat Flux Distribution ◽

Laminar Plasma Jet ◽

Surface Transformation

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Formation of Gradient Multiphase Nanostructured Surface Layers Using the Electron-Ion-Plasma Combined Method

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.756.236 ◽

2015 ◽

Vol 756 ◽

pp. 236-242 ◽

Cited By ~ 1

Author(s):

Yuriy F. Ivanov ◽

Anton D. Teresov ◽

Olga V. Ivanova ◽

Victor E. Gromov ◽

Evgeniy A. Budovskikh ◽

...

Keyword(s):

Titanium Alloy ◽

Subsequent Treatment ◽

Nanostructured Surface ◽

Combined Method ◽

Surface Layers ◽

Pulsed Electron Beam ◽

Mechanical And Tribological Properties ◽

Ion Plasma ◽

Defect Substructure ◽

Mechanical And Tribological Characteristics

The data of the study of the elemental and phase composition, the condition of the defect substructure, mechanical and tribological characteristics of titanium alloy VT6 subjected to electroexplosive carburization with a sample of titanium diboride powder and the subsequent treatment by high-intensity pulsed electron beam is presented. It has been established that the main mechanisms responsible for an increase in the mechanical and tribological properties of the material are solid, dispersion, and grain boundary.

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