Plasma Spraying Using Ar-He-H2 Gas Mixtures

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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Effect of Processing Parameters on Plasma Jet and In-flight Particles Characters in Supersonic Plasma Spraying

High Temperature Materials and Processes ◽

10.1515/htmp-2015-0077 ◽

2016 ◽

Vol 35 (8) ◽

pp. 775-786 ◽

Cited By ~ 2

Author(s):

Pei Wei ◽

Zhengying Wei ◽

Guangxi Zhao ◽

Y. Bai ◽

Chao Tan

Keyword(s):

Plasma Spraying ◽

Flow Rate ◽

Gas Flow ◽

Plasma Jet ◽

Processing Parameters ◽

Current Intensity ◽

Maximum Temperature ◽

Gas Flow Rate ◽

Average Maximum ◽

Supersonic Plasma

AbstractIn supersonic plasma spraying system (SAPS), heat transfer from arc plasma is characterized by several distinct features, such as transport of dissociation and ionization energy and of electrical charges in addition to mass transport. The thermodynamic and transport properties of plasma jet were influenced by several main parameters such as primary gas flow rate, the H2 vol.% and current intensity A. This paper first analyzes the effect of these parameters on the temperature and velocity of plasma jet theoretically. Further, the loading particles were melted and accelerated by plasma jet. Effects of several main parameters such as carrier gas flow rate, the H2 vol.%, the current intensity, the voltage and the spraying distance on temperature and velocity of in-flight particle were studied experimentally. The average maximum temperature and velocity of in-flight particle at any given parameters were systematically quantified. Optimal SAPS process parameters were given in this paper. In general, increasing the particles impacting velocity and surface temperature can improve the maximum spreading factor and decrease the coating porosity.

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Parameters Affecting the Antimicrobial Properties of Cold Atmospheric Plasma Jet

Journal of Clinical Medicine ◽

10.3390/jcm8111930 ◽

2019 ◽

Vol 8 (11) ◽

pp. 1930 ◽

Cited By ~ 7

Author(s):

Bih-Show Lou ◽

Chih-Ho Lai ◽

Teng-Ping Chu ◽

Jang-Hsing Hsieh ◽

Chun-Ming Chen ◽

...

Keyword(s):

Gas Flow ◽

Treatment Time ◽

Plasma Jet ◽

Atmospheric Plasma ◽

Gas Flow Rate ◽

Cold Atmospheric Plasma ◽

E Coli ◽

Antimicrobial Efficiency ◽

Ar Gas ◽

Sample Distance

Using the Taguchi method to narrow experimental parameters, the antimicrobial efficiency of a cold atmospheric plasma jet (CAPJ) treatment was investigated. An L9 array with four parameters of CAPJ treatments, including the application voltage, CAPJ-sample distance, argon (Ar) gas flow rate, and CAPJ treatment time, were applied to examine the antimicrobial activity against Escherichia coli (E. coli). CAPJ treatment time was found to be the most influential parameter in its antimicrobial ability by evaluation of signal to noise ratios and analysis of variance. 100% bactericidal activity was achieved under the optimal bactericidal activity parameters including the application voltage of 8.5 kV, CAPJ-sample distance of 10 mm, Ar gas flow rate of 500 sccm, and CAPJ treatment time of 300 s, which confirms the efficacy of the Taguchi method in this design. In terms of the mechanism of CAPJ’s antimicrobial ability, the intensity of hydroxyl radical produced by CAPJ positively correlated to its antimicrobial efficiency. The CAPJ antimicrobial efficiency was further evaluated by both DNA double-strand breaks analysis and scanning electron microscopy examination of CAPJ treated bacteria. CAPJ destroyed the cell wall of E. coli and further damaged its DNA structure, thus leading to successful killing of bacteria. This study suggests that optimal conditions of CPAJ can provide effective antimicrobial activity and may be grounds for a novel approach for eradicating bacterial infections.

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Effects of Gas Flow Rate on the Discharge Characteristics of a DC Excited Plasma Jet

Plasma Science and Technology ◽

10.1088/1009-0630/17/9/04 ◽

2015 ◽

Vol 17 (9) ◽

pp. 738-742 ◽

Cited By ~ 4

Author(s):

Xuechen Li ◽

Pengying Jia ◽

Cong Di ◽

Wenting Bao ◽

Chunyan Zhang

Keyword(s):

Flow Rate ◽

Gas Flow ◽

Plasma Jet ◽

Gas Flow Rate ◽

Discharge Characteristics

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Experimental Investigation of a Magnetically Balanced Arc in a Transverse Argon Flow

Journal of Engineering for Power ◽

10.1115/1.3678473 ◽

1966 ◽

Vol 88 (1) ◽

pp. 27-30 ◽

Cited By ~ 9

Author(s):

T. W. Myers ◽

C. N. McKinnon ◽

J. C. Lysen

Keyword(s):

Magnetic Field ◽

Experimental Study ◽

Atmospheric Pressure ◽

Gas Flow ◽

Electric Arc ◽

Test Apparatus ◽

Gas Velocity ◽

Argon Gas ◽

Argon Flow ◽

Arc Current

An experimental study of an electric arc in crossed convective and magnetic fields has been made. An electric arc was established across a rectangular test section through which argon gas was flowing at approximately atmospheric pressure and velocities up to 100 m/sec. Magnetic field strengths up to 3 webers/m2, oriented so that the Lorentz force opposed the convective force on the arc, were applied perpendicular to both the arc and the direction of the argon gas flow. The test apparatus and the procedure used to obtain the experimental relationship between the velocity of the argon flow and the balancing magnetic field are described. An analysis which assumed the magnetically balanced arc to be a gaseous cylinder positioned between the electrodes and with a diameter varying directly as the arc current satisfactorily explained the observed dependence of the balancing magnetic field on the gas velocity.

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