Arc Discharge Plasma Research Articles

Hybrid Additive and Subtractive Manufacturing Method Using Pulsed Arc Plasma.

In this study, a novel hybrid additive and subtractive manufacturing method using pulsed arc plasma (PAP-HASM) was developed to better integrate additive and subtractive processes. The PAP-HASM process is based on the flexible application of pulsed arc plasma. In this PAP-HASM method, wire arc additive manufacturing using pulsed arc plasma (PAP-WAAM) and dry electrical discharge machining (EDM) milling were used as additive and subtractive techniques, respectively; both are thermal machining processes based on pulsed arc plasma, and both are dry machining techniques requiring no working fluids. The PAP-HASM can be easily realized by only changing the pulsed power supply and tool electrodes. A key technological challenge is that the recast layer on the part surface after dry EDM milling may have a detrimental effect on the component fabricated by PAP-HASM. Here, the hybrid manufacturing method developed in this study was validated with commonly used 316L stainless steel. Preliminary experimental results showed that the PAP-HASM specimens exhibited excellent tensile properties, with an ultimate tensile strength of 539 ± 8 MPa and elongation of 46 ± 4%, which were comparable to the PAP-WAAM specimens. The recast layer on the surface after dry EDM milling has no significant detrimental effect on the mechanical properties of the parts fabricated by PAP-HASM. In addition, compared with components fabricated by PAP-WAAM, those fabricated by PAP-HASM showed significantly better surface roughness.

Inactivation of Salmonella enteritidis on the surface of eggs by air activated with gliding arc discharge plasma

Salmonella enteritidis, a Gram-negative foodborne pathogen, causes inflammation of the stomach and intestines. Poultry and poultry products are considered to be the main hosts of S. enteritidis, especially the most common edible eggs, and increase the risk of Salmonella infection. Therefore, developing the inactivation strategy of S. enteritidis on the surface of eggs is the key step during the egg production process. Gas plasma could effectively inactivate bacteria and fungi and is developed as a potential non-thermal sterilization method in the food industry. In this study, the plasma-activated air (PAA) prepared by the air activated with gliding arc discharge contained a variety of reactive species. When the PAA activated at the power of 50 W and 100 W was inducted into the incubation chamber, the numbers of S. enteritidis on egg fragments or the whole eggs were reduced below the detection limit. After PAA treatment, the eggshells exhibited no change in structure demonstrated by scanning electron microscope, the color of eggshells became a little decrease in red, the internal quality of both the raw egg and the cooked egg also exhibited no change, and trace reactive species remained in the albumen. Further, the PAA was also feasible for the batch treatment of stacked eggs. Therefore, this study supplied an effective and safe strategy for aseptic processing in the poultry industry.

Inactivation of Cercospora lactucae-sativa through Application of Non-Thermal Atmospheric Pressure Gliding Arc, Tesla Coil and Dielectric Barrier Discharge Plasmas

Cercospora leaf spot disease is a serious problem for lettuce cultivation worldwide. Cercospora lactucae-sativa, the causative agent of leaf spot disease on lettuce, was treated with non-thermal atmospheric pressure gliding arc (GA), tesla coil (TC) and dielectric barrier discharge (DBD) plasmas for the in vitro fungal inactivation of both mycelial growth and conidial germination. The fungus was exposed to the three plasmas individually for 5, 10, 15 and 20 min. The results showed that DBD plasma inactivated fungal growth during all exposure periods, and the highest inhibitory effect was caused by exposure to DBD plasma for 20 min, at 93.33% inhibition. The germination of fungal conidia was completely inactivated after exposure to all three non-thermal plasmas for 5 min, as observed 4 and 24 h after incubation. The pathogenesis of C. lactucae-sativa on lettuce after plasma treatments for 5 min was examined by spraying an inoculation of the treated conidia on lettuce. The results showed that all three plasmas reduced the disease incidence and severity compared to the non-treated control. Therefore, the non-thermal atmospheric pressure GA, TC and DBD plasmas have antifungal potential for the inactivation of C. lactucae-sativa, making them an interesting novel technology for plant disease control.

N-doping carbon-coated Cu@C(N) nanocapsules synthesized by arc plasma toward high-performance ORR electrocatalyst

The development of efficient and cost-effective methods for the synthesis of non-precious metal as the catalytic material for oxygen reduction reaction (ORR) is addressing a key barrier to fuel cell deployment in a wide range of applications. In this study, core-shell carbon-coated copper nanoparticles (Cu@C) were prepared using arc discharge plasma under argon and hydrogen atmospheres. And nitrogen doping was achieved during the subsequent heat treatment using dicyandiamide as the nitrogen source. The results showed that the catalysts had better ORR catalytic activity, better stability and better methanol tolerance than Pt/C, and the ORR reaction process was nearly four-electron pathway. The successful doping of nitrogen increased the reaction sites. And the addition of copper core improved the conductivity of the catalytic material. Meanwhile, the N-C shell layer protected the Cu nanoparticles from dissolving in aqueous solutions or being chemically oxidized, facilitating the electronic interaction of the core Cu nanoparticles with the N-C shell layer. This study provides an insight into the preparation of high-efficiency non-precious metal-based ORR electrocatalysts by DC arc plasma, a beneficial method.

Flow control effect of pulsed arc discharge plasma actuation on impinging shock wave/boundary layer interaction

The current study investigates the control effect of the pulsed arc discharge plasma on the impinging shock wave and boundary layer interaction (SWBLI) generated by a 14° wedge in a Mach 2.5 flow. The response characteristics of SWBLI on pulsed arc discharge actuation were illustrated, and the controlling mechanism of shock-induced flow separation under different plasma power settings was revealed. The results, which were well validated by the relative published experiment, showed that when setting the exciting power density ph as 1.0 × 1011 W/m3, the oblique shock wave obtained an obvious fluctuation, and the foot of the reattachment shock wave was partially removed. In addition, as the controlling gas bubble passed through the interaction region, the reverse flow zone was enlarged, and the separation shock wave was shifted upward. When ph was set to 4.8 × 109 W/m3, the flow separation induced by SWBLI was effectively suppressed and the size of the reverse flow zone was significantly reduced. Moreover, as the energy input was increased, the arc-induced blast wave (BW) velocity was obviously enhanced. Additionally, it is further found that the arc plasma energy deposition density in the discharge region was the determining factor for SWBLI control, even for a relatively small exciting energy input. Better drag reduction of the flow field would be achieved with the pulsed arc discharge plasma of higher power density, and a drag reduction rate of nearly 10.05% was obtained at ph = 1 × 1011 W/m3 control condition.

Structure and Vibrational Spectroscopy of C82 Fullerenol Valent Isomers: An Experimental and Theoretical Joint Study

Gd@C82OxHy endohedral complexes for advanced biomedical applications (computer tomography, cancer treatment, etc.) were synthesized using high-frequency arc plasma discharge through a mixture of graphite and Gd2O3 oxide. The Gd@C82 endohedral complex was isolated by high-efficiency liquid chromatography and consequently oxidized with the formation of a family of Gd endohedral fullerenols with gross formula Gd@C82O8(OH)20. Fourier-transformed infrared (FTIR) spectroscopy was used to study the structure and spectroscopic properties of the complexes in combination with the DFTB3 electronic structure calculations and infrared spectra simulations. It was shown that the main IR spectral features are formed by a fullerenole C82 cage that allows one to consider the force constants at the DFTB3 level of theory without consideration of gadolinium endohedral ions inside the carbon cage. Based on the comparison of experimental FTIR and theoretical DFTB3 IR spectra, it was found that oxidation of the C82 cage causes the formation of Gd@C82O28H20, with a breakdown of the integrity of the parent C82 cage with the formation of pores between neighboring carbonyl and carboxyl groups. The Gd@C82O6(OOH)2(OH)18 endohedral complex with epoxy, carbonyl and carboxyl groups was considered the most reliable fullerenole structural model.

Single-step synthesis of Mn3N2, MnxON and Mn3O4 nanoparticles by thermal plasma arc discharge technique and their comparative study as electrode material for supercapacitor application

In the present study, single-step synthesis of single-phase manganese nitride (Mn3N2), mixed phase manganese oxynitride (MnxON) and manganese oxide (Mn3O4) nanoparticles (NPs) was carried out using the thermal plasma arc discharge (TPAD) method. The experiments were carried out using nitrogen (N2), ammonia (NH3) and oxygen (O2) gas atmospheres at different plasma powers 2, 4 and 6 kW. The phase and elemental compositions of the prepared nanoparticles were examined using X-Ray Diffraction (XRD) and Energy Dispersive X-ray Spectroscopy (EDX) analysis. All the synthesized powder samples have nearly spherical morphology, which are determined by using Field Emission Scanning Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM) analysis. The surface area of the prepared NPs was investigated using Brunauer-Emmett-Teller (BET) analysis, and the obtained results are 40.1, 19.4 and 11.8 m2g−1 for Mn3N2, MnxON and Mn3O4 NPs respectively. The Mn3N2 NPs showed superior storage performance with an outstanding specific capacitance of 508.4 F/g at 1 A/g with pseudocapacitive behavior compared to the mixed and oxide NPs 335.1 and 150 F/g respectively. The Mn3N2 electrode exhibited higher cycling stability with 84.2% capacitance retention after 5000 cycles at a current density of 5 A/g. These results demonstrated that the plasma-prepared single-phase Mn3N2, which is used as a potential electrode material for supercapacitors applications.

Effect of arc current on the microstructure, tribological and corrosion performances of AISI 420 martensitic stainless steel treated by arc discharge plasma nitriding

Effect of arc current on the microstructure, tribological and corrosion performances of AISI 420 martensitic stainless steel treated by arc discharge plasma nitriding

Полученные плазменно-химическим осаждением a-C : ND покрытия: взаимосвязь эмиссионных свойств и фазового состава

The coatings comprised of the nanodiamond-based and amorphous-carbon-based phases (a-C:ND coatings) are investigated. The a-C:ND coatings were synthesized by chemical vapor deposition in the arc discharge plasma (by plasma chemical deposition) at various concentrations of Ar/H2/CH4. Raman spectroscopy showed that, apart from the diamond substructure, studied coatings contain amorphous-carbon-based and polyene-based phases, while diamond phase is passivated by hydrogen to different degrees. The interplay between the deposition parameters and materials' structure is analysed. It was shown that the ordering of the amorphous substructure and the formation of the phase boundaries affect the electron transport and secondary electron emission properties. The subject of the investigation of the true secondary electron spectra for the analysis of the nanostructured carbon materials is analysed. It was shown that the change of the polyene fraction in the structure of the samples leads to the variation of the ratio of field emission and thermionic emission. The influence of the structure and phase composition of the samples on their electron emission properties is investigated. In particular, their effect on the turn on-field, which value varied in the 9-18 V/μm range for the studied samples, is analysed.

Structure of the surface layer of high-chrome steel nitridated in the elion regime in the plasma of a suspended arc discharge with a heated cathode

The purpose of this work is to reveal the patterns of formation of the structure of the surface layer of high-chromium steel subjected to nitriding in a low-pressure gas discharge plasma using a plasma generator with a hot cathode "PINK". Heating of the samples to the nitriding temperature was carried out by the ionic component of the plasma, as well as by the electron and ionic components of the plasma (elion mode). The object of the study was heat-resistant corrosion-resistant steel of the austenitic class grade 20X23H18 (foreign analogue of AISI310S). The relevance of research is due to the relatively low level of hardness and wear resistance of steels of this class. Nitriding of steel was carried out on the TRIO installation, retrofitted with a switching unit for implementing the aelion (electronic and ionic) processing mode. It has been established that the thickness of the hardened layer is (55-60) pm and weakly depends on the method of nitriding, temperature (in the range of 793-873 K), and duration (3-5 hours) of the process. A nitriding regime has been revealed that makes it possible to form a surface layer with a microhardness of 13.7 GPa (ionic heating mode) and 10.8 GPa (elion heating mode). It has been established that the high strength and tribological properties of nitrided steel are due to the formation of a nanocrystalline structure in the surface layer, the main phases of which are iron nitrides Fe4N and chromium nitrides CrN. It is shown that heating the samples to the nitriding temperature in the aelion mode, which uses the electron and ion components of the plasma, leads to a significantly lower level of material roughness compared to the samples heated during nitriding by the ion component of the plasma.

Влияние размерного эффекта на проводимость наночастиц NiO плазмохимического синтеза

Nickel oxide nanoparticles were obtained by condensation from a vacuum arc discharge plasma and subsequent deposition on a substrate at various temperatures (300–700 K). The samples were characterized using X-ray diffraction and transmission electron microscopy. The formation of a phase of stoichiometric NiO, whose crystallite size increases with increasing substrate temperature, is confirmed. Electrophysical properties are investigated by measuring DC and AC conductivity and dielectric properties as a function of temperature. The frequency and temperature dependences of the dielectric permittivity and conductivity in alternating current demonstrate the behavior characteristic of dielectrics with a predominance of charge carriers.

Influence of low-temperature plasma on green algae culture

Influence of low-temperature plasma, which was formed in a high-resource arc-discharge plasma jet in an argon-air mixture, was studied for a community of green algae as Chlorella vulgaris Beyerinck [Beijerinck] and Stichococcus bacillaris Nägeli. It was found that the plasma treatment for 10 minutes led to partial cell death. At the same time, the species of C. vulgaris were less sensitive to the plasma treatment than the species of S. bacillaris. After plasma exposure, the predominant growth of the latter culture was observed in comparison with the control samples. This effect can be explained by an activation of biochemical processes in the algae due to the interaction with radicals in the low-temperature plasma. The results obtained indicate the selectivity of the low-temperature plasma effect on green algae community.

Treatment of water using Arc discharge plasma in Patan area

The quality of drinking water has been degraded and declining day by day and its impact is directly seen on human health and other organisms too. So, the way we want to solve this problem by using new technology which was not based on the Plasma Treatment. Plasma based technology which is one of the best and new technology it takes a short time for improvement of water quality. Water sample collected from various sources within Patan from different sources such as Jar water, Ground water, Tap water and Stone spout water. The concentration of ammonia in the Jar and Tap water increased at 10 seconds after the sample was treated with Plasma. The hardness of groundwater increased significantly in all time periods as compared to without treatment. Overall, the hardness of Tap water decreased when treated with Plasma. But in case of Stone Spout water, hardness increased during 5 and 15 seconds whereas it decreased at 10 seconds. The concentration of Chloride only decreased in case of Jar water whereas there was a significant increase in its amount in all other remaining samples in each time factors i.e., 5,10,15 seconds. By using this technology water quality can be improved within short time.

In Ukrainian

The review examines experimental and theoretical works devoted to the description of modern methods for the preparation of iron endometal-fullerenes(EMF), as well as works that dispute such results due to the extremely low efficiency of the used methods. The paper also considers the advantages and disadvantages of synthesis, as well as the areas of possible application of synthesis products. It is shown that EMF is obtained mainly by two methods - arc discharge (plasma) and synthesis using ablation and implantation methods. Despite a very small number of works on iron-endometal-fullerenes, the group of authors managed to achieve some progress in their analysis. Thus, the fact of obtaining Fe-endometal-fullerenes with their isolation from a mixture of synthesis products was proved. In addition, the influence of the magnetic state of metal atoms on the stability of endohedral fullerenes was predicted, a relationship between the EMF output and the plasma temperature, as well as the chemical nature of the precursor of iron atoms, was established. In particular, it was established that with an increase in the atomic mass of the elements, the EMF output decreases exponentially. It was concluded that the magnetic properties of EMF make them perspective materials in the field of clinical diagnostics (for example, as contrast agents in MRI) and medicine (for magnetically controlled delivery of drugs directly to a diseased organ).

DIAGNOSTICS OF THERMAL PLASMA WITH Cu AND Ni VAPOUR ADMIXTURES

This work is devoted to diagnostics of thermal electric arc discharge plasma with copper and nickel vapour admixtures by optical emission spectroscopy and possibility of its usage for investigation of plasma regions nearelectrodes surfaces. The spectra of plasma emission from such areas were obtained by registration device with spatial and spectral resolution. The Boltzmann plot technique was used to determine the radial distribution of plasma temperature of arc discharge channel in different cross-sections. Namely, the regions of arc discharge plasma in the vicinity of cathode and anode surfaces in the two different configuration of electrodes assembly (copper as a cathode, nickel as an anode and vice versa) were investigated.

PECULIARITIES OF INTERACTION OF Cu-W COMPOSITE MATERIALS WITH THERMAL ARC DISCHARGE PLASMA

This work is a part of acomplex investigation of the interaction of Cu-W composite materials with thermal electric arc discharge plasma. The plasma of 3.5 A DC arc discharge between novel Cu-W composite materials, fabricated by shock pressing technology at the temperature of 750°C, was studied at this stage. Spectra of such plasma emission were registered and treated to determine the radial distributions of plasma temperature in three different cross-sections of the plasma channel, namely in near-cathode, near-anode and middle cross-sections.

Dielectric behavior of nanocrystalline Cu-Fe ferrites synthesized by plasma arc discharge process

In this study, nanocrystalline Cu–Fe ferrite powders with the chemical composition of CuxFe1-xFe2O4 (where 0 ≤ x ≤ 0.5) were synthesized via the plasma arc discharge process. Regarding the phase analysis, a spinel structure of the nanocrystalline Cu–Fe ferrite phase has been developed successfully in all synthesized compositions. Dielectric properties were measured in the 100 Hz to 10 MHz range using an LCR meter. Results show that the substitution of Cu for Fe ions leads to a substantial increase in the dielectric constant due to the migration of some Fe3+ ions from tetrahedral to octahedral sites and the formation of Cu+/Cu2+ ion pairs in the octahedral sites contributing to the hopping process. The results also indicate that the low-frequency dielectric constant is influenced by grain boundary capacitance while grain capacitance plays a major contribution to the dielectric constant in the high-frequency region.

Ash and Slag Waste Processing in Self-Shielded Atmospheric DC Arc Discharge Plasma.

In this paper, we report the experimental results obtained in slag waste processing by direct current arc discharge initiated in ambient air. The method does not employ vacuum and gas equipment, therefore increasing the energy efficiency of processing. Plasma processing of coal slag was performed at different arc exposure times: 5, 10, 15, 20, and 25 s. The obtained materials contained a significant amount of graphite, which was removed through combustion. The micropowder based on silicon carbide and aluminum nitride was obtained and then sintered by spark plasma. The bulk ceramic samples based on silicon carbide with the hardness of ~10.4 GPa were finally fabricated.

Ethanol partial oxidative reforming in gliding arc discharge plasma: A better understanding by a kinetic model study

• Ethanol POR in a GAD plasma reactor was studied through experiments and modeling. • A 0-D model was found for elaborating main pathways of reaction processes. • Results of the model were close to experiment results, with the maximum error 8.6%. • Detailed pathways of main products and ethanol were analyzed based on the results. Ethanol plasma partial oxidative reforming process was investigated through experiments and modeling in a gliding arc discharge (GAD) plasma reactor. The effect of oxygen to ethanol (O 2 /EtOH) molar ratio, flux and input power were evaluated according to yields of main products. The highest yields of hydrogen and carbon monoxide are 38.6% and 55.4%, respectively. The excited-state species including C 2 (A 3 Π g -X 3 Π u ), the C 2 Swan band and the second positive system (SPS) of nitrogen were detected by optical emission spectroscopy (OES). A zero-dimension (0-D) model of ethanol plasma partial oxidative reforming containing 457 reactions was established for describing the pathways of reforming processes and calculated by Chemkin-PRO. The detailed pathways of ethanol dissociation and production of hydrogen, carbon monoxide, methane and carbon dioxide were sorted according to the calculation result of Chemkin-PRO. The frame mechanism of ethanol plasma partial oxidative reforming showed the main pathways in the reforming processes.

Design and Construction of a New Plasma Applicator for the Improved Disinfection and Activation of Large Surfaces

This paper describes the design and operation of a low-cost plasma applicator based on a patented, swirled-type dielectric barrier discharge configuration with a treatment width up to 300 mm. Differences from earlier plasma applicators include: blown cylindrical dielectric barrier discharge, combining the functional properties of the plasma jet systems, arc and corona discharge blown in a single type of universal applicator, and the possibility of treating large areas of samples with cold plasma generated in a certain type of specific process gas mixture chosen according to the type of desired effect. We tested the effect of the plasma on a few materials such as cotton and linen fabrics, glass wafers and printing cardboard, proving that the generated plasma can easily make hydrophilic or hydrophobic surfaces. We also tried the plasma’s sterilizing effect on Escherichia coli (E. coli) bacteria. The results suggest that our plasma system can be successfully applied to medical and biological fields as well, where the removal of bacteria and their fragments is required.