Arc Discharge Plasma Research Articles

INVESTIGATION OF STRUCTURAL FEATURES OF ASPHALTENES USED FOR CARBON MATERIALS SYNTHESIS BY ARC PLASMA TREATMENT

This study presents analysis of asphaltenes isolated from two crude oils: naphthenic-aromatic biodegraded oil and paraffin-naphthenic oil, which have been used as precursors for carbon materials synthesis. The aim of this study is to investigate the interrelationship between the initial structure of asphaltene and the properties of carbon materials. Based on number of spectroscopic and other data, it can be found out that the asphaltenes from napthenic-aromatic biodegraded oil contain less paraffin and more cyclic fragments (aromatic and aliphatic), that are larger and more densely stacked. The asphaltenes of paraffin-naphthenic oil contain a larger number of labile bonds and heteroatoms. Both the asphaltenes contain sulfur enclosed in thiophene and sulfide fragments, nitrogen and oxygen, which are incorporated in different units with different thermal stability. Carbon materials are obtained from both asphaltenes via plasma of an electric arc discharge. The asphaltenes undergo graphitization as a result of plasma treatment, the general trend is an elimination of functional groups and N, S, O. The yields of the carbon materials are almost equal for two studied asphaltenes, giving graphite-like materials as the major product in both cases. The carbon material obtained from the napthenic-aromatic asphaltenes is less thermally stable, the yield of nano-structures and nanofibers are higher compared to the asphaltenes from paraffinic oil, with trace metals remaining during the synthesis process. The carbon material from paraffin-naphthenic oil is amorphous with low heteroatoms content.

Synthesis of high-entropy Ti-Zr-Nb-Hf-Ta carbides and carbonitrides in high-speed arc discharge plasma jet

The interest in high-entropy materials has increased rapidly in recent decades due to their applications in various fields such as environmental barrier coatings, superhard and wear resistant coatings, nuclear energy, batteries, catalysts, thermoelectrics, supercapacitors, biocompatible structures, and microelectronics. In the present work, comprehensive theoretical and experimental studies are carried out to discover a new way to prepare high-entropy ceramic nanopowders of carbides and carbonitrides of IV-V transition metals. The possibility of (TiZrNbHfTa)CxNy formation is investigated using both ab initio and machine learning approaches. The chosen single-stage plasma dynamic technique allowed us to synthesize high-entropy carbide TiZrNbHfTaC5 and the corresponding carbonitrides (N up to 8 wt%) in the form of single-crystalline nanoparticles. By varying the experimental system conditions, we demonstrate not only the production of pure powders, but also the ability to apply different precursors, including pure metals and their oxides. The presented technique provides a simple and universal way to produce high-entropy nanomaterials and opens the door to the synthesis of many functional ceramic powders composed of other carbonitrides with selective nitrogen content.

The effect of plasma activated water on antimicrobial activity of silver nanoparticles biosynthesized by cyanobacterium Alborzia kermanshahica

BackgroundSilver nanoparticles are extensively researched for their antimicrobial properties. Cold atmospheric plasma, containing reactive oxygen and nitrogen species, is increasingly used for disinfecting microbes, wound healing, and cancer treatment. Therefore, this study examined the effect of water activated by dielectric barrier discharge (DBD) plasma and gliding arc discharge plasma on the antimicrobial activity of silver nanoparticles from Alborzia kermanshahica.MethodsSilver nanoparticles were synthesized using the boiling method, as well as biomass from Alborzia kermanshahica extract grown in water activated by DBD and GA plasma. The physicochemical properties of the synthesized nanoparticles were evaluated using UV-vis spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), zeta potential analysis, transmission electron microscopy (TEM), and gas chromatography-mass spectrometry (GC-MS) analysis. Additionally, the disk diffusion method was used to assess the antimicrobial efficacy of the manufactured nanoparticles against both Gram-positive and Gram-negative bacteria.ResultsThe spectroscopy results verified the presence of silver nanoparticles, indicating their biosynthesis. The highest amount of absorption (1.049) belonged to the nanoparticles synthesized by boiling under GA plasma conditions. Comparing the FTIR spectra of the plasma-treated samples with DBD and GA revealed that the DBD-treated samples had more intense peaks, indicating that the DBD method proved to be more effective in enhancing the functional groups on the silver nanoparticles. The DLS results revealed that the boiling method synthesized silver nanoparticles under DBD plasma treatment had a smaller particle size (149.89 nm) with a PDI of 0.251 compared to the GA method, and the DBD method produced nanoparticles with a higher zeta potential (27.7 mV) than the GA method, indicating greater stability of the biosynthesized nanoparticles. Moreover, the highest antimicrobial properties against E. coli (14.333 ± 0.47 mm) were found in the DBD-treated nanoparticles. TEM tests confirmed that spherical nanoparticles attacked the E. coli bacterial membrane, causing cell membrane destruction and cell death. The GC-MS results showed that compounds like 2-methylfuran, 3-methylbutanal, 2-methylbutanal, 3-hydroxy-2-butanone, benzaldehyde, 2-phenylethanol, and 3-octen-2-ol were much higher in the samples that were treated with DBD compared to the samples that were treated with GA plasma.ConclusionThe research indicated that DBD plasma was more efficient than GA plasma in boosting the antimicrobial characteristics of nanoparticles. These results might be a cornerstone for future advancements in utilizing cold plasma to create nanoparticles with enhanced antimicrobial properties.

A low voltage semiconductor arc discharge plasma actuator with long discharge gap distance

Long-gap spark discharge is beneficial for plasma-assisted combustion. However, the longer the discharge gap, the higher the breakdown voltage required, which is not feasible in practical applications. In the present study, based on a custom-built semiconductor, a long gap discharge plasma actuator is designed, and the breakdown voltage is relatively low compared with the normal spark discharge method. The breakdown discharge voltage for 25mm gap at atmospheric pressure is only 3.24kV. The discharge characteristics were investigated in detail. The influence of voltage, capacitance, and the semiconductor geometric parameters on the discharge characteristics is investigated. Based on a high-speed camera, the temporal and spatial long gap discharge process was captured firstly. Combined the discharge waveforms and images, the discharge process of the semiconductor arc discharge plasma actuator is divided into four stages: applying high voltage, surface discharge, air breakdown, and conduction discharge. Using digital image processing techniques, the influence of voltage, capacitance and air gap on surface discharge evolution velocity was studied.

Exploring novel magnetic behaviors in cobalt-doped magnetite synthesized by plasma arc discharge method

Magnetite, a naturally occurring iron oxide, has been widely studied due to its potential applications in various fields. Doping magnetite with foreign ions can significantly alter its structural and magnetic properties. This study aimed to investigate the effects of Co2+ ion doping on the structural and magnetic properties of magnetite. The work introduces cobalt-substituted iron ferrites synthesized using a novel plasma arc discharge (PAD) method and systematically explores how cobalt content affects magnetic properties, aiming to optimize the material for enhanced performance. A series of CoxFe1-xFe2O4 (x=0, 0.1, 0.2, 0.3, and 0.5) ferrites with varying Co2+ concentrations (x=0, 0.1, 0.2, 0.3, and 0.5) were synthesized using a PAD method. The synthesized materials were characterized using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). Magnetic properties were evaluated through magnetic hysteresis loops and permeability spectra. XRD analysis confirmed the formation of a nanostructured spinel-type oxide in all samples. FESEM images revealed ultra-fine particles with a homogeneous composition and narrow size distribution. The optimal combination of magnetic properties was achieved at a Co2+ concentration of x=0.1, which exhibited a high saturation magnetization, low coercivity, moderate effective anisotropy constant, and a relatively high magnetic permeability at 5 MHz. The results demonstrate that Co2+ ion doping can effectively tailor the structural and magnetic properties of magnetite. The optimized composition (x=0.1) offers promising potential for applications requiring a balance of high magnetization and low coercivity.

Structural, optical, magnetic, and photocatalytic degradation characteristics of Co0.5Ni0.5Fe2O4 nanoparticles synthesized by plasma arc discharge process

Co0.5Ni0.5Fe2O4 nanoparticles were prepared by the plasma arc discharge method under arc currents of 200, 300, and 400 A in an air atmosphere. The XRD patterns reveal the formation of a single-phase cubic spinel. According to FESEM results, the average particle size in all powders is less than 100 nm. X-ray elemental mapping data confirms the homogeneous composition of the as-synthesized powders. The magnetic and optical data demonstrate a primarily soft ferromagnetic semiconductor behavior, characterized by a saturation magnetization ranging from 62 to 83 emu/g and a band gap energy between 1.86 and 2.15 eV. The photocatalytic activity of the powders synthesized using a 200 A arc, which possesses the lowest band gap energy of 1.86 eV, was assessed by conducting photodegradation experiments on the dyes congo red, methylene blue, and malachite green under UV irradiation in the presence and absence of H2O2. After 105 min of irradiation, the photocatalytic efficiencies of the powders without H2O2 were determined to be 29 %, 57 %, and 83 % for congo red, methylene blue, and malachite green dyes, respectively. However, in the presence of H2O2, the efficiencies significantly increase to 91 %, 95 %, and 96 % for the respective dyes.

Investigation of the temperature and electron density of the gliding arc discharge plasma by optical emission spectroscopy

Investigation of the temperature and electron density of the gliding arc discharge plasma by optical emission spectroscopy

Effects and Modification Mechanisms of Different Plasma Treatments on the Surface Wettability of Different Woods

Plasma treatment of wood surfaces has shown significant effects, but different excitation methods used for different species of wood generally result in varied characteristics of wood surfaces. Secondly, plasma modification greatly enhances the absorption of liquids by wood, but the relationship between liquid absorption and surface wettability is rarely studied. Limited detailed investigation of the modification effects and mechanisms has hindered the large-scale applications of plasma treatment in the wood industry. In this study, two typical plasmas, radio frequency (RF) plasma and gliding arc discharge (GAD) plasma, were employed to treat three species of wood: poplar, black walnut, and sapele. By focusing on changes in the contact angle of the wood surface, an exponential equation fitting method is used to determine the measurement time for contact angles. The research identified that factors contributing to the decrease in contact angle after plasma modification include not only the increase in surface energy but also liquid absorption. SEM and XPS analyses demonstrate that plasma etching accelerated liquid absorption by modifying the surface topography, while the increase in surface energy was due to the addition of oxygen-containing groups. High-valence C=O and O-C=O groups serve as indicators of plasma-induced surface chemical reactions. RF modification primarily features surface etching, whereas GAD significantly increases the active surface groups. Thus, different plasmas, due to their distinct excitation modes, produce diverse modification effects on wood. Considering the various physical and chemical properties of plasma-modified wood surfaces, recommendations for adhesive use on plasma-modified wood are provided.

Synthesis of chromium carbide powder by vacuum-free electric arc plasma method

Chromium carbide powders were synthesized by vacuum-free electric arc method using pure chromium and carbon powder as starting components. The powders obtained in the experimental series were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), laser diffraction and differential thermal analysis. In the experiments, electrical parameters were recorded, and the thermal field generated in the reaction zone was measured using an infrared camera and tungsten‑rhenium thermocouples. The study results show the feasibility of plasma arc discharge synthesis of chromium carbide compounds Cr3C2 and Cr7C3 within 60 s at current intensity of 200 A. SEM analysis of the resulting powder shows that it consists of acute-angled particles of ∼9 to ∼50 μm in size. An updated design of the discharge circuit employed in the study significantly increases the purity of the final product. Vacuum-free electric arc synthesis of chromium carbide has been studied for the first time.

Characteristic simulation of underwater microsecond high-current pulsed arc discharge plasma

Modeling analysis of underwater pulsed arc discharge can predict the characteristics of plasma channels, providing theoretical guidance for the practical application of underwater pulsed discharge. Due to the complexity of experimental diagnostics for ‘kA’-level underwater pulsed discharge, there is currently a lack of precise experimental data to support the initial value selection and result optimization of the modeling. This paper established a plasma channel model for underwater pulsed arc discharge. In conjunction with the Saha ionization equilibrium equation, the model was capable of simulating the current, pressure, temperature, and electron density of the channel after gap breakdown. By utilizing spectroscopic diagnostic data and a multi-objective optimization algorithm, the initial values and key parameters of the model were reasonably determined. The simulation results were in good agreement with the experimental diagnostic results, reasonably representing the trends in electron density and blackbody radiation temperature. Moreover, the model was applicable for reasonably explaining the emission spectral mechanism of the arc channel and shock waves prediction under different discharge conditions.

Insight into the corrosion behaviors and mechanism of arc discharge plasma nitrided H13 steel in molten Al-Si

AISI H13 steels were nitrided via arc discharge plasma nitriding (ADPN) with various arc currents (55, 70, 85, and 100 A) at 400 °C. The surface microhardness, wear resistance, and molten Al-Si corrosion resistance of nitrided H13 steel exhibited significant enhancements. The surface microhardness and wear resistance of nitrided H13 steel were significantly improved due to the lubricity property of the ɛ-Fe3N phase formed on the surface and the solid solution strengthening of the αN. Meanwhile, the nitrided layer led to a change in the corrosion mechanism from dissolution to pitting. Compressive internal stresses in the nitrided layer inhibited crack formation and promoted passivation layer formation. The high-efficiency ADPN process not only yields a wear-resistant surface but also provides a potential solution for improving the corrosion resistance against molten alloys.

The effectiveness of gliding arc discharge plasma in sterilizing artificial seawater contaminated with Vibrio parahaemolyticus

The rapid proliferation of the halophilic pathogen Vibrio parahaemolyticus poses a severe health hazard to halobios and significantly impedes intensive mariculture. This study aimed to evaluate the potential application of gliding arc discharge plasma (GADP) to control the infection of Vibrio parahaemolyticus in mariculture. This study investigated the inactivation ability of GADP against Vibrio parahaemolyticus in artificial seawater (ASW), changes in the water quality of GADP-treated ASW, and possible inactivation mechanisms of GADP against Vibrio parahaemolyticus in ASW. The results indicate that GADP effectively inactivated Vibrio parahaemolyticus in ASW. As the volume of ASW increased, the time required for GADP sterilization also increased. However, the complete sterilization of 5000 mL of ASW containing Vibrio parahaemolyticus of approximately 1.0 × 104 CFU/mL was achieved within 20 min. Water quality tests of the GADP-treated ASW demonstrated that there were no significant changes in salinity or temperature when Vibrio parahaemolyticus (1.0 ×104 CFU/mL) was completely inactivated. In contrast to the acidification observed in plasma-activated water (PAW) in most studies, the pH of ASW did not decrease after treatment with GADP. The H2O2 concentration in the GADP-treated ASW decreased after post-treatment. The NO2-concentration in the GADP-treated ASW remained unchanged after post-treatment. Further analysis revealed that GADP induced oxidative stress in Vibrio parahaemolyticus, which increased cell membrane permeability and intracellular ROS levels of Vibrio parahaemolyticus. This study provides a viable solution for infection with the halophilic pathogen Vibrio parahaemolyticus and demonstrates the potential of GADP in mariculture.

Multifunctional assessment of copper-doped ZnO nanoparticles synthesized via gliding arc discharge plasma technique: antioxidant, antibacterial, and photocatalytic performance.

In this paper, undoped and copper-doped ZnO nanoparticles (NPs) were successfully synthesized using a gliding arc discharge (GAD) plasma technique, which is a sustainable, cost-effective, and scalable method. This method offers several advantages over traditional synthesis methods. The synthesized NPs were characterized by various techniques to understand their physicochemical properties. XRD analysis confirmed the presence of characteristic peaks of pure ZnO, while doped samples exhibited additional peaks corresponding to CuO crystal planes, indicating the successful incorporation of Cu into the lattice. As obvious, bare ZnO showed absorption peak at 378 nm corresponding to the band gap of 3.21 eV. The band gap of Cu-doped samples increased systematically, i.e., 3.35 eV for 2% Cu, 3.47 eV for 4% Cu, and 3.66 eV for 6% Cu. SEM images revealed aggregation and increase in particle size with the increasing in Cu concentration. EDAX analysis revealed a decrease in the weight percentage of oxygen and zinc with the increase in Cu concentration, suggesting structural changes within the lattice. Furthermore, the antibacterial activity against Gram-positive and Gram-negative bacteria, antioxidant activity, and photocatalytic activity against three different organic dyes such as Brilliant Cresyl Blue (BCB), Methylene Blue (MB), and Congo Red (CR) was studied. It is found that the photocatalytic activity of ZnO NPs varies with Cu concentration, leading to a decrease in its performance. The antibacterial activity of the NPs was also assessed, with undoped ZnO NPs showing dose-dependent effects against bacteria, while the Cu-doped ZnO NPs exhibited decreased efficacy. Interestingly, Cu doping significantly enhanced the antioxidant activity of the NPs compared to the undoped ZnO.

Single-step synthesis of MgAl2O4/MgO nanocomposites from MgAl scraps by thermal plasma technique for bi-functional applications of supercapacitor and waste-water treatment

Plasma-based methods present a highly efficient approach for reclaiming valuable metals and nanoparticles from discarded metal scraps and minerals. In this research, we employed the thermal plasma arc discharge (TPAD) method to synthesize mixed-phase spinal-type magnesium aluminate and magnesium oxide (MgAl2O4/MgO) nanocomposites ranging in size from 10 to 120 nm, using discarded MgAl alloy waste scraps as the primary material. By employing comprehensive characterization techniques such as powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy dispersive X-ray analysis (EDS), we successfully confirmed the formation of highly crystalline MgAl2O4/MgO nanocomposites, showcasing a nearly spherical morphology. The surface area of the prepared nanocomposites was investigated using Brunauer-Emmett-Teller (BET) analysis; the values are 51.3 m2g-1. The synthesized MgAl2O4/MgO nanocomposites displayed exceptional photocatalytic activity toward industrial wastewater and commercial dye. Moreover, investigated the storage properties of MgAl2O4/MgO nanocomposites as an electrode material, revealing a good specific capacitance of 379.2 F/g at a current density of 1 A/g, demonstrating pseudocapacitive behavior. These results offer valuable insights into sustainable waste utilization and the development of high-performance nanomaterials for practical applications in various fields.

Resistive switching properties of a nanostructured layer of mixed ZrO2 phases obtained in low-pressure arc discharge plasma

The controlled vacuum-arc synthesis of zirconium dioxide (ZrO2) nanoparticles is considered, which makes it possible to regulate the percentage ratio of the monoclinic and tetragonal phases. The samples were characterized using XRD analysis, SEM, HRTEM analysis, FT-IR analysis, TG/DTA analysis and EPR spectroscopy. It has been established that the formation of the tetragonal phase is associated with the formation of a large number of oxygen vacancies formed due to high-speed quenching of nanoparticles. Reducing the operating gas pressure in a vacuum chamber from 180 Pa to 30 Pa makes it possible to obtain nanoparticles up to 2 nm in size. The synthesized ZrO2 nanoparticles do not contain foreign impurities and when heated, the weight loss is up to 7 %. The process of local resistive switching in the contact of an atomic force microscope (AFM) probe to a nanostructured ZrO(2-x) layer on a conducting substrate has been studied. Cyclic current-voltage characteristics demonstrate the existence of stable states of high and low resistance, switched by changing the polarity of the applied voltage. The coexistence of the m- and t-ZrO2 phases (and the resulting oxygen nonstoichiometry in the interboundary regions) provides conditions for the formation/destruction of a filament from oxygen vacancies, which determine the conductivity of the dielectric in the LRS state.

Effect of Gas Flow Rate on Spectral Properties of Magnetically Stabilized Gliding Arc Discharge Plasma

Effect of Gas Flow Rate on Spectral Properties of Magnetically Stabilized Gliding Arc Discharge Plasma

Deposition of a‐C:H:SiOx Coatings Using Low‐Frequency Inductively Coupled Plasma

This article investigates the plasma‐enhanced chemical vapor deposition of a‐C:H:SiOx coatings in a non‐self‐sustaining arc discharge plasma with a hot cathode in combination with a low‐frequency (200 kHz) inductively coupled plasma. It is shown that increasing the inductor power from 0 to 600 W leads to a twofold increase in the ion current density on the substrate. An increase in ion bombardment intensity results in a 1.3‐fold reduction in the coating's growth rate due to the resputtering phenomenon, a 1.5‐fold reduction in surface roughness, and an improvement in the mechanical properties of the coatings. The hardness of the coating is increased by 9–11%, the plasticity index by 10–17%, and the resistance to plastic deformation by 32–49%.

Effects of ion-plasma treatment temperature of the aluminium coating on the structure and phase composition of the VT6 titanium alloy

In this study, we studied the effects of aluminum coating treatment temperature on the microstructure and phase composition when applied to a VT6 titanium alloy substrate within a low-pressure arc discharge plasma environment. The ion-plasma treatment was conducted at 450 and 500 °C, employing argon shielding, while the aluminum coating was deposited using the vacuum-arc process, resulting in a coating thickness of ~3 μm. Microstructural analysis was performed using a scanning electron microscope, and the structural and phase composition were examined using X-ray diffraction (XRD) imaging in symmetric imaging mode with CuKα radiation. Our findings demonstrate that the application of the aluminum coating initiates the formation of a near-surface α-stabilized layer, extending up to 2.5 μm in thickness due to the heat generated during the ion cleaning process. Subsequent ion-plasma treatment further results in the development of a TiAl3 intermetallide site, reaching thicknesses of up to 1.5 μm, while the α-stabilized region expands to 5.5 μm. Higher temperatures during the treatment process contribute to an increase in the thickness of these aforementioned layers and also lead to the emergence of an intermediate TiAl intermetallic layer.

A highly effective N2 fixation method based on reverse vortex flow gliding arc plasma under water

A gliding arc plasma has the advantages of strong reactivity, high energy density, and easy scale-up, so it is very competitive in the field of plasma-based N2 fixation. In this work, we designed an underwater transfer arc discharge plasma N2 fixation system based on a reverse vortex flow gliding arc. In full contact with air and water, the plasma could realize the efficient conversion of N2, O2, and H2O, obtaining gaseous NO, NO2, and activated water rich in NOx*. The experiment showed that an underwater transfer arc discharge was formed when the current was greater than 0.6 A. Under this operating condition, the conversion rate of N2 reached 1.63%, the concentration of NOx reached 2.4%, and the production rate of nitrogen-containing products was about 3.41 mol/h. In addition, the energy consumption was as low as 2.21 MJ/mol, the lowest reported value for atmospheric-pressure rotary gliding arc plasma-based N2 fixation. The generated activated water had abundant NO3− and NO2− ions, which could be directly applied as N2 fertilizer in agriculture, promoting plant germination and growth. This paper describes an environmentally friendly and efficient technical route toward developing industrial N2 fixation/green agriculture, strongly supporting the carbon neutrality concept.

Insights into n-dodecane steam reforming in gliding arc discharge plasma with experiment and kinetic model

n-dodecane steam reforming (SR) process was investigated from both experimental and modelling views in gliding arc plasma. The effects of water-carbon molar ratio, n-dodecane concentration, input power and residence time on the conversion, yield, energy efficiency EE(C12H26) and hydrogen energy yield EY(H2) were revealed. The most dominant spectral lines detected by optical emission spectroscopy (OES) are CN violet and Hα (3d2D-2p2p0). The highest yields of H2 and CO are 50.1% and 49.9%, respectively. A zero-dimension reaction kinetic model containing 105 species and 793 reactions was developed for the SR process. Using CHENKIN-PRO, the presumable reaction pathways of n-dodecane, H2, CO, H2O and CO2 were described in detail. H2 and CO were produced mainly through reaction C2H4+H⇌C2H3+H2 and reaction HCCO+H⇌CH2(S)+CO.