Arc Technology Research Articles

Environmentally Friendly and Simple Recycling of Titanium Alloy Scrap via Deoxygenation with Hybrid Hydrogen Plasma Arc.

The potential of hydrogen plasma arc technology for the efficient deoxygenation and recycling of titanium alloy scrap is explored. The results of thermodynamic analysis reveal that hydrogen plasma is suitable for oxygen removal. The intermediate stages of the deoxygenation process are sequentially analyzed, showing that the hydrogen plasma arc primarily facilitated the reduction and dissolution of oxides as well as eliminated interstitial oxygen. The experimental results demonstrate that the deoxygenation dynamics are governed by the interaction between the hydrogen partial pressure and the surface area of the hydrogen plasma arc irradiation range. Furthermore, the results of the detailed characterization of the recycled titanium alloys indicate that hydrogen plasma arc technology not only reduces the oxygen content to levels compliant with industrial standards for Ti-6Al-4V but also substantially enhances the tensile strength and ductility of Ti-6Al-4V compared with those of conventional cast titanium alloys. The results of microstructural analysis show that hydrogen tends to concentrate in the β phase, whereas oxygen is predominantly found in the α phase. These findings highlight the effectiveness of hydrogen plasma arc technology, which offers environmental benefits and improves the performance of the resulting material, indicating its promise as a solution for titanium recycling.

The feasibility study of transfer arc plasma pyrolysis system for petrochemical wastes: Hydrogen production from Antar, OTD, and Tar.

One of the best and most advanced methods for disposal of urban, hospital, industrial, and other hazardous waste is to convert waste into combustible gases in reactors based on plasma arc technology. Also used for renewable energy generation, this technology involves thermal treatment without a combustion process; therefore, the waste is completely decomposed into simple molecules in a near vacuum environment almost devoid of Oxygen at elevated temperatures. The present research uses a thermal transferred arc plasma reactor to conduct a feasibility study on the pyrolysis of three types of wastes: Antar, Orthotoluenediamine (OTD), and Tar. To this end, three experiments were conducted, and the effective parameters involved in preparing and producing common gaseous raw materials and products, such as hydrogen, and their production amounts were examined. The outcome demonstrates that there are no remnants of spent catalyst waste following the plasma pyrolysis process, confirming the feasibility of complete conversion. The findings of this study revealed that plasma waste reactors could generate recycled energy in the form of renewable fuel free of toxic gases and vapors released from conventional waste incinerators and create negligible amounts of environmental pollutants.

TECHNOLOGICAL AND ENVIRONMENTAL FEATURES OF PLANTS FOR PLASMA-CHEMICAL PYROLYSISOF MEDICAL WASTE

The protection of the environment and human health from the negative impact of waste, in particular medical and pharmaceutical waste, is a priority in the field of waste management. The term "medical waste" defines the full range of all categories and types of medical waste (MW) that are classified as hazardous in Ukraine. The unrestrained growth of the amount and rate of production of hazardous medical waste in the context of the Russian-Ukrainian war (MW) critically exacerbates the environmental situation in Ukraine. However, existing methods and technological means are not able to ensure their complete environmentally safe processing and utilization. The article analyzes the peculiarities of the method of incineration of medical, pharmaceutical and hospital waste. It is demonstrated that plasma arc technologies and plasma-chemical pyrolysis technologies are well-proven and commercially attractive for their application on an industrial scale, including in the medical field, for the disposal, recycling and destruction of hazardous waste. The incineration of medical waste in the open air or in incinerators has temperature limits of no more than 500 oC. The paper considers the technology of plasma-chemical pyrolysis at 1100-1250 oC as a high-temperature alternative to medical waste incineration, which is implemented in the form of a mobile plasma pyrolysis unit "Plazmon-3 , developed and created on the basis of the domestic plasma generator PUN-1. The advantages of using high-temperature plasma-chemical pyrolysis are shown, which make it, in terms of environmental safety, beyond the competition and, unlike smoke-emitting analogues, plasma-chemical pyrolysis technologies destroy medical waste without forming environmentally hazardous residues

Corrosion resistance of PPTA Ni-based hardfacing layers

Abstract In this study, the corrosion resistance of four different hardfacing layers in a 3.5% NaCl solution was tested. Using 316L steel as a reference material, NiCrBSi, NiCrBSi + 35 wt% WC, and NiCrCuMo were deposited onto a structural steel S235JR substrate using the plasma powder transferred arc technology and prepared samples in a disc form for testing. The purpose of this investigation was to propose an alternative material to the commonly known anti-corrosion protection product of 316L steel simultaneously with better wear resistance. Its corrosion damage mechanism was assessed based on electrochemical examination and is related to changes in the microstructure of the sample surface investigated by using a potentiostat and a scanning electron microscope. Polarization tests were carried out, which confirmed that all proposed overlayers provide effective anti-corrosion protection. For all samples, the corrosion current density did not exceed 0.3 µA/cm2, and the corrosion potential was not less than −290.9 mV, which were considered positive results.

Study of the Nature of the Destruction of Coatings Based on the ZrN System Deposited on a Titanium Alloy Substrate

The fracture strength was compared in a scratch test of coatings based on the ZrN system with the introduction of Ti, Nb and Hf, which were deposited on a titanium alloy substrate. The coatings were deposited using Controlled Accelerated Arc (CAA-PVD) technology. In coatings that simultaneously include Zr and Ti, a nanolayer structure is formed, while in coatings without Ti, the formation of a monolithic single-layer structure is observed. The comparison was carried out according to two parameters: adhesion strength to the substrate and overall coating strength. The (Zr,Hf)N coating showed better resistance to destruction, but had worse adhesion to the substrate. As a result, although the coating is retained directly in the scribing groove, a large area of delamination and destruction is formed around the groove. The (Ti,Zr,Nb)N coating, with its somewhat lower strength, has a high adhesion to the substrate; no noticeable delamination is observed along the groove boundary. In this paper, not only is the fracture resistance of various coatings deposited on a titanium alloy substrate compared, but the nature of this fracture is also investigated depending on the composition of the coatings.

Comparison of Corrosion Behavior of a-C Coatings Deposited by Cathode Vacuum Arc and Filter Cathode Vacuum Arc Techniques

This study explores the utilization of cathodic vacuum arc (CVA) technology to address the limitations of magnetron sputtering technology in preparing amorphous carbon (a-C) coatings, such as having a low ionization rate, low deposition rate, and insufficiently dense structure. Specifically, a-C coatings were prepared by the cathodic vacuum arc (CVA)and the filtered cathodic vacuum arc (FCVA) technology,, one with embedded carbon particles and one without, both having closely related carbon structures. Research is currently underway on bipolar plate coatings for fuel cells. The corrosion behavior of the prepared a-C coatings was examined through Tafel polarization analysis under simulated fuel cell operating conditions as well as potentiostatic analysis at 0.6 V under normal conditions and 1.6 V under start–stop conditions for 7200 s. The coatings before and after corrosion are characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy, and infrared spectroscopy. The results reveal that the incorporation of conductive graphite-like particles in the coatings reduces their contact resistance. However, the gaps between these particles and the coatings act as pathways for corrosive solution, exacerbating the corrosion of the coatings. After corrosion at 0.6 V, both sets of coatings with sp2-hybridized carbon structures are contaminated by elements such as hydrogen and oxygen, leading to an increase in their contact resistance. Under high potential conditions (1.6 V), large corrosion pits and defects appear at the locations of graphite-like carbon particles. Furthermore, both sets of samples exhibit more severe oxygen contamination and a transformation of broken carbon bonds from sp3- to sp2-hybridized forms, irrespective of whether embedded graphite particles are present.

Enhanced tribological behavior and corrosion resistance in AlSiC-based coatings through varied carbon content

Enhanced tribological behavior and corrosion resistance in AlSiC-based coatings through varied carbon content

Study on the sand erosion resistance of ZrN and ZrAlSiN coatings

Study on the sand erosion resistance of ZrN and ZrAlSiN coatings

Dispersed CeO2 Nanorods with Low-Speed Mixing for Mechanical Properties Promotion of PTA Steel Coatings

The plasma-transferred arc technology has been observed to induce preferential grain orientation in multiple directions, leading to nonuniform grain growth within the alloy coating material. The addition of nano-oxides can act as heterogeneous nucleation sites, reducing the preferred orientation of grains. In this study, a low-speed mixing method was employed to coat highly dispersed CeO2 nanorods (CNRs) onto the surface of 14Cr2NiSiVMn alloy powder particles. The aim was to analyze the influence of dispersed CNRs on grain growth orientation in different directions and the refinement and heterogeneous nucleation effect of CNR additives. The addition of 0.5 wt.% CNRs resulted in the refinement of dendritic grains along both the perpendicular and parallel directions to the coating cladding direction, leading to the formation of more uniform equiaxed crystals. The combination of Ce with Si and V elements formed submicron particles, which promoted grain nucleation and reduced defects in the coating. Consequently, the mechanical performance of the sample significantly improved. In the deposition direction, there was a notable improvement in microhardness (20.4%), tensile strength (97.6%), and elongation (59.0%). In the perpendicular deposition direction, the tensile strength increased by 88.1%, and the elongation increased by 33.9%. Additionally, the weight loss due to wear decreased by 44.2%, and the relative wear resistance improved by 79.3%.

Modelling of plasma discharge in a filament negative ion source

Most of the currently operating Negative ion Neutral Beam Injectors (N-NBIs) exploit filament powered sources for the generation of beam ions. Being widely used in fusion experiments, the filament arc technology has been thoroughly investigated and optimized over the years, allowing to achieve excellent performances in terms of extracted beam optics. The source geometry, the magnetic field topology and the arc power strongly influence both the plasma discharge and the background gas properties and, consequently, the beam features. In this framework, this contribution describes a numerical investigation of the plasma properties in a filament-powered negative ion source, performed by means of a 2D3V Particle In Cell-Monte Carlo Collisions (PIC-MCC) code. Specifically, we discuss plasma formation by the thermionic electrons emitted by the filaments, investigating their interaction with the background gas. We also study the plasma diffusion through the magnetic filter field and how the latter modifies plasma density, electron temperature and plasma potential along the axial direction when approaching the plasma facing electrode.

Optimization of welding process parameters of wire arc additive manufacturing

Wire arc additive manufacturing (WAAM) is a cost-effective and efficient method for producing intricate metal geometries. This study employs Design Expert software and the desirability function to optimize WAAM process parameters, focusing on maximizing bead width, height, and microhardness—critical factors determining mechanical properties. Through ANOVA analysis, the research identifies voltage, wire feed speed, and torch speed as significantly influencing welding characteristics. Increased voltage and wire feed speed yield wider beads, while higher torch and wire feed speeds enhance bead height and microhardness. Optimized parameters—16.44 V voltage, 8.99 m/min wire feed speed, and 9 mm/s torch speed—demonstrate precise control over bead properties. This study deepens our understanding of WAAM process parameters, offering valuable insights for consistently producing high-quality weld beads with desired mechanical properties. The findings have profound implications for the manufacturing industry, enabling enhanced efficiency, consistency, and quality in metal component production. Optimized parameters also pave the way for innovative designs, lightweight structures, and rapid prototyping, contributing to the advancement of additive manufacturing, particularly in the context of wire arc technology. This research establishes a foundation for future studies on process optimization, material selection, and widespread WAAM adoption in diverse manufacturing sectors.

Influence of ferrum film by FCVA deposition technique on properties of WE43 magnesium alloy

Influence of ferrum film by FCVA deposition technique on properties of WE43 magnesium alloy

Exploring Extreme Voltage Events in Hydrogen Arcs within Electric Arc Furnaces

This study highlights the potential utilization of hydrogen gas in electric arc furnaces for achieving cleaner and more sustainable steel production. The application of hydrogen offers a promising path for reducing carbon emissions, enhancing energy efficiency, and advancing the concept of “green steel”. This study employs a 2D axisymmetric induction-based model to simulate an electric arc under atmospheric pressure conditions. We conducted numerical simulations to compare compressible and incompressible models of an electric arc. The impact of compressibility on hydrogen arc characteristics such as arc velocity, temperature distribution, and voltage drop were investigated. Additionally, different applied current arcs were simulated using the compressible model. When compared to an incompressible arc, the compressible arc exhibits a higher voltage drop. This higher voltage drop is associated with lower temperatures and lower arc velocity. A rise in applied current results in an upward trend in the voltage drop and an increase in the arc radius. In addition, the increased applied current increases the probability of voltage fluctuations. The voltage fluctuations tend to become more extreme and exert more stress on the control circuit. This has an impact on emerging electric arc technologies, particularly those involving the use of hydrogen. These fluctuations affect arc stability, heat output, and the overall quality of processes. Thus, the precise prediction of voltage and the ability to stabilize the operation is critical for the successful implementation of new hydrogen technologies.

Mechanical and corrosion properties of hydrogen-free DLC coatings prepared on degradable as-extruded WE43 alloy using FCVA technology

Mechanical and corrosion properties of hydrogen-free DLC coatings prepared on degradable as-extruded WE43 alloy using FCVA technology

Preparation and performance of Ti/Ti-DLC composite coatings for precision glass molding

Preparation and performance of Ti/Ti-DLC composite coatings for precision glass molding

Corrosion behavior of TiN and TiCN coatings synthesized by PVD on the spark plasma sintered NiTi substrate

TiN and TiCN coatings have garnered widespread attentions in the field of materials science and engineering because of their exceptional characteristics, including high melting point, excellent thermal conductivity, remarkable chemical stability, superior corrosion and wear resistance, and notable biocompatibility. These properties make them highly suitable for coating various alloys, and as a result, they have been successfully applied in numerous applications. The aim of this research study is to delve into the corrosion behavior of spark plasma sintered NiTi substrates that were coated with TiN and TiCN employing physical vapor deposition (cathodic arc technology). In order to comprehensively analyze the corrosion response, potentiodynamic polarization and electrochemical impedance spectroscopy techniques were employed. To gain deeper insights into the impact of the coating, a meticulous comparison was conducted between the corrosion resistance of the uncoated specimen and that of the coated ones. The results showcased a significant enhancement in corrosion resistance for both coated samples when compared to the uncoated NiTi substrate. However, it was found that the TiN-coated specimen showed even higher corrosion resistance than the TiCN-coated counterpart. These findings highlight the superiority of TiN coatings in terms of corrosion resistance when applied on the NiTi substrate.

The Role of Period Modulation on the Structure, Composition and Mechanical Properties of Nanocomposite Multilayer TiAlSiN/AlSiN Coatings

This paper presents the results of the investigation of a multilayer TiAlSiN/AlSiN coating. A novel coating architecture with a period consisting of nanocomposite sublayers of TiAlSiN and AlSiN was developed. We discovered that the combination of a harder sublayer with a more elastic one allows for obtaining a suitable combination of superhardness and enhanced toughness. The coating was deposited by cathodic arc technology. The EDS, XRD, and XRS analyses revealed that the nanocomposite structure is composed of TiAlSiN and AlSiN nanocrystallites, with sizes of 12–13 nm and 4–5 nm, respectively. The nanograin phase is incorporated in an amorphous Si3N4 matrix. The achieved structure causes the presence of four factors contributing to the hardness increase: nanocomposition, solid solution, refinement hardening, and the formation of many interfaces. An instrumented indentation test was used to investigate the mechanical properties. The developed coating possesses a superhardness of 49.5 GPa and a low elastic modulus of 430 GPa, resulting in an improved elastic strain resistance of 0.11, a plastic deformation resistance of 0.58 GPa, and an elastic recovery of 68%. These results imply that the developed coating combines high stability with mechanical degradation under external influence and provides an improved ability to absorb energy at deformation before fracture, and high elastic recovery. The investigation of the effect of the period modulation on the structure, composition, and mechanical properties of the nanocomposite multilayer TiAlSiN/AlSiN coating showed that the superhardness was due to the nanocomposite and solid solution hardening rather than the increased number of interfaces. The demonstrated combination of superhardness with high elasticity and improved toughness determines the developed nanocomposite TiAlSiN/AlSiN coating as very suitable for industrial applications such as high speed and dry machining.

Improved deposition quality of calcium-phosphate coating on the surface of WE43 magnesium alloy via FCVA sputtering pretreatment

Improved deposition quality of calcium-phosphate coating on the surface of WE43 magnesium alloy via FCVA sputtering pretreatment

Lithiophilic Zn3N2-Modified Cu Current Collectors by a Novel FCVA Technology for Stable Anode-Free Lithium Metal Batteries.

Anode-free lithium metal batteries (AFLMBs) offer high-energy-density battery systems, but their commercial viability is hindered by irregular lithium dendrite growth and "dead Li" formation caused by current collector defects. This study employed filtered cathode vacuum arc (FCVA) technology to fabricate Cu current collectors (CCs) with a lithiophilic Zn3N2 film. This advanced preparation process ensures an evenly distributed film that reduces the nucleation overpotential, homogenizes the interfacial electric field during plating/stripping processes, inhibits lithium dendrite growth, and forms a stable solid-electrolyte interphase (SEI). Our results show that the advanced Zn3N2@Cu CCs exhibit superior performance with a high CE of above 99.3% after 230 cycles at a current density of 0.5 mA cm-2 and an area capacity of 1 mAh cm-2. Additionally, Li-Zn3N2@Cu||Li-Zn3N2@Cu symmetrical cells had a longer stable cycle time of over 1000 h than that of Li||Li and Li-Cu||Li-Cu symmetrical cells at a current density of 1 mA cm-2 and an area capacity of 2 mAh cm-2. Compared with bare Cu CCs, the capacity retention rate is increased from 14.9 to 63.1% after 100 cycles with a 0.5C rate in the AFLMBs with LFP as the cathode. This work provides a pioneering, eco-friendly, and effective solution for the fabrication of anode CCs in AFLMBs, addressing a significant challenge in their commercial application.

Co(OH)2 nanoneedles grown on Cu/NF current collector with high areal capacitance for supercapacitors

Co(OH)2 nanoneedles grown on Cu/NF current collector with high areal capacitance for supercapacitors