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The partial discharge (PD) in high voltage switch cabinet might develop into non-penetrating or penetrating arc under extreme conditions, which can lead to insulation failure in severe case. From the optical radiation characteristics of discharge, an optical detection method for abnormal arc was proposed. Multi-spectral characteristics of arc discharge were obtained by the synchronous monitoring of ultraviolet, visible, and infrared optical signals, and the average intensity of light pulse, average light intensity ratio and the light intensity ratio of three bands were analyzed. The results show that the average light pulse intensity of arc discharge and the proportion of three-band light intensity have obvious characteristics and there is a good corresponding relation between the amplitude of discharge light signal and the applied voltage.

Although many methods have been documented for carbon nanotube (CNT) synthesis, still, we notice many arguments, criticisms, and appeals for its optimization and process control. Industrial grade CNT production is urgent such that invention of novel methods and engineering principles for large-scale synthesis are needed. Here, we comprehensively review arc discharge (AD) and laser ablation (LA) methods with highlighted features for CNT production. We also display the growth mechanisms of CNT with reasonable grassroots knowledge to make the synthesis more efficient. We postulate the latest developments in engineering carbon feedstock, catalysts, and temperature cum other minor reaction parameters to optimize the CNT yield with desired diameter and chirality. The rate limiting steps of AD and LA are highlighted because of their direct role in tuning the growth process. Future roadmap towards the exploration of CNT synthesis methods is also outlined.

Electrical arc machining (EAM) technology offers a competitive and efficient method for removing material from Ti6Al4V alloys. This study investigates the crater morphology and efficient material removal characteristics of EAM. Single-pulse arc discharge experiments were conducted on Ti6Al4V in ambient air with a positive workpiece electrode polarity. The investigation evaluates the impact of discharge current and discharge duration on the diameter, depth, volume of material removal, and the diameter-to-depth ratio of discharge craters. The discharge voltage-current waveform exhibits a delay and a reverse waveform after completion of the discharge. The discharge maintenance voltage throughout the process ranges from 20 to 40 V. The results indicate that an increase in discharge current leads to larger diameters and volumes of material removal. The maximum diameter and material removal volume reach 2430 μm and 0.788 mm 3 , respectively, significantly surpassing the discharge crater parameters of Ti6Al4V processed by conventional electrical discharge machining. A longer duration could not result in a greater volume of material removal from the craters like discharge current. The derived material removal rate for continuous EAM of Ti6Al4V can reach 11,820 mm 3 /min at a discharge current of 500 A, a discharge duration of 2 ms and an interval of 2 ms. Higher current and longer duration enable higher energy density and conversion efficiency, resulting in an efficient material removal rate. This study unveils the characteristics of efficient material removal through single-pulse arc machining experiments and the analysis of discharge crater evolution, contributing to a deep understanding of efficient processing efficiency in EAM of Ti6Al4V.

Ta2O5 coatings were created using micro-arc discharges (MDs) during anodization on a tantalum substrate in a sodium phosphate electrolyte (10 g/L Na3PO4·10H2O). During the process, the size of MDs increases while the number of MDs decreases. The elements and their ionization states present in MDs were identified using optical emission spectroscopy. The hydrogen Balmer line Hβ shape analysis revealed the presence of two types of MDs, with estimated electron number densities of around 1.1 × 1021 m−3 and 7.3 × 1021 m−3. The effect of MDs duration on surface morphology, phase and chemical composition, optical absorption, and photoluminescent, properties of Ta2O5 coatings, as well as their applications in photocatalytic degradation of methyl orange, were investigated. The created coatings were crystalline and were primarily composed of Ta2O5 orthorhombic phase. Since Ta2O5 coatings feature strong absorption in the ultraviolet light region below 320 nm, their photocatalytic activity is very high and increases with the time of the MDs process. This was associated with an increase of oxygen vacancy defects in coatings formed during the MDs, which was confirmed by photoluminescent measurements. The photocatalytic activity after 8 h of irradiation was around 69%, 74%, 80%, and 88% for Ta2O5 coatings created after 3 min, 5 min, 10 min, and 15 min, respectively.

With recent trends moving towards sustainable approaches in adherence to environmental, social, and governance (ESG) standards, research is actively focused on sustainable production of high-potential materials. In this study, a successful synthesis pathway was demonstrated for a graphene/tungsten carbide (WC) nanocomposite via pulsed arc discharge in liquid medium, utilizing crude palm oil and commercial cooking palm oil as liquid precursors. The synthesis of the graphene/WC nanocomposites was carried out by applying current with amplitude of 80 A and 100 A to the tungsten electrode immersed in the liquid palm oil, subjected to 150 arc discharges. A comparative investigation was performed to examine the morphological and functional characteristics of the materials synthesized from the different types of palm oil under different current conditions. In addition, the synthesized nanocomposites were assessed with respect to their gas sensing performance. Impressively, the CRG100(150) nanocomposite (produced from crude palm oil with current of 100 A) exhibited gas sensing response of 4.853% upon injection of 200 ppm of ethanol. The CRG100(150) nanocomposite also demonstrated short response and recovery time of 43 s and 182 s, respectively. Thus, the successful synthesis of CRG100(150), utilizing a natural precursor via arc discharge in liquid, paves the way for the development of sustainable gas sensing materials.

Electro-arc machining (EAM) is a new electrical discharge machining method based on thermal energy. A large amount of thermal energy is released during arc formation to melt and vaporize the workpiece material. Many factors affect arc machining performance, such as electrical parameters (peak current, etc.), non-electrical parameters (flushing pressure, etc.), workpiece and electrode shape, and material parameters. The electrode shape influences the machining performance. Single-factor, single-pulse arc discharge experiments are carried out to evaluate the effect of the electrode’s shape. The polarity effect is verified, and the following results are obtained. For the same workpiece conditions, the arc pit diameter is larger for positive polarity than for negative polarity, suggesting that the arc machining performance is also better for positive polarity. The radius of curvature of the crater has a larger influence than the crater diameter. If a larger etching volume is required, the radius of curvature can be increased, but the etching depth is slightly reduced. The positive and negative polarity also affect the arc plasma characteristic. The compression-expansion effect of the plasma is more pronounced when the direct current is large and positive polarity is used. Waveform analysis shows that the processing stability is higher for positive polarity, whereas negative polarity is more likely to result in bridges and short circuits. As the radius of curvature increases, the processing time, processing instability, and the height of the crater wall increase. The height of the crater wall is higher for positive polarity than for negative polarity.

Simple and reliable method was engaged to obtain densely-packed and easy-to-manipulate arrays of iron nanoparticles protected from the potential action of atmospheric factors, which are in demand for catalytic applications. For the purpose, atmospheric arc discharge was initiated in a discharge gap of 10 mm between stainless steel electrodes. The gap was filled with a mixture of micrometre-sized powders of graphite and iron. After passing a direct arc current of 140 A for 2 min, a significant change in the morphology and chemical composition of the initial materials was observed. After a positive polarity was supplied to a smaller electrode, carbon nanosheets with an average width of 200 mm and thickness of about 20 nm that host Fe nanoparticles with diameters mostly ranging from 10 to 40 nm were found. Moreover, the initial oxygen content of 18% wt. was reduced to just 4% wt., as measured in the synthesized nanocomposites.

The erosion pattern of discharge device elements is studied in a high-voltage pulsed arc discharge initiated by an auxiliary spark discharge on the dielectric surface in a short vacuum gap. A dependence of the operating erosion mechanisms on the time profile of the flowing current is found.

A top priority for the scientific community is reducing the greenhouse effect. Developing new materials for gas storage is a critical aspect, and new materials suitable for the adsorption of greenhouse gases such as carbon dioxide and methane are being investigated. Carbon Nano-Onions (CNOs) are one of the most recently discovered carbon allotropes, which can be synthesized by several methods, including submerged arc-discharge in water (SADW). Although the SADW method is well known, the properties of CNOs synthesized by this method as gas adsorbents have not yet been studied. Therefore, the aim of this work is to study these properties. For this purpose, CNOs were synthesized by SADW and characterized by different methods (XRD, TEM, Raman spectroscopy, and TGA) to determine their structural defects, size, morphology, and thermal stability. Their surface area, volume, and average pore size were also determined by nitrogen adsorption at 77 K measurement. Subsequently, their adsorption capacities of methane and carbon dioxide were obtained from adsorption/desorption isotherms and compared with other adsorbents found in the literature, with promising results. The predominant adsorption mode was also studied from isotherm models, and possible interaction mechanisms were provided.

The effect of low-temperature arc discharge plasma treatment in a nitrogen atmosphere on the modification of the physicochemical properties of PLA-based scaffolds was studied. In addition, the cellular-mediated immune response when macrophages of three donors interact with the modified surfaces of PLA-based scaffolds was investigated. PLA surface carbonization, accompanied by a carbon atomic concentration increase, was revealed to occur because of plasma treatment. Nitrogen plasma significantly influenced the PLA wettability characteristics, namely, the hydrophilicity and lipophilicity were improved, as well as the surface energy being raised. The viability of cells in the presence of the plasma-modified PLA scaffolds was evaluated to be higher than that of the initial cells.