Pulsed Plasma Technique Research Articles

Inactivation effect and mechanism of Pediastrum by in-liquid pulsed discharge plasma

The issue of eutrophication in river and lake ecosystems is escalating, resulting in harmful algal blooms that adversely impact the aquatic environment. Thus, it is crucial to develop new technology that can effectively inactivate algae without causing secondary pollution to the water body. This work uses in-liquid pulsed discharge plasma technique to inactivate Pediastrum. The research investigates variations in inactivation ratios, chlorophyll-a concentrations, and the inactivation mechanisms under different discharge conditions. The results indicate that the optimal inactivation effect is achieved at a peak voltage of 30 kV, an electrode spacing of 7 mm, and a discharge duration of 20 min, resulting in a 90 % inactivation ratio and a reduction in chlorophyll-a concentration from 1.31 mg/L to 0.63 mg/L (on the fourth day of re-culturing). The discharge process generates strong shock waves, ultraviolet lights, and significant amounts of oxidizing agents, such as· O, H2O2, O3, leading to cell damage, cell wall disruption, and enzyme activity reduction, thereby achieving effective inactivation.

Analysis of Wear Using the Taguchi Method in TiSiNOS-Coated and Uncoated H13 Tool Steel

Titanium–silicon oxynitride sulfite (TiSiNOS) is a coating material that is deposited on H13 tool steel using the scalable pulsed power plasma (S3P) technique, where the coating deposition is a hybrid process consisting of a mix of sputtering and arc evaporation. The maximum hardness and coating thickness measured on TiSINOS-coated H13 tool steel are 38 GPa and 3.1 µm, respectively. After implementing the L9 orthogonal array, nine samples were coated with TiSiNOS, which consists of the same properties. The nine coated and uncoated samples were tested separately based on the L9 pattern to achieve accurate results. The experimental results indicate that the wear loss can be reduced by minimizing the load at 25 N even if the temperature rises to 250 °C. SEM analysis reveals that the uncoated sample has higher wear loss when compared with the coated samples, and material pullout is visible from the uncoated sample. Based on these results, it can be concluded that TiSINOS coating in H13 tool steel helps in improving the tool life during the drilling process. Taguchi was used in this research to evaluate the wear behavior. The data observed from the experiment were analyzed using the Minitab tool. The most crucial factor is to determine the effects of process parameters. A higher temperature influenced the wear behavior of the tool.

MACHINE LEARNING-BASED MODELING AND OPTIMIZATION IN HARD TURNING OF AISI D6 STEEL WITH ADVANCED AlTiSiN-COATED CARBIDE INSERTS TO PREDICT SURFACE ROUGHNESS AND OTHER MACHINING CHARACTERISTICS

In recent times, mechanical and production industries are facing increasing challenges related to the shift towards sustainable manufacturing. In this work, the machining was performed in dry cutting condition with the newly developed AlTiSiN-coated carbide inserts coated through scalable pulsed power plasma technique, and a dataset was generated for different machining parameters and output responses. The machining parameters are speed, feed and depth of cut, while the output responses are surface roughness, cutting force, crater wear length, crater wear width and flank wear. Abrasion and adhesion were found to be the two dominant wear mechanisms. With speed, the tool wear was found to increase. Cutting force was found to increase rapidly for higher speed ranges (70, 80 and 90[Formula: see text]m/min). But reduction of cutting force was observed in both low and medium ranges of cutting speed (40, 50, 55 and 60[Formula: see text]m/min). With higher values of feed and depth of cut, higher cutting force was also noticed. With the variation of depth of cut, the machined surface morphology and machined surface roughness were found to deteriorate. With higher feed and depth of cut values, more surface damages were observed compared to low values of feed and depth of cut. Both the feed rate and tool–chip contact length contributed significantly to the formation of crater on the tool rake surface. At high speed, continuous chips were observed. Both chip sliding and sticking were observed on the tool rake face. The data collected from the machining operation was used for the development of machine learning (ML)-based surrogate models to test, evaluate and optimize various input machining parameters. Different ML approaches such as polynomial regression (PR), random forests (RF) regression, gradient boosted (GB) trees and adaptive boosting (AB)-based regression were used to model different output responses in the hard machining of AISI D6 steel. Out of the four ML methodologies, RF and PR performed better in comparison to the other two algorithms in terms of the [Formula: see text] values of predictions. The surrogate models for different output responses were used to prepare a complex objective function for the germinal center algorithm-based optimization of the machining parameters of the hard turning operation.

Novel physical treatments (Pulsed light and cold plasma) improve the quality of postharvest apricots after long-distance simulated transportation

Biological control of postharvest transportation by non-thermal treatment is considered a promising physical preservation technology. This study investigated how apricot quality (before simulation of transport vibrations) increased using intense pulsed light (IPL) and dielectric barrier discharge plasma (DBD) techniques. The results showed that DBD and IPL treatments reduced damage to apricot fruit after vibration and inhibited microbial growth on the surface of apricot fruit. By increasing the content of non-enzymatic antioxidants (total phenols, total flavonoids, ABTS, and DPPH radical scavenging activity) and antioxidant enzyme activity (SOD, PPO, POD, and CAT), the antioxidant capacity of apricot fruit was increased, cell structure damage was reduced, and water migration and erosion were inhibited as well. In summary, DBD and IPL treatments inhibited adverse physiological changes in apricot fruit subjected to vibration and mechanical damage, maintained their sensory and nutritional quality, and extended their shelf life.

Development of Surface Properties of High-Carbon Steel by Pulse Plasma Technique

The surface of DIN 115CrV3 (high carbon steel) was chosen for the plasma pulse process. Different process parameters such as distance and number of pulses were tested. The effects of pulse plasma treatment on the morphology, phase, and crystallographic orientation of DIN 115CrV3 steel were analyzed. The cross section of modified surfaces was examined by optical microscope and scanning electron microscopy (SEM). The structure in the steel surface layer changes to nitride and an austenite phase is formed. The formed structure is composed of columnar and fine grains. X-ray diffraction (XRD) analysis was performed on the modified surface. The existence of complex phases and hard phases was shown in the modification layer. The microhardness was investigated before and after treatment using a microhardness tester. The hardness of treated steels was increased from 250 HV to 1600 HV after pulse plasma treatment. Wear testing of the modifed surface used a CSM linear wear test machine. The reciprocating wear method was preferred. Wear rate was calculated using CSM wear software. The friction coefficient and wear values were varied in accordance with parameters. The friction coefficient of treated samples was decreased, while the wear rate increased to four times than that of untreated samples. The mechanical properties of the surface, such as hardness and wear resistance, were improved after pulse plasma treatment. The SEM–energy-dispersive spectroscopy (EDS) analyses, atomic force microscopy (AFM), and three-dimensional (3D) profilometer techniques were used to investigate the worn surfaces of specimens. The surface of the treated sample was shown to experience less deformation during the wear test.

Eco-Friendly Synthesis of Silver Nanoparticles Using Pulsed Plasma in Liquid: Effect of Surfactants

Silver (Ag) nanoparticles were successfully prepared by using the in-liquid pulsed plasma technique. This method is based on a low voltage, pulsed spark discharge in a dielectric liquid. We explore the effect of the protecting ligands, specifically Cetyl Trimethylammonium Bromide (CTAB), Polyvinylpyrrolidone (PVP), and Sodium n-Dodecyl Sulphate (SDS), used as surfactant materials to prevent nanoparticle aggregation. The X-Ray Diffraction (XRD) patterns of the samples confirm the face-centered cubic crystalline structure of Ag nanoparticles with the presence of Ag2O skin. Scanning Transmission Electron Microscopy (STEM) reveals that spherically shaped Ag nanoparticles with a diameter of 2.2 ± 0.8 nm were synthesised in aqueous solution with PVP surfactant. Similarly, silver nanoparticles with a peak diameter of 1.9 ± 0.4 nm were obtained with SDS surfactant. A broad size distribution was found in the case of CTAB surfactant.

Experimental investigation into machinability of hardened AISI D6 steel using newly developed AlTiSiN coated carbide tools under sustainable finish dry hard turning

In the present study, a newly developed AlTiSiN coating material deposited on carbide insert by scalable pulsed power plasma (SPPP) technique is used for machinability investigation of hardened AISI D6 die steel (65HRC) in finish dry turning. Also, the cutting tool is characterized by various diagnostic tests to evaluate the effectiveness of nanocomposite AlTISiN coating material and its cutting performance. A series of machining trials have been performed under varied cutting conditions (feed, depth of cut, speed) to investigate the machinability concerning surface roughness, flank wear, and chip morphology. Further, an approach towards multi-response optimization and predictive modelling for minimization of flank wear and surface roughness have been performed using response surface methodology. Finally, a unique approach has been proposed for economic analysis and sustainability assessment in hard turning. Result shows that the nanostructured AlTiSiN coating developed lower range of tool wear (VB = 0.044–0.076 mm), produced surface finish (Ra) within 0.322–0.905 µm which is approaching the surface quality to that of cylindrical grinding because of minimum friction coefficient, good bonding capability and enhancement in hardness as well as wear resistance of coating material. Statistical analysis reveals that Ra and VB are influenced principally by feed (84.14%) and cutting speed (53.43%), respectively. With the tool life of 34 min, Gilbert's machining economic model calculated the overall machining cost per part of Rs.61.04 in hard turning using coated carbide insert. Chip morphology confirmed the formation of serrated type saw tooth chips. It is established that machining under dry condition provides environment friendliness, techno-economically feasible to improve sustainability.

Comparative assessment between AlTiN and AlTiSiN coated carbide tools towards machinability improvement of AISI D6 steel in dry hard turning

AISI D6 (hardness 65 HRC) is one of the hard-to-cut steel alloys and commonly used in mould and die making industries. In general, CBN and PCBN tools are used for machining hardened steel but its higher cost makes the use for limited applications. However, the usefulness of carbide tool with selective coatings is the best substitute having comparable tool life, and in terms of cost is approximately one-tenth of CBN tool. The present study highlights a detailed analysis on machinability investigation of hardened AISI D6 alloy die steel using newly developed SPPP-AlTiSiN coated carbide tools in finish dry turning operation. In addition, a comparative assessment has been performed based on the effectiveness of cutting tool performance of nanocomposite coating of AlTiN deposited by hyperlox PVD technique and a coating of AlTiSiN deposited by scalable pulsed power plasma (SPPP) technique. The required number of machining trials under varied cutting conditions (speed, depth of cut, feed) were based on L16 orthogonal array design which investigated the crater wear, flank wear, surface roughness, chip morphology, and cutting force in hard turning. Out of the two cutting tools, newly-developed nanocomposite (SPPP-AlTiSiN) coated carbide tool promises an improved surface finish, minimum cutting force, longer tool life due to lower value of crater & flank wears, and considerable improvement in tool life (i.e., by 47.83%). At higher cutting speeds, the crater wear length and flank wear increases whereas the surface roughness, crater wear width and cutting force decreases. Chip morphology confirmed the formation of serrated type saw tooth chips.

Surface properties of AISI 4140 steel modified by pulse plasma technique

The pulse plasma process is a kind of surface modification technique. In this study, the microstructure and mechanical properties of pulse plasma-treated AISI 4140 steel were studied. Four different sample-plasma gun nozzle distances and three different pulses were chosen for the surface modification at a constant battery capacity of 800 mf. The samples were subjected to optical microscope, SEM and EDS analyses, microhardness testing and X-ray diffraction (XRD) analysis. The columnar and fine grained structures were formed in modified layer. New and hard phases were formed on the modified layer. Hence, the hardness increased five times after pulse plasma treatment. The amount of wear for all specimens was evaluated by using the reciprocating wear (linear wear test machine) test with a 0.15 m/s constant sliding speed under 5, 7, and 9 N loads along a 200 m sliding distance. A WC ball (with 6 mm diameter) was used in this test. The friction coefficient and wear rate were changed in accordance with the applied load. The friction coefficient values decreased and the wear resistance increased in the surface-modified specimens compared to the non-modified ones. The wear rate and the friction coefficient were changed with the wear debris and load. The debris was increased by the resistance to wear of surface. The worn surfaces of the specimens were studied by using atomic force microscopy (AFM), scanning electron microscopy (SEM) and electron dispersive spectroscopy (EDS). The abrasive wear was shown on worn surface.

Wear Behavior of DIN 1.2210 Steel Modified by a Pulse Plasma Technique

In this study, the micro-hardness, wear behavior, and microstructure of AISI 8620 steel, which was initially annealed at 700°C and carburized for 2 h at 900°C, were studied before and after pulse-p...

나노 반도체 소자를 위한 펄스 플라즈마 식각 기술

As the size of the semiconductor devices shrinks to nanometer scale, the importance of plasma etching process to the fabrication of nanometer scale semiconductor devices is increasing further and further. But for the nanoscale devices, conventional plasma etching technique is extremely difficult to meet the requirement of the device fabrication, therefore, other etching techniques such as use of multi frequency plasma, source/bias/gas pulsing, etc. are investigated to meet the etching target. Until today, various pulsing techniques including pulsed plasma source and/or pulse-biased plasma etching have been tested on various materials. In this review, the experimental/theoretical studies of pulsed plasmas during the nanoscale plasma etching on etch profile, etch selectivity, uniformity, etc. have been summarized. Especially, the researches of pulsed plasma on the etching of silicon, <TEX>$SiO_2$</TEX>, and magnetic materials in the semiconductor industry for further device scaling have been discussed. Those results demonstrated the importance of pulse plasma on the pattern control for achieving the best performance. Although some of the pulsing mechanism is not well established, it is believed that this review will give a certain understanding on the pulsed plasma techniques.

Surface properties of M2 steel treated by pulse plasma technique

In this study, the surface properties of a M2 steel (high speed steel) was investigated in respect to mechanical and microstructural aspects. Three were three different sample-plasma gun nozzle distances (30, 40 and 50 mm) and two different pulse (20 and 50) were chosen for the surface modification at a constant battery capacity of 500 mf. After pulse plasma surface treatment, the modified surface layers were examined using an optical microscope and also with X-ray analysis. It was observed that surface treatment affects the formation of a new structure. The stoichiometry of these phases was FeN, Fe2N, γ-Fe, W3 Olocated in the modification layer. The samples were also subjected to micro-hardness measurements. It was found that the hardness values of modified surfaces are three times higher than that of the untreated samples. Hardness increased from 280 HV to approximately 1000 HV. For the fracture surface examinations using SEM and EDS, notched specimens were sunk into liquid nitrogen for one minute and then they were cracked by hammer. The cracks were taken place in two different fracture modes: one is the ductile fracture seen on the modified layer and second one is the transgranular fracture seen in the matrix (i.e. untreated sample layer).

Lastnosti površine AISI 4140, spremenjene s tehniko pulzirajoče plazme

Lastnosti površine AISI 4140, spremenjene s tehniko pulzirajoče plazme

Synthesis of Carbon Nanotubes and Nano-onions Using Electric Field Induced Needle-Pulsed Arc Discharge Plasma

Carbon nano-onions and multi-walled carbon nanotubes (MWCNTs) are synthesized by needle-pulsed arc discharge plasma. In a simple production apparatus, a needle pulsed plasma is applied between two graphite electrodes in the presence of an electric field between anode and cathode. The possibility of carbon nanotube production by short pulsed arc discharge technique is investigated in this article. The pulse width is 0.3 μsec. Acetone vapor as carbon source is introduced to plasma. A magnetic field, perpendicular to the plasma path, is provided. The advantages of using short pulsed plasma are studied in this work. The results show that applying a DC electric field between electrodes, increases plasma tendency toward cathode, enhances the chance of plasma-hydrocarbon interaction, prevents carbon ions from dispersion and finally makes it possible to produce CNTs by low-power short pulses in an arc-discharge plasma reactor. The products are examined using SPM techniques. In this work, adding an electric field to the pulsed plasma techniques, suggests a new method to produce carbon nano particles (CNPs) by short current pulses with lifetime of below one microsecond.

The Effect of Process Parameters on Surface Behaviors of Low Carbon Steels Modified by Pulse Plasma Technique

In this study, microstructure and surface properties of low carbon steels (St52) treated by pulse plasma were investigated. The surfaces of samples were modi ed by pulse plasma technique. Four di erent plasma gun nozzle distances as 50 mm, 60 mm, 70 mm, and 80 mm and one battery capacity were chosen for surface modi cation. Cross-section microstructures of samples were investigated and modi ed layer thicknesses were measured by optical microscope. The thickness values of modi ed layer were obtained in a range from 10 μm to 41 μm. The samples were immersed into liquid nitrogen and then breaked in a Charpy machine. The fractured surfaces were exposed to scanning electron microscopy analyses. At the end of the study, thin grains and small tungsten grains coming from tungsten electrode were detected. After pulse plasma treatment, new structures and new phases and high hardness values were obtained.

Pulsed plasma induced protection coatings on composite LiMn2O4 powder cathodes

A low temperature direct current pulsed plasma technique has been applied on laminated composite lithium manganese oxide powder cathodes containing the polyvinylidene fluoride binder and carbon black additive. The plasma treatment results in mass transport on the surface of the particles due to an ion bombardment induced atomic peening process. A thin layer is induced on the particle surface. This plasma induced surface layer acts as a protection coating, which improves the cycling and structural stability of the treated cathodes even at high discharge rates, high temperature (60°C) and low cut-off potential (2.0V). The X-ray photo electron spectra of Mn3p for the treated and untreated samples after high temperature (60°C) cycling reveal binding energy shift on the surface of the untreated sample, whereas a stable molecular structure is preserved in the pulsed plasma treated cathode.

Fabrication and performance of TiN/TiAlN nanometer modulated coatings

TiN/TiAlN multilayered coatings with bilayer periods (λ BD) ranging from 6 to 30 nm were prepared on TC4 alloy and Si (100) wafer substrates by magnetic filtered pulsed vacuum cathodic arc plasma technique. The analyses with scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray energy dispersive spectroscope (EDS) and X-ray photoelectron spectroscope (XPS) with Ar + sputtering indicated that the as-deposited coatings had nanometer modulated structure, TiN and TiAlN with (111) preferred orientation were the main compounds and the average atoms ratio of N:(Ti + Al) was about 1.24–1.29. Scratch test showed that the coatings were fairly adherent to TC4 substrates, and the maximal critical load was about 57 N. The highest nano-hardness and modulus about 28 GPa and 283 GPa, respectively, were obtained for the multilayer with λ BD = 12 nm, examined with nano-indentation method. The electrochemical corrosion test showed that the coatings improved the TC4 alloy's property of anti-corrosion effectively, especially with λ BD = 20 nm.

Ammonia absorption study of pulsed-plasma polyaniline by quartz crystal microgravimetry and UV/vis spectrometry

The ammonia absorption properties of polyaniline elaborated by the pulsed-plasma technique are studied. These properties depend on the structure of the polymer which is associated not only to plasma parameters such as peak power, ignition and extinction durations, pulse frequency and duty cycle, but also to the type of doping agent. Two methods of analysis are used: the UV/vis spectrometry and the quartz crystal microbalance. The results show that input power is the most influent plasma parameter on the sensitivity of the polyaniline film. Moreover, the oxidative doping is more efficient than the acidic one to create more polarons and then to obtain a more sensitive layer. The gravimetric study shows that the interaction between ammonia molecules and iodine-doped polyaniline corresponds to a multilayer reversible chemisorption.

Wear Behavior of AISI 8620 Steel Modified by a Pulse-Plasma Technique

In this study, the micro-hardness, wear behavior, and microstructure of AISI 8620 steel, which was initially annealed at 700°C and carburized for 2 h at 900°C, were studied before and after pulse-plasma treatment. The surfaces of the samples were modified by a mixture of nitrogen, C3H8, and oxygen gases by using a pulse-plasma technique. Two different battery capacities of 800 and 1000 μ F and two different sample plasma gun nozzle distances of 60 and 80 mm were chosen for surface modification. Microhardness measurements were carried out on the sections perpendicular to the surfaces treated and hardness profiles from the outer surface to the inner sections of the samples modified by pulse-plasma were determined. The measurements showed that pulse-plasma treatment resulted in a remarkable increase in surface hardness of an AISI 8620 steel after the conventional carburizing process and the maximum hardness value measured was as high as HV910. Ball-on-disc wear tests according to ASTM G99 were also conducted on the treated samples of AISI 8620 steels in order to investigate their wear and friction performance in dry sliding conditions. Worn surfaces were analyzed and dominant wear mechanisms were identified using the SEM and EDS techniques. It was found that the pulse-plasma treatment considerably improved the wear resistance of all treated materials. However, it was shown that the process parameters as well as the initial heat treatment had a profound effect on the wear rate and the maximum wear resistance was obtained from those initially subjected to heat treatment and then treated by pulse-plasma at the battery capacity of 800 μ F and nozzle distance of 80 mm.

(Ti,Al)N Film on Normalized T8 Carbon Tool Steel Prepared by Pulsed High Energy Density Plasma Technique

Under optimized operating parameters, a hard and wear resistant (Ti,Al)N film is prepared on a normalized T8 carbon tool steel substrate by using pulsed high energy density plasma technique. Microstructure and composition of the film are analysed by x-ray diffraction, x-ray photoelectron spectroscopy, Auger electron spectroscopy and scanning electron microscopy. Hardness profile and tribological properties of the film are tested with nano-indenter and ring-on-ring wear tester, respectively. The tested results show that the microstructure of the film is dense and uniform and is mainly composed of (Ti,Al)N and AlN hard phases. A wide transition interface exists between the film and the normalized T8 carbon tool steel substrate. Thickness of the film is about 1000 nm and mean hardness value of the film is about 26 GPa. Under dry sliding wear test conditions, relative wear resistance of the (Ti,Al)N film is approximately 9 times higher than that of the hardened T8 carbon tool steel reference sample. Meanwhile, the (Ti,Al)N film has low and stable friction coefficient compared with the hardened T8 carbon tool steel reference sample.