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4 pages, 172 KiB

Open AccessEditorial

Advances in Plasma and Laser Engineering

by Mariusz Jasiński

Materials 2024, 17(8), 1768; https://doi.org/10.3390/ma17081768 - 11 Apr 2024

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Abstract

Materials science, especially in the context of nanotechnology, plays a key role in today’s world, contributing to the development of advanced materials with unique properties [...] Full article

(This article belongs to the Special Issue Advances in Plasma and Laser Engineering)

Research

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18 pages, 2104 KiB

Open AccessArticle

On Relationships between Plasma Chemistry and Surface Reaction Kinetics Providing the Etching of Silicon in CF₄, CHF₃, and C₄F₈ Gases Mixed with Oxygen

by Seung Yong Baek, Alexander Efremov, Alexander Bobylev, Gilyoung Choi and Kwang-Ho Kwon

Materials 2023, 16(14), 5043; https://doi.org/10.3390/ma16145043 - 17 Jul 2023

Cited by 1 | Viewed by 1186

Abstract

In this work, we discuss the effects of component ratios on plasma characteristics, chemistry of active species, and silicon etching kinetics in CF₄ + O₂, CHF₃ + O₂, and C₄F₈ + O₂ gas [...] Read more.

In this work, we discuss the effects of component ratios on plasma characteristics, chemistry of active species, and silicon etching kinetics in CF₄ + O₂, CHF₃ + O₂, and C₄F₈ + O₂ gas mixtures. It was shown that the addition of O₂ changes electrons- and ions-related plasma parameters rapidly suppresses densities of CF_x radicals and influences F atoms kinetics through their formation rate and/or loss frequency. The dominant Si etching mechanism in all three cases is the chemical interaction with F atoms featured by the nonconstant reaction probability. The latter reflects both the remaining amount of fluorocarbon polymer and oxidation of silicon surface. Full article

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13 pages, 3990 KiB

Open AccessArticle

Laser-Treated Steel Surfaces Gliding on Snow at Different Temperatures

by Ettore Maggiore, Carmelo Corsaro, Enza Fazio, Inam Mirza, Francesco Ripamonti, Matteo Tommasini and Paolo M. Ossi

Materials 2023, 16(8), 3100; https://doi.org/10.3390/ma16083100 - 14 Apr 2023

Cited by 2 | Viewed by 988

Abstract

With the goal of substituting a hard metallic material for the soft Ultra High Molecular Weight Polyethylene (UHMWPE) presently used to make the bases of skis for alpine skiing, we used two non-thermodynamic equilibrium surface treatments with ultra-short (7–8 ps) laser pulses to [...] Read more.

With the goal of substituting a hard metallic material for the soft Ultra High Molecular Weight Polyethylene (UHMWPE) presently used to make the bases of skis for alpine skiing, we used two non-thermodynamic equilibrium surface treatments with ultra-short (7–8 ps) laser pulses to modify the surface of square plates (50 × 50 mm²) made of austenitic stainless steel AISI 301H. By irradiating with linearly polarized pulses, we obtained Laser Induced Periodic Surface Structures (LIPSS). By laser machining, we produced a laser engraving on the surface. Both treatments produce a surface pattern parallel to one side of the sample. For both treatments, we measured with a dedicated snow tribometer the friction coefficient µ on compacted snow at different temperatures (−10 °C; −5 °C; −3 °C) for a gliding speed range between 1 and 6.1 ms⁻¹. We compared the obtained µ values with those of untreated AISI 301H plates and of stone grinded, waxed UHMWPE plates. At the highest temperature (−3 °C), near the snow melting point, untreated AISI 301H shows the largest µ value (0.09), much higher than that of UHMWPE (0.04). Laser treatments on AISI 301H gave lower µ values approaching UHMWPE. We studied how the surface pattern disposition, with respect to the gliding direction of the sample on snow, affects the µ trend. For LIPSS with pattern, orientation perpendicular to the gliding direction on snow µ (0.05) is comparable with that of UHMWPE. We performed field tests on snow at high temperature (from −0.5 to 0 °C) using full-size skis equipped with bases made of the same materials used for the laboratory tests. We observed a moderate difference in performance between the untreated and the LIPSS treated bases; both performed worse than UHMWPE. Waxing improved the performance of all bases, especially LIPSS treated. Full article

(This article belongs to the Special Issue Advances in Plasma and Laser Engineering)

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16 pages, 3285 KiB

Open AccessArticle

Surface Modification of Silicone by Dielectric Barrier Discharge Plasma

by Krzysztof Krawczyk, Agnieszka Jankowska, Michał Młotek, Bogdan Ulejczyk, Tomasz Kobiela and Krystyna Ławniczak-Jabłońska

Materials 2023, 16(8), 2973; https://doi.org/10.3390/ma16082973 - 08 Apr 2023

Cited by 2 | Viewed by 1515

Abstract

The objective of the study was to modify the surface of the silicone rubber, using dielectric barrier discharge (DBD) to improve its hydrophilic properties. The influence of the exposure time, discharge power, and gas composition—in which the dielectric barrier discharge was generated—on the [...] Read more.

The objective of the study was to modify the surface of the silicone rubber, using dielectric barrier discharge (DBD) to improve its hydrophilic properties. The influence of the exposure time, discharge power, and gas composition—in which the dielectric barrier discharge was generated—on the properties of the silicone surface layer were examined. After the modification, the wetting angles of the surface were measured. Then, the value of surface free energy (SFE) and changes in the polar components of the modified silicone over time were determined using the Owens–Wendt method. The surfaces and morphology of the selected samples before and after plasma modification were examined by Fourier-transform infrared spectroscopy with attenuated total reflectance (FTIR–ATR), atomic force microscopy AFM, and X-ray photoelectron spectroscopy (XPS). Based on the research, it can be concluded that the silicone surface can be modified using a dielectric barrier discharge. Surface modification, regardless of the chosen method, is not permanent. The AFM and XPS study show that the structure’s ratio of oxygen to carbon increases. However, after less than four weeks, it decreases and reaches the value of the unmodified silicone. It was found that the cause of the changes in the parameters of the modified silicone rubber is the disappearance of oxygen-containing groups on the surface and a decrease in the molar ratio of oxygen to carbon, causing the RMS surface roughness and the roughness factor to return to the initial values. Full article

(This article belongs to the Special Issue Advances in Plasma and Laser Engineering)

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9 pages, 16519 KiB

Open AccessArticle

Efficient Broadband Light-Trapping Structures on Thin-Film Silicon Fabricated by Laser, Chemical and Hybrid Chemical/Laser Treatments

by Michael Kovalev, Ivan Podlesnykh, Alena Nastulyavichus, Nikita Stsepuro, Irina Mushkarina, Pavel Platonov, Evgeniy Terukov, Sergey Abolmasov, Aleksandr Dunaev, Andrey Akhmatkhanov, Vladimir Shur and Sergey Kudryashov

Materials 2023, 16(6), 2350; https://doi.org/10.3390/ma16062350 - 15 Mar 2023

Cited by 4 | Viewed by 1346

Abstract

Light-trapping structures formed on surfaces of various materials have attracted much attention in recent years due to their important role in many applications of science and technology. This article discusses various methods for manufacturing light-trapping “black” silicon, namely laser, chemical and hybrid chemical/laser [...] Read more.

Light-trapping structures formed on surfaces of various materials have attracted much attention in recent years due to their important role in many applications of science and technology. This article discusses various methods for manufacturing light-trapping “black” silicon, namely laser, chemical and hybrid chemical/laser ones. In addition to the widely explored laser texturing and chemical etching methods, we develop a hybrid chemical/laser texturing method, consisting in laser post-texturing of pyramidal structures obtained after chemical etching. After laser treatments the surface morphology was represented by a chaotic relief of microcones, while after chemical treatment it acquired a chaotic pyramidal relief. Moreover, laser texturing of preliminarily chemically microtextured silicon wafers is shown to take five-fold less time compared to bare flat silicon. In this case, the chemically/laser-treated samples exhibit average total reflectance in the spectral range of 250–1100 nm lower by 7–10% than after the purely chemical treatment. Full article

(This article belongs to the Special Issue Advances in Plasma and Laser Engineering)

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14 pages, 79344 KiB

Open AccessArticle

Dynamic Characteristics of Plasma in Ultrasonic-Assisted Narrow-Gap Laser Welding with Filler Wire

by Ren Wang, Zhenxing He, Xiaoyang Kan, Ke Li, Fugang Chen, Juan Fu and Yong Zhao

Materials 2023, 16(2), 502; https://doi.org/10.3390/ma16020502 - 04 Jan 2023

Cited by 3 | Viewed by 1053

Abstract

Laser welding with filler wire was applied to Q345D in a narrow gap under ultrasonic assistance, and the dynamic characteristics of plasma were studied by high-speed imaging and spectral acquisition. The results showed that the plasma area decreased gradually with increasing distance between [...] Read more.

Laser welding with filler wire was applied to Q345D in a narrow gap under ultrasonic assistance, and the dynamic characteristics of plasma were studied by high-speed imaging and spectral acquisition. The results showed that the plasma area decreased gradually with increasing distance between the ultrasonic loading position and welding seam. The electron density and temperature of the plasma with ultrasonic assistance were higher than those without ultrasound. The electron density was approximately 10¹⁶~10¹⁷ cm⁻³, and the plasma temperature was approximately 4000~6000 K. Ultrasonic assisted laser wire filling welding can bring about cavitation effect and significantly reduce the porosity problem. Full article

(This article belongs to the Special Issue Advances in Plasma and Laser Engineering)

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12 pages, 5353 KiB

Open AccessArticle

Microstructure and Texture Characterization of Duplex Stainless Steel Joints Welded by Alternating Magnetic Field-Assisted Hybrid Laser-GMAW Welding

by Juan Fu, Zhipeng Rao, Yong Zhao, Jiasheng Zou, Xin Liu and Yanfei Pan

Materials 2022, 15(24), 8741; https://doi.org/10.3390/ma15248741 - 07 Dec 2022

Cited by 6 | Viewed by 1401

Abstract

In this study, 2205 duplex stainless steel with 12 mm thickness was welded by alternating magnetic field-assisted laser arc hybrid welding. The effect of an alternating magnetic field on the proportion distribution of two phases of the welded joint was investigated. The texture [...] Read more.

In this study, 2205 duplex stainless steel with 12 mm thickness was welded by alternating magnetic field-assisted laser arc hybrid welding. The effect of an alternating magnetic field on the proportion distribution of two phases of the welded joint was investigated. The texture distribution, grain boundary misorientation, and grain size of welded joints were analyzed and characterized. The uniform distribution of alloying elements in the two phases was improved by a 20 mT alternating magnetic field. The diffusion dissolution of Ni and N elements into the γ phase was promoted, which was conducive to the transition from the α to γ phase and reduced the precipitation of Cr₂N, such that the ratio of γ to α was 43.4:56.6. The ratio of the two phases of the weld was balanced by the alternating magnetic field of 30 mT, such that the ratio of γ and α was 44.6:55.4 and the texture dispersion was weakened. The Σ3 twinning boundary of the austenite phase in the weld was transformed to HABs, the ferrite phase underwent dynamic recrystallization, and the austenite phase had a cube texture, copper texture, and goss texture. Full article

(This article belongs to the Special Issue Advances in Plasma and Laser Engineering)

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17 pages, 6338 KiB

Open AccessArticle

A New Insight into High-Aspect-Ratio Channel Drilling in Translucent Dielectrics with a KrF Laser for Waveguide Applications

by Igor V. Smetanin, Alexey V. Shutov, Nikolay N. Ustinovskii, Polad V. Veliev and Vladimir D. Zvorykin

Materials 2022, 15(23), 8347; https://doi.org/10.3390/ma15238347 - 24 Nov 2022

Cited by 4 | Viewed by 1179

Abstract

A new insight into capillary channel formation with a high aspect ratio in the translucent matter by nanosecond UV laser pulses is discussed based on our experiments on KrF laser multi-pulse drilling of polymethyl methacrylate and K8 silica glass. The proposed mechanism includes [...] Read more.

A new insight into capillary channel formation with a high aspect ratio in the translucent matter by nanosecond UV laser pulses is discussed based on our experiments on KrF laser multi-pulse drilling of polymethyl methacrylate and K8 silica glass. The proposed mechanism includes self-consistent laser beam filamentation along a small UV light penetration depth caused by a local refraction index increase due to material densification by both UV and ablation pressure, followed by filamentation-assisted ablation. A similar mechanism was shown to be realized in highly transparent media, i.e., KU-1 glass with a multiphoton absorption switched on instead of linear absorption. Waveguide laser beam propagation in long capillary channels was considered for direct electron acceleration by high-power laser pulses and nonlinear compression of excimer laser pulses into the picosecond range. Full article

(This article belongs to the Special Issue Advances in Plasma and Laser Engineering)

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16 pages, 3974 KiB

Open AccessArticle

Atmospheric Pressure Plasma-Treated Polyurethane Foam as Reusable Absorbent for Removal of Oils and Organic Solvents from Water

by Antonella Uricchio, Teresa Lasalandra, Eliana R. G. Tamborra, Gianvito Caputo, Rogério P. Mota and Fiorenza Fanelli

Materials 2022, 15(22), 7948; https://doi.org/10.3390/ma15227948 - 10 Nov 2022

Cited by 4 | Viewed by 1449

Abstract

This paper reports the optimization of a two-step atmospheric pressure plasma process to modify the surface properties of a polyurethane (PU) foam and, specifically, to prepare a superhydrophobic/superoleophilic absorbent for the removal of oils and nonpolar organic solvents from water. In particular, in [...] Read more.

This paper reports the optimization of a two-step atmospheric pressure plasma process to modify the surface properties of a polyurethane (PU) foam and, specifically, to prepare a superhydrophobic/superoleophilic absorbent for the removal of oils and nonpolar organic solvents from water. In particular, in the first step, an oxygen-containing dielectric barrier discharge (DBD) is used to induce the etching/nanotexturing of the foam surfaces; in the second step, an ethylene-containing DBD enables uniform overcoating with a low-surface-energy hydrocarbon polymer film. The combination of surface nanostructuring and low surface energy ultimately leads to simultaneous superhydrophobic and superoleophilic wetting properties. X-ray photoelectron spectroscopy, scanning electron microscopy and water contact angle measurements are used for the characterization of the samples. The plasma-treated PU foam selectively absorbs various kinds of hydrocarbon-based liquids (i.e., hydrocarbon solvents, mineral oils, motor oil, diesel and gasoline) up to 23 times its own weight, while it completely repels water. These absorption performances are maintained even after 50 absorption/desorption cycles and after immersion in hot water as well as acidic, basic and salt aqueous solutions. The plasma-treated foam can remove mineral oil while floating on the surface of mineral oil/water mixtures with a separation efficiency greater than 99%, which remains unaltered after 20 separation cycles. Full article

(This article belongs to the Special Issue Advances in Plasma and Laser Engineering)

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