ON THE TRANSPORT PHENOMENA IN HIGHLY IONIZED PULSED PLASMA DURING FeCuNbSiB THIN FILM DEPOSITION PROCESS

The transport of sputtered particles in a magnetron discharge is of considerable interest for optimizing the deposition technique with respect to both deposition rate and control of the thin film properties. The High Power Impulse Magnetron Sputtering (HiPIMS) is a relatively new sputtering-based ionized physical vapor deposition technique with high density and high ionization degree of sputtered atoms which offers favorable conditions for better control and high-quality growing of thin films. Operating the HiPIMS in short pulse mode allows increasing the deposition rate due to the reduced gas rarefaction effect and reducing the ion back-attraction of the ionized sputtered material. Results concerning the spatial and temporal evolution of both the sputtered atoms density and plasma potential, the temporal evolution of the ion current intensity recorded by an electrostatic probe placed close to the substrate and the total positive electrical charge collected by the target and the probe during Fe 73.5 Cu 1 Nb 3 Si 15.5 B 7 thin film deposition process are presented. Most of the depositions and investigations have been made for a constant pulse voltage value of -1 kV, short pulse durations (4-20 µs), 10 mTorr working gas pressure and 30 W average power

On the electromagnetic shielding properties of carbon fiber materials

Introduction. Due to the good electrical and thermal properties of carbon, carbon-based materials represent a major trend is various applications, including electromagnetic compatibility. Among carbon-based materials, graphite-impregnated woven fabrics represent a new trend in the field of electromagnetic shielding, with the perspective of being used for protective clothing. The novelty of the proposed work consists in the exhaustive comparative analysis of various carbon-based sample shields by employing both simulation and experimental methods. The selected configurations included a simple graphite plate, a graphite powder strip network, and a graphite-impregnated fabric with 2´2 twill weave. Purpose. The main scope of the analysis is to prove the efficiency of the graphite-impregnated twill woven fabric in the field of electromagnetic shielding. Methods. Two main research methods were employed: simulation and experiment, both following the same protocol: the shield placed in the middle, with the excitation (transmitting antenna) on one side and the measurement / receiving antenna on the other. The experimental stage was thorough, being performed in two different laboratories and by applying the double transverse electromagnetic (TEM) cell method and the shielded box method. Results. A significant difference yielded from the comparison of the simulation and experimental results for the shielding effectiveness, probably due to the fact that the virtual model is an idealized version of the physical one, not taking into account its imperfections. The virtual analysis yielded the graphite plate shield as the most efficient, followed closely by the twill fabric. The graphite strip network had significantly poorer performance compared to the other two shields, probably due to the electrical contact imperfections between the graphite strips and the optical transparency of the shield. The main focus of the analysis was the twill woven graphite-impregnated fabric; therefore, its shielding effectiveness was determined through simulation and experiment. The experimental analysis was performed in two stages in two different electromagnetic compatibility laboratories, by employing the double TEM cell method and the shielded box method, respectively, both methods providing similar results and classifying the shielding performance as good. Practical value. The paper provides an accurate analysis of the graphite-impregnated 2´2 twill woven fabric in terms of electromagnetic shielding effectiveness, by employing both simulation and experimental methods, and comparing its performance to the one other graphite-based shields.Вступ. Завдяки хорошим електричним і тепловим властивостям вуглецю, вуглецевмісні матеріали являють собою основні напрямки у різних застосуваннях, у тому числі в області електромагнітної сумісності, завдяки хорошим екрануючим властивостям. Серед матеріалів на основі вуглецю просочені графітом тканини є новою тенденцією в області електромагнітного екранування з перспективою використання для захисного одягу. Новизна запропонованої роботи полягає у вичерпному порівняльному аналізі різних зразків екранів на основі вуглецю з використанням як моделювання, так і експериментального методів. Вибрані конфігурації включали просту графітову пластину, сітку зі смуг з графітового порошку і просочену графітом тканину з переплетенням саржею 2´2. Ціль. Основною метою аналізу є доказ ефективності саржевого полотна, просоченого графітом, у галузі електромагнітного екранування. Методи. Використовувалися два основних методи дослідження: моделювання та експеримент, обидва слідували одному й тому ж протоколу: екран розташовувався посередині, з збуджуванням (передаючою антеною) з одного боку і вимірювальною/приймальною антеною з іншого. Експериментальний етап був ретельним і проводився у двох різних лабораторіях із застосуванням методу подвійної поперечної електромагнітної (ПЕМ) комірки та методу екранованої скриньки. Результати. Порівняння результатів моделювання та експериментів стосовно ефективності екранування демонструє суттєву відмінність, ймовірно, через те, що віртуальна модель є ідеалізованою версією фізичної, не враховуючи її недосконалості. Віртуальний аналіз показав, що екран із графітових пластин є найбільш ефективним, за ним близько слідує саржева тканина. Мережа з графітових смуг мала значно гірші характеристики порівняно з двома іншими екранами, ймовірно, через недосконалість електричного контакту між графітовими смужками та оптичною прозорістю екрана. Основним предметом аналізу була тканина саржевого переплетення, просочена графітом; тому її ефективність екранування визначалася шляхом моделювання та експерименту. Експериментальний аналіз був виконаний у два етапи у двох різних лабораторіях електромагнітної сумісності з використанням методу подвійної ПЕМ комірки та методу екранованої скриньки, відповідно, обидва методи дали аналогічні результати та визначили характеристики екранування як хороші. Практична цінність. У статті наведено точний аналіз просоченої графітом саржевої тканини 2´2 з точки зору ефективності електромагнітного екранування з використанням як моделювання, так і експериментальних методів, а також порівняння її характеристик з іншими екранами на основі графіту

Ti-Zr-Si-Nb nanocrystalline alloys and metallic glasses: Assessment on the structure, thermal stability, corrosion and mechanical properties

The development of novel Ti-based amorphous or \u3b2-phase nanostructured metallic materials could have significant benefits for implant applications, due to improved corrosion and mechanical characteristics (lower Young's modulus, better wear performance, improved fracture toughness) in comparison to the standardized \u3b1+\u3b2 titanium alloys. Moreover, the devitrification phenomenon, occurring during heating, could contribute to lower input power during additive manufacturing technologies. Ti-based alloy ribbons were obtained by melt-spinning, considering the ultra-fast cooling rates this method can provide. The titanium alloys contain in various proportions Zr, Nb, and Si (Ti60Zr10Si15Nb15, Ti64Zr10Si15Nb11, Ti56Zr10Si15Nb19) in various proportions. These elements were chosen due to their reported biological safety, as in the case of Zr and Nb, and the metallic glass-forming ability and biocompatibility of Si. The morphology and chemical composition were analyzed by scanning electron microscopy and energy-dispersive X-ray spectroscopy, while the structural features (crystallinity, phase attribution after devitrification (after heat treatment)) were assessed by X-ray diffraction. Some of the mechanical properties (hardness, Young's modulus) were assessed by instrumented indentation. The thermal stability and crystallization temperatures were measured by differential thermal analysis. High-intensity exothermal peaks were observed during heating of melt-spun ribbons. The corrosion behavior was assessed by electrocorrosion tests. The results show the potential of these alloys to be used as materials for biomedical applications

Plasma-wall interaction studies within the EUROfusion consortium: Progress on plasma-facing components development and qualification

This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.The provision of a particle and power exhaust solution which is compatible with first-wall components and edge-plasma conditions is a key area of present-day fusion research and mandatory for a successful operation of ITER and DEMO. The work package plasma-facing components (WP PFC) within the European fusion programme complements with laboratory experiments, i.e. in linear plasma devices, electron and ion beam loading facilities, the studies performed in toroidally confined magnetic devices, such as JET, ASDEX Upgrade, WEST etc. The connection of both groups is done via common physics and engineering studies, including the qualification and specification of plasma-facing components, and by modelling codes that simulate edge-plasma conditions and the plasma-material interaction as well as the study of fundamental processes. WP PFC addresses these critical points in order to ensure reliable and efficient use of conventional, solid PFCs in ITER (Be and W) and DEMO (W and steel) with respect to heat-load capabilities (transient and steady-state heat and particle loads), lifetime estimates (erosion, material mixing and surface morphology), and safety aspects (fuel retention, fuel removal, material migration and dust formation) particularly for quasi-steady-state conditions. Alternative scenarios and concepts (liquid Sn or Li as PFCs) for DEMO are developed and tested in the event that the conventional solution turns out to not be functional. Here, we present an overview of the activities with an emphasis on a few key results: (i) the observed synergistic effects in particle and heat loading of ITER-grade W with the available set of exposition devices on material properties such as roughness, ductility and microstructure; (ii) the progress in understanding of fuel retention, diffusion and outgassing in different W-based materials, including the impact of damage and impurities like N; and (iii), the preferential sputtering of Fe in EUROFER steel providing an in situ W surface and a potential first-wall solution for DEMO.European Commission; Consortium for Ocean Leadership 633053; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

The effect of vacuum and air annealing in the physical characteristics and photocatalytic efficiency of In2S3:Ag thin films produced by spray pyrolysis

Indium sulfide thin films, doped with silver, were synthesized by spray pyrolysis technique. These samples were subsequently annealed in air and in vacuum, at the temperature of 400 ◦C, for 2 h. This work reports the effect of the thermal treatments on the structure, morphology and optical characteristics of the films, but also the study of the photodegradation efficiency of methylene blue solution. The as-produced films are polycrystalline, exhibiting the tetragonal β-phase structure of In2S3. The annealing treatments cause an increase of 27% and 74% of the crystallite size, and of the roughness of the films (20% and 56%), for the vacuum and air annealed samples, respectively, but provoke a significant decrease of the optical transmittance. The optical band gap decreases from 2.71 eV in the as-produced film, to 2.45 eV and 2.39 eV in the vacuum and air-annealed films, respectively. The photodegradation efficiency of the methylene blue solution increases from 83.0% for the as-produced film to around 95.4%, regardless the type of annealing.Grant of the Romanian Ministry of Education and Research, CNCS - UEFISCDI, project number PN–III–P1-1.1-TE-2019-1209, within PNCDI II

Photocatalytical and corrosion behavior of sputtered zirconium oxynitride thin films doped with titanium

ZrTiON coatings were deposited by reactive magnetron sputtering process of a single Zr target, while Ti was added by placing Ti ribbons on the erosion track of the Zr sputtering target. The variation of parameters such as the number of Ti ribbons, the applied sputtering current, and the reactive gas flow led to obtaining different sample configurations. The coatings were analyzed in terms of chemistry (chemical composition and chemical states) by X-ray Photoelectron Spectroscopy, morphology by Atomic Force Microscopy, surface energy, photodegradation tests, electrochemical studies, and accelerated corrosion tests. It was found that the coatings show features of oxides, nitrides, and oxynitrides, depending on the deposition conditions applied. The photodegradation efficiency regarding methylene blue solutions under visible light varies between 58% and 96%, depending on the type of illuminant and the sample characteristics, while the lowest corrosion rate was exhibited by the reference samples deposited without the addition of Ti. The samples doped with Ti and deposited with 1.5 A sputtering current exhibited a more efficient photodegradation effect, compared to the reference ZrON sample. The accelerated corrosion tests showed that the coatings deposited with an applied current of 2 A behaved significantly better than the ones deposited with 1.5 A sputtering current after 8 h of exposure to the water vapor and sulfur dioxide gas atmosphere.This work was supported by a grant of the Romanian Ministry of Education and Research, CNCS - UEFISCDI, project number PN-IIIP1–1.1-TE-2019–1209, within PNCDI III. Part of the work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UIDB/04650/2020