Vacuum Arc Method Research Articles

Mass spectra and incident energy resolved spectra after collisions of hydrocarbon ions with fusion-plasma tungsten thin films

We have performed surface-induced dissociation studies of small deuterated hydrocarbon cations i.e. CDx+ with x=2-4, colliding with two types of tungsten-coated surfaces, in the incident energy range between Ein = 0 eV approximately, up to Ein = 100 eV. A 34 nm thick W layer deposited on stainless steel using the Thermionic Vacuum Arc (TVA) method and a small sample of a tile cut from ASDEX-Upgrade tiles, consisting of PlasmaSprayed (PS) tungsten on carbon, are exposed to ion flux in these experiments. A double-focussing reverse geometry BE mass spectrometer, is used under ultra high vacuum conditions. Mass spectra of secondary charged particles are recorded via time-of-flight mass analyser. For comparison, we have performed equivalent study on polished stainless steel under experimental status explained in Section 2 below. At very low energies i.e. below 10 eV, only surface reflected projectiles are seen, whereas most of them are neutralized by surface micro charges. We observed that the fragmentation pattern of the small molecular ions at a given energy is strongly dependent on the surface. The roughness of both of the said thin films and their reflectivity for the projectile ion beam is studied by analysis of the ion yields of the reaction products

Multi-layered gradient (Zr,Nb)N coatings deposited by the vacuum-arc method

Multi-layered gradient (Zr,Nb)N coatings were deposited with vacuum-arc evaporation of pure Zr and Nb metal cathodes. The gradient of the Nb concentration through the thickness was obtained by varying the arc discharge current with a Nb cathode within 80–150 A under the constant pressure of a working Ar/N2 gas mixture and a constant current of arc discharge with a Zr cathode. These coatings were studied by scanning and transmission electron microscopes, X-ray diffraction analysis, micro- and nanoindentation, and tribological measurements. The synthesized coatings show a high hardness, relatively low Young's modulus, relatively high H/E ratio, a high degree of elastic recovery, low surface roughness, a low friction coefficient, and a low wear rate. These coatings also feature a multiphase and multi-layered nanocrystalline structure with alternation of only layers with higher and lower Nb concentration.

Characterization of Platinum-Based Thin Films Deposited by Thermionic Vacuum Arc (TVA) Method.

The current work aimed to characterize the morphology, chemical, and mechanical properties of Pt and PtTi thin films deposited via thermionic vacuum arc (TVA) method on glass and silicon substrates. The deposited thin films were characterized by means of a scanning electron microscope technique (SEM). The quantitative elemental microanalysis was done using energy-dispersive X-ray spectroscopy (EDS). The tribological properties were studied by a ball-on-disc tribometer, and the mechanical properties were measured using nanoindentation tests. The roughness, as well as the micro and nanoscale features, were characterized using atomic force microscopy (AFM) and transmission electron microscopy (TEM). The wettability of the deposited Pt and PtTi thin films was investigated by the surface free energy evaluation (SFE) method. The purpose of our study was to prove the potential applications of Pt-based thin films in fields, such as nanoelectronics, fuel cells, medicine, and materials science.

Antibacterial Efficiency of Stainless-Steel Grids Coated with Cu-Ag by Thermionic Vacuum Arc Method

Autonomous smart natural ventilation systems (SVS) attached to the glass façade of living quarters and office buildings can help reducing the carbon footprint of city buildings in the future, especially during warm seasons and can represent an alternative to the conventional mechanical ventilation systems. The work performed in this manuscript focuses on the investigation of bacteria trapping and killing efficiency of stainless steel grids coated with a mixed layer of Cu-Ag. These grids are to be employed as decontamination filters for a smart natural ventilation prototype that we are currently building in our laboratory. The tested grids were coated with a mixed Cu-Ag layer using thermionic vacuum arc plasma processing technology. The fixed deposition geometry allowed the variation of Cu and Ag atomic concentration in coated layers as a function of substrate position in relation to plasma sources. The test conducted with air contaminated with a pathogen strain of staphylococcus aureus indicated that the filtering efficiency is influenced by two parameters: the pore size dimension and the coating layer composition. The results show that the highest filtering efficiency of 100% was obtained for fine pore (0.5 × 0.5 mm) grids coated with a mixed metallic layer composed of 65 at% Cu and 35 at% Ag. The second test performed only on reference grids and Cu-Ag (65–35 at%) under working conditions, confirm a similar filtering efficiency for the relevant microbiological markers. This particular sample was investigated from morphological, structural, and compositional point of view. The results show that the layer has a high surface roughness with good wear resistance and adhesion to the substrate. The depth profiles presented a uniform composition of Cu and Ag in the layer with small variations caused by changes in deposition rates during the coating process. Identification of the two metallic phases of the Cu and Ag in the layers evidences their crystalline nature. The calculated grain size of the nanocrystalline was in the range 14–21 nm.

Synthesis and Characterization of Complex Nanostructured Thin Films Based on Titanium for Industrial Applications.

Titanium-based composites—titanium and silver (TiAg) and titanium and carbon (TiC)—were synthesized by the Thermionic Vacuum Arc (TVA) method on substrates especially for gear wheels and camshaft coating as mechanical components of irrigation pumps. The films were characterized by surface morphology, microstructure, and roughness through X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Small-Angle Neutron Scattering (SANS). The silver (Ag) films crystallized into a cubic system with lattice a = 4.0833 Å at room temperature, indexed as cubic Ag group Fm3m. The crystallites were oriented in the [111] direction, and mean grain size was <D>111 = 265 Å. The TiC structure revealed a predominant cubic TiC phase, with a = 0.4098 as a lattice parameter determined by Cohen’s method. Average roughness (Ra) was 8 nm for the as-grown 170 nm thick TiAg film, and 1.8 nm for the as-grown 120 nm thick TiC film. Characteristic SANS contribution was detected from the TiAg layer deposited on a substrate of high-quality stainless steel with 0.45% carbon (OLC45) in the range of 0.015 Å−1 ≤ Q ≤ 0.4 Å−1, revealing the presence of sharp surfaces and an averaged triaxial ellipsoidal core-shell object.

Structural, Compositional, and Mechanical Characterization of WxCryFe1-x-y Layers Relevant to Nuclear Fusion, Obtained with TVA Technology.

Reduced activation ferritic and martensitic steel like EUROFER (9Cr-1W) are considered as potential structural materials for the first wall of the future next-generation DEMOnstration Power Station (DEMO) fusion reactor and as a reference material for the International Thermonuclear Experimental Reactor (ITER) test blanket module. The primary motivation of this work is to study the re-deposition of the main constituent materials of EUROFER, namely tungsten (W), iron (Fe), and chromium (Cr), in a DEMO type reactor by producing and analyzing complex WxCryFe1−x−y layers. The composite layers were produced in laboratory using the thermionic vacuum arc (TVA) method, and the morphology, crystalline structure, elemental composition, and mechanical properties were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-X-ray fluorescence (micro-XRF), and glow discharge optical emission spectrometry (GDOES), as well as nanoindentation and tribology measurements. The results show that the layer morphology is textured and is highly dependent on sample positioning during the deposition process. The formation of polycrystalline WxCryFe1−x−y was observed for all samples with the exception of the sample positioned closer to Fe anode during deposition. The crystalline grain size dimension varied between 10 and 20 nm. The composition and thickness of the layers were strongly influenced by the in-situ coating position, and the elemental depth profiles show a non-uniform distribution of Fe and Cr in the layers. The highest hardness was measured for the sample positioned near the Cr anode, 6.84 GPa, and the lowest was 4.84 GPa, measured for the sample positioned near the W anode. The tribology measurements showed an abrasive sliding wear behavior for most of the samples with a reduction of the friction coefficient with the increase of the normal load.

Effect of the pulse bias voltage parameters on the properties and composition of ZrN coatings deposited by vacuum arc method

In the work it is revealed that it is possible to control the structure, the phase and elemental composition of ZrN coatings by the change of the parameters of bias voltage (pulse repetition frequency, amplitude, pulse duty factor, etc.). It is established that optimum parameters of pulse bias voltage for the formation of ion-plasma ZrN coatings with a high hardness and wear resistance are Ub = –150 V, γ = 85%, f = 50 kHz. At these parameters the synthesized coating based on ZrN consists of ZrN crystallites with a cubic crystal lattice, which has [111] texture. The coating has the high hardness (30.5 GPa) and high wear resistance (1.1·10–6 mm3N–1m–1).

Effect of structure on the secondary electron emission of tetrahedral amorphous carbon films

Tetrahedral amorphous carbon (ta-C) films are appealing for electronic device due to its unique electronic and optical properties. In this work, ta-C films were prepared by filtered cathodic vacuum arc (FCVA) method which is developed by adopting a focusing-deflection system for adjusting the ion beam current density and increasing the deposition field size. The surface morphology of ta-C films prepared by this developed FCVA was presented by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results reveal that the roughness of these ta-C films is only ∼0.4 nm and bias voltages almost unaffected to the surface morphology of the films. Moreover, secondary electron emission properties of ta-C films were investigated with various bias voltages. Compared with bare stainless steel substrate, the secondary electron yield (SEY) of ta-C films decreases significantly. Furthermore, the films deposited at the bias voltages in the range of 110–155 V possess the highest maximum secondary electron emission coefficient (δmax) compared to others, which matches well with the variation of sp3content in the films from Raman spectra analyses. These results indicate that the SEY can be tailored by the sp3/sp2 ratio of ta-C films.

Nanostructured ceramic-metal coatings obtained by ion-plasma vacuum arc method

Ceramic-metal coatings (Ti,Al)N-Cu and (Ti,Al)N-Ni were obtained by Arc-PVD method. Metal components content in the coatings was regulated by varying the ratio between the surface area of the evaporated cathodes and the arcs current evaporating them. Concentration ranges of the metal components content in coatings which ensure the formation of an isomorphous nanocrystalline structure with a grain size of 15-20 nm, have been established. These coatings are characterized by superhardness of 43-51 GPa with preservation of viscosity (relative work of plastic deformation during nanoindentation ∼65-70%). At the same time, the coatings obtained are characterized by a low level of macrostresses.

The effect of substrate temperature on the properties of (AlCrNbSiTiV)N films deposited by HIPIMS

High-quality materials should always meet the requirements of industrial or consumer applications with the development of advanced technologies. In recent years, high-entropy alloys (HEAs) have been developed as new alloy materials due to their superior mechanical properties. Besides, difficult-to-cut materials have been also widely used in many different industrial applications. (AlCrNbSiTiV)N coatings as HEAs have been usually grown on tool, engine parts, MEMS processing components, and thermoelectric materials using vacuum arc and mechanical alloy methods. Hence, in order to improve the performance of tools and surface quality of workpieces in coolant-free turning process, a high-power impulse magnetron sputtering (HIPIMS) system was used to deposit (AlCrNbSiTiV)N films on the tool surface. In this study, the film thickness, deposition rate, and surface morphology at different substrate temperatures in turning chromium-molybdenum steel were investigated. The (AlCrNbSiTiV)N films coated in this study was homogeneous and very compact and showed good adhesion strength. Experimental results showed that increasing the substrate temperature from 100 to 400 °C during sputtering process indeed could improve the mobility of the atomic surface, the density of the films, and the hardness of the films. The maximum hardness and the elastic recovery rate (Re) of (AlCrNbSiTiV)N films were found to be 41.07 GPa and 80.21%, respectively, when the substrate temperature was increased to 400 °C. In addition, the performance of coated tools by (AlCrNbSiTiV)N film was comparatively much better than that of uncoated tools, which possessed broad application prospects in the future.

Structural Phase State and Thermal Cyclic Stability of the Thermal Barrier Zr–Si–O Coatings Deposited on a Copper Substrate by the Microplasma Method

In this work, preparation of thermal barrier coatings based on zirconium oxide is shown. The phased treatment of the copper substrate is proposed in order to obtain a layered thermal barrier oxide coating on it. The sample surface is nanostructured, titanium is deposited layer-by-layer (by the vacuum-arc method) and then zirconium (by the magnetron method), and then zirconium is converted into zirconium dioxide by the microplasma method. The formed oxide-ceramic coatings contain elements from a solution, according to the results of elemental analysis, and zirconium dioxide in tetragonal and monoclinic modifications, according to the results of X-ray diffraction. A study of thermal cyclic stability was carried out. It is revealed that an increase in the time of microplasma treatment to a certain value has a positive effect on the thermal cyclic properties of the obtained layer material and it is able to sustain more than 90 cycles without serious damage to the surface layer.

Plasma diagnostics and characterization of the Mg and Mg–Zn thin films deposited by thermionic vacuum arc (TVA) method

The Thermionic Vacuum Arc (TVA) is an original deposition method using a combination of anodic arc and powerful electron gun system (up to 600 W) for the growth of thin films from solid precursors under a vacuum of 10−4 Pa. The advantage of this technology is the comparatively high deposition rate while keeping good properties of the deposited films. The aim of this paper is to report on the characterization of the Mg and Mg–Zn thin films deposited by the TVA method. By careful selection of the deposition parameters, we have achieved a rather stable discharge that resulted in good film properties. The surface morphology and wettability of the deposited Mg and Mg–Zn thin films were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and free surface energy (FSE) by surface energy evaluation system. The results revealed that the size of crystallites is 5.0 nm in the case of Mg–Zn/Si and 6.5 nm in the case of Mg/Si sample; a promising result for future applications of the TVA. The film properties are complemented by plasma parameters measured by a heated probe.

Формирование ZrNbN-покрытий вакуумно-дуговым методом

Формирование ZrNbN-покрытий вакуумно-дуговым методом

Phase Composition, Mechanical and Tribological Properties of Ti–Al–N System Coatings Deposited by Vacuum-Arc Method

The results of the phase composition, mechanical and tribological properties of the vacuum arc (Ti,Al)N coatings using separated plasma flows are presented in this work. It has been determined that the formed Ti–Al–N coatings are of a nanoscale structure and characterized by high hardness and resistance to deformation, low friction coefficient. This allows for the use of such coatings for products operating under conditions of increased abrasive and adhesive wear.

The Thermionic Vacuum Arc Method for Rapid Deposition of Cu/CuO/Cu2O Thin Film

Copper oxide (CuOx) thin film has been deposited on glass substrate using the thermionic vacuum arc (TVA) method. The TVA system works in high-vacuum condition. The microstructural, surface, and optical properties were investigated. Reflection planes corresponding to Cu2O, CuO, and Cu crystal networks were detected in the x-ray diffraction (XRD) pattern. According to the XRD results, the deposited thin film was in polycrystalline form. The grain size, Miller indices, dislocation density, and microstrain were calculated. The crystalline size obtained from the CuO reflections was approximately 20 nm. The average roughness of the deposited film was measured to be 1.8 nm. The height distribution function of the grain size on the deposited surface was determined, revealing a mean grain height of 11 nm. The deposited film exhibited high transparency in the ultraviolet–visible (UV–Vis) spectroscopic region. The refractive index of the film was measured to be 2.20 at 632 nm. The optical bandgap and real part of the dielectric constant were found to be 1.5 eV and 4.84, respectively.

Nanostructured Coatings Based on Amorphous Carbon and Gold Nanoparticles Obtained by the Pulsed Vacuum-arc Method

Nanostructured Coatings Based on Amorphous Carbon and Gold Nanoparticles Obtained by the Pulsed Vacuum-arc Method

DLC Coatings on Spherical Elements of HIP Endoprostheses

Hard coatings are increasingly being used in medicine to protect metal endoprostheses The experimental process for the high-productive synthesis of high-quality diamond-like carbon (DLC) coatings with high hardness and a sufficiently high level of adhesion to the spherical shaped parts of the hip joint made from the stainless steel or cobalt-chrome alloy have been developed. DLC coating deposition was performed by vacuum-arc method from a high-productive source of the filtered vacuum-arc carbon plasma of rectilinear type with a "magnetic island". The high degree of thickness uniformity in the coating on the head of the hip joint with a high adhesion to the metal joint base was developed. Modernization of the vacuum arc plasma source allowed to accelerate the cathode spot motion, exclude substrate overheating and increase the diamond-like carbon hardness up to 30-40 GPa. The high adhesion level was achieved as a result of the high voltage pulsed of substrate bias potential use and multilayer architecture of DLC coating. The DLC coating on the heads of hip endoprosthesis did not peel off when boiling endoprosthesis or when immersing it into the liquid nitrogen. JEL O31

DLC Coatings on Spherical Elements of HIP Endoprostheses

Abstract Hard coatings are increasingly being used in medicine to protect metal endoprostheses The experimental process for the high-productive synthesis of high-quality diamond-like carbon (DLC) coatings with high hardness and a sufficiently high level of adhesion to the spherical shaped parts of the hip joint made from the stainless steel or cobalt-chrome alloy have been developed. DLC coating deposition was performed by vacuum-arc method from a high-productive source of the filtered vacuum-arc carbon plasma of rectilinear type with a "magnetic island". The high degree of thickness uniformity in the coating on the head of the hip joint with a high adhesion to the metal joint base was developed. Modernization of the vacuum arc plasma source allowed to accelerate the cathode spot motion, exclude substrate overheating and increase the diamond-like carbon hardness up to 30-40 GPa. The high adhesion level was achieved as a result of the high voltage pulsed of substrate bias potential use and multilayer architecture of DLC coating. The DLC coating on the heads of hip endoprosthesis did not peel off when boiling endoprosthesis or when immersing it into the liquid nitrogen.

Tribological and Electrical Properties of Diamond-Like Carbon Films Deposited by Filtered Vacuum Arc Method for Medical Guidewire Application.

A good medical guidewires are used to introduce stents, catheters, and other medical devices inside the human body. In this study, diamond-like carbon (DLC) film was proposed to solve the poor adhesion problem of guidewire and to improve the tribological performance of guidewire. DLC films were fabricated on Si substrate by using FVA (Filtered Vacuum Arc) method. In this work, the tribological, structural, and electrical properties of the fabricated DLC films with various arc currents were experimentally investigated. All DLC films showed smooth and uniform surface with increasing applied arc current. The rms surface roughness was increased and the value of contact angle on the film surface was decreased with increasing arc current. The hardness and elastic modulus of DLC films were improved, and the resistivity value of DLC films were decreased with increasing arc current. These results are associated with ion bombardment effects by the applied arc current and bias voltage.

Properties of Coatings Based on Carbon and Nitrogen-Doped Carbon Obtained Using a Pulsed Vacuum Arc Method

Diamond-like carbon coatings on hard-alloy substrates, including coatings doped with nitrogen about 1.0 μm thick have been obtained using a pulse vacuum-arc method. Three types of coatings have been investigated: a carbon diamond-like coating (C), a carbon coating doped with nitrogen (C: N), and a composite coating based on (C: N + C) layers. The coatings have been annealed in atmospheric air at a temperature of 400°C. The tribological characteristics (wear resistance and friction coefficient change dynamics), the adhesion strength, and the microhardness of coatings in the initial state and after annealing have been studied. The composite coating consisting of C: N + C layers surpasses the constituent coatings in properties, both in the initial state and after annealing at a temperature of 400°C.