In the present work, chemical and ion beam surface treatments were performed in order to modify the electrochemical behavior of industrial austenitic–martensitic steel VNS-5 in 3.5 wt. % NaCl. Immersion for 140 h in a solution containing 0.05 M potassium dichromate and 10% phosphoric acid promotes formation of chromium hydroxides in the outer surface layer. By means of a new type of ion source, based on a high-current pulsed magnetron discharge with injection of electrons from vacuum arc plasma, ion implantation with Ar+ and Cr+ ions of the VNS-5 steel was performed. It has been found that the ion implantation leads to formation of an Fe- and Cr-bearing oxide layer with advanced passivation ability. Moreover, the ion beam-treated steel exhibits a lower corrosion rate (by ~7.8 times) and higher charge transfer resistance in comparison with an initial (mechanically polished) substrate. Comprehensive electrochemical and XPS analysis has shown that a Cr2O3-rich oxide film is able to provide an improved corrosion performance of the steel, while the chromium hydroxides may increase the specific conductivity of the surface layer. A scheme of a charge transfer between the microgalvanic elements was proposed.

We report our experimental investigations of the effect on the ion composition, including the ion mass-to-charge composition, of electron injection into the plasma of a high-current pulsed magnetron discharge in the ultra-low operating pressure range. We show that changing the magnetron discharge voltage by injecting additional electrons with adjustable current allows implementation of two operating modes: one with a plasma in which metal ions dominate (including multiply charged ions for certain target materials with low sputtering yield), and the other a magnetron non-sputtering mode with plasma of only gaseous ions.

The surface morphology, structure of oxide layers and electrochemical properties in a physiological solution (0.9 wt. % NaCl) of nickel titanium (TiNi) alloy subjected by ion implantation were studied. It was found that an irradiation of the TiNi surface with titanium and niobium ions at an irradiation dose of 1·1017 cm–2 led to the increase of the surface roughness and improvement of corrosion properties. The corrosion performance of ion-beam modified alloy was associated with a higher charge transfer resistance and a lower anodic current. Comparative analysis of the oxide layer structure, performed by transmission electron microscopy, and electrochemical properties revealed that an inhibiting of anodic processes was related with the phase composition and electrical conductivity of the oxide layer. In particular, the ion-beam treatment with niobium resulted in formation of a thin (~ 2 nm) amorphous oxide film onto the TiNi surface, that effectively prevented an oxidation of nickel due to dielectric properties characterized by dielectric constant ε = 44.

The effect of high dose implantation of Ta+ ions (Dion = 5 ' 1016 cm -2) into samples from a TiNi shape memory alloy (SMA) on patterns of deformation and fracture mechanisms under quasi-static uniaxial tensile loads was studied. Using X-ray diffractometry, transmission electron microscopy, and scanning electron microscopy, it was shown that ion implantation resulted in amorphization of the surface layer with a thickness of -100 nm due to the formation of a chemical composition of approximately Ti36Ni41Ta23 (at.%), thermodynamically corresponding to the highest glass forming ability in the Ti-Ni-Ta system. In the implanted surface layer, both the microstructure and crystal structure defects subsystem were modified at a depth of -5 mm. Using the digital image correlation (DIC) method, the dynamics of changes in the integral and local (eyy longitudinal, exy shear and exx transverse) strain components were investigated in the tensile tests of both as-received and implanted TiNi SMA samples. On the basis of the obtained results, both integral and local stress-strain diagrams were plotted. In all studied cases, the main contribution to strain accumulation was made by the eyy and exx strains, which differed significantly for the as-received and implanted TiNi SMA samples. It was concluded that the positive effect of ion implantation was manifested in loading ranges close to the martensitic yield stress (at strain range of 1-6%), despite a noticeable decrease in the ultimate tensile strength and plasticity of the implanted TiNi samples.

Представлены результаты исследований импульсного периодического тлеющего разряда в потоке аргона при атмосферном давлении, при частоте следования импульсов до 100 кГц, длительности импульса несколько микросекунд и при значениях тока в импульсе от нескольких десятков миллиампер до 1 А. Выявлены условия, при которых в разрядной плазме наблюдается присутствие ионов и атомов материалов катодной вставки, в качестве которых применялись легкоплавкие металлы. Показано, что при остывании атомов металлов происходит их слипание в наноразмерные частицы и формирование порошков оксидов металлов.

The interaction of ion beams with dielectric materials is an urgent problem, both from the point of view of practical application in ion implantation processes and for understanding the fundamental processes of charge compensation and the effective interaction of beam ions with a target surface. This paper presents the results of studies of the processes of compensation of the surface charge of an insulated collector upon interaction with a beam of metal ions with energies up to 50–150 keV. At low pressure (about 10−6 torr), removing the collector from the region of extraction and beam formation makes it possible to reduce the floating potential to a value of 5–10% of the total accelerating voltage. This phenomenon allows for the efficient implantation of metal ions onto the surface of alumina ceramics. We have shown that the sheet resistance of dielectric targets depends on the material of the implanted metal ions and decreases with an increase in the implantation dose by 3–4 orders of magnitude compared with the initial value at the level of 1012 Ω per square.

Discharges with cathode spots can operate in a wide range of gas pressures. Erosion of the cathode material is an inherent property of such discharges. The erosion products are considered to be ionized atoms and electrically neutral microdroplets. In accordance with this concept, a plasma source based on a pulsed cathodic arc discharge in atmospheric-pressure argon with a current of up to 200 A, a pulse duration of 250 μs, and a pulse repetition rate of 10 Hz was implemented. Using this source, the synthesis of magnesium oxide powder was performed. The chemical composition of the erosion products was determined using the TEM/EDS method and the composition of the gas mixture in which the discharge system operated was evaluated by optical spectrometry. It was shown that particles of the synthesized powder have different morphological features, depending on the nature of the electrical erosion of the cathode material. Micron-sized particles are formed due to the removal of microdroplets from liquid–metal craters on the cathode surface at certain plasma pressures. Submicron particles are produced during the agglomeration of atoms originating from the plasma jets flowing out from cathode spots. These atoms are magnesium ions that are neutralized by collisions with gas particles. The advantages and disadvantages of this synthesis method are discussed in this paper. The reference methods for the powder synthesis of magnesium oxide are compared. The prospects of the studied method from the point of view of its application for obtaining ceramic materials are also evaluated.

The effect of ion- or electron-beam treatment on the structure and residual stresses formed in the surface layers of the Ta-doped TiNi alloy was revealed. The ion-beam treatment leads to the formation of a thin amorphous surface layer. An ion-beam treated sample does not exhibit residual stresses of the 1 st kind, but possesses a low level of residual stresses of the 2 nd kind. Surface alloy synthesis via an electron-beam melting of the Ti 60 Ta 40 (at.%)/TiNi system leads to the formation of the outer crystalline layer, amorphous sublayer, and large residual stresses localized in the heat-affected zone.

The synthesis of the nanopowders of magnesium oxide and magnesium fluoride during the operation of a repetitive diffuse nanosecond discharge in argon at various pressures was performed. Nanosecond voltage pulses with an amplitude of −70 kV, a rise time of 0.7 ns, and a duration of 0.7 ns were applied across a point-to-plane gap of 2 mm in length. The pulse repetition rate was 60 Hz. The high-voltage pointed electrode was made of magnesium. A diffuse discharge cold plasma was formed under these conditions. Nanoparticles were produced as a result of an explosion of microprotrusions on the surface of the magnesium electrode duo to a high current density. Lines of magnesium atoms and ions were observed in the emission optical spectrum. Under the actions of the gas dynamics processes caused by the plasma channel expansion during the interpulse period, nanoparticles were deposited onto the surface of the grounded plane electrode and the side wall of the gas discharge chamber. The morphology, elemental, and phase composition of the powders were studied using transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS).

The paper presents the results of a study of the current-voltage characteristics and optical emission spectra of plasma of a atmospheric pressure pulsed discharge plasma at a frequency of several tens of kilohertz and a pulse duration of up to 10 μs, in the mode of generation of plasma flows containing metal particles. The features of the plasma generator conclude in combination of the design of electrodes, as well as the modes of electric and gas supply of the discharge system. The cathode is a crucible containing a melting insert which allows the discharge operation in a low-current form with a current of 40 mA to 1 A, at a sufficiently high voltage of 150 to 200 V, without transition to arc discharge mode. Such parameters make it possible to generate atomic flows of a melting cathode insert, which are blown out by a jet of working argon gas, pumped at a flow rate of 1 l/min, outside the discharge system. The entry of a metal component into a gas-discharge plasma affects the parameters of the discharge operation, as well as the properties of its optical emission. In the context of this phenomenon, the spectral distributions of the intensity of optical radiation corresponding to the lines of magnesium, indium, and zinc were investigated, as well as their time dependence during the current pulse period operation, in relation to the identification of physical features leading to stable generation of flows of metal atoms at atmospheric pressure.

The near-equiatomic TiNi shape memory alloy passivated through electropolishing and ion implantation with titanium has been studied toward corrosion performance in simulated body fluids (0.9 wt% NaCl, artificial blood plasma). Corrosion rate, nickel oxidation, repassivation and charge transfer has been examined by conventional methods of potentiodynamic polarization, electrochemical impedance spectroscopy and cyclic voltammetry. Experimental validation of the electrochemical results was performed using electron-microscopic (SEM/TEM) techniques and Auger electron spectroscopy. It was revealed that the thickness of the passive layer (TiO + TiO2) could be increased by similar to 5 times after ion implantation. Regardless of the corrosion environment, the TiNi alloys exhibiting different surface finishes still suffer from pitting corrosion associated with leaching of nickel ions via oxidation reaction. The Ti-implanted alloy shows satisfactory corrosion resistance in comparison with the reference electropolished TiNi alloy. After ion implantation, the dissolution of the surface layer during anodic polarization was restricted due to the formation of the Ni-depleted amorphous sublayer. Auger Ti-and Ni-LMM peaks are found to be shifted to lower energies due to the contribution of Ni-O and Ti-O bonding. It has been shown that not the thickness, but rather the structure and phase composition of the oxide layer are main factors responsible for corrosion performance.

The results of a study of the processes involved in the production of indium oxide In2O3 powder, which is widely used to create transparent and electrically conducting ceramics, are described. The powder was produced in a flow of rare gas (argon or helium) at atmospheric pressure under conditions for the formation of metal-containing plasma in a non-arc discharge mode. The discharge operated in pulsed mode with a pulse repetition rate of 70 kHz and pulse duration of 12 μs. The discharge current was 670 mA and discharge voltages were 180 V and 250 V when the working gases were argon and helium, respectively. These parameters ensure a mode in which the indium cap of a molybdenum cathode suffers thermal erosion. The morphology and elemental and phase composition of the erosion products were studied using transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) analysis. It was shown that the structure of the synthesized powder particles corresponded to a phase of indium oxide (III) with a body-centered cubic (bcc) lattice with lattice parameter a = 1.013 nm. The powder particles, regardless of the working gas (Ar or He), consisted of non-stoichiometric indium oxide In2O3 with a nanocrystalline structure. The average particle diameter was = 13–16 nm.

Investigation of the processes involved in the synthesis of magnesium oxide and zinc oxide powders using the thermal effects of an atmospheric-pressure glow discharge plasma in an inert gas flow are described. The discharge operates in a repetitively pulsed mode with pulse repetition rate of several tens of kilohertz and pulse duration up to 12 mu s, discharge current of 600 mA and voltage up to 300 V. These parameters lead to thermal erosion of magnesium or zinc inserts in a molybdenum crucible. The chemical and phase composition of the erosion products were determined using TEM/EDS and X-ray diffraction analysis, and the composition of the plasma was assessed by optical emission spectrometry. This experimental approach allows fabrication of powders of these metal oxides with characteristic particle size 10-50 nm, and the formation of coatings of these materials in a one-step process.

Planar magnetrons with a heated crystalline boron target are promising for depositing boron coatings intended for a wide range of scientific and industrial applications. The promotion of this type of magnetrons requires an in-depth investigation of the coating deposition process. A new version of such a magnetron is created for the vacuum electron-ion-plasma (VEIP) test installation for in situ synchrotron radiation monitoring of the boron coating synthesis. The paper proposes the design and parameters for this magnetron and discusses the boron coating deposition using the VEIP test installation.

We describe our investigations of the electrophysical properties, phase composition and structure of Al2O3 ceramic particles in coatings formed by electron-beam evaporation of alumina ceramic and modified by implantation of tantalum ions. The ceramic coatings were synthesized in a helium atmosphere in the forevacuum pressure range of 1-10 Pa, at characteristic temperatures of beam target and substrate about 2500 and 250 Celsius, respectively, at a deposition rate of 500 nm/min. Ion implantation was performed using a metal ion source based on a vacuum arc discharge, at pressure of order 10-4 Pa; the mean tantalum ion energy was 90 keV and the implantation doses investigated were 1 x 1016, 5 x 1016, and 1 x 1017 ion/cm2. The original and modified ceramic coating samples were studied using a transmission electron microscopy technique. Measurements of the surface resistivity showed that the treatment of coatings by high-energy tantalum ion implantation leads to increase in specific resistance and decrease in sheet resistance.

Upgraded plasma source based on atmospheric pressure glow discharge device and features of its operation are presented. The main purpose of the upgraded device is the generation of metal-contained plasma flows. A brief review of the state-of-the-art methods for generating metal-containing plasma at atmospheric pressure is given. The possibilities of the application of the described discharge system in research on the production of ultrafine powders and functional coatings are indicated.

В настоящей работе исследован слаботочный разряд (до 1 А) атмосферного давления в режиме импульсного электропитания с частотой от 20 до 100 кГц в потоке аргона с расходом до 3 л/с. Увеличение частоты следования импульсов приводит к снижению напряжения инициирования разряда почти в 2.5 раза, и уменьшению времени фронта тока разряда почти в 2 раза. Данный экспериментальный факт обусловлен возрастанием концентрации возбужденных атомов рабочего газа аргона, смешанных с возбужденными молекулами воздуха в промежутках между импульсами на фоне снижения тока разряда.

We have explored the generation of plasma with high content (up to 70%) of calcium ions. The plasma is formed using an electron beam bombarding solid targets with electron energy up to 20 keV and power density up to 600 W/cm 2 . Target materials used are simple and readily available school chalk, limescale, and gypsum building plaster. Electron-beam erosion of the target material, production of unbound calcium atoms, and their ionization occur in a single cycle at a background pressure of a few pascals. This approach minimizes the effect of target surface charging by beam electrons and provides effective ionization of calcium-containing materials. The method described here is an alternative to the conventional method for the generation of calcium ions based on electron-cyclotron resonance systems, and is technically easier to implement.

Исследованы процессы распада плазмы вакуумной дуги после обрыва тока разряда в зависимости от импульсного слабо изменяющегося магнитного поля индукцией до 0.6 Тл. В качестве основного метода применялось измерение ионного тока коллектора, находящегося под плавающим потенциалом, смещение которого определялось потоком плазмы вакуумного дугового разряда. Во время функционирования вакуумного дугового разряда с плотностью тока на катоде около 1 кА/см 2 , характерной для большинства устройств на основе вакуумной дуги, ток коллектора определяется преимущественно более подвижными электронами. В результате прерывания тока дуги в цепи коллектора возникал ионный ток. Наличие магнитного поля в разрядном промежутке приводило к немонотонному затуханию импульса ионного тока, что выражалось в появлении нескольких пиков тока. Временной интервал между пиками также зависел от индукции магнитного поля. На основании этих результатов рассмотрено влияние магнитного поля на удержание плазмы в межэлектродном пространстве вакуумно-дуговой разрядной системы.