The work is devoted to identification and analysis of patterns of change in the elemental and phase composition, defective substructure, mecha­nical (microhardness) and tribological (wear resistance and friction coefficient) properties of stainless high-chromium steel subjected to complex processing, combining vacuum irradiation of the samples surface layer with an intense pulsed electron beam of submillisecond exposure duration and subsequent nitriding under electron-ionic heating conditions. High-chromium steel AISI 310S, which in the initial state is a polycrystalline aggregate based on γ-iron, was used as the research material. Pulsed electron beam treatment of steel was carried out on a “SOLO” installation equipped with an electron source with a plasma cathode based on a low-pressure pulsed arc discharge with grid stabilization of the cathode plasma boundary and an open anode plasma boundary. Steel nitriding was carried out on a “TRIO” installation with a chamber size of 600×600×600 mm, equipped with a switching unit to implement the electron-ionic processing mode. Nitriding was carried out at 723, 793, and 873 K temperatures for 1, 3 and 5 h. It was found that electron-ionic nitriding of the samples pre-irradiated with an electron beam (10 J/cm2, 200 μs, 3 pulses at 723 and 793 K for 3 h) is accompanied by the formation of a ceramic layer containing only iron and chromium nitrides. The highest values of steel wear resistance after electron-ionic nitriding, exceeding the wear resistance of the initial steel by more than 700 times, are observed at nitriding parameters of 793 K, 3 h.

Результатом модификации поверхности металлов и сплавов путем комбинированной обработки (напыления тонких металлических пленок с последующим перемешиванием под действием высокоинтенсивных потоков энергии) является формирование градиентной структуры поверхностного слоя материала, характеризующейся изменяющимися по глубине концентрацией легирующих элементов, фазовым составом и состоянием дефектной субструктуры, что положительно сказывается на механических и трибологических свойствах материала. Целью настоящей работы является формирование высокопрочных силицидо- и нитридосодержащих поверхностных слоев при комплексной обработке в едином вакуумном цикле, включающей нанесение покрытий тугоплавкого металла и кремния, облучение высокоинтенсивным импульсным электронным пучком и дополнительное азотирование в плазме газового разряда низкого давления. Модифицирование, сочетающее многоцикловое (до пяти циклов облучения системы «пленка/подложка») высокоскоростное плавления системы «пленка (Si (0.2 мкм) + Nb (0.2 мкм))/(сталь 40Х) подложка» интенсивным импульсным электронным пучком осуществляли на установке «КОМПЛЕКС» (Институт сильноточной электроники СО РАН) в едином вакуумном пространстве. Часть образцов была дополнительно подвергнута азотированию в плазме газового разряда низкого давления (773-873 К, 1-5 час.). Выполнены исследования и выявлен режим комплексного модифицирования, позволивший многократно повысить износостойкость (более чем в 100 раз) и микротвердость (более чем в 5 раза) поверхностного слоя исходной стали. Высказаны предположения о физической природе повышения трибологических и прочностных свойств материала.

Работа посвящена анализу результатов, полученных при исследовании структуры, механических (микротвердость) и трибологических (параметр износа и коэффициент трения) свойств высокохромистой стали марки 20Х23Н18, подвергнутой комплексной обработке, сочетающей облучение импульсным электронным пучком и последующее азотирование в плазме несамостоятельного дугового разряда с накаленным катодом. Установлено, что предварительное облучение стали импульсным электронным пучком в режиме плавления тонкого поверхностного слоя и последующее азотирование приводит к существенному (на 39%) увеличению твердости относительно азотированной необлученной стали и многократному (в 9 раз) увеличению твердости относительно исходной стали. Показано, что азотирование стали 20Х23Н18 (не зависимо от предварительной обработки), позволяет повысить износостойкость материала в 100 и более раз.

The parameters of the plasma of a non-self-sustaining glow discharge generated inside a metal hollow cathode 300 mm long and 25 mm in inner diameter are investigated. A feature of this system is the additional injection of electrons from the auxiliary discharge plasma, formed by a plasma source with a combined heated and hollow cathode «PINK». The dependences and combustion modes of a non-self-sustaining glow discharge are presented and described at a pressure in the range (0.06 ÷ 1.4) Pa and a combustion voltage (70 ÷ 300) V. Studies of plasma parameters using double Langmuir probes have shown that this discharge system provides generation nitrogen plasma inside the hollow cathode with inhomogeneity from ± 12 to ± 63%.

A method and experiments of nitriding AISI 1020 steel with simultaneous heating of the samples with the electron component of plasma are described. A nitriding regime is explained that makes it possible to form a hardened layer up to 500 µm thick. It is shown that the microhardness of the surface layer of the steel increases with the increase in the nitriding temperature and correlates with the relative content of the nitride phase. It has found that in the nitriding temperature range from 450 °C to 600 °C, the maximum microhardness is formed in the near-surface layer at the depth of ~10 µm at 520 °C. It has been established that the steel wear resistance is determined by the concentration of nitrogen atoms in the α-Fe crystal lattice. It has been shown that micropores formed in the surface layer of the steel nitrided at 520 °C contribute to an increase in material wear under dry friction.

Осуществлено поверхностное легирование методом одноциклового и многоциклового (5 циклов «напыление-облучение» в каждом цикле толщина пленки титана 0,5 мкм) высокоскоростного плавления системы «пленка (Ti)/(сталь 20X23H18) подложка» импульсным электронным пучком. Азотирование (793 К; 1, 3 и 5 час.) проводили в условиях реализации элионного (электронного и ионного) режима обработки. Рассмотрены изотермические сечения тройных систем диаграммы состояния сплава Cr - Fe - Ni - Ti - N, формирующегося на различных стадиях комплексной обработки стали. Исследования показали, что, во-первых, облучение стали импульсным электронным пучком сопровождается формированием структуры высокоскоростной ячеистой кристаллизации твердого раствора на основе γ - Fe; во-вторых, азотирование стали в исходном состоянии сопровождается формированием нитридов железа FeN и хрома CrN суммарным содержанием 79,8 масс.%; в-третьих, предварительное облучение стали импульсным электронным пучком приводит к снижению скорости нитридообразования при последующем азотировании; суммарное содержание нитридов 53 масс.%; в-четвертых, независимо от количества циклов легирования (концентрации титана в поверхностном слое) после пяти часов азотирования в образцах формируется поверхностный слой, образованный нитридами хрома и железа (1 цикл легирования) или нитридами хрома и титана (5 циклов легирования). The surface alloying was carried out by single-cycle and multi-cycle (5 cycles «sputtering-irradiation», in each cycle the thickness of the titanium film 0,5 µm), i.e. high-speed melting of the system «film (Ti)/(steel AISI 310S) substrate» by pulsed electron beam. Nitriding (793 K; for 1, 3 and 5 hours) was carried out under conditions of realization of the elion (electron and ion) treatment mode. The isothermal cross sections of the ternary systems of the state diagram of the Cr - Fe - Ni - Ti - N alloy formed at different stages of the complex treatment of steel are considered. It is shown that (1) irradiation of steel by a pulsed electron beam is accompanied by the formation of a structure of high-speed cellular crystallization of solid solution based on γ-Fe; (2) nitriding of steel in the initial state is accompanied by formation of nitrides of iron FeN and chrome CrN with a total content of 79,8 wt.%; (3) pulsed electron-beam pre-irradiation of steel leads to a decrease in the rate of nitride formation during subsequent nitriding; the total nitride content of 53 wt.%; (4) regardless of the number of alloying cycles (titanium concentration in the surface layer) after five hours of nitriding in the samples formed a surface layer of nitrides of chromium and iron (1 cycle of doping) or nitrides of chromium and titanium (5 cycles of doping).

Complex alloying, combining in a certain sequence the saturation of surface layer of material with atoms of metals and gases, is now widely used in most industrialized countries of the world. The present work is devoted to the revelation and analysis of dependences of element and phase composition, defect substructure, mechanical (microhardness) and tribological (wear resistance and friction coefficient) properties changes of alloying carbon steel subjected to combined treatment including the saturation of the sample surface layer by aluminum and subsequent nitriding. The material used for the study was AISI 5135 steel, which in the initial state has a structure represented by ferrite grains and pearlite grains of lamellar morphology. The combined modification was carried out in a single vacuum space on the TRIO setup with the chamber dimensions of 600×600×600 mm3 equipped by switching unit for realization of elion (electron and ion) mode of treatment. Aluminizing was carried out at the temperature of 963 К during 4 h. The cathode of electroarc evaporator was made of A7 grade aluminum alloy (98.8 % Al). Subsequent nitriding of aluminized layer was carried out at the temperature of 803 К during 2 h. It was established that the modified layer with the thickness of 70 μm is formed as a result of the combined treatment. It is demonstrated that the combined steel modification is accompanied by the formation of multiphase submicro- and nanostructure state including aluminum nitrides, iron and chromium nitrides and aluminides. It is revealed that the steel hardness is maximal on the modification surface and it exceeds by 3 times that of the initial steel. Wear resistance under the dry conditions decreases after the combined modification.

The results of investigation of a low-pressure glow discharge with a hollow cathode and a large-volume hollow anode in argon and nitrogen are presented. The data on plasma density and electron temperature are obtained. A model is proposed, which describes the mechanisms of plasma sustainment in a hollow anode. The model includes the non-uniformity of plasma density distribution in the anode cavity. The estimations of the plasma parameters are made. The model is in a good agreement with the experimental data.

Using the probe technique, a comparative analysis of parameters of the gas-metal plasma generated by low-pressure discharges is performed during variation of their main characteristics. It is shown that by varying the discharge current of the gas plasma source it is possible to readily change the fraction of gas ions in the gas-metal plasma generated by the arc evaporator and the gas plasma source with thermionic and hollow cathodes. In the case of nitride coatings, it is found out that the concentration of nitrogen in the coatings formed by the vacuum-arc plasma-assisted deposition increases, without any changes in the nitrogen working pressure. Using the coatings based on the Mo–N and Ti–N systems as examples, a twofold increase in the nitrogen concentration is shown as the ion current density of the gas plasma source increases by a factor of three in comparison with the modes without using this source. The method discussed in this study exhibits lower inertia compared to the traditional gas pressure variation.

The work is devoted to the identification and analysis of the regularities of the elemental and phase composition, to the change in the defective substructure and mechanical properties of carbon steel subjected to complex processing, combining the samples surface layer saturation with aluminum and subsequent nitriding. The material used for the study was carbon AISI 1020 steel (20 steel), which in the initial state has a ferrite-pearlite structure. The complex modification was carried out in a single vacuum space on the TRIO installation with a chamber size of 600 x 600 x 600 mm(3), equipped with a switching unit to implement the elion (electron-ion) mode. Alumunizing was carried out at a temperature of 963 K during 4 h. The cathode of the arc evaporator was made of A7 aluminum alloy (98.8% Al). Subsequent nitriding of the aluminized layer was carried out at a temperature of 803 K for 2 h. It was found that as a result of complex processing, a modified layer up to 80-mu m thick was formed. It is shown that the complex modification of carbon steel is accompanied by the formation of a multiphase submicro- and nanostructure state containing iron nitrides of Fe4N and Fe3N composition and aluminum nitride-AlN. The hardness of steel is maximum on the modified surface and exceeds that of the initial material by 4 times. The wear resistance of the modified layer is higher by 2.5 times than that of steel in the initial state.

This work represents the investigations for decreasing acceleration gap breakdown probability of plasma source of electrons SOLO, with grid stabilization of the boundaries of the arc cathode plasma. We increased the distance to the treated target, bent the transportation channel of the electron beam, created additional plasma in the anode space, and increased the beam front. The effect of the above measures on the breakdown probability when the target is exposed of a low-energy electron beam with a power density of up to 0.5 MW/cm 2 with a diameter of 2.5 cm was investigated separately. Beam deflection is most effective at relatively long pulse durations of 150 μs and accelerating voltage of 20 kV, rather than a lower one. It was possible to double the maximum power for the same beam transport length applied to a low-melting target. Preionization in the anode proved to be effective for relatively short beams of 15 μs duration.

The results of experiments on low-energy implantation of AISI 321 stainless steel by nitrogen ions are presented. The treatment was carried out by a pulsed beam of nitrogen ions obtained using a ballistic ion focusing system. The surface modification occurs with the formation of a two-layer structure, which is typical for ion-plasma nitriding processes of stainless steels. The thickness of the modified layer can reach 27 μm after 1 hour of ion-plasma treatment. The influence of subsequent modification of the ion-doped layer by the action on the surface of the pulsed high-current electron beam of microsecond duration is studied. The work presents the results of the studying the regularities of changes in the depth distribution of dopants, microstructure and phase composition of the modified and matrix layers by optical metallography, diffraction analysis and transmission electron microscopy.

The paper presents research into the low-pressure hollow-cathode and hollow-anode glow discharge. The data are obtained for the plasma potential, concentration and electron temperature in the hollow anode. The proposed model explains the plasma maintenance mechanisms in the hollow anode. The basic idea of the model is that the plasma inside the hollow anode is a potential electron trap. The discharge current is transported to the anode by not only electrons, but also ions. The plasma parameters in the hollow anode are estimated in this paper. It is shown that the theoretical calculations are in good agreement with the experimental data.

In a plasma-cathode electron source with a grid-stabilized emission boundary, a discharge in crossed fields was used to create an auxiliary anode plasma before the generation of an electron beam. Such a plasma formed in the beam transport region shortens the rise time of the beam current and eliminates or at least minimizes its highfrequency oscillations at low pressures, making possible electron beams of several microseconds long and stable lower-pressure modes with less probable acceleration gap breakdowns. These effects are explained primarily by gas pre-ionization in the beam acceleration and transport region and by ion flows from the acceleration gap to the plasma cathode of the source.

This paper presents the results of a study of an electron-ion-plasma alitization system using two arc plasma generators: a gas plasma generator based on a non-self-sustained arc discharge with a thermionic cathode “PINK” and a gas-metal plasma generator based on an arc discharge with a cathode spot. The system for discharges supplying and biasing of the samples assumes two sub-modes of operation: the ion cleaning sub-mode (ion sub-mode) and the sub-mode of samples electron heating (electron sub-mode), thus realizing the “elion” mode of the system operation. During the experiments, both the dependences of the average values of currents and voltages of discharges burning and probe measurements of the instantaneous plasma parameters values in both system operating sub-modes were investigated. It is shown, that the electron sub-mode of system operation is characterized by an increased burning voltage, which is caused by the formation of a positive anode drop of more than 10 V in the plasmas. Such a potential distribution in the discharges ensures effective heating of the samples by the discharges plasmas electron component.

This article describes a plasma-generating system based on a non-self-sustained glow discharge with external electron injection and a hollow cathode in the shape of a tube with an internal diameter of 25 mm and a length of 300 mm made of stainless steel AISI 321. It is proved that the parameters of the non-self- sustained glow discharge under (0.2-1) Pa, (100-280) V, and (2-6) A depend on the auxiliary discharge current to a great extent, which is due to the determining influence of electrons injected from the auxiliary discharge plasma on the physical processes in the main discharge. The study of uniformity of temperature distribution on the hollow cathode walls has shown that it can reach +/- 10% of the average value and greatly depends not only on electric characteristics of the discharge but also on its working pressure. The study further demonstrates that such discharge can burn not only in elongated hollow rectilinear cathodes but also in hollow cathodes of a complex shape produced by welding two tubes at a 90% angle. The efficiency of using emitted electrons to sustain discharge and uniformity of temperature distribution on the walls is improved in the latter configuration. The discharge can be used for ion plasma nitriding of inner surfaces with treatment uniformity of +/- 8.5% of the average value for complex-shaped hollow cathodes. The mean thickness of the nitrided layer after 1 h of processing steel AISI 321 at 630 degrees C was similar to 50 mu m and the hardness of the nitrided layer exceeded the original value by approximate to 3 times.

The paper presents the results of modification of the silumin surface layer using a multicycle processing technique which combines the formation of the film (titanium)-substrate (silumin) system and the low energy high current pulsed electron beam (LEHCPEB) irradiation of submillisecond duration in one cycle. A KOMPLEX plasma-ion-assisted electron-beam setup (Institute of High Current Electronics SB RAS, Tomsk, Russia) is used for silumin treatment. Titanium is used as an alloying element. The thickness of the deposited film is 0.5 μm in each alloying cycle, the number of which is 1, 5 and 10. Surface alloying includes ion-bombardment cleaning and heating by hot and hollow cathodes of argon plasma discharge, with negative bias voltage supply to the specimen (initial heating up to preset temperature, surface cleaning and activation); plasma-enhanced chemical vapor deposition of metal films (argon is used as a carrier gas); and LEHCPEB irradiation of the film (titanium)-substrate (silumin) system. It is shown that multicycle alloying of the grade АK12 silumin (G-AlSi12, DIN, Germany) with titanium leads to a dissolution of silicon and intermetallic inclusions in the surface layer up to 30 μm thick, the formation of submicro- and nanocrystalline multiphase structure with the microhardness and wear resistance, which are 1.4 and 14.2 times higher than in cast silumin.