The present work deals with the problem of creating dielectric (ceramic) coating on the surfaces of conductive materials for endowing them with insulating properties. The coatings have been created ...using the electron-beam evaporation of aluminum oxide ceramics. A plasma electron source operating in the forevacuum range of pressure (5-100 Pa) have been used as a source of electrons. It has enabled an effective transport of the electron beam onto the ceramic non-conductive surface and its melting and evaporation. During this process, the electric charge brought by the electron beam onto the surface of the ceramic target is completely neutralized by the ions of gas discharge plasma generated by the electron beam along its transport path towards the target.
The paper presents the results of studies of the effect of electron beam parameters on the geometric dimensions of the hole created in quartz glass by an electron beam with the power density of up to ...106 W·cm−2 generated by a forevacuum plasma source. It is shown that the electron beam with such specific power is capable of creating holes up to several centimeters deep. At the same time with the passage of time the hole acquires an established form. The dependences of the geometrical dimensions of the steady-state form of the hole depending on the parameters of the electron beam are presented.
We present the results of sintering of a metal-ceramic sample consisting of alumina ceramics and titanium. Sintering has been conducted via the surface scanning by the electron beam generated by a ...plasma electron source. It has been shown that the bake-out temperature affects the formation of the layer with a uniform distribution of elements. We have determined the sintering regimes that enable fabrication of samples with uniformly distributed elements over volume.
The paper describes the investigations of the influence of a redistributing electrode on the formation of emission plasma near the electron extraction region in a pulsed forevacuum-pressure ...plasma-cathode electron source utilizing a cathodic arc for generation of emission plasma. The authors show that the use of the redistributing electrode with optimal geometry in the discharge gap of the source provides a fairly uniform emission plasma density distribution. For the used discharge gap and pulse duration up to 5 ms, the use of the spherical stainless-steel redistributing electrode with radius of 6 mm provides rather uniform plasma density distribution near electron extraction region in the investigated gas pressure range 3-15 Pa. A model simulating the formation of plasma in the forevacuum pressure range has been developed. The model considers the scattering of ions of the arc plasma by gas atoms and the formation of gas ions by ionization of the operating gas by high-energy electrons. The calculated distributions of emission plasma density are consistent with the experimental data for different sizes of the redistributing electrode and for different gas pressures. The model and experiment show that the plasma density near the anode mesh increases with increasing gas pressure, for example, increase in gas pressure from 5 to 10 Pa leads to an 80% increase in density of emission plasma.
The article presents the results of modernization of the accelerating interval of the forvacuum plasma electron source. The source generates an electron beam in the form of a sheet at pressures of ...10-30 Pa. To increase the homogeneity, a multi-aperture extraction system was used. The optimal distances between the anode and the extractor, as well as the ratio between the cell sizes of the multi-aperture system, allowing to obtain a homogeneous electron beam width of 30 cm are determined.
We present experimental results on geometry optimization of the emission electrode in a plasma cathode electron source operating in the forevacuum range of pressure. For the 2-mm thick emission ...electrode, we have determined an optimal diameter of the emission aperture that provides the most efficient electron extraction from a hollow cathode glow discharge plasma in helium. At the working pressure of helium in the vacuum chamber 30 Pa, the beam power during emission from a single aperture can vary from 2 to 6 kW, while the beam diameter does not exceed 0.5 mm.
The paper presents electron beam sintering of functionally gradient (FGM) Al2O3/ZrO2 materials. An electron beam generated by a pre-vacuum plasma electron source for sintering was used. FGM were ...manufactured with different number of layers of aluminum oxide and zirconium dioxide powders. The layers differed in the percentage of components by volume. It is shown that the sintering of the composite sample occurs during electron-beam heating. After sintering for 10 min at 1600°C, the sample density increases up to 4 g/cm3. The presented photos of cross-sections of the samples indicate low pore content after sintering.
The paper presents the results of studies devoted to an effect of deviation and scanning parameters on the value of power density of a focused electron beam generated by a plasma electron source in ...the forevacuum pressure range. It is shown that the change in the beam power density does not exceed 20% with an angle of beam deviation within 20 degrees in the investigated pressure range of 6-8 pascals in air. The results of selective sintering of powder system of zirconia-alumina by an electron beam generated by a forevacuum plasma electron source are demonstrated.
Ceramic-metal composite materials combine high strength of ceramic and plasticity of metal. The combination of these properties allows the use of cermet in many industries and medicine. Cermet ...materials are made using powder technology by sintering a compact consisting of a mixture of pressed powders. The properties of the resulting product are determined by both the initial component composition and the sintering method. In the present work, electron beam sintering in the fore-vacuum pressure range was used to obtain cermet. The feature of this method is the possibility of flexible control of the sintering process by changing the parameters of the electron beam. To heat compacts consisting of pressed powders of alumina ceramics and titanium, the surface of compacts was scanned with an electron beam with the diameter of less than 1 mm and the power of 500 W. The surface temperature of the compact during sintering was 1600 °C, and the time of isothermal exposure was 10 minutes. It has been shown that compact thickness has a significant effect on obtaining homogeneous sintered material. Samples with a microhardness of 27 GPa were obtained. The ways of further improving the technology of electron beam sintering of cermet are determined.
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