The possibility of increasing the mechanical strength of porous materials from sponge titanium powders by two methods has been investigated. In the first case, sintering activation was carried out using alloying additives based on Al, ZnO and TiH2. It was found that the maximum (1.8–1.9 times) increase in strength compared to samples made only from titanium powder is achieved by adding up to 0.5 % TiH2. With the introduction of other alloying additives (Al, ZnO), the mechanical strength increases by no more than 16–20 %. The influence of sintering regimes and atmosphere on the mechanical strength of porous titanium has been studied. It is shown that samples sintered in a vacuum have 1.85–1.90 times higher mechanical strength compared to the same samples sintered in an argon atmosphere. In the second case, to increase the mechanical strength of porous titanium, it was proposed to use bidisperse mixtures consisting of fine and coarse titanium powders. For this purpose, up to 20 wt.% of a fine titanium powder with a particle size of 100–160, 40–100 or <40 μm was added to the titanium sponge powder with a particle size of 630–1000 μm. It was found that the introduction of 10–12 wt.% of the finest (<40 μm) titanium powder leads to a 4‑fold increase in the tensile strength of the porous material compared to porous materials made only from coarse (630–1000 μm) titanium powder of the same chemical composition.

Polycrystals of solid solutions MnxFe1_xIn2S4 were prepared by the two-temperature method. The degrees of phase transformations were defined by differential thermal analysis (DTA), and a phase diagram of the MnIn2S4-FeIn2S4 system was obtained. The phase diagram is described by a narrow crystallization interval and classified as type I according to the Roozeboom classification. Single crystals of solid solutions MnxFe1_ xIn2S4 were grown by vertical gradient freeze method of synthesized polycrystals. The elemental composition of the obtained samples was in good agreement with the calculated composition. The structure was defined by XRD. Prepared samples had a cubic structure, and the parameters of the elementary cell were calculated by the method of least squares. The thermal linear expansion coefficient was investigated in the temperature range T = 80-550 K. Based on the obtained data, the values of the Debye temperature and the root-mean-square atomic shifts were determined, and their concentration dependencies are presented. The thermal conductivity was studied using the absolute method in the temperature range T = 300-550 K. The form of the concentration dependence, the contribution of the lattice and electronic components, and an analytical dependence of the thermal conductivity for the entire range of solid solution were established.

Radio‑absorbing composite materials, coatings and shields based on aluminum and iron oxides have been developed for protection of microwave devices from electromagnetic radiation (EMR). The patterns of changes in the characteristics of EMR reflection and transmission of electromagnetic shields based on the said powder‑like oxides have been established. It has been shown that the use of these composite materials for EMR shields can reduce the EMR reflection coefficient by 2–10 dB in the frequency range of 0.7–17.0 GHz and in the microwave range, and improve the operational properties of existing electromagnetic shields for the protection of electronic devices used for processing of limited distribution information, as well as in architectural electromagnetic shielding systems.Keywords. Composite materials, electromagnetic radiation, elecomagnetic radiation shields, aluminum and iron oxides.

The article introduces the results of the experimental substantiation of the possibility to use the electromagnetic shields based on powdered aluminum oxides to reduce the electromagnetic radiation energy introduced by electronic devices. To achieve this goal, a methodology has been developed for assessing the effect of materials on the electromagnetic radiation level of electronic devices, and a methodology for estimating the radius of the controlled zone of the secondary electromagnetic radiation of computer equipment has been systematized. In accordance with the indicated methods, the study has been carried out, based on the results of which it was determined that electromagnetic shields containing the composite coating based on powdered aluminum oxides and iron oxide provide suppression of the electromagnetic radiation energy of electronic devices, as well as a reduction of up to 2 times the radius of the controlled zone of the secondary electromagnetic radiation of computer equipment. Recommendations for the practical application of the composite coatings based on the powdered alumina and iron oxide have been developed. In accordance with these recommendations, such coatings can be used in the process of manufacturing or improving the technical and functional properties of electromagnetic shields designed to ensure the electromagnetic compatibility of electronic devices, as well as to solve problems related to the information security.

The production activity of many industries is associated with the release of highly dispersed particles and aerosols, as well as the subsequent capture of fine particles. Such processes take place, for example, in the production of fillers and polymers, powdered pigments and chemicals, carbon black, plant protection chemicals, lime and cement, pulverized quartz and asbestos, in the melting of non-ferrous and rare metals. According to doctors, highly dispersed particles, penetrating into the alveoli of the lungs, cause various occupational diseases of workers in the mining, coal, machine-building industries – pneumoconiosis. For example, when working in the environment containing silicon dioxide dust, workers develop one of the severe forms of pneumoconiosis – silicosis, and exposure to beryllium dust causes a very serious disease – berylliosis. To purify air and other gases from mechanical impurities, a variety of physical forces and means are used: gravitational forces, inertial forces, centrifugal forces, electric interaction forces of charged particles, capillary forces, as well as filter partitions with the appropriate pore size. To solve the problem of cleaning indoor air from highly dispersed particles and aerosols that cause the greatest harm to health, in this paper it is proposed to use electrostatic filters that provide filtration in an electric field through highly porous cellular materials. As a result of the theoretical and experimental studies, the parameters of the cleaning process and the design parameters of the electrostatic filter were determined, ensuring high process performance and the degree of purification.

Heat pipes are designed to effective removing heat from heating elements and reducing the temperature of various devices. Heat pipes with capillary porous structures are designed to operate under conditions of unfavorable gravity forces. Their main advantages are their high heat transfer capacity, as well as the ability to retain the coolant in a capillary-porous structure under dynamic power loads. The purpose of this work is to study the process of obtaining capillary-porous materials from metal powders for heat pipes with increased efficiency of using the vibration molding method. The article substantiates the relevance of creating heat pipes from metal powders. The information about the influence of the contact angle, surface tension and capillary pressure on the heat transfer capacity of a heat pipe is provided. It is shown that for the efficient operation of the heat pipe it is necessary to create such a capillary structure of the porous material, which could simultaneously provide a high speed of movement of the coolant and its rise to a given height. The above requirements can be satisfied by creating a capillary structure using powder metallurgy methods by optimizing the distribution of pore sizes. In this case, the most promising method seems to be the method of molding when applying a vibration to a mold with a powder. It is possible to obtain the required pore distribution in this way by choosing the correct particle size, shape and vibration parameters. This makes it possible to ensure the packing of particles in size, which affects their packing density, pore size, tortuosity and length of pore channels. The distribution of the maximum pore sizes over the thickness of the samples obtained from powders of various granulometric composition with the use of vibration has been investigated. As a result, a process was developed for obtaining capillary structures by the method of vibration molding of metal powders, depending on the size of the powder particles, the amplitude and frequency of vibration. It is shown that this method can provide a given pore distribution of the capillary structure for heat pipes, which makes it possible to increase their heat transfer capacity.

Stricter requirements for the quality and reliability of manufactured products, as well as the need to increase the service life of machines, mechanisms and various devices, the operation of which is associated with the use of liquid or gas-air media, is the reason for the emergence of new and improvement of traditional methods for obtaining filter materials with higher performance characteristics. A method for a comprehensive analysis of the properties of regenerated filter materials for fine air purification is proposed. The overwhelming majority of filters, after their service life is exhausted, cannot be regenerated, since this, as a rule, is associated with high energy costs. At the same time, the development of methods for such regeneration is quite relevant from the point of view of resource conservation. In this regard, the purpose of this work is to use a number of physical research methods for the purpose of a comprehensive analysis of polymeric fibrous filter materials for air purification that have undergone regeneration. Filtration materials obtained by the «melt-blowing» method from polymer granules by processing the granulate in an extruder, aerodynamic spraying of the melt and the formation of a fibrous-porous layer on a forming mandrel were selected for research. The main filtration characteristics of the original and regenerated filter materials (breakthrough coefficient, aerodynamic drag),as well as the electrophysical properties of the primary and secondary filter materials, the presence of a spontaneous electret charge have been investigated. The main stages of regeneration and evaluation of physicochemical, mechanical and operational properties of fibrous-porous materials that have undergone secondary thermo-aerodynamic processing in comparison with the original ones are described. It is shown that the studied materials retain their basic properties, while the structure of the fibers changes and the electret effect is enhanced.

The article presents the results of experimental substantiation of the method for improving the shielding properties of composite coatings based on powdered alumina (electrocorundum, alum earth), which consists in modifying the composition of such coatings by adding to it powdered iron oxide. This experimental substantiation consisted in the development of the technique for obtaining composite coatings based on powdered alumina and iron oxide, the manufacture of the experimental samplesusing the developed technique, measurements of electromagnetic radiation reflection and transmission coefficients values in the frequency range 0.7…17.0 GHz of the manufactured samples; implementation of the comparative analysis of the measured values with the similar values typical for the composite coatings filled with powdered alumina oxides, and composite coatings with the fillers such as powdered iron oxide. The obtained results revealed that by adding powdered iron oxide to the composite coatings based on powdered alumina oxides, it is possible to reduce by 1.0…8.0 dB their electromagnetic radiation transmission coefficient values in the frequency range 0.7…17.0 GHz. In addition, we found that the implementation of the proposed method allows one to decrease by 2.0…20.0 dB the electromagnetic radiation reflection coefficient values in the specified frequency range of the considered composite coatings, if such are applied to metal substrates. We propose to use the composite coatings, obtained on the base of the substantiated method, in order to ensure the electromagnetic compatibility of radio-electronic equipment.

Приведены результаты исследований процесса получения глушителей шума пневматических систем с повышенной эффективностью из пористых порошковых материалов методом вибрационного формования.

One of the main means of reducing aerodynamic noise is the use of silencers, which can be made of various porous materials, depending on the specific operating conditions. The aim of the work is to study the dependence of the noise reduction on the characteristics of porous permeable materials (PPM) obtained by vibration molding from metal powders. Such PPMs have a wide range of porosity, high permeability, mechanical strength, provide the ability to work in a wide temperature range, high corrosion resistance, and therefore find more and more widespread application in practice. When designing silencers, their pore size, permeability, mechanical strength, cost, and the chemical composition of the material are taken into account. Basic research methods – determination of noise level, powder particle size, permeability coefficient, pore size. Vibration molding of PPM samples for experimental studies was carried out on a ВЭДС 10-1А vibration bench with vibration parameters that ensured the maximum bulk density of the powder in the mold (acceleration 10 m/s2, frequency 500 Hz). Main results – the dependence of the noise reduction value on the PPM characteristics obtained by the method of vibration molding of metal powders of various grades of various particle size distribution was studied. It has been shown that the most effective damping is provided by PPM from spherical bronze powder of the БрОФ10-1 grade with particle sizes of 350–400 microns, which provides at the same time a combination of a high level of noise reduction and high permeability to air or gas. It was found that the thickness of the muff significantly affects the efficiency of noise suppression, while the minimum thickness of the muff, which provides a sufficiently high degree of noise reduction, is about 3.5 mm, therefore it is not practical to increase the thickness of the muffler material above this value.

СРАВНИТЕЛЬНЫЙ АНАЛИЗ ХАРАКТЕРИСТИК ОТРАЖЕНИЯ И ПЕРЕДАЧИ ЭЛЕКТРОМАГНИТНОГО ИЗЛУЧЕНИЯ ЭКРАНОВ НА ОСНОВЕ ПОРОШКООБРАЗНЫХ ФЕРРИТОВ И ЭЛЕКТРОКОРУНДА

The results of studies of the effect of particle size, pore size, shape, metallic-ray powder osteointergatsii quality (germination of bone tissue into the pores of the implant) are given. It is shown that the adhesion strength at the bone tissue implant made from titanium sponge powder 8-11 % higher than that of the implants obtained from spherical powders.

There are given the results of research the process of receiving by method of self-extending high-temperature synthesis of porous vacuum inserts of the faceplates used by production of semiconductor silicon plates at the enterprises of electronic mechanical engineering.

The paper reveals that the highest colmatation efficiency of charged and neutral particles is achieved in a polarizing electrostatic filter with a dielectric filter material which is placed in an electric field of high intensity created by surrounding metal electrodes. Due to polarization of dielectric jumpers (dipole formation) strong electric charges are initiated on their surface and in consequence of these charges forces of Coulombic and induction particle settling are dominating there. These forces are considered as the most efficient mechanisms for settling of dielectric and electrically-conductive finely-dispersed particles.

The paper reveals that the highest colmatation efficiency of charged and neutral particles is achieved in a polarizing electrostatic filter with a dielectric filter material which is placed in an electric field of high intensity created by surrounding metal electrodes. Due to polarization of dielectric jumpers (dipole formation) strong electric charges are initiated on their surface and in consequence of these charges forces of Coulombic and induction particle settling are dominating there. These forces are considered as the most efficient mechanisms for settling of dielectric and electrically-conductive finely-dispersed particles.

A theoretical analysis of colmatation regularities pertaining to high disperse particles from gas streams in various porous materials has been carried out in the paper. The paper reveals that under usual conditions the colmatation efficiency of high disperse particles having diameter 0.5 microns and less basically depends on a stream velocity and size of filter fibers that is higher velocity and larger fiber diameter entail lower colmatation efficiency. An increase in density of filter material packing makes insignificant impact on the rate of particles catching but leads to growth of resistance and correspondingly to reduction of the filter productivity. A joint action of diffusion mechanisms, a contact, and partially inertia is observed at high stream velocities.

The theoretical analysis of regularities in colmatation of highly dispersed particles from gas streams in porous fibrous materials influenced by electric field has been carried out in the paper. The paper reveals that the use of an electric field can significantly increase colmatation efficiency of highly dispersed dp < 0,5 µm sized particles and what is especially important that is colmatation efficiency of the most hard-to-capture dp ≈ 0,3 μm sized particles. Its highest values are achieved in the case of charged particle filtration through charged fibers. The colmatation efficiency is increased with higher particle and fiber charge, higher packaging density and specific surface and decrease of filtration speed.

The theoretical analysis of regularities in colmatation of highly dispersed particles from gas streams in porous fibrous materials influenced by electric field has been carried out in the paper. The paper reveals that the use of an electric field can significantly increase colmatation efficiency of highly dispersed d p < 0 , 5 µm sized particles and what is especially important that is colmatation efficiency of the most hard-to-capture d p ≈ 0 , 3 μm sized particles. Its highest values are achieved in the case of charged particle filtration through charged fibers. The colmatation efficiency is increased with higher particle and fiber charge, higher packaging density and specific surface and decrease of filtration speed.

A theoretical analysis of colmatation regularities pertaining to high disperse particles from gas streams in various porous materials has been carried out in the paper. The paper reveals that under usual conditions the colmatation efficiency of high disperse particles having diameter 0.5 microns and less basically depends on a stream velocity and size of filter fibers that is higher velocity and larger fiber diameter entail lower colmatation efficiency. An increase in density of filter material packing makes insignificant impact on the rate of particles catching but leads to growth of resistance and correspondingly to reduction of the filter productivity. A joint action of diffusion mechanisms, a contact, and partially inertia is observed at high stream velocities.