Electromagnetic (EMR) and ionizing (IR) radiation are one of the main destabilizing factors which affect functional equipment of space-rocket, aviation and ground-based complexes. Therefore, the direction of physical materials science, associated with the development of new materials and technologies for high-efficiency electromagnetic and radiation protection is of current interest. In the Scientific and Practical Materials Research Center of the National Academy of Sciences of Belarus new materials and technological processes for the formation of electromagnetic and radiation protection of the devices packages and elements of a wide range of purposes have been developed. A constant magnetic field and a powerful electromagnetic pulse are the most difficult variants for protection against EMR. Symmetric and gradient multilayer film structures are the promising materials for solving this problem. Thus, experimental results on the investigation of the efficiency of electromagnetic shields based on the structures of the system (Fe–Co–Ni)/Cu in a constant magnetic field, low-frequency and pulsed EMR are considered. It is shown that while choosing materials for magnetostatic shields, the main magnetic characteristics and the role of the inhomogeneity of the magnetic field in the shield volume and the nonlinearity of the magnetic permeability should be considered. It is concluded about the high efficiency of attenuation of microsecond duration pulsed magnetic fields by the gradient structures, which are 58÷40 dB at the magnetic field strengths of 1.25÷12.0 kA/m, respectively. A composite material based on the tungsten-copper system is proposed for electronic components and integrated circuits protection from the effects of IR. It is demonstrated that radiation shields based on it provide the effective protection against electron- and proton radiation with energies up to 2 MeV and up to 500 MeV, respectively. The practical application results of developed materials and technologies are given.

Experimental investigations of ultradispersed silicon powder produced by mechanical grinding are conducted. The process of scaling powders using mechanochemical grinding was studied. It was found that the dimension of crystallites of the silicon powder determines their physical and chemical properties. Finely divided powders of silicon with a particle size ≤10 nm easily decompose water at room temperature into hydrogen and oxygen, they are easily oxidized by air oxygen and actively interact with hydroxides and acids with the release of significant amount of heat. The rate of saturation of micro- and ultradispersed powders with hydrogen at a constant rate of flow in the flow system depends on the temperature of the hydrogen hydrogenation process. It was found that the hydride formed at a low temperature (≤573 K) is in an equilibrium state when it is being hydrogenated in a flow reactor. The treated powder passes into a metastable state with the termination of the thermal action after hydrogenation. Hydrogen, entering the volume of micro- and ultradispersed silicon powder in the temperature range 373–723 K due to the diffusion process, can react not only with silicon atoms to form hydrides of the SiH₂ type, but also with hydrides of less active radicals of the type of Si₂H₄, Si₂H₆. The hydrogenation process has two distinct stages. It is shown that the temperature of the transition between the stages is determined by the dispersion of micro- and ultradispersed silicon powders and by the structure of hydrides on the particle surface. As a result, it is established that the optimum temperature of hydrogenation should be taken at a temperature of 623 K, at which the maximum mobility of silicon atoms is reached during the formation of hydride. Sharp decrease in the hydrogen content is observed at a temperature above 723 K for the Si₂H₄ (SiH₂).

Materials based on MAX phases have a unique combination of properties. They combine the best properties of metals and ceramics. Such a set of useful operational parameters allows for wide technical application in various industries. However, despite the large number of research works carried out in this area, obtaining a dense, uniform MAX material remains an unresolved issue. The possibilities of the pulsed compacting method with blasting explosives for obtaining products from MAX phase powders were investigated. As a model material for the research, powders of MAX phases based on Ti₂AlC and Ti₃AlC₂ synthesized by free sintering in vacuum were used. It was shown that double pulse compacting powders based Ti₂AlC Ti₃AlC₂ and reducing compacts porosity from 22 % to 9 %, is practically unchanged while the phase composition of the material. Test samples obtained by pulsed compaction in oxidation resistance showed that the method of the shock-wave loading applicable for competitive materials realizing potential properties of MAX phases. It is noted that to increase the heat resistance it is necessary to minimize the porosity of the material. Significant reduction in porosity can be achieved due to repeated shock-wave loading of the material.

 

Several methods have been described for increasing the main characteristics (density, heat of combustion, combustion temperature, gas formation index) and operating properties (combustion speed and temperature, total and specific impulse, properties of combustion products) of an energy-saturated heterogeneous composite material by introducing energy additives in the form of fine-dispersed spherical powders of high-energy metals or their alloys, non-metallic materials. Their efficiency has been estimated taking into account the workability and safety of use. The influence of the main ingredients of the composite material on its operating properties has been considered. An analysis of modern approaches of leading manufacturers has been given to increase the operational properties of energy-saturated heterogeneous composite material by introducing into its composition one of the cyclic nitramines with subsequent modification by plasticizers, providing a decrease in the sensitivity of the material. Thermodynamic calculations have been carried out for a number of compositions of an energy-saturated heterogeneous composite material containing plasticized secondary cyclic nitramines. A complex of experimental studies of material samples of various compositions has been performed and their main properties have been determined.  A possibility of an equivalent substitution of finely dispersed aluminum powder in the composition of an energy-saturated heterogeneous composite material for one of the phlegmatized cyclic nitramines. According to the results of thermodynamic calculations and a complex of experimental studies of the energy characteristics of the material, the possibility of such a substitution has been confirmed and the boundaries of the acceptable content of cyclic nitramines in the composition of an energy-saturated heterogeneous composite material have been determined. The tasks for entering the industrial technology of manufacturing at the domestic enterprises of the considered class of materials modified with cyclic nitramines have been formulated.

 

Development of modern industries requires creation of new materials, which have, along with special properties, high strength and heat resistance. The most difficult is the provision of the latter. To increase it, it is necessary to reduce the amount of free movement of dislocations to a maximum permissible value, localize movement of defects of the crystal structure within the grain (subgrain), minimize the runoff of defects of the crystal structure at grain boundaries, exclude intergranular sliding, which can be successfully realized in dispersion-hardened materials. To obtain them, a promising technology is based on the reaction mechanical alloying. The article presents the results of the author’s work, which made it possible to establish the regularities in the formation of phase composition, structure and properties at all stages of obtaining mechanically alloyed dispersed-hardened materials based on metals, which are the basis for the production of basic structural alloys-aluminum, copper, iron and nickel. These alloys are used for products operating under severe temperature-strength conditions – at temperatures reaching 0.85T_ml of the substrate. They have tensile strength 1.2–1.5 times higher than that of analogues, and on their basis a new area of materials science of structural materials was created – nanostructured mechanically alloyed dispersed-hardened materials based on metals. The most promising areas of application of technologies based on reaction mechanical alloying in the field of materials science are: 1) high-strength materials for machine parts, tooling and products of various functional purposes operating under severe temperature and force conditions; 2) powders for gas-thermal spraying and coating of them; 3) nanocrystalline modifying ligatures and modifiers. The results of industrial introduction are given – two small-scale enterprises for the production of import-substituting science-intensive products were created. 

The work presents a physicomechanical model developed for calculating the force action on the punch with high-speed impact extrusion of bimetallic stepped rod products under conditions of plane deformation. In order to obtain the result, the process of impact loading of the workpiece is divided into two stages – acceleration and braking. At the acceleration stage, a linear dependence on the graph P_n(h_n) “force on the punch – the deformation line” is adopted. For the braking stage, a procedure is given for calculating the force acting on the punch with the plastic flow of the bimetallic workpiece in a stepped narrowing cavity with three deformation centers. Based on the method of upper evaluation for the case of plastic flow at the final stage of the process, an equation is derived for calculating the force acting on the punch through deformation centers. By solving the problem in a quasistatic formulation (the action of dynamic tensions on the surfaces of velocity discontinuity and inertia forces does not affect the type and shape of the velocity and acceleration hodographs constructed), starting from the condition of the minimum power of plastic shaping, the dependences for calculating the optimum angles of the matrix cavity α_опт, β_опт, γ_оптdepending on the stretching λ and the coefficient of friction μ were determined. The use of a matrix with the optimum taper angles will allow us to realize the process of high-speed impact extrusion with minimum load acting on the punch. On the basis of the developed model, an equation for calculating the minimum upper force P_n,min acting on the punch under high-speed impact plastic flow of metals through the deformation centers was obtained within the framework of the adopted assumptions. The equation presents the rheological characteristics of the deformed main part of the workpiece (k, ρ), technological parameters (λ₁, λ₂, λ₃, V), contact friction coefficients μ for different parts of the surface of the matrix cavity, the impacting masses of the punch and the workpiece. The developed model for calculating the optimal power regime and equation can be used in engineering practice to develop a technology for high-speed impact extrusion of flat-step bimetallic products for various purposes.

The processes occurring in the contact of solids differ in their variety, their dependence on the scale of the region under consideration and the values of the acting forces. The study of such processes requires a comprehensive approach to the instrumental and methodological support of research. To establish the mechanisms that take place in nanometer gaps between solids, an instrument for measuring intermolecular and capillary forces has been developed; its design and operating principle have been described. Technical solutions for measuring frictional forces at low loads and measuring submicron wear values are presented. The methods for studying wear mechanisms at friction with terms of the morphology of wear particles and local damage of friction surfaces are described. The methods of diagnostics and estimation of the current state of friction units based on the classification of surface damages and fragments of their fractures by morphological types are considered. A method of estimating the parametric equivalence of full-scale and laboratory tests for friction and wear is given, which opens the possibility of comparing the data obtained under different conditions and establishing the cause of their discrepancy. The capabilities of the method are demonstrated by an example of acting space factors estimation in the framework of the planned experiment on friction study at the International Space Station.

Possibilities of increase of cutting speed at simultaneous increase of accuracy of coordinate movements and decrease of dynamical loads at initial, the most dangerous from emergence of chips and breakages, moment of interaction of 15–120 microns thick diamond wheel with a wafer having 250–500 microns thickness and diameter of 50–250 mm, at its chipping are shown. The table with a wafer makes reciprocal coordinate cyclic movements at cutting. In the course of its acceleration to working feed rate there are mechanical oscillations in the direction of driving, which have natural frequency. These oscillations can lead to a table deviation from the machine coordinate and to occurance of accelerations, significantly differ with predicted ones, at achievement of working feed rate and subsequent contact of a wafer with a diamond wheel. That can be considered at realization of a production cycle, and, in some cases, oscillations can be operated programmatically by the choice of rational ratios of values of working stroke, length of non-working stroke and free frequency that allows reducing or exclusion of chips and breakages of wafers and diamond wheel, reducing their thickness and increasing processing speed by 1,5–2 times. Possibilities of creation of combined system of drives which use allows exclusion emergence of mechanical oscillations are shown.

It is noted that the main components of the quantitative evaluation of the performance of tractors are the indicators of their energy saturation and universality. The key characteristic of tractors of agricultural purpose is the traction class, which characterizes, first of all, the energy saturation of a tractor. Universality of agricultural tractors is characterized, mainly, by their maximum speeds of movement and average speeds of performance of transport works. It has been established that the most important directions for the development of the design of agricultural tractors are based on increasing their productivity. Increasing productivity is achieved by increasing both energy saturation and versatility, which allows to increase the time of continuous operation and the coefficient of using the tractor. It is determined that the increase in energy saturation is ensured by increasing the power of the power unit of wheeled tractors to 600 hp, as well as the addition of model series with new-level caterpillar tractors, closely aligned with wheel-type models of similar power. At the same time, the leading manufacturers of tractors are performing research and development in the development of the concept of an agricultural tractor with an engine of more than 500 hp. The increase in the universality of tractors is accompanied by the development of their construction, which ensures an increase in the maximum and average speeds of movement. The increase in transport speeds of up to 50–60 km/h and more is achieved by the improvement of stepped gearboxes, the development and introduction of continuously variable transmissions, the use and improvement of the characteristics of the suspension of the front driving axles, the cabin and the operator’s seat, the use of brakes of the front driving axle wheels, anti-lock and anti-traction systems, and all-wheel steering. It is shown that to increase the technical level of tractor equipment, great attention is paid to improving the operator’s working conditions, including by improving the design, improving the ergonomic and aesthetic properties of the cabins, automating work processes by developing and implementing on-board electronic control systems, diagnostics and controls. To reduce costs and increase the efficiency of agricultural production, the use of precision farming systems is becoming increasingly widespread.

An attempt has been made to analyze qualitatively and quantitatively the thermodynamic cycle of detonative combustion and to compare it with the Otto and Brayton cycles in order to establish the degree of its thermodynamic perfection. A comparison of the thermodynamic cycles of Otto, Brayton, and detonation was carried out for equivalent Carnot cycles, which has the same degree of thermodynamic perfection as the investigated cycles. To determine the parameters of the detonation cycle, the classical detonation theory based on the laws of thermodynamics and gasdynamics was used. It is shown that the detonation cycle in comparison with the cycles of Brayton and Otto has larger entropy at the end of the heat supply and smaller one at the end of the heat removal. That means it has a higher mean-integral temperature of heat input and a lower mean-integral temperature of heat removal. Thus, in the range of characteristic values of the adiabatic index k, the temperature at the end of the heat input process in the detonation cycle exceeds the Otto cycle temperature by about 7–15 %. Consequently, the detonation cycle is thermally more efficient, since the thermal efficiency of the cycle increases with the expansion of the temperature boundaries of the equivalent Carnot cycle.

A methodology of forecasting the main characteristics of load duration curves is described: the coefficient of unevenness, the load factor and the magnitude of power consumption. The characteristics are necessary for predicting of the electrical load duration curves over long time periods. Based on extensive statistical information on the hourly loads of the Belarusian energy system for the period from 1997 to 2014, historical trends of characteristics change were found. Each edge scenario was formed by combining the main characteristics of the load duration curve. Scenario approach and the previously developed method of operative restoration of the curves of the duration of the electrical load on the basis of its main characteristics make it possible to obtain possible boundary forms of these curves for a number of future years. A feature of the approach of the proposed methodology is that such characteristics as the amount of power consumption, as well as the shape of the curves of the duration of electric load are predicted in a certain ranges. The width of the ranges is justified by the analysis of the retrospective information and can be adjusted taking into account the newly received information. The proposed approach can be used in optimization programs of energy system planning. The obtained numerical results can be used to optimize the structure of the Belarusian energy system.

Assessment of radiation effect on nuclear power plant staff was made for design basis accident. The considered accident scenario includes spent fuel assembly drop into the reactor core or fuel pool during load-unload operations with fuel assemblies damage and radionuclide emission. The proposed method included the assessment of radionuclide sedimentation on characteristic surfaces of nuclear power plant site, calculations of radioactive aerosol distribution depending on the distance of emission source in COMSOL 3.5 program. The software module is based on highly detailed account of the infrastructure of the nuclear power plant industrial site according to the master plan, which allows obtaining more accurate estimation of radioactive substances deposition and, as a result, more accurate calculation of doses for staff and population. The assessment of average volume activity in lower air layer on site during VVER design basis accident is performed. Doses from radioactive cloud (external exposure) and from inhalation (internal exposure) were estimated for following radionuclides: ¹³⁷Cs, ¹³¹I, ¹³³I, ⁹⁰Sr. In the case of the design basis accident associated with the fall of the assembly during fuel load-unload operations the received value of the total effective dose of staff exposure is 7.80 mSv for the first 8 hours after the accident beginning. This number is well below the threshold of the allowable annual dose limit for personnel in emergency situations (50 mSv).

 

Leading companies in the field of obtaining data from Earth remote sensing from space are building Satellite constellations to increase the frequency (multiplicity) and monitor various parts of the Earth’s surface. The Satellite constellation remote sensing equipment from Airbus (France) allows daily observation of any point on the Earth’s surface with high spatial resolution, and the grouping of DigitalGlobe (USA) – with ultra-high spatial resolution. The analysis of the mutual exploitation of the national space systems of the Socialist Republic of Vietnam and the Republic of Belarus has been carried out. There have been analyzed the joint capabilities of VNREDSat-1 (Vietnam) and BKA (Belarus) Earth Observation Systems for the monitoring of natural resources, the environment and natural disasters by comparison of their space and temporal characteristics (orbit parameters and re-visit time) as well as spectral-energetic characteristics (space, spectral and radiometric resolutions). The accepted correlation of technical parameters for solving the previously mentioned tasks having into account the different phases of the mentioned satellites has been determined. The conclusions have been reinforced by the results of live experiments with archival and instant data from both EO satellites.