In order to obtain biologically compatible objects with mechanical properties close to living tissues, 3D printing with biocompatible sodium alginate hydrogel at room temperature on the modified desktop 3D printer Up! Mini (manufactured by PP3DP, China) was carried out. The standard print head was replaced with a special syringe-extruder to allow the extrusion of a hydrogel, the details of which were made by 3D printing from ABS plastic. Of the parameters, the standard material feed and print head movement rates were changed. For accurate reproduction of object sizes using 3D printing from this hydrogel the next parameters were established: the optimal concentration of sodium alginate in extruded hydrogel (2.5 wt.%); the composition of the “support” gelatin suspension, which was fixed on the printing table of a 3D printer and served as volumetric support for hydrogel (10 g of calcium chloride CaCl2 and 13.5 g of gelatin per 500 ml of distilled water). The method of its preparation includes 1 minute mixing of components blend, dispersion at 9000 rpm on IKA ULTRA-TURRAX T 25 digital disperser, 4 hours settling at 4 °C, 3 minutes centrifuging at 5500 rpm, removal of the supernatant. The optimal movement speed of the print head during 3D printing and the speed of extrusion of the hydrogel during the formation of the external perimeter of the printing object are 9–11 and 5 mm/s, respectively, as well as the speed of material extrusion during the formation of the internal filling of the model is 0.83 mm/s.

The effect of ultrasound oscillations (USO) on the combustion velocity and temperature, phase composition and microstructure of compounds produced by the self-propagating high-temperature synthesis (SHS) in the Ti–B system is studied using the earlier developed experimental setup. It is shown that the effect of powerful ultrasound on SHS is connected with the thermal factor, viz. the enhancement of heat removal from the specimen surface due to forced convection, and the physical (non-thermal) factor that consists in the influence of USO on the melt spreading and crystallization of different phases in the SHS wave. It is demonstrated that for multiphase system Ti–B an increase of the boron content in the initial charge leads to grain refinement of the synthesized product and the imposition of USO on the SHS results in a change in the grain morphology: their shape becomes closer to equiaxial. In composition Ti+1.5B, under the action of USO cubic-shape product grains are observed on the inner surface of pores, and in composition Ti+2.0B the synthesized TiB2 grains become more vividly facetted.

As a result of imposition of ultrasound on the synthesis process, grain refinement is observed for all the compositions along with the formation of a large number of borides and their redistribution in the volume. The use of ultrasound brings about changes in the quantitative phase composition of the synthesis products and the ratio between the orthorhombic and cubic modifications of phase TiB. The research has shown that the presence of pores in the initial charge plays an important role in the structure formation of the final product, and hence it appears impossible to obtain an equilibrium material by the SHS method. It is found that an optimal USO amplitude exists at which it is possible to obtain uniform fine-grained structure of the material. This permits controlling the structure formation at SHS. 

 Various methods are applied in the world practice to increase wear resistance, fatigue strength and corrosion resistance of aviation equipment, machinery and medicine parts made of titanium and its alloys. Ion-plasma nitriding provides the ultimate effect making it possible to obtain hardened layers with hardness of HV0.01 650–1000 with a thickness of 0.07–0.20 mm for 3–6 hours, depending on the grade of the titanium alloy.

Technological factors effecting on the efficiency of ion-plasma nitriding of materials are the process temperature, duration of saturation, pressure, composition and flow rate of the working gas mixture. The effect of these technological parameters on the microstructure, microhardness and depth of hardened layers is investigated in the work. It is shown that hardness and depth of the nitrided layer can be controlled by changing the composition, volume and periodicity of the gaseous medium (nitrogen and argon) supply at the stages of heating and holding time of the samples from titanium and its alloys under ion-plasma nitriding. The tribological characteristics of titanium alloys as-received and the same ones subjected to ion-plasma nitriding under friction conditions without a lubricant were studied. For VT1-0 and VT6 alloys in the as-received state during the tests there is a monotonous decrease of the friction coefficient from 0.35–0.40 to 0.25, after nitriding the friction coefficient monotonically increases from 0.14 up to 0.30 when removing the hardened layer.

Studies of corrosion resistance of titanium VT1-0, carried out in a 10 % solution of sulfuric acid, showed that after ion-plasma nitriding at a temperature of 830 °C for 6 hours, the corrosion resistance increases, as the positive polarization potential of the sample shows.

Results of comparative researches of the initial and processed in a plasma flow oxidic microcomposites, consisting of TiO2, SiO2, Al2O3, ZrO2, and plasma coverings from them – the materials which are characterized by amorphous and crystal structure and strengthened by ultradispersed phases of the stishovit, are presented. It is shown the influence of a type, structure and a way of processing of material (initial powder of different dispersion; the powder obtained in a plasma flow at the different modes and with the normal and accelerated cooling; a plasma layered composite) on the content of silicon oxides, aluminum and titanium, on the type of polymorphic transformations (anatase is found both in powders, and in coverings; the accelerated cooling of spheroids leads to growth of its contents in microcomposites) and also on feature of forming in ceramic materials of a high-bar phase – the stishovit (stishovit it is found only in coverings). It is established that increase in power of the plasma generator leads to increase in extent of amorphicity of plasma-layered composites. In the structure of layered composites three groups of the inclusions, combined by the composition, are revealed: two groups of aluminosilicates and inclusions on the basis of zirconium dioxide. Inclusions of the third group are characterized by two types of structures: homogeneous, consisting of zircon, and plated (with a kernel of dioxide of zirconium and a cover from zircon). The developed layered composites are characterized by high wear resistance, corrosion resistance and antifriction properties. In the conditions of low-temperature plasma at atmospheric pressure the stishovit-containing materials are obtained for the first time.

The results of the development of electromagnetic radiation shields with flexibility and minor weight and size parameters are presented. Needle-punched material was chosen as the basis for the shields of electromagnetic radiation, which was coated with conductive or dielectric coatings. It has been proved that when applied to a needle-punched material of thin (up to 5 mm) conductive or dielectric coatings, the ultimate strength increases to 5–10 kgf/mm2 and the surface resistance decreases to 0.05 MOhm/sq, while the weight and size parameters of the shields do not change significantly. It was shown that the frequency dependencies of the reflection and transmission coefficients correlate for coatings of various types. A sample of an electromagnetic radiation shields based on a needle-punched coated material consisting of powdered shungite has a reflection coefficient measured in the short circuit mode is about –22.8 dB in the 2–4 GHz frequency range, which allows to use this material to ensure electromagnetic compatibility, information security and personnel protection from electromagnetic radiation.

The analysis of the influence of electroslag remelting steel structure on the properties of cemented and nitrided surfaces of machine parts is carried out. It is noted that when using electroslag remelting, the greatest efficiency is achieved in the production of large-sized gearwheels, hardened by cementation and ion nitriding. It is shown that cast steel, crystallized in a water cooled crystallizer, has a strength not lower than forged or rolled with significantly lower anisotropy properties and accelerated carbon diffusion when cementation. The discovered patterns are caused by the structural and chemical homogeneity of boundary grain volumes, which formation is affected by copper impurities. Uniform density of copper in the said volumes not only reduces their propensity to localize plastic deformation, but contributes to a higher ability for uniform carburization of these steels in the process of cementation. This causes a change in the main characteristics of the cemented layers and is the basis for increasing the bearing capacity of the gearwheels. The obtained results also testify to the fact that controlling grain-boundary effects in steel material at the stage of crystallization of blanks can be a significant factor in increasing the characteristics of the hardened layer in the manufacture of nitrided gearwheels from cast blanks of the electroslag redistribution. A set of studies was carried out and results were obtained which indicate that the control of grain boundary effects in modern steel material at the stage of its crystallization may be a significant factor in improving the characteristics of the hardened layer in the manufacture of cemented and nitrated gear wheels from cast billets electroslag remelting.

The results of experimental studies on determination of the effect of the deflector-type sprinkler geometric parameters on the air-mechanical foam formation process are presented in the article. A collapsible sprinkler was developed for the experiment. The elements of the collapsible sprinkler which allow creating its various configurations in a fairly wide range of geometric parameters were made from polylactide (PLA-plastic) with the help of 3D printing. The dependencies of the air-mechanical foam expansion rate and stability on the sprinkler holder length, as well as the external diameter, the taper angle and the ledges height of the sprinkler sprayer were established. The ranges of optimal values along the holder length L = 45÷55 mm and the sprayer ledges height h = 1÷3 mm of the sprinkler for generation of foam with the greatest expansion rate and stability were determined, as well as the ranges of values of these parameters at which the change in the quality characteristics does not occur (L = 90÷150 mm, h = 5÷15 mm). A decrease in the foam quality characteristics with an increase in the sprayer taper angle of the sprinkler was established. Approximate dependencies of the foam expansion rate and stability on the sprayer taper angle of the sprinkler in the range α = 30÷135° were obtained. In addition, it is determined that an increase in the sprayer external diameter in the range from 20 mm to 100 mm results in a gradual deterioration in the foam qua lity. The results of the conducted researches will allow optimizing geometrical parameters of existing designs of deflector-type sprinklers with the aim to increase their fire extinguishing efficiency.

Exact and approximate solutions to the non-stationary problem on the heat conduction in a semi-bounded body exposed to a pulsed laser radiation flow have been obtained. The action of rectangular, triangular and parabolic laser radiation pulses on this body was investigated. Polynomial relations have been constructed on the basis of the boundary-characteristic method with introduction into consideration of the temperature-disturbance front, and they made it possible to obtain practically exact solutions for the temperature function and its time derivative at both the stages of heating and cooling of the body. It is shown by some examples that the success in solving problems on the pulsed plasma heating of bodies is associated in many respects with the necessity of definition of the time law of movement of the temperature-disturbance front with the use of the Pade diagonal approximation, which excludes, practically completely, the divergence of the power series defining the law of movement of this front, in particular, in small time intervals. The approach proposed for solving heat-conduction problems with the second-kind boundary condition allows one to simply and effectively find solutions for isotherms and lines of equal heating and cooling. Analysis of the results obtained allows the conclusion that the effectiveness of solving various technological problems, based on the use of pulsed laser radiation, is determined by the success in solving the problems on control of the time shape of a laser pulse and determination of the temperature fields in the body on the basis of polynomial representations.

The concept of “steam thermolysis”, specifically, the use of overheated water steam as an effective coolant and inert medium to reduce the formation of environmentally hazardous compounds in the process of thermochemical decomposition of organic waste and to have the possibility of obtaining valuable end products that can be certified as fuels, fuel additives, raw materials and components for certain products, is grounded. Based on the study of decomposition of organic waste in a superheated water steam environment, a thermochemical technology for processing of hydrocarbon-containing raw materials has been developed.

To implement the technology of processing hydrocarbon-containing raw materials, it is necessary to heat the raw material up to the specified temperature, maintain the raw material at this temperature for the time required for complete removal of hydrocarbons and water, to cool and condense the steam-gas products, and to cool the solid products. All these processes (heating, holding at a given temperature, cooling, condensation) are associated with the supply of energy (heating and soaking) and energy removal (condensation and cooling of products). On the basis of the law of conservation of energy, the heat transfer equation is formulated and its solution is computed, which makes it possible to calculate the necessary time for the complete course of the thermal decomposition of hydrocarbons.

The new technology is instrumentally designed as a line for processing of oil-containing waste, installed on the territory of the company Industrial-transport corporation LLC (Angarsk, Russia). With the help of this equipment, it was proved experimentally under experimental industrial conditions, that as a result of steam thermolysis of oil sludges, the formation of a gasoline fraction occurs, the content of kerosene and diesel fractions increases, and the content of the black oil fraction decreases significantly. 

An experimental investigation of the heat-transfer coefficient to a spherical probe in a cyclone-bed chamber with fluidized bed in the “cold” and “hot” regimes has been carried out. The heat-transfer coefficient was determined by the regular thermal regime. The dependences of the heat-transfer coefficient in the vortex-bed furnace on the various parameters: the diameter of the outlet hole, the air flow rate, the share of the bottom blast and the location of the probe were determined. It is revealed that in the “cold” regime the heat-transfer coefficient has practically constant value in the radial direction, it almost does not depend on the diameter of the outlet hole and the share of the bottom blast and depends significantly on the position of the probe along the height of the furnace and the air flow rate. The effect of flow swirling on the heat-transfer coefficient in a cyclone-bed chamber with fluidized bed is determined. When the fuel burns (“hot” regime), the heat-transfer coefficient is not constant in the radial direction and accept the maximum values in the central area of the chamber. At the same time, the part of conductive-convective component in the total heat-transfer coefficient to the spherical probe, depending on its radial position, is estimated at 40–70 %. The results can be used in the design and creation of modern high-efficiency furnaces for burning local solid biofuels.

In the work the technology of radio-frequency identification of objects with inductive coupling is considered, using passive electric oscillating circuits tuned to fixed frequencies from the working frequency range as identification features of the object. The choice of the primary measuring transducer and the informative parameter is based on the results of the analysis of the system of inductively coupled active and passive electric oscillation circuits, known from the theory of radio engineering circuits. The parameters of the measuring transducer ensuring the fulfillment of the requirements for identification and localization of objects specified by technological conditions are substantiated. Factors that are potentially dangerous with respect to reducing the information reliability of the measuring transducer are considered, as well as the possibility of reducing their influence to a minimum. The problems of experimental research are formulated. It is shown that the analysis can be performed by software discrete adjustment of the primary measuring transducer and the generator feeding it. In this case, the task of increasing the speed is targeted at decreasing the duration of the step of tuning the primary measuring transducer. The required reliability of object identification is achieved by: ensuring high stability of the frequencies of the generator supplying the primary measuring transducer; accuracy and stability of tuning of the primary measuring transducer to the frequencies of the supplying generator; protection of the primary measuring transducer from the influence of interference generated by external sources and other measuring converters of the object identification system (electromagnetic compatibility of the object identification system); sufficient magnitude of the response of the primary measuring transducer to the introduction of passive electrical oscillation circuits; sufficient frequency tuning interval for passive electric oscillation circuits; accuracy and stability of tuning of passive electric oscillation circuits; stability of the detection threshold relative to the initial level of the informative parameter. Electromagnetic compatibility of measuring transducers, whose sensing elements are in the zone of mutual influence, is provided by synchronizing the operation of measuring transducers with shunting of inactive sensors, screening, mutual orientation and spacing of sensing elements.

This work is the further development of the theory of norms of syndromes: the theory of polynomial invariants of G-orbits of errors expands with the group G of automorphisms of binary cyclic BCH codes obtained by joining the degrees of cyclotomic permutation to the group Γ and practically exhausting the group of automorphisms of BCH codes. It is determined that polynomial invariants, like the norms of syndromes, have a scalar character and are one-to-one characteristics of their orbits for BCH codes with a constructive distance of five. The paper introduces the corresponding vector polynomial invariants for primitive cyclic BCH codes with a constructive distance of seven, next to the norms of the syndromes that are already vector quantities; the basic properties of the vector polynomial invariants are investigated. It is established that the property of mutual unambiguity is violated: there are G-orbit-isomers, which are different, but have the same vector polynomial invariants. It is substantiated and demonstrated by examples that this circumstance greatly complicates error decoding algorithms based on polynomial invariants

When eddy-current thickness measurement is carried out, one of the disturbing factors leading to an error in determining the thickness of the conductive coating on a conducting ferromagnetic or non-ferromagnetic substrate are the variations of the electromagnetic parameters of the coating and the substrate observed when the transducer moves from point to point along the surface of the controlled product, when moving from one product to another, at presence of  heat treatment or other thermal effects on the controlled product after coating. The paper presents the results of experimental studies of the influence of variations in the electromagnetic parameters of a conducting ferromagnetic substrate on the phase of the emf, introduced into the superimposed transducer. It is shown, when the minimum influence of such variations on the specified phase is achieved. As a result, it was suggested to use the multi-frequency method to reduce the influence of variations of electromagnetic parameters on the accuracy of determining the coating thickness during application of the phase control method. It consists in the fact that the frequency of the excitation current of the transducer, mounted on the monitored product, is discretely reduced from a certain maximum to a certain minimum frequency during measurements. At the high frequency, the specific electric conductivity of the coating material is taken into account, with decreasing frequency, such a value is determined when the electromagnetic parameters of the substrate begin to affect the phase formation. Then, using the calibration curve obtained from samples from the same coating material and substrate as the controlled article and having a known coating thickness, the desired coating thickness on the product to be tested is determined.