Search

The numerical simulations of the deformation and fracture in an iron boride coating – steel substrate composition are presented. The dynamic boundary-value problem is solved numerically by the finite-difference method. A complex geometry of the borided coating – steel substrate interface is taken into account explicitly. To simulate the mechanical behavior of the steel substrate, use is made of an isotropic strain hardening model including a relation for shear band propagation. Local regions of bulk tension are shown to arise near the interface even under simple uniaxial compression of the composition and in so doing they determine the mesoscale mechanisms of fracture. The interrelation between plastic deformation in the steel substrate and cracking of the borided coating is studied. Stages of shear band front propagation attributable to the interface complex geometry have been revealed. The coating cracking pattern, location of the fracture onset regions and the total crack length are found to depend on the front velocity in the steel substrate.

The article presents a microstructure-based mechanical model of hexagonal close-packed (hcp) a-titanium representative of the mesoscale and analyzes the contribution of a pyramidal slip to plastic deformation. We discuss the size of a representative volume element (RVE) enabling mesoscale phenomena to be correctly reproduced, focusing on deformation-induced surface roughening (DISR) and plastic strain localization. It is shown that the ignorance of a pyramidal slip in simulations leads to overestimated stress values in an hcp material. A polycrystalline model is capable of reproducing the mesoscale phenomena until plastic strain begins to localize at the length scale comparable to the model size

The effect of 6 MeV gamma photons on thermally stimulated exoelectron emission (TSEE) spectra of MgO films was studied. The films were fabricated on Si/SiO2 substrates using the extraction-pyrolytic method. The crystalline structure and surface morphology of the films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). TSEE spectra of MgO films had emission peaks at about 450 oC and 525 oC. The area under the TSEE peaks increased after repeated TSEE measurements. In the case of gamma-irradiated films, the percentage increase in the area depended on the radiation dose, decreasing linearly with an increase in the radiation dose from 0 to 80 Gy. The results suggest that gamma radiation reduced the density of trapped electrons present in the as-grown MgO films or created competing hole traps that inhibited TSEE from the films.

This work studies the formation and evolution of residual stresses in metal matrix composites with different volume fractions and sizes of reinforcement particles. The investigation was performed on hot-pressed samples of pure aluminum with boron and titanium carbide particles. The samples were subjected to mechanical compression tests to study their fracture behavior. Residual stresses were measured after cooling, as well as at different degrees of deformation of the composites. Some samples were subjected to electron beam processing. The phase composition and size of boron carbide particles in their recast surface layers, which were formed by recrystallization from the liquid phase during irradiation, were examined by X-ray diffraction. The cooling process followed by mechanical loading of the composites was simulated by simultaneously taking into account the fracture of the matrix and particles. The formation of residual stresses in composites with different particle volume fractions was numerically investigated.

This paper experimentally investigates the process of deformation-induced mesoscopic surface roughening in commercially pure aluminum under uniaxial tension. Surface profiles are recorded in selected observation areas at different stages of stretching using a contact profilometer. It is shown that multiscale undulations are formed on the surface from the very beginning of plastic deformation and evolve during stretching. The undulations formed due to the collective displacement of 10–15 grains make the greatest contribution to roughening. A quantitative assessment and comparison of the behavior of mesoscopic undulations are carried out using a dimensionless parameter of the degree of roughness, which is the ratio of profile length to evaluation length, determined for the obtained surface profiles in the studied strain range. A correlation between the roughness degree and local plastic strains is established.

The paper provides the results of the studies on the influence of high temperatures and aggressive media on the performance properties of O-rings having one name but made by different manufacturers. O-rings by supplier No. 1 are made from fluorosilicone rubber, and O-rings by supplier No. 2 are made from fluororubber. The analysis of O-rings showed that the color of O-rings made from fluorosilicone rubber changed and their physical mechanical properties decreased after operation when subjected to G-energy Si-OAT and G-energy SNF coolants. The comparative analysis of TGA curves of O-rings showed that O-rings made from fluororubber were more heat stable than O-rings made from fluorosilicone rubber, i.e. they can withstand higher operating temperatures in an air atmosphere. Fluoroelastomers can recover quickly and are used to manufacture products which should have a high heat resistance during operation and high resistance to aggressive coolants.

Layered van~der~Waals materials of the family TaTMTe$_4$ (TM=Ir, Rh, Ru) are showing very interesting electronic properties. Here we report the synthesis, crystal growth and structural characterization of TaIrTe$_4$, TaRhTe$_4$, TaIr$_{1-x}$Rh$_{x}$Te$_4$ ($x = 0.06$; 0.14; 0.78; 0.92) and Ta$_{1+x}$Ru$_{1-x}$Te$_4$ single crystals. For Ta$_{1+x}$Ru$_{1-x}$Te$_4$ off-stoichiometry is shown. X-ray powder diffraction confirms that TaRhTe4 is isostructural to TaIrTe4. We show that all these compounds are metallic with diamagnetic behavior. Ta$_{1.26(2)}$Ru$_{0.75(2)}$Te$_{4.000(8)}$ exhibits an upturn in the resistivity at low temperatures which is strongly field dependent. Below $T \approx 4$K we observed signatures of the superconductivity in the TaIr$_{1-x}$Rh$_{x}$Te$_4$ compounds for $x = 0.92$. Magnetotransport measurements on all samples show weak magnetoresistance (MR) field dependence that is typically quadratic-in-field. However, for TaIr$_{1-x}$Rh$_{x}$Te$_4$ with $x\approx 0.78$, the MR has a linear term dominating in low fields that indicates the presence of Dirac cones in the vicinity of the Fermi energy. For TaRhTe$_4$ series the MR is almost isotropic. We have performed electronic structure calculations for isostructural TaIrTe$_4$ and TaRhTe$_4$ together with the projected total density of states. The main difference is appearance of the Rh-band close to the Fermi level.

The article deals with the role of electrodes materials in improving the industrial wastewater treatment from pollutants by electrochemical action. The instability constants of the complexes and coordinated ligand molecules were calculated. Based on the research conducted regarding the rationalisation of the poly-ligand electrolytes and electrolysis modes, a variative flow scheme of the coatings deposition by triple alloy has been developed. The corrosion resistance characteristics of the coatings obtained in the form of alloy, that were obtained from complex electrolyte that satisfy the necessary coatings requirements for effective treatment of wastewater have been researched. The obtained coatings have better corrosion resistance than in special steels of electrochemical purpose.

The article analyses the effect of temperature distribution at different points of the irradiation zone on the nature of leakage of structural-phase transformations. The results of the X-structural analysis are given, which shows the presence of martensite and residual austenite in the treatment zone. The peculiarities of structural-phase transformations during laser heating are studied and their effect on strain value during laser shaping is determined. The results of experimental studies are given, according to which, if the mechanisms for forming the temperature gradient and polymorphic transformations (for 65G steel) operate in parallel, the amount of deformation is one third of the sample for which only the temperature gradient mechanism works (12Х18N10Т steel).

Laser shaping of sheet materials is a flexible process and is carried out without force contact on the material, it allows forming, among other things, brittle, elastic and difficult-to-deformed materials. It is known that the main parameters of laser shaping are the beam power, the size of the focus zone and the speed of beam movement along the surface of the workpiece, however, the range of variation of these parameters is not unlimited, but due to the characteristics of a particular equipment. Therefore, it is necessary to develop an approach to selecting processing modes that can be selected from the range available on the equipment and at the same time obtain a predictable result. There is also a need to investigate a reproducibility of laser shaping results with a lot of pass-through processing. Actually, this study is aimed at solving these issues. In particular, the article formulates a provision on complex formation parameters that allow determining interchangeable modes of laser molding processing and varying parameters in ranges available on equipment. For this, the basic processing mode was chosen, formation was carried out with a fixed number of passes, after which, using complex parameters, alternative modes were determined and formation was carried out under these conditions with the same number of passes. The article also presents the methodology and results of experimental studies of checking the interchangeability of formation modes and the repeatability of formation results during processing along parallel and multi-directional trajectories. It was experimentally found that the deviation of the strain value obtained in alternative modes, compared to the base, and did not exceed 2.46% for a three-pass cycle and 5.8% - for a nine-pass cycle. And the repeatability of the formation results during laser shaping is quite high; the discrepancy in the deformation value did not exceed 5%, and, preferably, was lower.

In this paper the results of the investigation of the possibility of strengthening of aluminum alloys with hollow ceramic microspheres and also microspheres modified by pyrolytic chromium coatings, which increase the adhesion between the melt and the microspheres, are presented. Pyrolytic chromium coatings on the microsphere surface were obtained by vapor deposition (metal-organic chemical vapor deposition (MOCVD) method) using organochromium liquid, OCL, commercial name Barkhos. A number of aluminum-matrix composite materials based on the heat-treated by an “artificial aging” AK12ch alloy and heat-treated by “quenching and artificial aging” AK9ch alloy as well as non-heat-treated A6 alloy filled with ceramic microspheres having diameters of 40–80 μm and 100–200 μm have been obtained.

The calorimetry method was employed to determine the mixing enthalpies of Gd–Sn melts and the ideal associated solution (IAS) model to calculate and optimize the thermodynamic properties of Gd–Sn alloys at 1510, 1640, and 1873 K in the composition range 0 ≤ x ≤ 1.0. The minimum mixing enthalpies were –69.7 ± 0.6 kJ/mole (1873 K) and –77.9 ± 0.7 (1510 K) kJ/mole at x = = 0.45. Using our own and published data on the thermochemical properties of melts and compounds and assuming the formation of two associates in the melt, GdSn and GdSn, we calculated the activities of components, enthalpies, Gibbs energies, and entropies of formation for the liquid alloys and intermediate phases within the IAS model. The thermodynamic activities of components in the studied melts showed very large negative deviations from the ideal solutions. The mixing enthalpies of Sn–Gd melts optimized within the IAS model agreed well with the experimental values. The ΔH¯Gd∞ temperature dependence agrees only qualitatively with other experimental data because of great errors in the published data. The excess Gibbs energy and mixing enthalpy of Gd–Sn melts calculated with the IAS model at 1873 K greatly differed in magnitude, being indicative of a significant contribution of the entropy component to the excess molar Gibbs energy. According to the calculations, the minimum excess mixing entropy for Gd–Sn melts at 1873 K was –20.3 J/(mole · K) at x = 0.45. The calculated and optimized enthalpies and entropies of formation for intermetallic phases in the Gd–Sn system, along with the IAS model parameters for melts, were used to calculate the liquidus and solidus curves of the phase diagram. Good agreement with most experimental data on the phase equilibria involving liquid and crystalline phases was shown.

This article presents experimental results for analysis of possibility to replace SCh24 cast iron with aluminum-based composite material produced by internal oxidation. The thermophysical properties of the materials, coefficient of friction, and wear intensity of the considered materials, as well as the temperature dynamics during braking, have been determined.

The enthalpies of mixing of Ni–Ln NiPr melts (0 < xNi < 0.6) are studied via isoperibol calorimetry at 1600 ± 1 K. The enthalpies of mixing for Ni–Pr melts are characterized by high exothermic values. The minimum enthalpy of mixing for the melts of the considered system is −35.3 ± 0.9 kJ/mol at xNi = 0.6. The activities of the components and the molar fractions of the most stable associates in melts of the Ni–Pr system are estimated using the model of ideal associated solutions (IAS). Literature data (enthalpies of formation of PrmNin compounds, phase diagram of the Ni–Pr system) and the obtained thermochemical data are both used. Five associates are selected for calculations. It is shown that the activities of the components in the melts of this system display large negative deviations from Raoult’s law, and the PrNi2 associate predominates in them.

Problem statement. In recent decades, there has been a tendency to increase the mechanical properties of low-carbon, low-alloyed steel plate iron by using controlled rolling or hardening heat treatment of finished steel parts. At the same time, for welded parts, the most suitable is a metal having a ferrite-bainite (or bainite) structure. The work investigated the features of the ferrite-bainite structure of low-carbon and low-alloyed steel 15ХСНД for the production of connecting pipeline parts. Purpose of the article. To establish the laws of formation of a ferritic-bainitic structure in low-carbon low-alloy steels depending on the parameters of heat treatment. Determine the effect of heat treatment parameters on the properties of the connecting parts of pipelines made of these steels. Conclusion. The regularities of the influence of heat treatment parameters on the structure, mechanical properties and topography of fractures of impact samples of 15ХСНД steel with a ferrite-bainitic structure are established. Keywords: stamped-welded connecting parts of man pipelines; heat treatment; microstructure; bainite;mechanical properties; fractography

The method of isoportic calorimetry investigated the thermochemical properties of the melt In—Tb system in the range of compositions 0 < xIn < 0,4 at 1625 ± 1 K. The obtained data were extrapolated on a non-investigated concentration interval, given that when xTb = 1 integral and partial to Tb enthalpia mixing is zero. It was established that the first partial for Terbium and the minimum enthalpy of mixing is –145 ± 7 and –40,1 ± 0,2 kJ/mol respectively. Comparison of ΔHmin, the melt of five previously investigated In—Ln systems from the serial number Ln (zLn), together with the data obtained in this papper, showed that they are described by one trend line. For ΔHmin In—Eu (Yb) melts (Yb) are very slight deviations from the trend line. But for dimensional factor, these deviations from the trend line are more significant. Enthalpia of the formation of some In—Ln intermetallides are known, with most of them relate to the LnIn3 compound. But there is no full reconciliation between these data. The results of the most modern work exhibit less dependence on the serial number of lanthanides and are more exothermic for heavy lanthanides, compared with other data. Comparing thermochemical properties of double Sn (Sb) —REM melt systems. It has been established that the energy of the interaction between the data p-elements and REM increases in such a sequence: In-REM → Sn—REM → Sb—REM. This is due to the fact that the stibium is the best acceptor of electrons. Keywords: thermochemical properties, melts, compounds, In, Tb.

Information about the wastes of chromium ferroalloy production in the Russian Federation, their characteristics, and composition is given. The fractional compositions of powdered slags and dust are studied. The true densities of self-disintegrating slags and dust are determined by the picnometric method. New data on the viscosity and solidification temperature of the slag and dust melts of ferrochrome production are obtained, and their phase composition is studied.

The paper shows the applicability of expandable graphite METOPAC EG 350-50 (80) in a rigid PU foam system as a substance that reduces the flammability (flame retardant) and improves the usability. The studies of the physical mechanical and thermal properties of PU foam with a higher graphite content revealed a higher normal sound absorption coefficient; insignificant influence on the thermal conductivity; a higher decomposition onset temperature; more difficult ignition. PU foam sample with a ratio of 15 graphite weight fractions to 100 polyol weight fractions has the highest physical mechanical and thermal properties, and, as compared to the starting PU foam, it features an increase in normal sound absorption coefficient by an average of 3 times; a decrease in the thermal conductivity by 8 %; an increase in the decomposition onset temperature by 6.7 °С. Therefore, the modification of PU foam with expandable graphite makes it possible not only to develop hardly combustible polyurethanes but also to improve its physical mechanical and thermal properties.

It has been observed that critical failures and loss of function occur in a shorter period than specified service life during operation of polypropylene pipes in hot water systems. The paper analyzes the failure causes of polypropylene pipes in closed loop hot water systems, and provides recommendations for increasing their service life. It has been established that the primary factors responsible for ageing and failure of polypropylene pipes during operation are medium temperature, stress due to internal pressure, water composition. It has been observed that a combined influence of the above mentioned factors provides a synergistic effect. We developed the recommendations for increasing a pipe service life, including close monitoring and recording of energy carrier temperature and pressure; changes in specifications for propylene pipes, including the recommendation for using random propylene pipe grades with high thermal oxidation stability in hot water systems.

Field-effect graphene transistors (FGTs) based on single-layer graphene using the developed simplified combined self-consistent model are simulated. It is used to compare the results of calculating the current–voltage (I–V) characteristics of five devices with the same geometric parameters with different materials of the gate dielectric of the upper gate. The influence of the thickness of the dielectrics of the upper and lower gates on the transfer I–V characteristic of a dual-gate FGTs is analyzed

Techniques are described that make it possible to measure the X-ray transport velocity in closed cavities, the time of radiation heating of foils, the radiation temperature, and the timing parameters of X-ray pulses in experiments at the ISKRA-5 facility. The methods are based on position-sensitive time-resolving (with a spatial resolution of 150 µm and a time resolution of 50 ps) measurements of X-rays in four narrow spectral regions of 0.2–1.0 keV using X-ray streak cameras, as well as on multiframe recording (with a frame duration of 100 ps, ​​a frame number of 10, and a spatial resolution of 30 µm). In the experiments the peak Planck temperature of the radiation was 110–150 eV in the irradiating target and 50–90 eV in the additional box and behind the foils; the X-ray transport velocity in closed cavities ranged from 0.5 to 13 mm/ns and the time of thermal breakdown of foils was in range of 50–550 ps.

Current publications on bipolar welding use the electrical characteristics of uncompressed biological tissue. This reduces the accuracy of calculating the distribution of the density of the flowing currents and the strength of the electric fields in the zone of the fabric to be welded when it is squeezed. The aim of the work is to show a methodology for calculating the change in the specific electrical conductivity of biological tissue under local compression by electrodes and the effect of this factor on the results of modeling electrical processes of biological welding. A geometric interpretation of the change in the electrical conductivity of the pig's heart muscle when squeezed by bipolar welding electrodes in relative units is proposed. The principle of similarity of the geometric parameters of the physical experiment and the graphic model of COMSOL multyphysics is used, as a result of which the dependences of the three main geometric parameters of the model on the magnitude of the relative compression are determined. The method of successive approximations of the values of the total electrical resistance of biological tissue in a physical experiment at frequencies of 0,3, 30, and 300 kHz and the calculated resistances on the model with a change in the basic geometric parameters of specific electrical conductivity was used. A model of bipolar welding of biological tissues is obtained, which takes into account the anisotropy factor of the electrical conductivity of biological tissue under compression. Some results of investigations of the regularities of the current flow in the tissue, taking into account the arising anisotropy, are presented. References 12, figures 5, tables 4.

Enthalpies of mixing of liquid alloys are determined via isoperibol calorimetry for the Gd–Sn system throughout the range of concentrations at 1873, 1640, and 1510 K, and for the Gd–Sn–Ni system along the radial section with a constant ratio of atomic fractions of tin and nickel: xSn/xNi = 0.68/0.32 at 1873 ± 5 K up to xGd ∼ 0.25. It is found that the melts of the Gd–Sn system form with the release of a large amount of heat ( $$\Delta {{{H}}_{{\min }}}$$ = −68.4 ± 0.4 kJ/mol at xSn = 0.45). The calculations are performed using the geometric and analytical Redlich–Kister–Muggianu models of ΔH for melts of the ternary Gd–Sn–Ni system from similar data for binary boundary subsystems at 1873 K. The results show the minimum enthalpy of mixing of these ternary melts was established for the Gd0.55Sn0.45 alloy. It is shown that the experimentally investigated enthalpies of mixing of the Gd–Sn–Ni melts and calculated data using the Redlich–Kister–Muggianu model with ternary interaction parameter L = 500 kJ/mol agree satisfactorily with one another.

The article addresses the features of rock disintegration based on the principles of selective and preferential destruction in high-frequency cone vibratory crushers with a free-turning inner cone. Based on the common method for determining the ultimate strength of rocks, a method for investigating the process of ore destruction under repeated and versatile influences has been proposed depending on the structure of the crushed material. The results of an experimental research of the destruction of rock samples on a press with limited force are given.

The IBR-2 (JINR) pulsed reactor is used in the field of solid state physics for experiments on extracted beams. It is predicted that the IBR-2 reactor will reach resource limits in 2032–2037. To keep and develop beam research at JINR, the development of a new pulsed neutron source has begun. According to estimates, the reactor will have average thermal power 12–15 MW, extracted by sodium coolant. At this power, the average flux density of thermal neutrons on the surface of the water moderator will reach 1014 sec–1·cm–2 and the peak density 5·1016 sec–1·cm–2, which is more than 10 times higher than the analogous parameters of the operating IBR-2 reactor. The new reactor is supposed to use neptunium-based fuel. The main characteristics and concept of the new reactor are presented.

This paper numerically investigates the stress-strain behavior at the scale of the dendritic structure in an aluminum-silicon alloy additively manufactured by selective laser melting. The stress-strain state in the eutectic phase is studied under the assumption that the continuum mechanics principles are applicable on the scales considered. The averaged characteristics of the eutectic phase are used as input parameters for modeling the deformation of a dendritic structure fragment of a grain, for which significant structural elements are introduced explicitly on each considered scale. It is shown that, on the one hand, the eutectic matrix in dendritic grains of additively manufactured aluminum-silicon alloys inhibits plastic deformation in the dendrite, while on the other it can be a source of stress concentration and microdefect formation already at the early stage of deformation.

The mesoscale deformation-induced surface roughening is formed by grain clusters involved in collective out-of-plane displacements. In order to reproduce these processes in simulations by the crystal plasticity finite element method, a polycrystalline structure is introduced into consideration explicitly. A topical issue related to this kind of simulations is how many grains the model should contain to be a representative of the mesoscale. In this study, four polycrystalline models with different sizes and a number of grains are examined to determine the representative volume element capable of reproducing mesoscale deformation-related phenomena. It is shown that the range of plastic deformation where the model is applicable directly correlates with its size and a number of grains. The more grains are arranged along the axis of tension, the larger plastic strain the model is able to accommodate.

The paper provides the results of the studies of compositions made from unplasticized polyvinyl chloride (PVC). It shows the influence of the formulation of compositions and process parameters that determine the degree of gelation on the quality of PVC parts. It has been found that the high content of fillers (40% wt.) and the presence of recycled PVC have a negative impact on the mechanical and performance properties in long-term use. It has been revealed that PVC parts with a degree of gelation of approximately 98% feature the best possible extrusion parameters, which is confirmed by long-term use of these PVC parts. Therefore, DSC analysis can be used to control the quality of PVC-U parts and control such parameters as the presence of additives, degree of gelation.

The electrical characteristics including the electrical resistance, impedance, I–V characteristics, capacitance, dissipation factor, and thermoelectric power of the Bi2Sn2-хFeхO7 (х = 0.1, 0.2) stannates have been investigated in the temperature range of 100–600 K at frequencies of 102–106 Hz. The paramagnetic contribution of electrons to the dynamic magnetic susceptibility has been established. The conductivity mechanism of the compounds has been found from the I–V characteristics and the change in the carrier sign has been determined from the thermoelectric power . The hysteresis of the I–V curves, charge transfer currents and polarization current have been observed in the Bi2Sn1·8Fe0·2O7 compound. A nonlinear field dependence of the polarization in the orthorhombic phase has been found. The correlation between the obtained characteristics and the phase structure transitions has been established. Two relaxation channels and activation energy have been found using the Debye model. The hysteretic I–V characteristics have been explained using a model of the electronic structure and the dipole and migration polarization.

Polysilazane-based ceramic coatings have ever-increasing applications in critical and high-power engineering. This paper analyzes the effects of the substrate grain size, the curvature of the coati...

The structural model of hybrid composites angle-ply that were reinforced parallel to some plane is constructed for the analytical determination of the composition’s yield loci while considering the plane stress state in all components. The materials of the components are homogeneous and isotropic, as well as have different yield strengths in tension and compression. Their mechanical behavior is described by the associated flow law for a rigid-plastic body with the piecewise-linear yield conditions of Johansen, Tresca, Hu, and Ishlinsky–Ivlev. The cases of fiber placement along the trajectories of the principal stresses in the composition and the cases of angle-ply reinforcement symmetric with respect to these trajectories are considered. The influence of the reinforcement structure (of directions and densities) on the size and shape of the yield loci of compositions is investigated. It is shown by numerical computations that the plastic flow in the compositions is associated with the calculated yield loci of reinforced media. As an example, yield loci for metal compositions with high-strength and low-strength binder and for fiberglass reinforced media are constructed. The calculated yield loci of the compositions are compared with the ones determined using different variants of the structural model with one-dimensional stress state in fibers.

The causes and mechanism of metal degradation in damaged regions of heat-exchange pipes (coil) of the sodium–air heat exchanger of the secondary circuit in the IBR-2 research nuclear facility are found due to experimental investigations. The defects that do not lead to the initiation and development of cracks in contact with a sodium coolant are studied. As follows from the experimental results, it is necessary to pay attention to an involuntary change in the heat removal and to the local loads that cause plastic deformation of the pipe metal during erecting work.

The mixing enthalpies for liquid Ba–Sn alloys were determined by isoperibolic calorimetry at 1300 K over the entire composition range. Large exothermic mixing effects ( ∆Hmin = –54.8 ±± 1.8 kJ/mole at xBa = 0.56) were found. They are indicative of strong interaction between different components and of short ordering in the liquid alloys. The thermochemical properties of the melts and barium stannides and the phase equilibria in the Ba–Sn system were used to calculate the activities of components, molar fractions of associates, and formation enthalpies and entropies for liquid BaxSn1–x alloys with the ideal associated solution (IAS) model. Two associates, BaSn and Ba2Sn, were selected for the calculation. The calculated activities of components in the Ba–Sn melts show very large negative deviations from the ideal solution, which is consistent with their thermochemical properties. The maximum concentration of each associate is approximately 0.65 for respective compositions. The calculated formation enthalpies for BamSnn intermetallics are quite high exothermic values that agree well with the published data for BaSn3 and only qualitatively for Ba2Sn. The formation enthalpy for the associate agrees with that for the respective BaSn intermetallic and is slightly less exothermic for Ba2Sn. This all indicates that the bonding energies between different atoms in the respective intermetallics and melts are close to each other and quite high. The formation entropy for the Ba2Sn associate is lower and that for BaSn is higher in magnitude. This demonstrates different degrees of ordering in BaSn and Ba2Sn associates and intermetallics. This may be due to different changes in the oscillation frequencies of atoms and other factors. The calculated liquidus curve of the Ba–Sn phase diagram agrees with data for the Sn–Sr system.

Active and passive hybrid ways are described for controlling biofilms and the planktonic form of pathogenic microorganisms based on different bactericidal nanomaterials obtained with modern laser technologies. An innovative mobile laser application of the complete suppression of biofilms in situ is described.

A theoretical model of the dynamic bending of rigid-plastic hybrid composite, arbitrary curvilinear doubly connected thin plates is developed. Inner contour of the plate is simply supported or clamped and outer one is free. The plates are on a viscous basis and under the action of uniformly distributed loads of explosive type. The plates are laminated and fibrous, with layers arranged symmetrically with respect to the middle surface. In each layer the reinforcing fibers, made of different materials, are located in directions parallel or normal to inner contour of plate. The structural model of the reinforced layer considering the plane stress state in fibers is used. The equations of the dynamic deformation of plate and simple analytical formula for the limit load are obtained. Numerical examples are given for a fiber-reinforced four-layered curvilinear plate with a supported hole in the form of ellipse and super-ellipse at the same total amount of reinforcement.

Some properties (enthalpy of formation, glass transition temperature and rheological parameters) of hyperbranched polyglycidol derivatives containing nitrate and azide functional groups were investigated. The dependence of the found properties on the molecular weight, composition and structure of the investigated substances was determined.

Plastic strain localization and fracture in the nugget and thermo-mechanically affected zone of a friction stir welded Al6061-T6 alloy are numerically investigated. Dynamic boundary-value problems are solved by the finite-difference method. A procedure for generating ordered and disordered polycrystalline microstructures experimentally observed in different weld zones is developed. A physically-based relaxation constitutive equation is developed to describe dynamic thermomechanical response of the aluminum alloy. Calculations of microstructure tension in polycrystals are performed. The effect of the degree of order and strain rate on the material dynamic strength and fracture are studied.

In additive manufacturing (also known as 3D printing), a layer-by-layer buildup process is used for manufacturing parts. Modern laser 3D printers can work with various materials including metal powders. In particular, mixing various-sized spherical powders of titanium alloys is considered most promising for the aerospace industry. To achieve desired mechanical properties of the final product, it is necessary to maintain a certain proportional ratio between different powder fractions. In this paper, a modeling approach for filling up a rectangular 3D volume by unequal spheres in a layer-by-layer manner is proposed. A relative number of spheres of a given radius (relative frequency) are known and have to be fulfilled in the final packing. A fast heuristic has been developed to solve this special packing problem. Numerical results are compared with experimental findings for titanium alloy spherical powders. The relative frequencies obtained by using the imposed algorithm are very close to those obtained by the experiment. This provides an opportunity for using a cheap numerical modeling instead of expensive experimental study.

In the present article a spatial confinement of microobjects were explored in the radiofrequency Paul trap at normal pressure. Spores of Lycopodium Clavatum, 33 μm in diameter, and CdSe/ZnS (core/shell) quantum dots conglomerates with size of 2–7 μm were used as such microobjects. Zero-crossing orbits of these objects were observed for the first time what indicates the nonlinear nature of dynamics of these particles in localization area. Mathematical description of particle dynamics in a viscous is presented. It is shown that friction value depends on the radius of microobjects and dynamic viscosity. Moreover, zero-crossing orbits of charged particles in the radiofrequency Paul trap were numerically simulated. A new method of comparative analysis of the morphology of microparticles is proposed.

The rat bone tissue has been studied when modeling osteoresorption under microgravity conditions. Bone samples of female and male rats with osteoporosis have been studied in the treatment of hydroxyapatite using Raman spectroscopy. The spectral differences between the studied samples (control samples, samples with a model of osteoporosis, and samples with a model of osteoporosis in the treatment of hydroxyapatite) have been established.

The paper provides the results of the investigation in the influence of heat treatment on the quality of vehicle component parts made of rigid polyurethane integral foam. The temperature of heat treatment was based on the exo-peak of the first heat cycle in DSC curve, and was equal to 135 °С. At that temperature, the samples were treated for 2-8 hours, and, as a result, they experienced an abnormal exo-effect in the glass transition region, which was indicative of thermal relaxation. The paper shows that the additional heat treatment stage for parts made of rigid polyurethane integral foam results in an increase in molecular mass of polymer, due to a smaller quantity of end groups, and, thus, in an increase in glass transition temperature from 169 °С to 176 °С. An increase in heat treatment time to 6 hours at 135 °С leads to a higher ultimate bending strength, which reaches its maximum, while further heat treatment (up to 8 hours) lowers this value. Therefore, with a higher degree of cross-linking the fracture toughness increases and passes its maximum, after that it starts to decrease, and the material becomes brittle.

The paper provides the results of failure analysis of the air intake pipe in the truck compressor. The thermal studies were carried out to identify a material, and to analyze the thermal oxidative degradation caused by excessively high operating temperatures. The study of the vehicle component part showed that it was made from polypropylene block copolymer. Analysis of the thermo-physical properties of the warranty polypropylene part showed that the thermal degradation led to a higher polymer crystallization and, as a result, a lower molecular mass due to high temperatures. The results of the thermal studies showed that the polypropylene part was subjected to excessively high operating temperatures which caused the thermal degradation and, as a result, catastrophic failure of the material.

When creating filled polymer composite materials, difficulties often arise due to poor compatibility of polymers with modifying additives. To solve such problems, surface-active substances (SAS) are successfully used in many industries, but they are practically not used in polymer processing. This is largely due to the insufficient assortment of surfactants produced that are suitable for introduction into polymers, especially film-forming ones. Anionic and nonionic surfactants are used in the synthesis and processing of elastomers, but they are not used in the production of film materials. As for the use of cationic surfactants, there are still no data at all. They differ from other types of surfactants in a variety of structures, in the number and relative positions of cationic centers and hydrophobic radicals, and also in antimicrobial properties. The prospects of using quaternary ammonium salts for the modification of packaging materials are shown. The expediency of using cationic surfactants for the modification of polymeric materials is proved. It is shown that the use of quaternary ammonium salts improves the physical and mechanical properties of films based on polyethylene and polypropylene. It is proved that cationic surfactants are technologically compatible with polyolefins, which allows the processing of polymer compositions by extrusion. Today, the most common polymers for food packaging are polyethylene and polypropylene. This is due to their low cost, safety in contact with food products, and suitability for processing into films of different thicknesses. More and more attention is being paid to the creation of packaging materials with antimicrobial properties. The imparting of such properties is achieved by introducing an antimicrobial additive into the polymer melt. It is most expedient to introduce additives directly into the melt of the polymer composition during processing, since, for example, during the extrusion process, polymer homogenization with the additive.