Microstructure investigations of Fe–Cr–Ni stainless steel’s sintered samples manufactured by selective laser melting on Concept Laser M2 facility using atomized metallic powder were held. Mechanical properties (tensile strength and plasticity) and corrosion resistance of the samples at the initial state and after hot isostatic pressing and heat treatment were estimate.

It is shown that initial state material’s structure is quite inhomogeneous and consists of fine grain sells oriented along the crystallization direction which is due to selective laser melting process features and large heat flow from melting point. Application of hot isostatic pressing and heat treatment allows to achieve 0,02 % residual porosity and transition electron microscopy analysis shows that microstructure becomes more homogeneous consisting in recrystallization process, appearing of equiaxed grains and precipitation hardening. It is revealed that sintered microstructure after treatment takes the form of identical one of the casting material. Corrosion resistance test shows satisfactory results and estimates that high solidification velocity during selective laser melting process prevent carbide formation applied as well as heat treatment promotes carbide’s dissolution in the case of their formation. It has a positive effect on the overall corrosion resistance of sintered material.

Due to results of mechanical tests anisotropy of the mechanical properties intrinsic to the sintered state is not observed. This allows to use the material in responsible details of fasteners and brackets, without taking into account the orientation of the sintered part during selective laser melting process.

The article deals with VKNA type alloys doped with AL in the amount of 8–9% by weight. They are distinguished by lower density compared to JS type nickel alloys, stability of structural and phase characteristics, which provides creep resistance and performance at temperatures up to 1200°C for a long time, up to 1250°C short-term in aggressive oxidizing environments, used with (CLC) [111] and new ones intended for the manufacture of single-crystal turbine blades and other parts with CSC – alloy VIN3 and alloy VIN4.

The paper presents a comparative study of the influence of thermal conditions of the process of directional crystallization in plants of two types: with liquid metal cooling (UVNK-9A installation) – LMC process (Liquid Metal Cooling) and with radiation cooling (ALD installation) – HRS process (High Rate of Solidification) on the parameters of the VKNA-4U Mono alloy cast structure. A comparative quantitative analysis of the microstructure (interdendritic distance, microporosity), strength characteristics during short-term tensile tests of castings from VKNA-4Umono alloy with crystallographic orientation (CGO) [111], obtained by two schemes of the process of directional crystallization and analysis of fractures of samples after testing.

The results of the study of the influence of the crystallization temperature gradient on the structural-phase parameters of the VIN4 intermetallic alloy with CGO , with different temperature gradients of crystallization are shown (samples were obtained on UVNK-9A foundry installations with G=60–80°С/cm and UVNS-6 s G=150°C/cm.

Comparative studies of the microstructure of cast billets from VKNA-4U alloy obtained on UVNK-9A (with liquid metal cooling) and ALD (with radiation cooling) installations did

The article considers the technology of electric fusion welding of heat – resisting alloy VZh159-ID and the determination of optimal modes of heat – treated samples in the order to achieve a high – quality weldments that are maintaining heat – resisting properties and the age – hardening ability.

A welding seam and a heat – affected zone expand as the result of the heating process. Actions made at the side of the less heated part of the element and are directed to the high – heat area cause the compressive deformation that is turning into the inelastic one. The deformation arising with later cooling prevents the decreasing of the welding seam and leads to the emergence of the tension stress. The reduction of the level of residual stresses is performed by the heat treatment of the welding assembly. The temperature of the heat treatment leads to tension stress relieving and hardens the welding seam. It is necessary to provide the depression strengthening of the welding seam and the parent metal both taking into account specific properties and thermal actions.

In the case of age hardened details and weak welding seam the reduction of the level of residual stresses is better to perform using the local heat treatment in the heat – affected zone.

The local heat treatment like as isothermal one should provide the depression strengthening of the welding seam without thermal overload of the material and take a little time to prevent the age – hardening of the base metal.

The determination of the temperature ranges of the welding seam changing under the heat process and optimal modes of temperature level is performed using the method of X-ray photoelectron spectroscopy. The sample is heated by step – by – step method of election &

The article provides an overview of foreign and domestic publications in the field of magnesium alloys used for the manufacture of biodegradable and biocompatible materials for imlants, with a limited period of existence required for the restoration of damage. To this end, the article view 4 groups of materials: pure magnesium, alloys of system Mg-Al, alloys of Mg–REE alloys of Mg–Zn. The influence of alloying elements on the properties of magnesium alloys (strength and corrosion) is considered, the norms of the content of these elements in the human body are Given and the negative consequence of their excess for the human body is shown.

Magnesium-based alloys have the most preferred complex of mechanical properties (tensile strength, yield strength, density, modulus of elasticity) most close to the human bone relative to other biodegradable materials. In addition, magnesium ions are an important chemical component in the process of human metabolism, which explains their natural presence in bone tissue and, accordingly, the affinity of the magnesium implant to the natural chemical environment of the body. But, there are some restrictions on the use of magnesium alloys as implants. Corrosion processes occurring during the decomposition of magnesium in the body, lead to the formation of hydrogen, which is rapidly absorbed by the body and in contact with the blood can cause an embolism, leading to death. In addition, changes in pH in the area surrounding the corroding surface can adversely affect the process of tissue repair.

To achieve this goal, it is necessary to solve the problem of optimizing the number of alloying elements in accordance with the norms of the physiological environment in the areas of implantation and the creation of a protective coating to slow the process of biodegradation, thereby allowing to control the release of metal ions int

Using the methods of light metallography, electron microscopy, the influence of the structural- phase state of ingots (volume fraction of eutectic excess phases, size and density of zirconium-containing secondary dispersoids b' (ZrAl₃)) formed in the process of homogenization annealing in one- and two-step regimes on the resistance deformation and technological plasticity of flat ingots of aluminum-lithium alloy 1441 was studied.

By the method of differential thermal analysis (DTA) it was found that the temperature at which the alloy began to melt (solidus point) of the alloy 1441 is 573°C.

The efficiency of the homogenization regimes was assessed by the change after the homogenization heating of the volume fraction of the undissolved eutectic components arranged, mainly, at the boundaries of the dendritic cells.

It was revealing that the most complete dissolution of the excess primary eutectic phases in the ingot, occurs when the homogenization of the two-stage regime. The volume fraction of undissolved phases decreases from 4,2% in the non-homogenized ingot to 0,9–1,1% in the homogenized samples.

 By the method of analytical transmission electron microscopy, it was revealing that that microparticles of the S phase are present in the structure of the non-homogenized ingot, and the zirconium-containing dispersoid (phase-β ') is not detected. In the structure of ingots from alloy 1441, after homogenization in different regimes, there are secondary microparticles of the phases: β '(Al₃Zr), δ' (Al₃Li) and S '(Al₂CuMg). The particle size of these phases is from 5 to 50 nm.
As the temperature and duration of homogenization increase, the size increases and the number of spherical β '(Al₃Zr) particles

One of key indicators of high technological effectiveness of constructional nodes, especially for nodes in which according to operational requirements it is necessary to provide tightness, simplicity of their assembly and disassembly is. The task of operation of such designs can be complicated by additional requirements - for example the operation temperature Wednesday from which it is necessary to seal nodes etc.

High technological effectiveness of constructive decisions is characterized also by opportunity quickly to replace, sort or collect nodes with use of the hi-tech materials providing the solution of functional tasks with separate nodes or products as a whole.

By the purpose of this work was to determine technological and operation capabilities of tape hermetic.

In the course of research four pilot lots of hermetic tape on installation developed by VIAM Federal State Unitary Enterprise are made. Experimental samples are made on compounding, modes of preparation of paste, operations of formation of pressurizing cloth on thickness, the speed of broach, time of curing and other parameters with deviations within possible deviations when manufacturing tape hermetic.

The analysis of properties of experimental samples of tape hermetic has shown that experimental samples completely correspond to requirements of tape hermetic.

On experimental samples technical characteristics on manufacturing of tape hermetic are confirmed, deformation of pressurizing layer is defined at controlled efforts of compression. It is established residual to deformation after compressive force removal. Degree of fit of tape hermetic on interfaced surfaces is established.

Influence of form of joint in pressurized layer on its durability is in

This article discusses the technological features of the formation of thick-walled materials from polymer composite materials. Thick-walled parts in structures are used in aviation for the manufacture of heavily loaded parts of the wing, fuselage, center section, in the railway industry, etc.

The quality of the manufactured thick-walled part is influenced by many factors: the temperature-time mode of curing, the method of molding, the pressure value, the equipment, the raw materials used, the choice of control method and analysis of process parameters, as well as personnel qualifications.

The peculiarity of manufacturing is that during the formation of the product, due to the exothermic effect, zones with uneven temperature distribution may occur. In areas with elevated temperature residual stresses may occur, which affects the occurrence of cracks and delamination. They may also be the destruction of the material or even its fire. Because of this, along with the lack of solidity of the part and the problem of choosing the correct molding mode, it is necessary to solve the problem of eliminating the above mentioned phenomena.

Due to the polymerization reaction occurring, intense heat generation occurs. Due to the fact that the polymer has a low thermal conductivity, the outflow of heat from the inner layers is difficult, which can lead to a sharp jump in temperature.

For thick-walled parts, increased porosity may be observed, since the release of gases released by the reaction may be difficult.

Thus, when forming a part, it is necessary to choose the optimal method of their manufacture. For example, a stepped temperature rise prevents the part from overheating. The method of blowing increases heat transfer and reduces the effect of heat exposure, which<

The developed methods of determining the fiber-matrix adhesive strength include approaches in which the loading of single fibers in the matrix or composite block is carried out, and methods in which the load acts on a model sample or a standard sample of a fibrous composite. The first group includes the following methods: pull-out test, microbond test; various options of push-out test. The second group includes the method of fiber fragmentation, methods of testing samples for interlayer shear and interlaminar fracture toughness.

Currently, a large number of works are devoted to theoretical and experimental aspects of the method of pushing the fiber out of the matrix. This approach makes it possible to measure the adhesive strength on real fibrous composites.

In the load-displacement diagram, when a single fiber is pushed out, several characteristic areas are distinguished, which differ in the state of the interface. The diagram includes the linear growth of stress due to elastic deformation of the boundary layer at the beginning of loading, the deviation from the linear dependence associated with the beginning of the matrix detachment from the fiber, the maximum stress and its drop when the fiber slides under conditions of complete destruction of the interface.

The main methodological issues of this approach are the sample preparation, the influence of the indenter geometry and the indentation modes on the measurement results.

Sample preparation in most works involves cutting a sample about 1 mm thick perpendicular to the fiber axis, mechanical thinning and grinding, as well as final polishing with abrasive colloidal suspensions, after which the thickness of the polymer composite sample is from 20 to 40 microns.

The most used indenters are the three-sid

Silicon carbide has a number of unique physical and chemical properties, including significant hardness and mechanical strength at high temperatures, high thermal conductivity and low temperature coefficient of linear expansion, excellent wear resistance and resistance to aggressive environment. Silicon carbide–based ceramics is widely used in the automotive and aerospace industry as a structural, semiconductor, abrasive, as well as high-temperature material for the manufacture of engine parts, electronics, thermal installations. According to some researchers, the volume of ceramics produced on the basis of SiC, Al₂O₃, ZrO₂ in the world market of structural materials will grow significantly in the near future.

Among the methods for producing silicon carbide–based ceramics are the most common reaction sintering, sintering without pressure, hot pressing and spark plasma sintering. Each method has its own characteristics and disadvantages, but the key are high sintering temperatures (about 2000 °C), which entail significant energy and resource consumption and unsatisfactory with the growing requirements of scientific and technological progress indicators of the basic properties of ceramics. Studies in the field of silicon carbide–based materials densification in the synthesis process have shown that a promising method of consolidation is liquid–phase sintering with the additives of different composition, contributing to reduction of the synthesis temperature to 1850 °C, intensification of diffusion processes, filling of intergranular pores and restructuring of silicon carbide grains. In addition, each additive makes an individual contribution to the characteristics of the synthesized material. Such additives are: Al₂O₃, Y₂O₃, ZrO₂, CaO, MgO, La₂O₃, SiO_2<

Development of the materials preventing frosting of various designs is one of relevant tasks of the modern polymeric industry. In this work, we studied the adhesion characteristics of ice to coatings based on polyurethanes of various grades: polypropylene glycol, polybutylene adipate, polycaprolactone diol, fluorine-containing oligodiol of the MAOK brand, including those modified with carbon Taunit-MD nanotubes. Researches of dependence of the dynamic module of elasticity of polymeric matrixes on temperature are conducted. It is shown that the elastic modulus of the investigated coatings lies in the range from 116 to 297 MPa. The amount of adhesion of ice to the investigated coatings ranges from 40 to 210 kPa. Introduction to structure of initial polyurethane compositions of carbon nanotubes leads to decrease in glass transition temperature the coatings. It is established that the size of adhesion of ice to the studied coatings is defined by the coatings thickness, density of a grid of cross chemical stitchings and also structure of a physical grid of gearing.

This article is about to assess the influence of the type of loading on high-cycle fatigue of heat-resistant nickel alloys GS6U, EI698 and heat-resistant titanium alloy VT8M-1. Considered influence of the type of loading on high-cycle fatigue of heat-resistant nickel alloys GS6U, EI698 and heat-resistant titanium alloy VT8M-1. The study of resistance fatigue was carried out according to the «pure bending with rotation» and «tension-compression» loading conditions. Investigated loading conditions imply different stress states, so with the «pure bending with rotation» loading conditions the maximum stress concentration is on the surface of the cross section of the working part of the sample, and under the «tension-compression» loading conditions the maximum stresses are uniformly distributed over the entire cross-sectional area of the sample. Comparative tests for high-cycle fatigue were carried out at room and operating temperatures of the alloys. It was established that the values of the limits of high-cycle fatigue when testing smooth samples from heat-resistant nickel alloys GS6U, EI698 and heat-resistant titanium alloy VT8M-1 according to the «pure bend with rotation» loading conditions exceed the values of the limits of high-cycle fatigue obtained according to the «tension–compression» loading conditions. This excess of limits of a high-cycle fatigue follows from the fact that at tests according to the «tension-compression» loading conditions the bigger amount of material works at the maximum tension in comparison with the «pure bending with rotation» loading conditions. The coefficient of comparative evaluation of the results of tests for high-cycle fatigue under the «tension-compression» loading conditions with the results of the tests under the «pure bending with rotation» loading conditions (K) is intro

Recently in the world the great attention is given to PKM creation on basis both epoxy, and tsianefirny binding which allow to receive the composite materials possessing high mechanical, dielectric and heatphysical characteristics, and also high stability of properties in different operating conditions, including at influence of elevated temperatures and humidity.

On example of fibreglass of aviation assignment research of influence of influence of set of climatic factors under natural conditions different types of climatic zones on keeping of their strength characteristics is conducted at normal and increased temperatures, and also impact assessment of impact on structural changes (glass transition temperature change) and saving of dielectric characteristics is carried out.

After assessment of physicomechanical and dielectric properties of samples of fibreglass, and also assessment of structural changes conclusions have been drawn on firmness of fibreglass on the basis of tsianefirny binding to influence of climates of different types. In article it is shown that wet and warm conditions of tropical and subtropical climates most influences falling of physicomechanical properties. The thermal resource of studied material high that is confirmed by rather high firmness in the conditions of tropical arid climate of Arizona. Weather conditions of cold and moderate climates of Russia to a lesser extent affect studied material during the whole period of exposure.

It has been noted that at carrying out assessment of changes of physicomechanical characteristics after exposure at climatic stations it is necessary to consider also what of characteristics is the most sensitive to change in specific conditions of operation, including temperatures.