Articles

 


№1 | №2 | №3 | №4 | №5 | №6 | №7 | №8 | №9 | №10 | №11 | №12





1.
dx.doi.org/ 10.18577/2307-6046-2018-0-8-3-22
УДК 669.295
Kashapov O.S., Pavlova T.V., Kalashnikov V.S., Zavodov A.V.
THE PHENOMENON OF FORMATION AND LOW-TEMPERATURE DIFFUSION TRANSFORMATION OF METASTABLE SOLID SOLUTIONS WITH THE RELEASE OF DISPERSED PARTICLES OF INTRAGRANULAR WIDMANSTATTEN ALPHA PHASE IN HEAT-RESISTANT TITANIUM ALLOYS

In the article discuss the phenomenon of formation of low-temperature metastable solid solutions α and β with the allocation of dispersed particles of the tertiary α-phase (intragranular or Widmanstatten α, αwi) in heat-resistant titanium alloys ВT3-1, ВT8 and its modifications, ВT9, ВТ25У, ВТ41, ВТ46.

It follows from the literature data on alloys Ti64, Ti6246, Ti17 that for more density two-phase alloys like Ti6246 and Ti17 it is possible to obtain «triplex» structures in industrial conditions. For the more «simple» Ti64 alloy, close to near-alpha, the technological interval of tertiary alpha phase formation is rather narrow, which does not allow to obtain in practice a stable heterogeneous structure of the material with higher strength.

It is shown that the tertiary alpha phase in Russian heat-resistance alloys can be formed during the cooling after heat treatment with a solid solution at relatively low temperatures and cooling rates, as well as a result of low-temperature annealing (aging). Examples of heterogeneous structures in various semi-finished items (disks and blades die forgings and bars) and titanium alloy parts (disks, blisks and blades) are given. The changes in the mechanical properties of ВT8, ВT41 and ВT46 alloys at room temperature due to structural dispersion hardening are considered. On the example of ВT8 alloy it is shown that the diffusion transformation of β-solid solution is observed at relatively low temperatures during cyclic loads as result of jet engine exploitation for compressor disks material.

The presence of zirconium and iron alloying elements in the composition of the alloy contributes to obtaining heterogeneous structures as a result of heat treatment. It is found that the increase in the strength of the material is accomp

Read in Russian

2.
dx.doi.org/ 10.18577/2307-6046-2018-0-8-23-27
УДК 678.83
Malysheva G.V., Guzeva T.A., Grachshencov D.V., Raskutin A.E.
THE INFLUENCE OF HEATING TECHNOLOGY ON THE DURATION OF THE CURING PROCESS OF POLYMER COMPOSITE MATERIALS

The wide spread of glass, carbon and organoplastics products requires constant improvement of technological processes, which ensure improvement of their performance properties and cost reduction. One of the final technological operations, which forms the quality of the finished product, is – curing, a distinctive feature of which is its long duration and energy intensity.

To reduce the duration of the curing operation, it is proposed to use microwave heating. The results of experimental studies of the properties of organoplastics made by wet winding technology using epoxy binder are presented. Curing was carried out in two different ways: in electric and microwave ovens using two modes of temperature rise to a predetermined value (single-stage and three-stage). It is shown that the use of microwave heating can not only significantly reduce the curing time, but also leads to an increase in the modulus of elasticity. It is experimentally established that the degree of conversion when using an electric furnace is higher than when microwave heating, and the form error is significantly less. At the same time, the value of the modulus of elasticity, when curing microwave method is higher than when using standard equipment. The shrinkage and porosity properties of organoplastics are the same and do not depend on the heating method used. However, the values of standard deviations in porosity and shrinkage when using microwave heating are much higher than when using an electric furnace. As a result of the research it was found that the use of microwave curing can lead to errors in the form, which does not allow to recommend this method for its wide application. However, for a number of parts made of organoplastics, which do not have high requirements associated with the geometric accuracy of the manufactured product, this curing technology can be successfully applied.

Read in Russian

3.
dx.doi.org/ 10.18577/2307-6046-2018-0-8-28-37
УДК 669.293:669.018.95
Svetlov I.L., Kuzmina N.A., Zavodov A.V., Zaysev D.V.
THERMAL STABILITY OF INTERFACES BETWEEN THE NIOBIUM MATRIX AND γ-Nb5Si3 SILICIDE IN EUTECTIC Nb–Si COMPOSITES

The interfaces between the matrix and the reinforcing phases play an important role in the formation of the mechanical properties of composite materials. The feature of eutectic in situ composites is that the structure of interfaces is formed in accordance with the phase diagrams in the process of crystallization. The phase composition of the in situ composites in the doped Nb-Si system depends on the crystallization conditions and is determined by the kinetics of the solid-phase eutectoid reaction.

In accordance with the principle of the Dankov-Konobeevsky structural and dimensional relationship in diffusion-controlled solid-phase reactions, the crystal structures of the reaction products are oriented with such a ratio that the interphase energy between them is minimal. The high thermal stability of the structure of the Nb-Si composite was experimentally investigated and substantiated from the crystallochemical standpoint in the article.

On the basis of the metallographic analysis of the microstructure of the composite in the initial state and after high-temperature homogenization for 10 and 20 hours at a temperature of 1500°C in vacuum, a conclusion is drawn about the high thermal stability of the morphology of the interface surfaces of the niobium matrix and silicide formed as a result of solid-phase reactions.

The phenomenon of micrliquation of alloying elements within the cell has been studied using the MRSA. The nature of microliquation of "low-melting" and "refractory" elements obeys the general pattern of distribution of alloying elements in cellular crystallization.

Pole figures were obtained by X-ray diffraction and the direction of predominant growth of the niobium matrix and niobium silicide with directional crystallization was determined.

<p style="text-align: j

Read in Russian

4.
dx.doi.org/ 10.18577/2307-6046-2018-0-8-38-46
УДК 678.8
Timoshkov P.N., Usacheva M.N., Khrulkov A.V.
STICKINESS AND POSSIBILITY OF USING PREPREGS FOR AUTOMATED TECHNOLOGIES (review)

This article discusses the property of prepreg as the stickiness that affects the parameters of the layout of various blanks of parts from polymer composite materials (PCM).

As you know, PCM are widely used in industry, have high physical and mechanical characteristics. Such materials can be obtained by various methods, in particular, automated laying: ATL (automated laying tapes) and AFP (automated laying fibers). In these processes, despite the many advantages, there is a drawback – sensitivity to the stickiness of the prepregs. The success of the automated calculation depends on this parameter.

The material should easily be separated from the tooling, so that neither the resin nor the part of the prepreg remains on it. In this prepreg should stick to avoid peeling of the material from the tooling. Thus, stickiness characterizes the quality of adhesion. In case of poor adhesion the automated computation becomes impossible.

Stickiness is one of the most important properties, depending on many factors: environmental conditions (temperature, humidity), volatile substances and the binder. It is important to control this parameter. As a rule, to determine the stickiness, subjective tactile sensations are used, combining with the rolling method.

However, to date, the quantitative determination of stickiness is a problem, since there is no single method of measurement. Each method evaluates a certain parameter, and the stickiness of the prepregs can be compared only within one method.

The article also discussed the dependence of the tackiness from the temperature. At a certain temperature, the stickiness reaches a maximum. The analysis of this dependence will allow for the automatic layout to ensure the separation of the prepreg from the substrate, goo

Read in Russian

5.
dx.doi.org/ 10.18577/2307-6046-2018-0-8-47-60
УДК 674.038
Sevastyanov D.V., Daskovskiy M.I., Doriomedov M.S., Skripachyov S.Yu.
BIOMORPHIC COMPOSITES: A PROMISING CLASS OF MATERIALS (review) Part 1. History of creation, methods of the production

Overview and history for biomorphic composites (a wood-based promising class of materials) were presented. Methods for the preparation of such composites (liquid silicon infiltration, gaseous Si or SiO infiltration, SiO2 precursor infiltration with subsequent carbothermal reduction) were introduced. In all cases wood pyrolysis with strict control of operating temperature ensuring preparation of crack-free monoliths is used as the initial stage of the process.

Wood-derived biomorphic ceramics have developed tremendously from the late 1990s. In spite of wide range of possible application fields, some difficulties remain that preclude large-scale production of these materials. One of the main problem is the limited size of the components that can be manufactured. It may be caused by two reasons. First, the wood precursor can develop cracks during pyrolysis if heating rates are not kept low enough, due to pressure buildup inside the pores if the organic substances and volatiles can’t be transported away from the material at a fast enough rate. Second, infiltration sometimes can lead to cracking in the final component due to thermal gradients (interaction of Si and C is highly exothermic). To solve this problem, several approaches can be used, such as manufacturing complex components in several parts while still in the carbon phase and the joining them. Another possibility could be to use additive manufacturing techniques to print a porous carbon preform for subsequent infiltration

Read in Russian

6.
dx.doi.org/ 10.18577/2307-6046-2018-0-8-61-69
УДК 674.038
Sevastyanov D.V., Doriomedov M.S., Daskovskiy M.I., Skripachyov S.Yu.
BIOMORPHIC COMPOSITES: A PROMISING CLASS OF MATERIALS (review) Part 2. Mechanical properties, application

Analysis of mechanical properties for biomorphic composites was performed. It was shown that properties in axial direction exceeded the ones in radial and tangential directions. This fact can be explained by the preservation of microstructure on going from a piece of wood to a biomorphic composite. Prospects for application of biomorphic composites in various industrial fields (as catalyst support, high-temperature gas filtration materials, armor materials as well as in medicine, radio electronics, and power engineering) were discussed.

In addition to the dimensional limitation of the components based on biomorphic composites (see the Part 1), the second disadvantage of biomorphic materials is the lack of mechanical strength. Biomorphic ceramics from Si vapor infiltration or carbothermal reduction suffer from low compressive and bending strength due to the lack of connectivity between struts and between grains inside the struts. It is possible to obtain porous biomorphic SiC with reasonable mechanical strength by chemical etching of the silicon in melt-infiltrated biomorphic SiC, but the large quantities of dangerous acids such as HF or HNO3 required make this route inviable for large-scale production, for both economic and environmental reasons. An alternative is the modification of a wood precursor.

As compared to widely used C/C and C/SiC composites, wood-derived biomorphic materials are characterized by lower level of mechanical properties. On the other hand, biomorphic composites possess flexibility in selection of the required microstructure and the optimum strength-to-density ratio.

Read in Russian

7.
dx.doi.org/ 10.18577/2307-6046-2018-0-8-70-80
УДК 62-762
Farafonov D.P., Migunov V.P., Saraev A.A., Leschev N.E.
ABRADABILITY AND EROSION RESISTANCE OF SEALS IN TURBINE ENGINE AIR-GAS CHANNEL

At solution of the problem of increase of efficiency of gas turbine engines the important role is allocated for reduction of gaps between tips of blades and working rings, and also gaps in labyrinth seals. Indispensable condition for minimization of size of radial gap is application of the special materials connected with stator which are easily abraded at interaction with tips of blades or combs of labyrinths, eliminating that their possible excessive wear and even destruction. Efficiency of application of such sealing materials depends on their abradability together with material of rotor and erosion resistance. The ratio of wear of sealing covering usually is accepted to abradability of sealing material on stator and blades. The size of the radial gap which is forming as a result of wear of details of rotor or stator at their contact, and, therefore, size of gas leaks depends on abradability of sealing material. Erosion resistance of sealing material is defined as time spent for erosive wear process of unit of volume of material. On the basis of erosion resistance the resource of sealing material is evaluated. Abradability and erosion resistance depend on strength properties of materials and are inversely proportional sizes therefore creation of effective abraded sealing materials is one of the most complex and actual challenges of aviation materials science. In FSUE «VIAM» techniques are developed and the specialized test equipment is created, allowing in vitro to evaluate number of office characteristics of sealing materials, including their abradability together with compressor blades and turbines GTE.

In article results of comparative researches of abradability and erosion resistance of the sealing materials applied in compressors and turbines of modern GTE, and also the pilot materials developed by VIAM Federal State Unitary Enterprise are provided. Tests were carried out within

Read in Russian

8.
dx.doi.org/ 10.18577/2307-6046-2018-0-8-81-88
УДК 666.7:629.7
Zhitnyuk S.V.
OXYGEN-FREE CERAMIC MATERIALS FOR THE SPACE TECHNICS (review)

In the present days scientific and technical progress requires from the scientists new materials, capable to keep the working capacity in the conditions of high power and heat loads. In this regard it is perspective to use ultrahigh-temperature oxygen-free ceramics as material for the space equipment, bearing functional loadings at ultrahigh temperatures. In article the main properties, methods of synthesis and perspective of use of ultrahigh-temperature ceramics based on hafnium borides and zirconium, metal composite materials based on titanium, reinforced by continuous fibers of silicon carbide, and also crystal indicators of maximum temperatures are considered.

On the basis of the analysis of literary data it is established that at high temperatures on ceramics surface based on hafnium borides and zirconium the oxide layer possessing sufficient for expected operating conditions mechanical strength and interfering further oxidation of material that has to promote the greatest possible preservation of geometry of the product influencing aerodynamic characteristics is formed.

It is shown that reinforcing of titanium matrix by ceramic fibers of silicon carbide allows to increase mechanical strength in the cross direction in one and a half time that gives the chance to apply such composites in designs of jet engines as the material keeping working capacity at high temperatures.

Expediency of use of crystal indicators of maximum temperatures based on silicon carbide along with traditional measuring instruments for ensuring control of temperatures of elements of the heat-shielding working at high temperatures is established.

By results of work prospects of oxygen-free ceramics as material for manufacturing of thermal protection of reusable spacecrafts, leading edges and stabilizers of aviation

Read in Russian

9.
dx.doi.org/ 10.18577/2307-6046-2018-0-8-89-97
УДК 669.245
Letov A.F., Karachevtsev F.N., Zagvozdkina T.N.
DEVELOPMENT THE SET OF METHODS MEASUREMENTS OF THE CHEMICAL COMPOSITION OF NICKEL-BASED ALLOYS

Weights of samples, acid mixtures and methods for dissolving samples for determination of harmful impurities and impurities by the mass spectrometric method of analysis were selected. The settings of the attachment of hydride vapor generation were determined to determine the content of Se and As in nickel alloys by mass spectrometric analysis with hydride vapor generation.

The conditions for preparing the surface of samples of nickel alloys, the effect of surface roughness on the RMS of the results obtained for the optical-emission and mass spectrometric methods with laser sampling are chosen. The conditions for measuring and adjusting the instruments for all the above methods are estimated and chosen.

Based on the studies carried out, the following are developed and certified:

– MI 1.2.052–2013 «Method for measuring the mass fraction of harmful impurities (P, Mn, Fe, Cu, Zn, As, Se, Ag, Cd, Sn, Sb, Te, Tl, Pb, Bi) in nickel alloys by the mass method spectrometry with inductively coupled plasma»;

– MI 1.2.053–2013 «Method for measuring the mass fraction of impurities (B, Si, Ca, Mg) in nickel alloys by inductively coupled plasma mass spectrometry»;

– MI 1.2.060–2014 «Method for measuring the mass fraction of harmful impurities (As, Se) in nickel alloys by mass spectrometry with inductively coupled plasma with hydride vapor generation";

– MI 1.2.061–2014 «Method for measuring the mass fraction of alloying elements and impurities in nickel alloys using the optic-emission method of analysis»;

– MI 1.2.071–2015 «Methods for measuring the mass fraction of alloying elements and im

Read in Russian

10.
dx.doi.org/ 10.18577/2307-6046-2018-0-8-98-111
УДК 669.1.017
Grigorenko V.B., Morozova L.V.
THE USAGE OF FRACTOGRAPHIC ANALYSIS TO DIAGNOSTIC THE CAUSES OF DESTRUCTION OF PRODUCTS FROM MEDIUM-CARBON STEEL

Features of destruction of steel ropes (cables) from steels 60 and 55 with galvanothermic coatings on the basis of zinc, and springs from steel 51ХФА are considered.

The studies were carried out with a scanning electron microscope JSM-6490LV with an attachment for X-ray spectral analysis of INCA x-sight. Also, the optical microscope Olympus GX51F was used.

Analysis of the chemical composition of the materials was performed by infrared absorption spectroscopy on a LECO CS-600 instrument and atomic emission method with inductively coupled plasma on a Varian 730 ES device in accordance with GOST 22536.0-GOST 22536.9. Tests of cables and individual wires on stretching were performed on an electromechanical testing machine Zwick / Roell Z100; tests on the wear of springs in the joint were carried out for 900 hours.

The conducted studies showed that the material of the products (steel 60, steel 55 and steel 51ХФА) meets the requirements of the normative documentation on the composition, structure and content of non-metallic inclusions. The presence of zinc coating on wire ropes does not affect the nature of the destruction.

The cause of the destruction of the steel rope was a significant plastic deformation near the tip due to the action of the complex static load. It is shown that the breakage of individual wires of the cable of the foot control is associated with the formation of risks or other defects on their surface, which leads to the formation and growth of fatigue cracks. The cause of premature failure of the springs during the tests was the presence of contact fatigue, which was promoted by a high level of stress under asymmetric loading. It is shown that the operation of springs under conditions of increased stresses leads to the formation of fragile intergranular fracture in the fatigue zones.

The descriptions of the differences in the structure of the fractures obtained from the action of the complex stati

Read in Russian

11.
dx.doi.org/ 10.18577/2307-6046-2018-0-8-112-119
УДК 543.51:621.762
Alekseev A.V., Rastegayeva G.Yu., Pahomkina T.N.
DETERMINATION OF OXYGEN AND NITROGEN IN NICKEL ALLOY POWDERS

Additive technologies at the moment are one of the advanced ways of producing modern materials. The advantages of these technologies include the ability to manufacture products of virtually any shape, the absence of a large amount of waste, flexible production control with the ability to correct the synthesized product during the manufacturing process, the use of 3D modeling with the subsequent «three-dimensional printing»

At the same time, with the use of additive technologies, it is extremely important to control the quality of the feedstock. As regards powder metallurgy, the chemical composition of the powders of metals and alloys, in particular the content of harmful impurities such as oxygen and nitrogen, is of great importance.

One of the most successfully used methods for determining nitrogen and oxygen in metals and alloys is reductive melting in a vacuum or in the flow of an inert carrier gas. When using this method of analysis to determine oxygen and nitrogen in alloy powders, it was necessary to select a catalyst, a substance that accelerates and supports the burning of metals in the furnace of the device, and also selects the mass of the sample weighed.

In the course of the work, an analysis of the powders of three alloys – EP648, VPr50 and VZh159 was performed. It was found that the mass of the sample does not affect the results of the determination of oxygen and nitrogen in any way, but to obtain the maximum analytical signal the sample should be the largest. The best powder analysis results were obtained using tungsten with tin (LECOCELIIHP 502-173) as a catalyst, with complete convergence of the oxygen and nitrogen contents for the two samples of the same material, and these values are maximum, indicating complete recovery of oxygen and nitrogen from the samples and, as a consequence, the exa

Read in Russian

12.
dx.doi.org/ 10.18577/2307-6046-2018-0-8-120-129
УДК 669.017
Gorlov D.S., Shchepilov A.V., Zaklyakova O.V., Gadzhikhalilova S.I.
INFLUENCE OF THE COATING TYPE ON THE DAMPING ABILITY

During operation, various kinds of oscillations arise in the gas turbine engine blades. The source of oscillations excitation of the blades is the gas influence, moreover, oscillations can arise due to deformation of the rotor. Various damping mechanisms are used to damp vibrations of the blades.

One way to reduce alternating stresses in resonance is to apply special coatings.

This article is focused on the influence of the coating types on damping capacity of a flat specimen in a technological capture with a rig for a vibrodynamic stand in vibration tests based on the first flexural shape.

It is shown that, due to the application of coatings on the edge part, it is possible to improve the damping characteristics of the compressor’s blade roots.

Among the types of studied coatings, the most effective one for increasing the damping capacity and having the lowest Q-factor of the vibrational system is the anti-friction coating VFP-5 based on molybdenum disulfide and graphite, the application of which allows to reduce the amplitude of oscillations of the free end of the sample by 22–29%. A minor effect was shown by a coating based on an aluminum alloy VSDP28, deposited with the ion-plasma method, which reduces the amplitude of oscillations of the free end of the sample by 5–12%. When coatings of TiN / CrN, Ti-TiN and nickel-based alloy SPD-2 are applied on the edges of the samples, an increase of the amplitude of the oscillations of the free end of the samples is observed.

The dependence of the quality factor of the vibrational system on various types of coatings ~30 μm thick was determined, and tribological characteristics of the coatings studied.

A solid lubricating coating of grade VFP-5, deposite

Read in Russian