The paper presents the results of studies of paint coatings system based on natural drying polyurethane enamel in the initial state and after accelerated climatic tests. It has been determined that the use of an epoxy-rubber primer provides the coating with high resistance to erosion wear, both in the initial state and after various aging factors, as well as a high level of protection against corrosion of the aluminum alloy. It has been defined that exposure to elevated temperatures has a positive effect on the erosion resistance of paint and varnish systems.
The paper examines four brands of polyetheretherketones of foreign and domestic production as binders for thermoplastic carbon plastics and estimates their main characteristics. Two polymer composite materials (PCM) manufacturing technologies have been tested – a film and a prepreg. It has been determined that prepreg technology makes it possible to produce carbon plastics with higher mechanical characteristics. The influence of the melt flow rate of a thermoplastic binder on the properties of PCM was evaluated and it was defined that powdered polyetheretherketones with low fluidity do not allow obtaining carbon plastics with a high level of mechanical properties.
Compact specimens of a low-alloy copper alloy of the composition Cu–Cr with a relative density of 99.8 %. The influence of hot isostatic pressing and its combination with quenching and aging on the structure evolution of synthesized copper alloy samples. After gasostatic post-treatment of the synthesized samples, followed by quenching and aging, highly dispersed Cr(Cu) particles precipitated from the copper matrix, which led to an increase in tensile strength. Anisotropy was evaluated under tension of vertical and horizontal specimens after various types of post-processing.
The paper studies the effect of electron-beam welding modes on the structure and mechanical properties of workpiece joints obtained by selective laser melting metal-powder composition of EP648 alloy. The technological characteristics of serial brazing alloys of grades VPr4, VPr11-40N, VPr42, VPr50, VPr24 and the strength of joints at elevated temperatures during soldering of the EP648-PS alloy have been determined. We also studied the feasibility of using vacuum heat treatment before brazing the EP648 synthesized material and homogenizing heat treatment after it.
The paper considers the traditional and promising technological schemes in the field of production of titanium alloy ingots for the aviation industry. The paper analyses the main advantages and disadvantages of individual technological schemes and provides methods for minimizing the risks of negative consequences. It concludes that it is necessary to update the industry regulatory documents that specify the permissible technologies for the production of ingots from titanium alloys of aviation quality.
The paper considers the theoretical and experimental questions connected with researches of elastic and plastic deformation of metal materials. The article shows that joint multilevel large-scale study performed by physics-mechanics and material engineers of the patterns connecting characteristics of stress-strain state with parameters of a structural condition of a metal material will allow to develop modern physical and mathematical models of a material. For this purpose in-depth study of the shift deformations forming plastic properties of a material and processes formation of defects and a new free surface is necessary. The paper presents the examples of such a research, and provides methods of analysis of structure and physical and mechanical characteristics at different structural levels of a polycrystalline metal material.
The paper examines the properties of paint coatings’ systems based on fluoropolyurethane enamel and primers of various chemical nature in the initial state and after exposure to aging factors. It has been determined that the chemical nature of the primer layer during the formation of a coating system using fluoropolyurethane enamel affects not only the adhesive properties, but also physical and mechanical properties of the coating system both in the initial state and after exposure to various aging factors. It has been shown that coating systems with the use of epoxy primers, including those modified with nitrile butanediene rubber, have the best properties.
The paper studies the effect of mechanically activated serpentine and magnesium spinel on the deformation-strength and tribotechnical characteristics and structure of polytetrafluoroethylene (PTFE). It has been determined that with the simultaneous introduction of fillers, an increase in wear resistance is observed up to 1125 times while maintaining and even slightly increasing the deformation and strength characteristics of the PTFE. It has been concluded that filler particles contribute to a change in the supramolecular structure of the PTFE, and also affect the formation of a protective secondary structure on the friction surface with the effect of solid lubrication. The developed materials can be used as parts of pneumatic-, hydro- and fuel systems for arctic and aviation equipment.
. The paper presents the results of a systematic study of detonation spraying of wear-resistant coatings from composites based on tungsten carbide used for hardening parts of aircraft vehicles. Using the LIH computer code the spraying modes were optimized and coatings from powders of domestic and foreign manufacturers were sprayed by the CCDS2000 plant. We measured the hardness, porosity, wear resistance and adhesion of obtained coatings and made a comparative characterization of residual stresses. The influence of spraying distance in the range from 50 to 400 mm and the angle of inclination of the treated surface up to 60 degrees on the quality of the coating was studied. Coatings with adhesion not less than 180 MPa and wear resistance characterized by specific wear less than 1.0 mm3/1000 rpm by ASTM G65 standard have been obtained which exceeds ten times the abrasion resistance of the VT20 titanium alloy.
A study was made of the influence of temperature and duration of heat treatment on the formation of diffusion zinc, aluminum and aluminum-zinc coatings. It is shown that at a heat treatment temperature of 400 °C, a three-phase structure in zinc coating is formed. Mutual diffusion occurs on samples with an aluminium-zinc coating with the formation of Al–Zn alloy, samples with an aluminum coating do not undergo structural changes under the studied heat treatment modes. According to the results of corrosion studies it has been revealed that in terms of their properties, mixed aluminum-zinc coatings are closer to the zinc-coated sample than to the aluminum-coated sample.
Fiber-laminated metal materials – as a class of metal-polymer composite materials, in which both metals and composites are used, have shown great prospects as lightweight structural materials in the transport industry. In this regard, technologies for the production of such materials and production of parts from them are of increasing interest to researchers. The review evaluates various aspects of the current state of researches and problems associated with such materials and the technologies of their shaping, and shows the prospects for their further development.
The paper provides a technique for the determination of silver by inductively coupled plasma atomic emission spectrometry in aluminum alloys. Analytical lines of silver free from significant spectral overlaps have been selected. The sample preparation method was selected, that is dissolution in concentrated nitric acid. The metrological characteristics of the technique were examined: for silver content from 0.1 to 0.7 % (by mass) the accuracy indicator is 4 % rel., which fully ensures the control of the silver content in products made of such alloys as B-1213, B-1469, B-1480, B-1481.
The paper provides the results of studies of lacquer coatings made on the basis of epoxy oligomers of different molecular mass hardened by the amine type hardeners. Thermal resistance, erosion resistance, strength and deformation characteristics of free lacquer films, as well as their physical and mechanical properties have been examined. It has been determined that the properties of epoxy lacquer coatings are significantly influenced by the molecular mass of the oligomer and hardener used to produce these coatings. It is shown that with the increase in the molecular mass used to obtain coatings epoxy oligomers improve their operational properties, such as heat resistance, erosion resistance, physical and mechanical properties.
In order to set up research works and determine the requirements for the promising options of protective coatings he paper studies an experimental version of a complex multilayer heat-resistant ion-plasma coating at high-temperature deformation of samples from an intermetallic titanium alloy. The article shows that at high values of residual deformation (up to 11%) of a base made of an intermetallic titanium alloy the multilayer coating is capable of providing sufficiently high level of protective properties.
The paper considers a justification of the minimum samples amounts (quantity samples of tests) necessary for an assessment with the pre-set probability of the initial moments of distribution of tensile ultimate strength for the standard samples of the main types of structural metallic materials: aluminum and titanium alloys and some steels. It’ has been demonstrated that the minimum amount of samples for the assessment of the initial moments of distribution – expected value and standard deviation of tensile strength – significantly depends on factors of variation of experimental data, as well as on the requirements imposed to the accuracy of the received estimates. There has also been formulated a hypothesis of «conditional general sample».
In work, the rheological heat-resistant and elastic-strength characteristics of thermosetting systems developed at FSUE «VIAM» (epoxy matrices of grades VSE-20, VSE-30, VSE-33, bismaleimide grade VST-57 and cyan ester matrices of grades VST-1210 and VST-60) processed by non-autoclave technologies. These resins make it possible to obtain composite materials for structural purposes with an operating temperature from -60 to 250 °C by the methods of vacuum infusion, impregnation under pressure and film technology. The work also presents glass transition temperatures and mechanical properties of carbon and fiberglass plastics obtained on their basis.
The paper presents the results of studies of the influence of the Zn:Mg ratio on the hardenability, structure and complex of mechanical and corrosive characteristics of forgings with 150 mm thickness made of alloys based on Al–Zn–Mg–Cu system, manufactured in the production conditions of metallurgical plants of JSC AMR and Public Corporation “KUMZ”. It has been determined that an alloy of the Al–Zn–Mg–Cu system with Zn:Mg ratio of not less than 4,1:1 and copper mass content of not more than 1.2% has a higher hardenability compared to the 1933 alloy of standard composition, which ensures homogeneous structure and indicators of mechanical and corrosion properties over the thickness of semi-finished pro-ducts; in metallurgical industry at the stage of manufacturing this allows reducing the residual quenching stresses in massive forgings by means of straightening by reduction in an as-quenched state.
The article presents the results of an experiment on the application of a silicon carbide coating on an alumina fiber and studies the properties of the resulting coated fibers. The purpose of applying a barrier coating to the fibers is to protect the fiber from degradation during the manufacturing of a ceramic composite material. The paper gives the characteristics of barrier coatings, such as thickness, continuity, structure, thermal and thermo-oxidative properties. The obtained data will be useful in the development of new types of ceramic composite materials reinforced with fibers.
The article presents the results of researche of galvanic corrosion possibility of brazed connections of steels 13Сr11Ni2W2MoV and 12Cr18Ni10Тi with use of the solders VPr4 and VPr50, which are used in design of aviation engineering engines. The research was carried out by electrochemical methods. Corrosion currents’ density and contact pairs’ potentials in chloride solutions have been determined. It is determined that 13Сr11Ni2W2MoV steel can be exposed to galvanic corrosion in a place of brazed connection. Thus the greatest danger to it is represented by VPr4 solder. The mechanism of corrosion of 13Сr11Ni2W2MoV steel in neutral environments has been examined and recommendations about its protection against galvanic corrosion are made.
The paper gives an analytical review of existing technologies of production and application of micron-sized rare-earth magnets of the RE–TM–B group (microparticles, microwires, films). The specificity of their magnetic properties, which appears at the micron scale, is considered. The analytical comparison of the methods for preparing micromagnets has been carried out. Possible practical applications of micromagnets and their application in various fields of modern technology are systematized. Possible directions of development of micromagnetic technologies are discussed.
