Key Engineering Materials Vol. 910

Abstract: Composite materials are widely used in various industries due to their high specific characteristics. The most common composites are laminates, which consist of multidirectional layers with unidirectional fibers adapted to stresses of the laminates. However, the efficiency of such structures is significantly reduced when there are stress concentrators. One of the ways to increase the efficiency of composite structures with stress concentrators is to change the reinforcement structure and use the transition from unidirectional fibers to curvilinear fibers, which could be adapted to both the geometry and the loads of the composite structures. This short review describes the various methods by which it is possible to manufacture composite structures with curved fibers and change the reinforcement structure. Composite structures both unidirectional fibers and curved fibers made by different manufacturing technologies are considered and compared as well as the efficiency of the composites is analyzed.

Abstract: The static and cyclic mechanical behavior of samples of composite material with a matrix made of silicone rubber or low-pressure polyethylene reinforced with fibers of titanium nickelide with a martensitic structure has been investigated. It is shown that such composite materials have high deformation cycle resistance.

Abstract: The paper presents an algorithm, methodology and results of solving the primary problem of determining the stress-strain state and choosing design parameters for a three-layer structure under uniform pressure loading, depending on the size and pitch of support filler’s cells, as well as geometry features of the simulated structure.

Abstract: The questions of application of nanomaterials in mechanical engineering are considered. Concept of electrochemical processing products in mechanical engineering with the use of a solid nanodisperse phase is defined. The characteristics and methods of application in the processes of electrodeposition of carbon nanomaterials are determined. The results of experimental investigations of electrolytic chrome plating with multi-walled carbon nanotubes of the "Taunit" series are presented.

Abstract: Nitrides of ‘2:17’ - type based on rare earth metals and iron are of interest as promising magnetic materials for the development of high-energy permanent magnets. The magnetic properties and phase composition of the starting compound Sm_1.8Er_0.2Fe₁₇, nitride Sm_1.8Er_0.2Fe₁₇N_2.1 and its crushed powders have been investigated. The magnetic measurements of the samples were studied in magnetic fields up to 70 kOe at room temperature. It was found that the introduction of nitrogen atoms into the crystal lattice of the substituted composition (Sm,Er)₂Fe₁₇ in combination with the effect of high-energy milling of nitride leads to an increase in the saturation magnetization (σ_S) and coercive force (H_C).

Abstract: In this work we report the kinetics of plasticity of St3 low-carbon steel-based composite alloy prepared via vacuum electron beam cladding of 09G2S steel wire. The digital image correlation method revealed the existence of macroscopic localization of plastic flow at the yield plateau and parabolic hardening stage. The kinetic characteristics of localized plasticity domains were measured in various composite layers, as well.

Abstract: The results of studies of microstructure and of mechanical properties of the superalloy Udimet 720 in initial and aged states at various temperatures (850 °С, 1000 °С и 1200 °С) are presented in the paper. Mathematical processing methods were used during the analysis of morphological and geometric characteristics of strengthening phases in the alloy. Dependencies of mechanical properties indices on parameters of strengthening phases of the microstructure have been revealed. It has been found that the downtrend of strength and plastic characteristics of the alloy that was aged at high temperatures is due to changes in morphology and content of intermetallic phase.

Abstract: A new surfacing material consisting of the Fe-Si-Cr-Cu-C-B system sparingly alloyed with chromium is proposed for agricultural machine parts hardening by induction surfacing method capable to replace the currently widely used materials like Sormite No. 1, 2, PG-US25/27 and those similar to them. The chromium content in the new material is 4.3 %, which is 3-8 times less than that in analogs. The new material was obtained metallurgically, its phase, chemical composition and properties were investigated. The main phase of the alloy is Ferrosilide FeSi_n, along the grain boundaries of which a carbide phase is precipitated represented by small particles of Cr₂C₃, Cr₇C₃ carbides of regular and acicular shapes, as well as large particles of special chromium carbides (Cr,Fe)₇C₃, (Cr,Fe)₂₃C₆. In terms of the relative content, the carbides present in the new material can be conventionally arranged in the following series: (Cr,Fe)₂₃C₆ > (Cr,Fe)₇C₃ > Cr₇C₃ > Cr₂C₃.

Abstract: The article considers the possibility of applying the eddy current method of non-destructive testing for measuring the electrical conductivity of new material - thin metal films. Copper films of various thickness obtained by physical vapour deposition were used as the measurement object. The deposition method and the hardware and software complex for measuring the electrical conductivity of the film were briefly described. A calibration curve that makes it possible to restore the values of the electrical conductivity of the material by the signal value of the eddy current probe was presented. The test results of films with different characteristics were given, and the distribution of the electrical conductivity of the films depending on the batch was shown. Based on different values of the electrical conductivity in a batch, the difference in deposition quality of various films was found.

Abstract: Composite gypsum binders harden quickly, gain strength quickly and have positive environmental properties. Moreover, they are characterized by increased moisture resistance, which significantly expands the field of application of such gypsum materials. Dispersed reinforcement of composite gypsum binders with polypropylene fibers makes it possible to obtain composites characterized by high performance properties. On basis of developed compositions of gypsum-cement-pozzolanic and composite gypsum binders with polymer fibers, gypsum composites have been created, characterized by increased strength, water resistance, frost and corrosion resistance.