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The features of the structural and tribotechnical characteristics of copper alloys and coatings during friction of a steel–steel pair are analyzed. Copper-based coatings obtained by gas-dynamic ...spraying have been experimentally studied. The wear resistance and microgeometric characteristics of the surface of steels with coatings of the composition Cu : Al
2
O
3
= 55 : 45 (wt %) and Cu : Zn : Al
2
O
3
= 35 : 35 : 30 (wt %) are determined. A coating is formed from a powder mixture of copper and corundum, mainly consisting of copper. Corundum is present in the form of particles with a size of 0.05 μm
2
in an amount of less than 1%. The coating has a high performance when tested under friction and wear conditions: wear intensity
I
h
(coating) ≈ (1.1–1.5) × 10
–10
and
I
h
(counterbody) ≈ (0.3–0.4) × 10
–11
under friction in I-20A mineral oil;
I
h
(coatings) ≈ (2–5) × 10
–10
and
I
h
(counterbodies) ≈ 0.2 × 10
–11
during friction in Litol-24 grease. Heat treatment of such a coating causes diffusion of zinc into copper with the formation of a solid solution of zinc in copper (α-phase) and an electron-type solid solution based on CuZn is also formed. The mechanism of contact interaction of steel coated with Cu–Zn–Al
2
O
3
in a pair with ShKh15 steel is based on the process of mass transfer in the zone of surface plastic deformation, which minimizes the level of surface destruction of the pair as a whole, reducing it to practical wearlessness at high external pressures. Deformation, diffusion, and mass transfer in the zone of contact interaction during friction point to the effect of “classical wearlessness,” a distinctive feature of which is the formation of a copper-zinc third body interspersed with corundum, which has the ability to transfer from the sample on the counterbody and vice versa, providing protection of the surface layers from destruction but not a servovite copper film (with a special structural state). High wear resistance of friction pair materials is achieved due to frictional mass transfer films.
The article overviews scientific research studies that examine the interaction between railway vehicle wheel and rail, and the
phenomena of wear on wheel rolling surface. Unique experimental research ...has been conducted, in which regularity of weariness
on rolling surface of exploitable locomotive wheel and phenomena of metal fatigue on wheel were researched. A hypothesis is
made, that according to the differences in weariness intensity of wheel rolling surface it is possible to determine the start of metal
fatigue. The inequality of wear intensity of different locomotive wheels is assessed by the Sharpe ratio, adapting it to describe the
wheel wear intensity criteria. Based on the results of research, the authors propose a simplified and reliable methodology for determining metal fatigue on locomotive wheels at initial stages. The uneven wear on rolling surface of different wheels of wheelset
inevitably changes the values of Sharpe ratio, which can accurately describe the conditions in which the critical metal fatigue on
wheels begins to emerge.
The results of a study of the friction and wear characteristics of the developed nanostructured glass-composite self-lubricating detonation coatings with the composition SiC–Ni–Cu–Al–Si–C ...additionally containing a SiO
2
–Al
2
O
3
–B
2
O
3
aluminoborosilicate glass phase and structurally free MgC
2
, which forms α‑graphite during thermal decomposition are presented. It is indicated that their synergistic effect promotes the creation of an antifriction surface layer that minimizes contact parameters. An increase in the adhesion strength of the coatings is achieved by preliminarily applying a sublayer of glass-like sodium silicate Na
2
O(SiO
2
)
2
onto the working surface. It is noted that the intercalation of the graphite layer by the particles of the subsurface zone does not affect the tribotechnical characteristics of the coatings. The developed coatings show high performance properties; here, the way of wear stabilization is the presence of a thin-film antifriction layer based on α-graphite, which shields unacceptable processes of molecular adhesion interaction.
Polyurethanes are materials usable in wide spectrum of applications. This article is aimed at the properties tailoring of selected polymers by an alteration in initial materials. To achieve that ...goal, we proposed form the polyurethane matrix by mixing materials that have a different ratio of the initial components. Mathematical model has been developed that describes relationship of structure and strength, deformation, rheological and tribotechnical characteristics of linear block-polyurethanes based on oligoether blends. Oligoethers blend samples were obtained by injection moulding on an automatic thermoplastication machine with varying proportions of the starting components over the whole concentration range. A significant change of properties over the whole concentration range was observed and compositions with unique combination of characteristics have been determined. Obtained dependencies allow to predict the composition of the binary mixture with a tailored level of strength, deformation, rheological and tribotechnical characteristics. The obtained results are fully consistent with the practical experience of processing and exploitation of initial polyurethanes.
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An analysis has been made of the literature on friction and wear of polymer composites and nanocomposites prepared by compounding nanofillers with a polymer matrix. The most important group of ...triboengineering nanocomposites includes polymers containing carbon nanomaterials and nanosilicates. Nanofillers significantly affect the behavior of polymer macromolecules under friction, formation of transfer layers and wear debris, and finally the tribological performance of the composite. PEEK-based nanocomposites are becoming one of the most promising materials for applications in polymer–metal tribosystems. They were tested under dry friction against steel with standard conditions recommended by the International Organization for Standardization. The test data have confirmed the positive effect of combining nanofillers with conventional additives to a PEEK matrix.
Based on the methods of non-equilibrium thermodynamics, it was found that the implementation of spontaneous processes with positive entropy production during friction leads to an increase in the wear ...intensity. Non-spontaneous processes with negative entropy production lead to a decrease in wear intensity. The tribological characteristics of diamond-like carbon (DLC) with different silicon content were studied. The wear intensity practically does not correlate with the friction coefficient. It is shown that DLC with the highest content of diamond-like inclusions (sp3) in the coating has the highest wear rate. In the same DLC, the most intense sp3–sp2 transformation during friction was observed. The sp3–sp2 transformation is a spontaneous process.
Metallographic studies of hardened zones of steel 40Kh were carried out. Regression equations were obtained and the surface depth and width of the hardened zones as functions of the beam scanning ...speed and radiation power at different beam defocusing were plotted with the help of a full factorial experiment. Comparative wear tests showed that, with increasing hardening area to 100% of the friction surface, the wear resistance increases by a factor of 4.47 as compared to normalized steel.
Sintered Al-40Sn samples were subjected to tribological tests by the “pin-on-disk” scheme without liquid lubrication. A steel disk was pressed to the upper and lower face surfaces of a vertically ...located sample. It is revealed that the location of counterbodies relative to the frictional contact plane can significantly influence their wear intensity. These differences are explained by the different composition and structure of friction surfaces of counterbodies the nature of formation of which depends on the gravity vector direction defining the features of displacement of wear particles over the friction surface.
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