Application of the phenomenon of self-organization for the development of wear resistant materials has been reviewed. For this purpose the term of self-organization and dissipative structures as applied to tribology have been discussed. The applications of this phenomenon have been shown in order to develop new wear resistant-and antifriction materials. Specific examples have been shown for the application of the self-organization phenomenon and the generation of dissipative structures for the formation of tribotechnical materials with enhanced wear resistance for current collecting materials and antifriction materials of bearings.
The processes taking place on the friction surface of high-alloyed aluminum alloys working with steel whilst replacing bronze journal bearings with aluminum are investigated. In this regard, eight experimental aluminum alloys with an Sn content from 5.4% to 11.0%, which also included Pb, Zn, Si, Mg, and Cu, were cast. The surface and subsurface layer of experimental aluminum bearings were studied before and after tribological tests with a 38HN3MA steel counterbody by scanning electron microscopy including energy-dispersive analysis. The best aluminum alloy, which had an Sn content of 5.8% after the friction tests, showed 6.5-times better wear resistance and steel counterbody wear rate than the bronze reference. Both structural and compositional changes in the surface layer were observed. It was revealed that secondary structures formed on the surface during the friction process and included all of the chemical elements in the tribosystem, which is a consequence of its self-organization. Generally, the secondary structures are thin metal-polymer films generated as a result of the high carbon and oxygen content. The interaction behavior of some of the chemical elements in the tribosystem is shown and discussed. In addition, the influence that Sn, Pb, Cu, and C content in the secondary structures has on the tribological properties of low-tin and medium-tin alloys is shown.
The possibility of changing bronze in the manufacture of monometallic cast plain bearings with multicomponent aluminum antifriction alloys is considered. Due to alloying of aluminum with tin, lead, copper, zinc, silicon, magnesium and titanium, it was possible to create alloys with increased ability to adapt friction surfaces. According to laboratory tests, the main results of which are given in the article, it is proved that aluminum alloys on a complex of mechanical and tribotechnical properties are close or superior to the investigated bronze BrO4C4S17. Laboratory tests have shown the possibility of manufacturing monometallic plain bearings from experimental cast aluminum alloys, which by mechanical properties are not inferior to the most solid among antifriction bronzes - bronze BrO4C4S17. On a complex of tribotechnical properties, experimental alloys exceed bronze. Due to their high-fusibility, lower density, lower cost and better workability, aluminum alloys have an almost 3-5-fold advantage over economic indicators before tin bronzes. The scope of the proposed alloys will be determined in the course of bench and operational tests. To date, an experimental batch of monometallic bearings of turbochargers TK 33N-02 has been manufactured from the alloy of the AO6S3M4CT series of “Spets Dizel Servis” (Novosibirsk), which successfully passed the bench tests. Bushings 3404.00.112, 3404.00.032 and bearings 3409.00.20, made from an experimental alloy, showed the possibility of replacing the standard bronze BrO8S12 in these turbochargers. It is advisable to carry out operational tests of bearing sleeves from the alloy AO6S3M4CT for turbochargers TK 34, TK 30 and TK 33, as well as bearing inserts for diesel locomotives.
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.
This article describes the elemental composition of secondary structures formed on the steel contact surface during wear test against experimental Al alloys. Wear tests were carried out according to the rotating steel roller-fixed shoe of an antifriction alloy scheme under boundary lubrication conditions. The duration of the test was 40 h, and motor oil M14V2 was used as a lubricant. The microstructure and elemental characterization of the steel surface before and after the tribological test was obtained by scanning electron microscopy equipped with EDX. The simultaneous presence of various constituents of oil, steel, and Al alloys can produce both positive and negative effects on the friction characteristic of the tribosystem. It was shown that presence of Mo, F, S, Si, Ni, and Cr have a favorable effect on the wear resistance of steel and the friction coefficient of the rubbing surfaces due to the formation of secondary structures with optimal composition.
The paper investigates the relationship between the tribological properties/compositions of new aluminum antifriction alloys and compositions of the secondary structures formed on their friction surfaces. Eight alloys with various compositions have been analyzed. The elemental compositions of the secondary structures on their friction surfaces have been determined. The relationship between the alloy secondary structure compositions with wear rate has been found. An attempt has been made to determine the secondary structure composition patterns based on the non-equilibrium thermodynamics and self-organization theory.
In this work, aluminum multicomponent alloys were studied after friction with steel in a mixed lubrication regime. The resulting secondary structures on the friction surface were investigated by scanning electron microscopy (SEM), energy dispersive analysis (EDX), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction analysis (XRD). In addition to the mass transfer of steel counterbody particles, phase transformations and new chemical compounds formed as a result of interaction with the lubricant were revealed. The release of elements, mainly magnesium and to a lesser extent zinc, from a solid solution of aluminum alloy was also observed, which indicates the occurrence of a non-spontaneous reaction with a negative entropy production.
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