Study and development of the technology for hardening rope blocks by reeling

A rheological model of stress relaxation in a thin lubricant film, which is formed on the friction surface under the influence of the force field of the friction surface in the presence of fullerene compositions in lubricants, was developed. Analysis of the model made it possible to establish that the existence of elastic or viscous properties in surface structures depends on the ratio of two parameters. This is the time of stress relaxation in the structure on spots of actual contact and the duration of stress action on these spots, which is termed the lifetime of an actual contact spot. It was shown that an increase in the sliding rate reduces the time of relaxation of stresses in the surface structure. This is due to the destruction of aggregates in the structure of gel and the appearance of rotational movements of separate units ‒ flocs. An increase in the load on the tribosystem significantly increases the value of relaxation time. This is due to squeezing the viscous component out of the structure of a surface film. It was established that if the relaxation time exceeds the duration of actions of stresses on actual contact spots, the structure of a surface film behaves like an elastic solid. Conversely, if relaxation time becomes shorter than the duration of stress action, the film behaves like a viscous medium. Theoretically, it was shown that in the range of sliding and loading rates, when a film behaves like an elastic solid, a decrease in stresses on actual contact spots does not exceed the values of 1.1‒22.8 %. This property provides the bearing capacity of a film. The development of the model will make it possible to simulate elastic and viscous properties of "stitched" structures and substantiate the rational concentrations of additives to lubricants, as well as the ranges of their use.

Section: Discussion Of Results Of Studying the Rheological Properties Of Structures That Are Formed On The Friction Surface Of Tribologicsupporting

confidence: 64%

Section: Substantiation Of the Structure Of The Rheological Model Of Stress Relaxation In A Lubricant Film On The Friction Surface Of Trimentioning

confidence: 99%

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Development of a rheological model of stress relaxation in the structure of an oil film on the friction surface with fullerene additives

Suska

Biekirov

Levkin

2021

“…The influence of the structural orientation of the fragments of the microstructure of metal materials on the processes of friction and wear was modeled in work [13]; however, the features of the structure of polymers were not taken into consideration in the model. Modeling an active experiment established correlation influences of the strengthened steel surface on the wear of the polymer in [14] without taking into consideration the frictional heating of surfaces. The influence of composition modification on the sliding friction and wear of supporting steel was investigated for the developed binary epoxy composites in [15,16].…”

Section: Literature Review and Problem Statementmentioning

confidence: 99%

Influence of the structure and thermomechanical properties of oriented carbon plastics on their tribotechnical characteristics

Dykha

Drobot

Oleksandrenko

et al. 2021

Self Cite

It has been established that carbon plastics are increasingly used in various industries as structural materials. By the set of their properties, carbon plastics outperform steel, cast iron, alloys of non-ferrous metals. However, the application of these materials for parts of machine friction units is still limited due to the difficult operating conditions of modern tribosystems. This work aims to conduct a comprehensive experimental study of the tribological properties of materials in the tribosystem "carbon plastic-metal" taking into consideration their structure, as well as the mechanical-thermal characteristics. Comparative tests of the dependence of the friction coefficient on load for metal and polymeric anti-friction materials have shown a decrease in the friction coefficient for plastics by 3...4 times (textolite, carbotextolite, and carbon-fiber plastics). The influence of the filler orientation relative to the slip plane on the anti-friction properties of carbon-fiber plastics was investigated; it was found that the direction of fiber reinforcement in parallel to the friction area ensures less carbon-fiber plastic wear. A linear dependence of the wear intensity of carbon-fiber plastics, reinforced with graphite fibers, on the heat capacity and energy intensity of the mated steel surface has been established. Based on the microstructural analysis, a layered mechanism of the surface destruction of carbon-fiber plastics was established caused by the rupture of bonds between the fiber parts, taking into consideration the direction of the fibers' location to the friction surface. The results reported here could provide practical recommendations in order to select the composition and structure of materials for the tribosystem "carbon-fiber plastic-metal" to be used in machine friction units based on the criterion of improved wear resistance

“…are developing quite intensively. Combined methods make it possible to form surface layers with the required mechanical properties and significantly increase the contact strength and wear resistance of components in friction couples [9][10][11][12][13][14][15][16][17][18]. Therefore, it is relevant to determine the effectiveness of improving the wear resistance of heavy-loaded parts in tribomechanical systems by a combined laser-thermochemical treatment method.…”

Section: Introductionmentioning

confidence: 99%

Improving the wear resistance of heavy-duty elements in tribomechanical systems by a combined laser-thermochemical processing method

Киндрачук

Духота

Тіsov

et al. 2021

This paper reports an analysis of the state of tribological support in the aviation industry. The use of surface strengthening technologies to extend the resource of friction node parts has been prioritized. Modern combined technologies of nitriding and laser treatment of steel surfaces have been reviewed. The mechanism has been elucidated that damages steel 30H2NVFA in the jackscrew actuator of transport aircraft flaps, which occurs due to insufficient surface hardness of the material after a generally accepted heat treatment. Auger electron spectroscopy analysis revealed a high concentration of oxygen on the surface: up to 41.4 at. %; the friction surface carbonation has been detected, especially significant at the surface of the pitting damage. A comprehensive technology of surface strengthening by nitriding+laser selective hardening has been suggested. The radiation power was 1 KW, the diameter of the focus spot was 2.5 mm, and the pitch between the focus spot centers was 2.5 mm. The total area of laser processing was 70 %. The steel temperature exceeded Ас3 and corresponded to the hardening temperature range. The depth of the nitrided layer increased to 400 µm, the maximum hardness on the surface was 1,350–1,380 HV0.2. The formation of a solid nitrided layer with a thickness of 200‒250 µm was observed, as well as a transition zone composed of column-shaped iron nitrides, which are introduced into the matrix material. As a result, a sharp gradient in the mechanical properties disappears. The tests confirmed that the wear resistance of the comprehensively treated surface was 2.1 times higher under dry friction conditions, and 4.5 times higher when lubricated with the "Era" grease (RF), compared with the 30H2NVFA steel nitrided by the conventional technology. In addition, there was no fragile destruction of the surface; the interaction with oxygen reduced significantly