No abstract

The purpose of this work was to develop a criterion for estimating the quality factor of the tribosystem and to assess its effect on wear rate, friction coefficient and run-in time. The basis of the methodological approach when developing a criterion for the quality of the tribosystem is the parameters that take into account the construction of the tribosystem, the thermal diffusivity of materials and the loading conditions of the tribosystems.The definition of the quality of the tribosystem has been further developed, which, unlike the known one, takes into account the geometric dimensions and kinematic scheme of the tribosystem, the thermal diffusivity of materials and the rate of propagation of deformation in the surface layers of the triboelement materials during their contact interaction. Theoretical and experimental studies established the relationship between the quality value, wear rate and the friction coefficient in the process of running-in. It is shown that the increase in quality helps to reduce the above-mentioned parameters.The relationship between the running-in time and the quality value is established. It is shown that the process of running-in can be controlled. To reduce the running-in time, it is necessary to reduce the sliding speed during the transient process and to increase the tribological properties of the lubricating medium. The presented theoretical and experimental studies allow us to state that the quality of tribosystems Q can be a measure of the potential ability of the tribosystem to adapt (adapt) to operating conditions, providing the maximum resource.

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.