Том 40, № 5 (2019)

The problem of increasing the antifriction properties of oxide-ceramic coatings obtained by microarc oxidation on the surface of aluminum alloys is considered. This problem was solved by the impregnation of oxide-ceramic coatings with solutions of polymers (oligomers), which, upon further heat treatment and polymerization, give the oxide-ceramic coatings antifriction properties. Laboratory tests of the tribotechnical properties of the obtained polymer–ceramic coatings were carried out. The areas of possible practical application of the obtained polymer-ceramic coatings are considered.

This paper discusses tribological tests and microscopy studies of experimental Al–Si–Cu alloys with low-melting dopants (Bi, Cd, In, Pb in amounts up to 1%). Scoring resistance and wear resistance were studied. Sclerometry was performed using a spherical indenter under normal conditions at 90°C. Wear was evaluated without lubrication by block-on-ring tests. The topography and chemical composition of selected surfaces were studied using a scanning electron microscope before and after tests. Comparative analysis of experimental results and microscopy is presented.

The problem of burnishing metal samples with a smooth surface using a spherical indenter is considered. The nonlocal plastic strains in the burnished sample are taken into account. The dimensionless parameters are found that determine the effective friction coefficient under the influence of external oscillations. Numerical modeling is used to obtain the dependencies of the effective friction coefficient on the dimensionless parameters.

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.

Properties of the abrasive wear of antifriction material based on modified birchwood on samples with a linearly varying density along fibers impregnated and not impregnated with a lubricant were studied. The study was conducted by scratching. Results show that pressing allows for reducing the depth of penetration of an abrasive particle and the force of scratching, which contributes to a decrease of coefficient of friction and wear rate in the case of ingress of abrasive into the friction unit. Impregnation with a lubricant used to ensure the self-lubricity of compressed wood slightly increases the penetration depth of the abrasive particle. Nature of the abrasive wear of pressed birchwood was investigated by the scratch microstructure. It is shown that pressed wood on the contact surface of friction is destroyed as a homogeneous material. The effect of the stratification of material and the propagation of cracks along the fibers in pressed wood in the case of abrasive wear is not observed in comparison with natural wood with the same loading conditions of scratching.

An experimental study was carried out to investigate the effect of adding nanoparticles of different size and materials on the friction coefficient of water-based drilling muds. Silicon oxides and ultradisperse diamond particles were considered as the nanoparticles. An aqueous bentonite solution with a mass fraction of 5% was used as the basic drilling mud model. The nanoparticle concentration in solutions ranged from 0.06 to 2.00 wt %. The size of nanoparticles ranged from 5 to 100 nm. It was shown the adding nanoparticles to drilling muds significantly decreases the friction coefficient, the value of which depends on the size of nanoparticles and changes appreciably at low concentrations.

The computational procedure of a gearing module of enclosed gear transmission operating under rolling with slip both with and without abrasive particles in the oil of the friction unit of mobile machines, taking into account the geometric and kinematical parameters of tooth engagement, the mechanical properties of the material of gearwheels, the strength, and the concentration and the size of abrasive particles influencing on the wear resistance of gearwheel teeth, is considered. The proposed computational procedure of the gearing module of the gear transmission differs from the conventional computational procedure.

The effect of carbon nanomaterials (CNMs) of various structures (multi-layered oxidized graphene, single-walled and multi-walled carbon nanotubes, schungite carbon nanoparticles) on the friction coefficient and scoring resistance of industrially manufactured imported and domestic plastic lubricant materials (PLMs) has been experimentally investigated. It is shown, that the addition of CNMs to domestic PLMs leads to an increase in durability, and the resulting effect on the friction coefficient depends on different factors, such as the type of base PLM, the structure of CNMs, the concentration of CNMs, and the load.

The effect of acidic, alkaline and neutral media on wear kinetics and mechanism for fluoroplastics and polyolefins has been studied. Equations for fluoroplastic and polyolefin wear intensity are obtained based on the thermochemical and mechanical model of their destruction. The values of the activation energies for the surface destruction onset over the entire wear cycle of the polymer surface spherulite are determined.