An Erratum to this paper has been published: https://doi.org/10.3103/S0025654422320012. © 2022, Allerton Press, Inc.

In this paper, we consider the contact of an infinitely extended plane indenter and a viscoelastic layer within the framework of the Deryagin self-consistent approach with surface (traditional formulation) and volumetric (refined formulation) application of intermolecular interaction forces. Equations that describe the time change in the contact gap for such a contact are obtained. A condition, under which an abrupt time change in the contact gap is possible, is formulated. Calculations that indicate the nonmonotonic nature of the time dependences of the contact gap and pressure in the indenter approach and retract modes are performed. It is shown that the traditional and refined problem formulations can lead to significantly different results of calculating the characteristics of the contact between the indenter and the viscoelastic layer.

The paper studies the effect of adhesion and surface relief of laminated plywood on rubber friction. Samples of birch plywood are studied, the surfaces of which have different texture and roughness and are made on the basis of two different resins: phenol formaldehyde and melamine. The study of the static and dynamic friction coefficient is carried out on a tribometer according to the ring-disk contact scheme at room temperature of 23 degrees C in the range of normal pressures from 0.1 to 0.5 MPa in dry and lubricated friction mode. The study of the adhesion properties of the coatings was carried out on an atomic force microscope with a 900 nm ball at the tip. The refined contact interaction model of the spherical tip with the plywood surface made it possible to estimate the surface energies of the coatings. The findings show that when using plywood in dry contact only, it is necessary, first of all, to increase the adhesion properties of its surface, for example by introducing filler-adhesives or using a polymer resin with increased adhesive properties as the base of the laminated coating. If it is assumed that liquids or contaminants enter the plywood surface during operation, then the best effect is the application of a two-level texture: deep dents to remove water from the contact area and surface roughness to increase adhesive properties. It should be noted that the roughness on some types of laminated films can change rapidly due to wear, therefore the use of films with increased adhesive properties is an advantage for increasing the adhesive properties of the surface of laminated plywood.

Many algorithms that are capable of determining the indent area in automatic processing of optical images of imprints have found application in hardness measurements using the Vickers method. A robust interactive algorithm based on the maximum separation of color image components in the indentation area and an unstrained surface is described. The efficiency and stability of the presented method are evaluated using indents on several materials with different morphology and deformation character.

The contact between an infinitely extended plane indentor and a viscoelastic layer is considered within the Derjaguin self-consistent approach with the surface (traditional formulation) and bulk (refined formulation) application of intermolecular interaction forces. Some analytical expressions are derived for the stress-strain state. Using the first law of thermodynamics, the energy dissipation in a viscoelastic layer is calculated. It is shown that the traditional and refined problem formulations may lead to essentially different results of calculation for the characteristics of contact between an indentor and a viscoelastic layer.

The method of siliconizing carbon fabric with SiO vapours yields a textile SiC material that preserves the structure and integrity of the fibers of the original fabric, as well as the average diameter of the monofilament. According to X-ray phase analysis, it was found that SiC fibres obtained by siliconizing silicon fabric with SiO vapor consist of a mixture of two modifications of 3C-SiC and 6H-SiC. According to infrared absorption, the oxygen content in the composition of silicon carbide fibers does not exceed 2.1 wt%. The mechanical properties of the obtained fibers were investigations: the mechanical tensile strength of silicon carbide fibers is op = 1350 +/- 120 MPa, the nanoscale hardness is 10 +/- 0.5 GPa, and the elastic modulus is 100 +/- 10 GPa.

The influence of the oxygen flow rate on the friction coefficient of titanium oxynitride films deposited by reactive magnetron sputtering at a constant current of a hot target was investigated. The study used the plans of the active experiment and regression models of the first and second order. It is found that the increase of the oxygen flow rate in the gas environment leads to the increase of the film friction coefficient.

The influence of the oxygen flow rate on the friction coefficient of titanium oxynitride films deposited by reactive magnetron sputtering at a constant current of a hot target was investigated. The study used the plans of the active experiment and regression models of the first and second order. It is found that the increase of the oxygen flow rate in the gas environment leads to the increase of the film friction coefficient.