Several energy parameters of molecular models of polytetrafluoroethylene and its composite F4K20 are calculated. As a result of friction and wear modeling, the energies of intermolecular bonds in the volume of the constructed U_inter^V models, in the surface zone U_inter^S , and at the transfer layer–counterbody interface are determined, and the shear moduli of the material models under study are assessed. It is found that, in F4K20, compared with the original matrix, all of the above parameters increase, which may indicate stabilization of the kinetic state of molecules in the presence of a filler. Based on the results of a comparative analysis of U_inter^V , U_inter^S , and U_inter^ad with the value of the linear wear rate determined for the materials under study as a result of tribological tests, the U_inter^V value is proposed as a wear-sensitive criterion at the molecular level, and the U_inter^ad value is proposed as an additional parameter characterizing the adhesive strength of the transfer layers.

Parts wear process always associates with the operation of machines and mechanisms. An important task is to minimize friction energy losses, and it is lubricants that are used for that, which, in turn, can contain various dispersed components. These components are divided into three groups: being formed during the friction process, some entering friction units from the outside and others, being purposefully added. The paper studies in detail the influence of such dispersed components as microorganisms (microscopic mold fungi) and purposefully added fillers, in particular, serpentinite, on the processes of friction and wear. The conditions of occurrence and mechanism of biological damage, as well as toxins released by microorganisms are viewed. The structure and principle of action of serpentinite are given. To perform the tests, four different brands of greases were used (Lita, TSIATIM-201, GOI-54p and MS-70), as well as samples of lubricants with mycotic molds lesion in Petri dishes and fine serpentinite powder. Tribological tests were carried out on a Bosch PBD-40 machine, and the diameters of wear spots of the balls located in the friction unit were measured using a DigiMicro 2.0 digital microscope. As a result of conducted tests, it was found that in case of using greases with mold fungi in the friction unit, deterioration of tribotechnical characteristics such as average friction force and mean diameter of the wear spot was most often observed as compared to basic lubricants. And when using a lubricant composition consisting of contaminated lubricant and serpenitinite, there has always been an improvement in these tribotechnical indicators as compared to contaminated greases without serpentinite, so it proves the effectiveness of filler addition.

This work is the first systematic study of the microhardness, scratch resistance, and abrasion resistance of protective silica‐like layers deposited on polycarbonate by atmospheric pressure plasma‐enhanced chemical vapor deposition (AP PECVD) from tetraethoxysilane (TEOS) and hexamethyldisiloxane (HMDSO). The influence of the layer composition on the abovementioned mechanical properties was considered in detail. It has been found that the films deposited from HMDSO at 110°C are characterized by a microhardness value that is almost three times higher than that of the films deposited from TEOS under similar conditions. The lower carbon content and, most likely, the partial substitution of oxygen in the SiO 2 matrix with carbon, leading to the formation of an oxycarbide structure, are responsible for the improved mechanical properties of the films deposited from HMDSO.

A mathematical model describing the law of contact gliding friction, taking into account changes in the sliding contact states, is proposed for consideration. The generalization of classical linear models of contact friction is carried out by putting in more additive components allowing for new state transitions of frictional interaction. The developed mathematical model makes it possible to give analytic description of the schematic diagram of classical slip coefficient change depending on the load of B.I. Kostetsky and allows adding to

In this work, double wire arc addictive manufacturing (WAAM) of Fe3Al parts was implemented and high -temperature properties of produced structures were studied. In-situ fabrication of several wall-shaped inter -metallic structures was performed using a dual wire feeding system, designed for unsymmetrical transfer of Fe -and Al-based wires. Mechanical properties, such as strength and ductility, as well as phase composition and microstructure of produced material were studied. Enhanced ductility at room temperatures and superplastic behavior at high temperatures were revealed by tensile tests. Furthermore, anomaly in temperature dependance of ultimate tensile strength has been revealed and discussed. Wear properties analysis demonstrated higher friction coefficient with lower wear rate for Fe3Al than for stainless steel.

Results of comparative research of wear resistance of polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK), ultrahigh molecular weight polyethylene (UHMWPE) and polyamide 6 (PA6) in friction pairs with 18Kh2N4МА, 08Kh18N10Т and 40Kh13 are presented. Self-lubricating ability of polymers was determined by the contact pressure value corresponding to the upper border of the diapason, in which the effect of stabilization of linear wear intensity values and by the length of this diapason along the axis of loads is shown. Carbon steel 45 was used as a base steel in the comparison. PEEK, UHMWPE and PA6 friction pairs show higher values of intensity of linear wear but decrease in ability to self-lubrication. However in friction pair PTFE – steel 18Kh2N4МА with the prevailing content of nickel (about 4%), expansion of a range of stabilization of linear wear intensity is observed. In friction pairs PTFE with steel 40Kh13, containing a considerable percentage of chrome (13%), in absence of nickel, and with steel 18Kh2N4МА containing a complex of nickel and chrome (10% and 18%, respectively), the least wear resistance and ability to self-lubrication of polymer are marked. Temperatures on polymer tribocontact corresponding to ranges of wear stabilization loadings in researched friction pairs are determined.

The analysis of the known friction-temperature laws is carried out in the article. A mathematical model of external friction of F.F. Ling and E. Seibel coefficient dependence on temperature, activation energies of formation and destruction of friction bonds and other factors, developed using the equations of absolute rates of chemical reactions, is analyzed. An approxima-tion of this model is implemented in temperature independence case for Bowden and Tabor shear strength. A mathematical model, describing sliding friction force-temperature relation under frictional interaction of spatially ordered rubbers hav-ing steel surface, is proposed. A distinctive feature of the proposed mathematical model is that it can simultaneously describe areas of constancy, friction force linear and nonlinear scaling under temperature changes. The testing and verification of the developed mathematical model is fulfilled through digitizing and processing experimental data, obtained by the fric-tional interaction of bars, made of spatially ordered natural rubber and spatially ordered rubber SCS-50 with a prism made of steel st.3. Analyzing the approximating dependencies, it is found, that for spatially ordered natural rubber, the maximum value of the friction force is 2,0 kgf under the temperature of approximately 37,6 ℃, and the average value of the friction coefficient is 0,987, for spatially ordered natural rubber, the maximum value of the friction force is 1.84 kgf under the tem-perature of approximately 31,4 ℃, while the average value of the coefficient of friction is 0,853. New tribotechnical charac-teristics have been introduced making possible to give a more detailed characterization of the frictional interaction in the rubber-steel system for the cases of temperature changes.

The drilling conditions are becoming more severe, which leads to the need to select new polymeric materials that can withstand heavy loads, provide a longer resource and are more resistant to high temperatures. To solve the problem, a set of laboratory tests on standard and specialized tribological equipment is proposed. The friction force, wear resistance under various conditions and according to various criteria, hardness at normal and elevated temperatures, thermal field during tests, change in the roughness of a steel counterbody as a result of tests are evaluated. Wear resistance is determined using a PBD-40 friction machine. Samples are cylindrical bodies with a diameter of (5.0 ± 0.5) mm, a height of 10.0 mm from the materials under study. The samples are fixed in the designed fixture. As a result of the tests, the average values ​​of the parameters for the investigated materials were determined, and the effects arising from friction were noted. The criteria for choosing a material have been formulated and the most suitable material for the tread has been selected.

Depending on operating conditions, metals and alloys are exposed to various factors: wear, friction, corrosion, and others. Plasma surface alloying of machine and tool parts is now an effective surface treatment process of commercial and strategic importance. The plasma surface alloying process involves adding the required elements (carbon, chromium, titanium, silicon, nickel, etc.) to the surface layer of the metal during the melting process. A thin layer of the compound is pre-applied to the substrate, then melted and intensively mixed under the influence of a plasma arc, and during the solidification process, a new surface layer with optimal mechanical properties is formed. Copper-based alloys-Cu-X, where X is Fe, Cr, V, Nb, Mo, Ta, and W-belong to an immiscible binary system with high mechanical strength, electrical conductivity, and magnetism (for Fe-Cu) and also high thermal characteristics. At the same time, copper-based alloys have low hardness. In this article, wear tests were carried out on coatings obtained by plasma alloying of CuSn10 and CrxCy under various friction conditions. The following were chosen as a modifying element: chromium carbide to increase hardness and iron to increase surface tension. It is noted that an increase in the chromium carbide content to 20% leads to the formation of a martensitic structure. As a result, the microhardness of the layer increased to 700 HV. The addition of CuSn10 + 20% CrxCy and an additional 5% iron to the composition of the coating improves the formation of the surface layer. Friction tests on fixed abrasive particles were carried out at various loads of 5, 10, and 50 N. According to the test results, the alloy layer of the Fe-Cr-C-Cu-Sn system has the greatest wear resistance under abrasive conditions and dry sliding friction conditions.

Новые технологии, Химическая промышленность, Химическая технология, Научные журналы, Защита от коррозии, Технология металлов, Свойства материалов, Технические журналы, Наука и технологии, Справочная литература, Научные разработки

В работе приведены результаты исследований анизотропии антифрикционных свойств уплотнений из терморасширенного графита. Установлено, что сила трения поверхностей реальных уплотнений из терморасширенного графита по стали зависит от направления движения.

The influence of adding 10 wt % MoS2 particles to a Litol-24 lubricant on the sliding friction of R6M5 steel on grade 45 steel according to the roller–roller scheme is studied at a load of up to 800 N and a rotation speed of 1500 min–1. The determined general laws of sliding friction are shown not to change in comparison with the previously established ones. The dependences of the frictional force on the normal force (load) have two linear sections, in which the Amonton–Coulomb law is valid. In general, the generalized version of the Amonton–Coulomb law also holds true. The addition of MoS2 increases the lubricant viscosity and the bearing capacity of the lubricant layer. In the load range 510–725 N, the critical load increases by ≈1.6 times and the best antifriction characteristics are achieved.

Two variants of the generalized three-component mathematical model of external sliding friction are proposed. This approach involves the Deryagin molecular friction theory and allows describing the dependence of friction force on load under one or more changes in friction modes caused by complex physicochemical and mechanical processes in the friction contact area. The change in friction is shown to have a piecewise linear character, whereas such parameters of frictional interaction as the differential coefficient of friction, the equilibrium force of molecular attraction, and the molecular component of friction force change in a sigmoid manner.

The sliding friction of R6M5 steel on grade 45 steel in the load range from 0 to 700 N in the medium of a plastic Litol-24 lubricant modified with dispersed graphite particles is studied. The dependence of the frictional force on the normal force is found to have a piecewise linear form with two linear sections. Both classical and generalized versions of the Amonton–Coulomb law are shown to be valid for the materials under study. Graphite particles are found to improve the antifriction characteristics in the load range 442–614 N and to increase the critical load from 390 to 540 N and the bearing capacity of the lubricating layer. A mathematical model is proposed to describe the viscosity of plastic lubricants with dispersed additives.

В работе дано описание приспособления для исследования антифрикционных свойств уплотнений из терморасширенного графита и других материалов. Детально описаны основные элементы устройства и их функциональное назначение.

The article presents a new empirical mathematical model for describing the change in the friction coefficient depending on the sliding speed, including such characteristics as the initial intensity of the change in the friction coefficient, the increment in the intensity of the change in the friction coefficient when switching to a new mode, the sharpness of the change in the friction coefficient when switching to a new mode, the value sliding speed corresponding to the minimum "acceleration" of the change in the friction coefficient during the transition to a new friction mode.The validity of the developed mathematical model is shown for the friction of guides made of gray cast iron SCh21-40 in the medium of lubricating oils "Industrialnoe 12 "Industrialnoe 45 "Avtol 18".

The level of corrosion resistance and conditions of corrosion cracking of the bush insert of two-layer oil well tubing fabricated from 5Kh13N2MB martensitic stainless steel are found. The average rate of general corrosion under the conditions of autoclave testing is found, which is used for the evaluation of the service life of tubes. It is found that the fabrication technology of two-layer tubes being used has a negative effect on the corrosion properties of the material of the bush insert.

The sliding friction of R6M5 steel on grade 45 steel at a load of up to 1400 N under the lubrication conditions of Litol-24 grease modified with zinc and cadmium in an amount of 3 and 2 wt