Open Access
Access granted
Subscription Access
Vol 37, No 1 (2016)
- Year: 2016
- Articles: 16
- URL: https://ogarev-online.ru/1068-3666/issue/view/14060
Article
Tribological characteristics of hip joint endoprostheses
Abstract
We have studied the friction pairs for a head–insert kinematic node of human hip endoprostheses and rabbit hip endoprostheses, both normal (intact) and with an osteoarthritis model, in conditions of dry friction and lubrication with biological medium. We have discovered that the rabbit hip with an osteoarthritis model exhibits deterioration of tribological characteristics. From the tribological point of view, the most suitable friction pairs for human hip endoprostheses are zirconium ceramics–aluminum ceramics, Oxinium–aluminum ceramics, aluminum ceramics–aluminum ceramics, and aluminum ceramics–polyethylene, which have shown the smallest coefficient of friction, the lowest adhesion bond strength when sheared, and minimal dependence of these parameters on the value of external load.
1-6
Surface modification of diamond-like carbon coatings to control over run-in processes in friction pair
Abstract
The effect of the nanostructure and chemical composition of thin Mo–Se–C films on the run-in of the diamond-like carbon coating (a-C) and the steel counterbody during ball-on-disk sliding test is studied. At the final stage of the deposition of the a-C coating on the steel substrate, a flow of atoms from the MoSe2 target was added to the flow of atoms being deposited. The influence of the air humidity on the selection of optimum structure and chemical composition of the film, which provide a fairly low (<0.07) coefficient of friction during the entire period of the run-in stage, is considered. In order to explain the effect of the modifying films, analysis of the specific features of the friction-induced changes in the composition of the films during wear debris formation has been carried out using Raman spectroscopy.
7-14
Tribochemical processes in epoxyorganic textolite–steel friction pair
Abstract
The role of a phenol formaldehyde oligomer additive to the epoxy binder in friction of organic textolite is studied. It is shown that, in the course of friction, the polymer surface becomes enriched in the tribochemically stable phenolic component, while new C=O and O–C–O bonds appear that result from the oxidation of the aliphatic epoxy groups of macromolecules. During friction, the aliphatic component of the polymer specimen is predominantly involved in reactions with the counterbody; this selective wear makes the outer surface of the polymer specimen less hydrophilic. Comparative tribological and thermofrictional tests have shown that, unlike the phenol structure, the use of an epoxy-phenolic structure in the materials reinforced by polyoxadiazole fabrics is more efficient at low temperatures, while phenol formaldehyde binder exhibits better stability at high temperatures.
15-22
The interrelation of the run-in ability of bronzes and aluminum-based antifriction alloys with their mechanical properties and degree of alloying
Abstract
Combined tests are carried out to determine the mechanical characteristics of pilot antifriction alloys based on aluminum and BrO4Ts4S17 commercial bronze; they are also tested in the laboratory tests for run-in ability. The interrelation of the mechanical characteristics of these pilot alloys with their run-in ability is determined. The interrelation of the mechanical characteristics of aluminum-based alloys with their run-in ability is considered for various degrees of alloying with hardening elements and elements that provide the presence of the soft structural constituent.
23-26
Formation of wear-resistant nanostructured TiN/Cu coatings
Abstract
Results of studying the structural and physicomechanical properties of TiN/Cu coatings deposited from multicomponent separated vacuum-arc plasma are presented. Specific features of the formation of the nanostructured TiN-based coatings, which are alloyed with an element that does not form chemical compounds with titanium and nitrogen under the selected conditions of deposition, are considered. It is shown that alloying of the coating with this element leads to refinement of its structure. Regularities of variations in the microhardness and the tribological characteristics of TiN/Cu coatings of different elemental compositions are investigated. It has been found that the coatings that contain 2–4% of Cu have the highest microhardness (39–40 GPa) and the lowest coefficient of friction (0.2–0.4). Main factors responsible for the high wear resistance of the coatings are determined.
27-31
Statistical description of formation of microgeometry on the friction surface of a diamond drill
Abstract
The formation of the microgeometry of the friction surface of an annular drill made of a diamond-containing hard-alloy powder material is studied. A specific feature of the run-in of the friction surface is the formation of elongated zones of the matrix material behind randomly arranged diamond grains. To carry out statistical description of the formation of the friction surface of the diamond-containing material, it is proposed to use correlation of the wear of the profile of the powder material across the friction path. It is shown that this approach yields a qualitative description of specific features of the formation of the microgeometry on the friction surface of the diamond-containing powder material.
32-38
Simulation of the thermal process and friction diagnostics in a system of nonlubricated sliding bearings on a common shaft
Abstract
The development of a method of thermal diagnostics of friction allowing evaluating friction torque in a system of sliding bearings on a common shaft by temperature data under the assumption of uniform temperature distributions on the cross section of a shaft and along the length of bearings in the case of dependence of thermal properties of materials on temperature is described. The resistance of the obtained solutions to errors in temperature data is shown.
39-46
Determination of the efficiency of high-entropy cutting tool materials
Abstract
Modern approaches to determination of the durability of cutting tool materials taking into account the effect of their entropy, Thermo-EMF, and the functional relationships between them are presented. It is confirmed that the tribological properties of complex alloyed high-speed steels and experimental cemented carbide hard alloys (ECCs) with modified cobalt binder as high-entropy materials can be improved. The results of a study of wear resistance, oxidation resistance, and optimum cutting conditions of ECCs are presented.
47-54
Mechanisms of wear of elastomers under direct impact of abrasive particles
Abstract
The possibility of simulation of a single impact of an abrasive particle on the surface of an elastomer is shown. Experimental study of the direct impact has made it possible to distinguish two fracture mechanisms responsible for the wear of rubbers. Fracture of the rubber surface occurs via the delamination of thin destructed rubber flakes. Under more severe conditions of loading, cracks appear, propagate, and merge, which is followed by spalling of fragments of the material.
55-59
A grinding force model allowing for dulling of abrasive wheel cutting grains in plunge cylindrical grinding
Abstract
A mathematical model is developed for the grinding force in cylindrical plunge grinding that allows for the grinding conditions, the size of the flank wear land areas formed on the grinding wheel cutting grains, the properties of the work material, and the geometrical parameters of the grinding tool and work surface. A formula is obtained for calculating the stock removal rate as a function of the degree of dulling (glazing) of the grinding wheel. The adequacy of the mathematical model of the grinding force in cylindrical plunge grinding is established.
60-65
The effect of electric-spark treatment on the structure and properties of modified friction surfaces
Abstract
The effect of the materials of alloying electrodes and conditions of electric-spark treatment on the microhardness, structure, and tribological characteristics of modified surface layers formed under various conditions of treatment is studied. It has been found that, with increasing parameters of the energy conditions of electric-spark treatment, the microhardness of the surface layers grows and the wear rate of the mated polymer parts decreases.
66-70
Evaluation of the strength, wear, and durability of a corrected cylindrical involute gearing, with due regard for the tooth engagement conditions
Abstract
A method for calculating the wear and durability of helical gearings is used to investigate the effect of double–single–double tooth engagement on the maximum contact pressures, tooth wear, and durability of a corrected cylindrical involute gearing under constant tooth contact conditions. A technique is presented for determination of the angles of transition from the doubleto the single-tooth contact and vice versa. Gear tooth profile correction is found to reduce the maximum contact pressures by up to 20%. The teeth of the gear wheel reach their wear allowance faster than those of the pinion do. Depending on the degree of correction, the maximum wear occurs at different characteristic contact points: at the entry to the double-tooth mesh, at the entry to the single-tooth mesh, or at the exit out of the mesh. The durability of the gearing is found to be at its maximum at certain overlap ratios, its magnitude being observed to increase substantially (by up to 50%). The results obtained are presented in graphic form, which enables one to reveal the laws governing the effect of the engagement conditions.
71-77
Features of interaction of traction wheels of an electric locomotive and a diesel locomotive with rails in the conditions of open mountain works
Abstract
Comparative analysis of conditions of interaction of locomotive wheels with rails is provided under electric and diesel traction for an open-pit railway transport. A description of conditions that promote the formation of welding bridges (setting) between microbridges of the contacting surfaces is given. Conclusions are drawn on the influence of the interaction modes of locomotive wheels with the rails on their traction ability.
78-82
Performance characteristics and wear pattern of precision parts of cotton tractor hydraulics
Abstract
Specific properties of hydraulic system performance in a cotton tractor have been described. The influence of hydraulic oil purity and intensity of directional control valves’ actuations upon wear of precision parts has been demonstrated.
83-85
Dry friction of pure aluminum against steel
Abstract
The behavior of aluminum during dry friction against a steel disk is studied. It has been found that, in the course of dry friction, severe wear of the surfaces of both materials occurs. With an increase in the applied pressure, the wear intensity of the friction pair grows, while the coefficient of friction decreases. The examination of the structure of the subsurface layers of the aluminum specimens has shown that the deformation that occurs in these layers makes a substantial contribution to the wear of these specimens.
86-93
Modeling of abrasive wear by the meshless smoothed particle hydrodynamics method
Abstract
Numerical modeling of surface wear proves to be a very challenging mathematical and numerical problem. Basically nonlinear processes of wear and creation of plastic zones are only the beginning of a large list of factors that have to be incorporated into a numerical model to adequately describe the frictional interaction of solid bodies. This article presents a new approach to numerical modeling of abrasive wear of friction composites under nonstationary friction. It utilizes the meshless smoothed particle hydrodynamics method together with the standard finite element method. The presented numerical examples illustrate both verification of the new approach, as well as results of abrasive wear modeling.
94-99