Showing papers in "Journal of Friction and Wear in 2007"
TL;DR: In this paper, the features of traditional and nanodispersed fillers in polymer composites are discussed, and the fields of the application of nanodispered nanocomposites are considered.
Abstract: Literature data and original research in the field of the technology and tribology of nanocomposites produced by the dispersion of nanofillers including organoclay, carbon nanomaterials, and metal-containing compounds in thermoplastics and elastomers melts are analyzed. The features of their structure and tribological behavior are discussed. The combination of traditional and nanodispersed fillers in polymer composites is shown to hold promise, and the fields of the application of nanodispersed nanocomposites are considered.
53 citations
TL;DR: In this paper, the results of studies of the friction of solids at elevated temperatures in a vacuum and in air have enabled the identification of promising materials for use as solid-lubricating substances within various temperature ranges.
Abstract: An evaluation of the results of studies of the friction of solids at elevated temperatures in a vacuum and in air has enabled the identification of promising materials for use as solid-lubricating substances within various temperature ranges. Solid-lubricating substances (solid greases) are commonly incorporated into composite materials and coatings. When several solid greases are introduced into a composition, their action results in synergism.
12 citations
TL;DR: In this paper, a new class of antifriction polymer composite materials, i.e., carbon plastics, is considered in terms of their application in machine building, and the use of sliding bearings made of carbon plastics in ship and energy machine building has shown their high efficiency.
Abstract: A new class of antifriction polymer composite materials, i.e. carbon plastics, is considered in terms of their application in machine building. They exceed traditional antifriction polymer materials in their characteristics. The use of sliding bearings made of carbon plastics in ship and energy machine building has shown their high efficiency.
11 citations
TL;DR: In this paper, the authors evaluated the thermodynamic properties of non-spontaneous chemical reactions induced by friction using the expression for the dissipative function of tribosystems in which at least one tribochemical reaction occurs.
Abstract: Thermodynamic characteristics of non-spontaneous chemical reactions induced by friction are evaluated using the expression for the dissipative function of tribosystems in which at least one tribochemical reaction occurs. The model describing the rate of tribochemical reactions within framework of the activated complex theory is proposed. The estimates show that even at low coefficients of friction, sliding velocities, and loads triboactivation provides the occurrence of tribochemical reactions in the contact zone with a high negative chemical affinity. In case of wearless friction the energy of tibochemical reactions is sufficient to excite at least conformation transitions in structurally non-rigid molecules of the lubricant and other low-energy transformations.
10 citations
TL;DR: In this paper, small free oscillations of the physical pendulum supported by two balls lying on an elastically deformable surface have been studied theoretically for the case when the ball displacements are considerably smaller than the contact spot radius.
Abstract: Small free oscillations of the physical pendulum supported by two balls lying on an elastically deformable surface have been studied theoretically for the case when the ball displacements are considerably smaller than the contact spot radius The differential equation of oscillations is derived with account for the surface deformation and the deformation component of the friction force The deformation component of rolling friction is shown to be a particular case of internal hysteresis friction The coefficient of elastic rigidity of the support surface and the hysteresis constant are introduced Formulas for calculating the oscillation amplitude as a function of the time and the oscillation period as a function of the amplitude are derived
9 citations
TL;DR: In this paper, a technique of optimal design of experiments for determining the resistance to rolling of motor tires has been developed based on the mathematical model involving the second-order regression equation, and regression analysis of the test results of mass tires for which the external factors (the pressure in the tire, the load, and the rolling velocity) varied shows the essentially nonlinear dependence of the coefficient of resistance on the load.
Abstract: The technique of optimal design of experiments for determining the resistance to rolling of motor tires has been developed. It is based on the mathematical model involving the second-order regression equation. The regression analysis of the test results of mass tires for which the external factors (the pressure in the tire, the load, and the rolling velocity) varied shows the essentially nonlinear dependence of the coefficient of resistance to rolling on the load.
7 citations
TL;DR: In this article, the average temperature of the shaft of cylindrical bearing in the contact of shaft with bushing was determined and the coefficient κ 1 remained unknown in that formula.
Abstract: Paper [1] was published earlier in which formula (1.4) was given for the average temperature of the shaft of cylindrical bearing in the contact of shaft with bushing. The coefficient κ1 remained unknown in that formula. The present paper provides a method of its determination.
7 citations
TL;DR: In this paper, the contact problem for the elastic layer of an arbitrary thickness and the rigid cylinder with friction forces acting in the contact area is solved and the solution is analyzed and the applicability of the widely used solutions, i.e., the solution for a rigid cylinder and elastic half-space and for a thin elastic layer, are determined for the contact under consideration.
Abstract: The contact problem for the elastic layer of an arbitrary thickness and the rigid cylinder with friction forces acting in the contact area is solved and the solution is analyzed. Domains of applicability of the widely used solutions, i.e. the solution for a rigid cylinder and elastic half-space and the solution for a thin elastic layer, are determined for the contact under consideration. It is shown that for coatings from composite materials with a low elastic modulus both solutions can result in a significant error. Typical modes of the elastic displacement of the layer surface are given for different contact area width, Poisson’s ratio, and friction coefficient. The example of the calculation of the particular contact for the layer of the polymer composite with a low elastic modulus is presented.
7 citations
Abstract: A method of calculating nonlinear vibrational oscillations in mechanical contact systems with amplitude-dependent forces of hysteresis type is considered. The method is based on the representation of solutions of forced oscillation equation as nonlinear shapes corresponding to a model conservative system. Two-and three-dimensional dynamic characteristics of the principal and subharmonic modes of symmetrical tangential oscillations are obtained. Conditions under which friction contact oversteps the limits of the pre-sliding at force and kinematic vibrational loadings are specified. The results are compared to the Coulomb model of the friction force and this model is shown to be unsuitable for calculating contact oscillations with small amplitudes.
7 citations
TL;DR: In this paper, the average dimensionless wear rate and friction coefficient of the pendulum bearings are derived and the use of the bearings as seismic dampers of shell drilling rigs is described and characteristics of the frictional pendulum bearing are given.
Abstract: Frictional pendulum bearings have universal properties that can meet various requirements at service of buildings, bridges, and industrial constructions. The formulas for the average dimensionless wear rate and friction coefficient of the bearings are obtained. The use of the bearings as seismic dampers of shell drilling rigs is described and characteristics of the frictional pendulum bearings are given.
7 citations
TL;DR: The paper shows the results of tribological studies and clinical trials providing evidence that the patient’s blood serum can be used as an absolutely compatible lubricating fluid to restore the functions of the articular synovial medium.
Abstract: A concept is advanced and a structural diagram is shown of the synovial joint as an “intelligent” friction unit possessing the properties of a cybernetic system. The joint demonstrates a record-low friction coefficient and compensation of cartilage wear as a triboengineering material maintaining human locomotor activity for many years. It is provided with a feedback system with the sympathetic center controlling the lubricating conditions of the movable joint of the articular bone ends, the lubricating fluid composition, and the elimination of debris from the articular capsule. The main reason why the joint fails is insufficient lubrication due to disruption of the exchange between the bloodstream and the joint synovial shell inducing a deficit of the lubricating synovial fluid. The disruption of the exchange is compensated by injecting synovial fluid substitutes. The paper shows the results of tribological studies and clinical trials providing evidence that the patient’s blood serum can be used as an absolutely compatible lubricating fluid to restore the functions of the articular synovial medium.
TL;DR: In this paper, a numerical simulation was used to determine the meniscus and Van der Waals forces depending on the distance between the bodies in contact and theoretical dependencies were used when interpreting experimental data obtained with the contact adhesion meter.
Abstract: The condensation of water in the gaps between members of microelecromechanical systems and precision friction units is caused by the presence of water vapors in air. The formation of liquid meniscus induces an additional force and affects considerably other surface forces. Numerical simulation was used to determine the meniscus and Van der Waals forces depending on the distance between the bodies in contact. Theoretical dependencies are used when interpreting experimental data obtained with the contact adhesion meter. Different factors that affect surface interaction and the application of the proposed approach to micro-and nanotribology are discussed.
TL;DR: An analytical model for the calculation of the deformation component of a friction force in sliding of a hard spherical indenter on a viscoelastic material that is modeled as a Kelvin solid is constructed in this article.
Abstract: An analytical model for the calculation of the deformation component of a friction force in sliding of a hard spherical indenter on a viscoelastic material that is modeled as a Kelvin solid is constructed. The influence of mechanical properties of a material and slip velocity of an indenter on the contact characteristics and deformation component of the coefficient of friction is studied. An experimental method for estimation of deformation loss under friction of a high-elasticity material is proposed. A comparison of the results obtained with the use of theoretical model with experimental data is performed.
TL;DR: In this paper, a method for determining the microhardness of thin coatings by scratching was proposed, which was applied to determine the scratch width and the optimal load on the indenter.
Abstract: The method is proposed for determining the microhardness of thin coatings by scratching. Atomic force microscopy was applied to determine the scratch width and the optimal load on the indenter. Combined coatings 4 μm thick based on Ti, Cr, Mo2N, and alloy ZrHf obtained by the combination of electric-arc evaporation and ion nitridizing were studied. The combined coatings are shown to have better micromechanical characteristics compared to the nitride coatings deposited by the electric-arc evaporation of these refractory metals and alloys.
TL;DR: In this paper, the structure and regularities of deformation of surface layers on metals and alloys in friction were analyzed using speckle-interferometry, electron, optic, and atom-force microscopy.
Abstract: The methods of speckle-interferometry, electron, optic, and atom-force microscopy were used to study the structure and regularities of deformation of surface layers on metals and alloys in friction. The causes of deformation localization are analyzed. An explanation of the strong wear resistance of Hadfield steel is proposed using data on the evolution of the surface layer structure.
TL;DR: The conditions of operation of metal cutting tools in various applications and of various standard dimensions are analyzed in this article, and the main causes of failure of the tools have been established in response to the conditions of their operation and design features.
Abstract: The conditions of operation of metal-cutting tools in various applications and of various standard dimensions are analyzed. Long-standing statistical observations at a number of industrial facilities have revealed the dominating mechanisms of wear and the main causes of failure of the tools have been established in response to the conditions of their operation and design features. A range of tools has been selected for comparative durability tests in industrial conditions.
TL;DR: In this article, the local pattern of initial fracture of machine parts is discussed and the practical significance of determination of the zone of manifestation is highlighted and the temperature is considered the main factor in the process of improvement of the thermal friction problem governing operation of a heavily stressed contact.
Abstract: The local pattern of initial of fracture of machine parts is discussed and the practical significance of determination of the zone of manifestation is highlighted. The temperature is considered the main factor in the process of improvement of the thermal friction problem governing operation of a heavily stressed contact. The results of calculation of brakes with the method of thermal dynamics of friction and wear are demonstrated.
TL;DR: In this paper, a method of determining the temperature field under real conditions of the cutting of natural diamond monocrystals using a thermograph is described, and the advantages of the thermography over the method of artificial thermocouples are discussed.
Abstract: The paper describes a method of determining the temperature field under real conditions of the cutting of natural diamond monocrystals using a thermograph. The advantages of the thermography over the method of artificial thermocouples are discussed. The temperature distribution along the cutting direction is given and temperature kinetic dependencies are explained. It is shown that under severe cutting conditions the crystal temperature can reach values close to the diamond graphitization temperature. In those cases single large wear particles of diamond appear.
TL;DR: In this article, an analytical solution of the boundary heat conduction problem and the corresponding boundary thermoelasticity problem were obtained for the tribos system consisting of a semi-infinite base and a plane-parallel layer sliding over its surface.
Abstract: Analytical solutions of the boundary heat conduction problem and the corresponding boundary thermoelasticity problem are obtained for the tribosystem consisting of a semi-infinite base and a plane-parallel layer sliding over its surface. The kinetics of temperatures, heat flows, and thermoelastic displacements and their distributions in depth of the rubbing members are studied for the aluminum-steel pair.
TL;DR: In this article, the effect of polymer filler F-4MB on the properties of a composite based on polytetrafluoroethylene (PTFE) and magnesium nanospinel has been studied.
Abstract: The effect of polymer filler F-4MB on the properties of a composite based on polytetrafluoroethylene (PTFE) and magnesium nanospinel has been studied. The filler was found to exert a plasticizing effect on the polymer system. This promotes the formation of mobile interfacial layers, intensifies interfacial interaction between the composite components, and initiates a strong effect of nanospinel on strength and triboengineering characteristics of the composite. To provide adaptation of the polymer composite surface layer to frictional conditions, a plasticizing additive F-4MB is introduced during friction.
TL;DR: In this article, a macroscopic model of friction is presented which considers changes in elastic characteristics of the material caused by frictional heating and strain hardening, and a single act of contact between a microasperity made of a ductile hardenable material and the counterbody was calculated for various contact spot sizes.
Abstract: A one-dimensional macroscopic model of friction is presented which considers changes in elastic characteristics of the material caused by frictional heating and strain hardening. A single act of contact between a microasperity made of a ductile hardenable material and the counterbody was calculated for various contact spot sizes. It is shown that the contact spot size affects considerably the temperature, plastic deformation, and changes in the material elastic characteristics. Shears of surface layers relatively to the base material observed experimentally are explained proceeding from the modeling results.
TL;DR: The influence of additives containing coordination compounds of copper, zinc, nickel, and cobalt and ligands and complex ethers on lubricating properties of industrial, hydraulic, transmission, and motor oils is investigated in this paper.
Abstract: The influence of additives containing coordination compounds of copper, zinc, nickel, and cobalt and ligands and complex ethers on lubricating properties of industrial, hydraulic, transmission, and motor oils is investigated. It is shown that the insertion of these additives substantially increases the load of seizure and decreases the coefficient of friction and wear rate of tribological conjunction.
TL;DR: In this article, the tribological properties of the nanostructured 12%Co coatings deposited by the detonation method have been investigated and it was found experimentally that their wear resistance depends on the concentration of monocarbide WC.
Abstract: The study deals with tribological properties of the nanostructured WC-12%Co coatings deposited by the detonation method. It is found experimentally that their wear resistance depends on the concentration of monocarbide WC. The dependence of the WC concentration in the coating on deposition conditions is obtained. The microstructure of the coatings, their physical-mechanical properties, phase composition, porosity, hardness, and modulus of elasticity are studied. The advantage of the nanostructured coatings over the coatings deposited from micropowders is shown.
TL;DR: In this paper, it was shown that the apparent activation energy of seizure in friction against steel coated with carbon is by almost an order of magnitude higher than friction against uncoated steel.
Abstract: The apparent activation energy of seizure in boundary lubrication was calculated using the temperature-kinetic approach to the description of boundary lubrication. The tests were carried out with the ball-on-disc machine. The ball was made of chromium ball-bearing steel and the disc was made of stainless steel. Discs made of stainless steel coated with aluminum nitride and high-ordered polycrystalline carbon were also used. The pair was lubricated with model lubricants. It was shown that the apparent activation energy of seizure in friction against steel coated with carbon is by almost an order of magnitude higher than in friction against uncoated steel.
TL;DR: In this article, the effect of the sliding velocity and surface quality of the bodies on friction at the pre-sliding stage is studied, and a method of the precise determination of characteristics of presliding is developed.
Abstract: A method of the precise determination of characteristics of pre-sliding is developed. Standard equipment for the mechanical testing of materials is involved. The effect of the sliding velocity and surface quality of the bodies on friction at the pre-sliding stage is studied.
TL;DR: The dependence of the wear rate of WSe2-Ga/In coatings on the environment conditions (air, vacuum, temperature) and counterbody material is obtained in this paper.
Abstract: The dependence of the wear rate of WSe2-Ga/In coatings on the environment conditions (air, vacuum, temperature) and counterbody material is obtained. The formation of films in the friction contact zone is shown to occur owing to the transfer of individual lubricant components and their reactions with each other and with atmospheric oxygen.
TL;DR: In this article, the structure, phase composition, and tribological behavior of intermetallic Fe3Al alloy subjected to ion-beam nitriding at 670-870 have been studied.
Abstract: The structure, phase composition, and tribological behavior of intermetallic Fe3Al alloy subjected to ion-beam nitriding at 670–870 have been studied. The ion-beam treatment of the alloy proved to result in nitrogen-modified layers of up to 15–18 nm thick and microhardness up to 13200 MPa. The formation of nitride AlN phases with cubic and hexagonal lattices was registered in the nitrided layers. The formation of aluminum nitrides with the cubic lattice of NaCl structural type is shown to increase the wear resistance of Fe3Al alloy 25–28 times, and with the hexagonal one it increases 5–8 times.
TL;DR: In this article, the friction coefficient when fibrous composite material is rubbed against the homogeneous rigid material is calculated and the wear of the composite is taken into consideration in the calculation.
Abstract: We present the formulas for calculating the friction coefficient when fibrous composite material is rubbed against the homogeneous rigid material. The wear of the composite is taken into consideration in the calculation.
TL;DR: In this article, a hydrodynamic sliding bearing model was developed that takes into account the effect of the deformation of sliding surfaces on the bearing characteristics, and the deformed surfaces were determined when solving the problem of elastohydrodynamic contact of the journal and bearing with account for the pressure in the lubricating film.
Abstract: The model of a hydrodynamic sliding bearing has been developed that takes into consideration the effect of the deformation of sliding surfaces on the bearing characteristics. The deformations of the sliding surfaces are determined when solving the problem of elastohydrodynamic contact of the journal and bearing with account for the pressure in the lubricating film. Variation in the clearance size at the deformation of the bearing and shaft surfaces is found by iterations when solving jointly the problems of lubricant flow and working surface deformation. Elastic deformations of the working surfaces are calculated using a two-dimensional boundary element model and a three-dimensional finite element model of the shaft and bearing. The method of finite elements is applied to calculate the parameters of lubricant flow in the bearing based on the solution of Reynolds equation in the disturbed form. The rigidity and damping characteristics of the sliding bearing with the deformable surfaces are compared to those of the bearing with the rigid surfaces; the results of the two-dimensional model of bearing deformation are compared to those of the three-dimensional one.
TL;DR: The methods of drop spreading over the solid body surface and rotational viscosimetry have been used to explore the processes of structurization of lubricating material in this paper.
Abstract: The methods of drop spreading over the solid body surface and rotational viscosimetry have been used to explore the processes of structurization of lubricating material. It is demonstrated how the surfactants and superdispersed oil particles (artificial structurization nuclei) influence the evolution of these processes.