Formation of a surfactant adsorption layer on microroughnesses of friction surfaces

Formation of an adsorption surface layer on microneralities of friction surfaces. The model of interaction of the molecule of surface-active substance with the microasperity of friction surface has been given. It has been found that the distance of interaction and the thickness of an adsorbed layer of surface-active substances depend on value of a field of an adsorbing surface and energy of thermal oscillations of molecules of surface-active. It has been shown that the distance of interaction and the thickness of an adsorbed layer of surface-active substances decrease at magnification of temperature of working liquid.

Improvement of the tribological properties of heavy-loaded friction units “Centre block-footstep bearing” of a freight car

Various problems and different approaches of solution of such a problematic unit as “centre block-footstep bearing” of freight cars are discussed in the paper. The methods of improving the tribological properties of this friction unit by means of material modification of friction surfaces and perfection of physical, chemical and tribological properties of the used lubricants were studied. Grease lubricants common for friction units of railway machinery were used after being modified with inorganic polymers based on double metaphosphates. Bench and operational tests of the developed additive of the polymeric double metaphosphates were carried out. This additive reduces wear and increases the service life of the friction unit, due to the better adhesion properties of this additive. The variants with a change in the geometry of the contact surface of the disk between the bolster and the “centre block-footstep bearing” arrangement of the car are considered. Simulation of the parameters of movement in curved sections is proposed.

Enhancement of the Mechanical and Tribological Properties of Aluminum-Based Alloys Fabricated by SPS and Alloyed with Mo and Cr

Multicomponent aluminum-based alloys doped with chromium (Cr) and molybdenum (Mo), fabricated by spark plasma sintering (SPS), derived from a powder mixture prepared by mechanical alloying, were studied in this work. The morphology of the pristine and worn surfaces was analyzed using a scanning electron microscope equipped with an energy-dispersive X-ray spectroscopy system. The obtained alloys exhibited higher hardness (73 and 72) for the Al–Mo and Al–Cr alloys, respectively, compared to reference bronze. Besides improved hardness, SPS-sintered alloys also showed a lower value of the weight and linear wear and the highest score-resistance compared to bronze. The enhanced tribological behavior is related to the formation of secondary structures on the friction surfaces of rubbing pairs, which in turn reduce wear. For the first time, the present research has demonstrated the effectiveness of the addition of Mo and Cr for the fabrication of sintered multicomponent Al-based alloys with a tailored microstructure that induces the formation of secondary structures on the tribosurfaces due to the self-organization processes during friction.

Influence of Hydrogen-Containing Fuels and Environmentally Friendly Lubricating Coolant on Nitrogen Steels’ Wear Resistance for Spark Ignition Engine Pistons and Rings Kit Gasket Set

In this study, modern nitrogen steels used for the manufacture of rings for Honda engines (70CC, 90CC, CRF70F, XL70, XR70, C70, CT70, ATC70, CL70) as well as other transport tribotechnical units was investigated. Due to the present ecological situation in the world, new environmentally friendly lubricating fluids for nitrogen steels’ tribotechnical units and surface treatments have been proposed. The results of tribotechnical tests are presented in the form of diagrams, graphs and step polynomials obtained by mathematically describing the changes in wear intensity when the load changes for different lubricating fluids. Friction pairs were compared with ShellHF-E 46 (synthetic lubricating fluid), ShellHF-R (biological origin) and lubricating and cooling liquids with 1%, 3% and 5% vegetable oil concentrations. In tribocoupling it was found that hydrogen diffuses into the metal because the tribodestruction of lubricating coolants plays an active role in the destruction of friction surfaces.

Operational characteristics of new biological lubricants

The lubricating characteristics of ultrathin interlayers of bio-oil RMO made from coastal algae P.Moriformis are investigated in this work. One of the most important qualities of the oil is its lubricity of the friction surfaces. It determines the possibility of formation of a stable separating film between contact surfaces, with orientational ordering in wall adjacent layers, with the strength value required in the boundary friction regime. The structural characteristics of such epitropic-liquid crystal (ELC) layers are essential when choosing a lubricant. Static friction pair was studied by the optical method of admixtured absorption dichroism. It was found that the value of the order parameter of ELC layer and its equilibrium thickness are much higher in compare with the layers of aliphatic hydrocarbons, which are the basis of modern mineral lubricants. The rheological characteristics of ultrathin interlayers were studied in a dynamic triad of friction. Processing of the effective viscosity coefficient dependence on the shear rate, interlayer thickness and temperature allowed us to estimate the value of equilibrium thickness of the ELC layer, which coincides with the results of optical measurements. The marked structural peculiarities of the ELC in the biooil interlayers are conditioned with the formation of molecular associates of oleic acid, which is the main component of studied oil.

Research of the frictional interaction of a powder coating and a metal counterbody during sliding friction

Methods of metallographic analysis and profilometry are used to study the friction surfaces of wear-resistant coatings with CоAl2O4 and CuAl2O4 modifying additives of ultradispersed spinels during sliding friction with counterbodies made of VK6 hard alloy and St6 steel. To describe the frictional interaction of a powder coating with a metal counterbody during steady-state wear, a statistical model is developed based on the binomial distribution of removed particles. Keywords: coating, counterbody, sliding friction, frictional interaction, wear, statistical modeling, binomial distribution. [email protected]

Torque capacity of multidisc wet clutch with reference to friction occurrence on its spline connections

In this article developed mathematical model that includes friction occurrence on spline connections is presented. The work also contains results of experimental research on torque capacity of multidisc wet clutch. These results are expressed as a function of contact pressure for different number of friction surfaces. Due to increased interest in research concerning multidisc wet clutches it is essential to determine impact of friction on fit connections on transmitted torque. Analytical calculations that include both known loss coefficient and assumed lack of friction on fit connections are compared to results of experiments. The paper contains detailed description of test stand and methodology of experiment. As a result of conducted tests it was found that correction coefficients known from literature are highly inaccurate. Measured values of torque indicate that transmitted torque reach significantly higher values. It was also revealed that after slippage appeared, the pressure plate usually moved in the direction of exerted clamping force, but movement in reversed direction also took place for some experiments. While movement corresponding to clamping force reached ca. 0.08 mm, in opposite direction amounted to 0.02 mm. Furthermore, studies presented that lapping of adjacent friction surfaces greatly affects differences between respective results obtained for a specific experiment.

ESTIMATION OF THE EFFICIENCY OF THE LUBRICATION OF THE WORKING SURFACES OF THE SADDLE-COUPLING DEVICE OF THE FOREST TRUCK

The importance of the need for further constructive improvement of fifth-wheel couplings of timber tractors with semi-trailers has been substantiated. The main operational factors arising during the movement of a timber tractor with a semitrailer in the process of hauling timber and affecting the premature failure of the main parts of the fifth wheel coupling are considered. The influence on the resource of the fifth wheel coupling device of strict fulfillment of the mandatory operations of periodic lubrication of the saddle and the base plate of the semitrailer in the process of connecting and disconnecting it with a timber tractor is given. Described is the actual problem associated with excessive consumption of lubricant in the process of applying it to the friction surfaces of the saddle and the base plate of the semitrailer by the traditional method of extrusion. A possible method of dosed supply of the required volume of lubricant through the optimal number of lubrication holes to the friction surfaces is considered, which makes it possible to significantly reduce the cost of maintaining the operable state of the fifth wheel coupling. In order to preliminary evaluate the application of this lubrication method, which ensures the effective functioning of the fifth wheel coupling of a timber tractor with a semitrailer, several series of computer experiments were performed to determine the optimal number of lubrication holes in the saddle that evenly and dosed distribute the lubricant between the saddle and the base plate of the semitrailer.