Vol 40, No 1 (2019)

The embedding of ethanol amines and cholestetic liquid crystal nanomaterials is experimentally found to improve the screening effect of general-purpose calcium plastic lubricants. A particular enhancement of this effect is pronounced in plastic lubricants where conventional industrial oils as the dispersion medium are replaced by petroleum refining products, such as petroleum vacuum distillates, which have been exposed to no special purification. This is due to the fact that petroleum vacuum distillates are based on the active naphthenic acids that form the boundary lubricant layers with high screening properties upon interaction with ethanol amines and cholesteric liquid crystal nanomaterials, which ensure the lower friction and wear of conjugated surfaces.

Poly(arylene ether ketone)s containing pendent bulky cardo groups in the monomer unit, while having a high antifrictionality, do not obey the earlier established regularity of the relationship between chemical structure and friction. The necessity of taking into account the flexibility of macromolecules is an additional factor for these polymers. To XPS study the tribochemical processes of carded polymers, “flexible chain” and “rigid chain” copolyarylene ether ketones (co-PAEKs) were used. It was found that the flexible moieties of the macromolecule favor a decrease in the friction coefficient and an increase in the wear resistance. Impaired tribochemical indices of the rigid cardo polymer are caused by active tribodestruction of phthalimidine groups.

The effect of residual stresses that arise during the treatment of friction-pair surfaces by various techniques on the rate of damage accumulation caused by contact fatigue is considered for cyclic loading of bodies under rolling friction. It is assumed that the rate of damage accumulation is a function of the peak values of the principal shear stresses that arise in the surface layers of the material under deformation. The influence of the relative slippage, sliding friction coefficients, and value of residual stresses on the distribution of the peak values of the principal shear stresses is analyzed. The results are used to study the effect of the residual stress field in the subsurface layers of the material due to surface treatment on the rate of damage accumulation from contact fatigue.

The main types of available mechanical seals are considered briefly. The operating conditions of a membrane contact mechanical seal with a stationary secondary seal are analyzed. The design procedure of friction torque of the seal under consideration is presented for the example of a pumping unit feeding the fuel components of the steering assembly of LRE.

A software program has been developed that allows prediction by computer-based simulation of the thermal resistance of the contact between rough surfaces including those furnished with functional coatings. The proposed model was validated by comparing the results of numerical simulation with calculated and experimental data. The results can be used to design thermally stressed rough-surfaced junctions.

The results of theoretical and experimental investigations of the interaction between the working surfaces of wheel treads of open-pit locomotives with rails are presented. The actual values of the height of microroughness when profiling the working surface of the rail head for reducing the running-in period of the wheel–rail system are determined, which positively influences increasing the adhesion coefficient and economic operation life of industrial railway transport. The optimal value of the height of microroughnesses of the interacting surfaces under rail-grinding, which can be within R_z = 40–20 μm, is determined. Guaranteeing the optimal height of microroughnesses of the working surfaces of the wheel–rail system, in turn, will make it possible to calculate the predicted design value of the friction coefficient of the wheel tread of the open-pit locomotive with the rail.

A method for forming an exact self-similar solution to the problem of hydrodynamic calculation of a radial plain bearing that operates in a steady-state friction mode in the presence of a lubricant has been constructed. Based on the equation of motion for a viscous incompressible electrically conducting liquid in the case of a “thin layer,” the continuity equation, and expressions for the dissipation rate of mechanical energy, an analytical relationship for the molten surface profile of fusible coating on a bearing bush taking into account the viscosity and electrical conductivity of a liquid lubricant depending on pressure is obtained. The effect of the parameters characterizing the dependence of viscosity and electrical conductivity on pressure and the effect of a parameter caused by melting the fusible coating surface of the bearing bush exerted on the bearing capacity and friction force are demonstrated.

The mechanical and tribological properties of the steel Hardox 400 after electro-spark deposition (ESD) using electrodes made of hard-alloy carbides T15K6 (79% WC + 15% TiC + 6% Co), WK6 (94% WC + 6% Co), and composite materials based on iron such as 12S2 (12% Ni + 2% Si + 15% Cr₃C₂ + 71% Fe), K4F (15% WK3 (97 WC + 3 Co) + 4% Cr₃C₂ + 1% V + 80% Fe), and tungsten disilicide WSi₂ (76.6% W; 23.4% Si) have been studied. The energy parameters (the energy of pulsed discharges, the amplitude and repetition rate thereof) and technological parameters (the type of processing electrode motion, vibration or vibration/rotation) for the ESD process, as well as the electrode composition at which the highest quality surface layers with high wear resistance is observed, have been optimized. The effect of the energy and technological parameters of the ESD process exerted on the properties of the coatings obtained has been determined. The studies have shown that coatings of WC–TiC–Co and WC–Co applied onto steel Hardox 400 exhibit a twofold decrease in abrasive wear. At the same time, it has been found that the wear resistance of composite coatings is sufficiently affected by the application modes (up to a 2.5-fold decrease in the wear level), and the coatings made of composites 12S2 and K4F are competitive with respect to coatings made of hard alloys based on tungsten carbides.