We describe the external and internal hydrogen interaction on contacting surfaces in the “cylinder–piston rings” friction coupling. Under the influence of high temperatures and pressure, the oil in the combustion chamber at a temperature up to 1473 K decomposes and forms small amounts of water. External hydrogen (H₂) is subsequently formed. Hydrogen removal from the piston rings reduces the heterogeneity of the structure, residual stresses, and uneven physical and chemical properties of the near-surface layers, which reduces the stress concentration and, as a consequence, results in an improvement in the performance characteristics of the surface layers of the friction couple “cylinder-piston rings” of the spark ignition engine.

The article is devoted to the following issues: boiling of fluid in the cooling jacket of the engine cylinder head; agents that influenced the thermal conductivity coefficient of nanofluids; behavior of nanoparticles and devices with nanoparticles in the engine’s cylinder head cooling system. The permissible temperature level of internal combustion engines is ensured by intensification of heat transfer in cooling systems due to the change of coolants with “light” and “heavy” nanoparticles. It was established that the introduction of “light” nanoparticles of aluminum oxide $A{l}_2{O}_3$ $A{l}_2{O}_3$ into the water in a mass concentration of 0.75% led to an increase in its thermal conductivity coefficient by 60% compared to the base fluid at a coolant temperature of 90 °C, which corresponds to the operating temperature of the engine cooling systems. At the indicated temperature, the base fluid has a thermal conductivity coefficient of 0.545 $\frac{W}{\left(m^2\times °\mathrm{C}\right)}$ W/(m °C), for nanofluid with $A{l}_2{O}_3$ particles its value was 0.872 $\frac{W}{\left(m^2\times °\mathrm{C}\right)}$. At the same time, a positive change in the parameters of the nanofluid in the engine cooling system was noted: the average movement speed increased from 0.2 to 2.0 m/s; the average temperature is in the range of 60–90 °C; heat flux density 2 × 10²–2 × 10⁶ $\frac{W}{m^2}$; heat transfer coefficient 150–1000 $\frac{W}{\left(m^2\times °\mathrm{C}\right)}$. Growth of the thermal conductivity coefficient of the cooling nanofluid was achieved. This increase is determined by the change in the mass concentration of aluminum oxide nanoparticles in the base fluid. This will make it possible to create coolants with such thermophysical characteristics that are required to ensure intensive heat transfer in cooling systems of engines with various capacities.

This study discusses the effect of a duplex aging + nitriding process on the wear resistance of an aged double-phase titanium alloy, BT22. Nitriding was applied simultaneously with the heat treatment of the alloy, which is advantageous over the conventional heat and surface treatment methods applied to titanium alloys. According to the results, the thickness of the case depth of the nitrided samples was 40–50 μm. Moreover, nitrogen was uniformly dispersed in the substrate, which was indicated by the hardness tests. The average microhardness of the substrate material was 300 HV_0.01, while the hardness of the top layer was 1190 HV_0.01, which is an almost four-fold increase. The applied duplex treatment substantially affected the wear performance of the tested alloy. For the untreated alloy, the maximum coefficient of friction was 0.8, while in the surface-modified sample, the maximum fluctuations reached 0.6. The abrasive wear process was dominant in the nitrided samples, while delamination and adhesive wear were observed for the untreated specimens. The nitrided alloy exhibited double the wear resistance of the untreated samples. The proposed treatment does not require additional time or energy consumption, providing a substantial technological advantage over conventional methods. Though the alpha case reduces the mechanical performance of titanium, the nitriding of only the component sections intended to withstand friction will have a positive effect.

Textured surfaces with partially regular micro relief (PRMR) are reported to be an effective means to control lublication. It was found they are good wear debris trap and suppliers of lubricant directly to the actual friction area. Their tribological properties depend on the clearance between mating surfaces, relative slip speed, direction of motion. These parameters change the lubrication regime, and vice versa changing geometry of PRMR it is possible to predict and control lubrication regime for given conditions. Application of micro textured surface is prospective for high precision sliding units – valve slides of oil and hydraulic systems, faces of gear pump gears, ring-to-cylinder interface of aircraft reciprocating engines etc. providing high service life. On other side, changing texture parameters it is possible to stop the leakage of fluid through the gap, what may be efficiently utilized in aircraft non-contacting mechanical (hydrodynamic and hydrostatic) seals of gas compressors and gear mechanisms. This paper discloses some peculiarities of transition lubrication regimes for textured surfaces in lubricated contact.