The aim of the article was to identify the effect of material hardness on the tribocorrosion process by comparing two material solutions. The analysis concerned the assessment of the process intensity and the identification of the mechanisms responsible for material loss. Possible mechanisms of tribocorrosion common for materials of high hardness were determined. Two classic material solutions (based on AISI 1045 steel) ensuring high hardness of the subsurface layers were tested: nitriding with an additional oxidation and impregnation process, and Physical Vapour Deposition (PVD) coating. In order to better identify the impact of hardness on the tribocorrosion process in each individual test, the pressures in the contact zone were increased. The tribocorrosion tests were carried out in 3.5% NaCl with free corrosion potential (OCP) for the ball-on-plate system. The results of the tribocorrosion tests presented in the article indicate that the synergy effect of friction and corrosion can be generated by the same mechanisms of material removal in both the material solutions tested. The intensity of these mechanisms is determined by material hardness. The likely mechanism of generating the synergy effect may be related to the formation of local pits along the friction path. The corrosion processes that are initiated by the cracking of the hard surface layer create local cavities, which most probably intensify frictional wear in successive time intervals. The area around the cavities facilitates plastic deformation, the initiation of cracking of the cyclically deformed layer and the tearing of larger pieces of material (especially at higher unit pressures in the frictional contact zone).

This article compares the rheological and tribological properties of three ionic liquids: Tributyl(methyl)phosphonium dimethyl phosphate 97%—MFCD, 1-Butyl-3-methylimidazolium hexafluorophosphate 97%—BMIMPF6, and 1-Butyl-3-methylimidazolium tetrafluoroborate 98%—BMIMBF4. Their density and kinematic viscosity at 20 °C and 40 °C were investigated, and tribological tests were carried out at the same temperatures with ball-on-disc contact. The test materials were made of 100Cr6 steel. A scanning electron microscope was used to image the wear tracks, while an EDS analyzer was employed to determine the chemical composition at the points of wear on the samples. A confocal microscope was used to analyze the geometric structure of the samples before and after the tribological tests. The results of the tests indicated that an increase in temperature reduced the dynamic viscosity of all the ionic liquids tested. At the same time, an increase in the MFCD and BMIMBF4 ionic liquid density and a decrease in the density of the BMIMPF6 ionic liquid were observed. The BMIMPF6 ionic liquid used for this study provided the lowest value of linear wear at both temperatures, ambient and 40 °C. However, for the BMIMBF4 ionic liquid, significant wear was observed for the tested discs and balls, with corrosive pitting on their surfaces.

This article demonstrated that environmentally friendly lubricants—glycerol–water-based oil (GWB) and rapeseed oil-based oil (RSB)—would provide comparable conditions (wear of node components, friction resistance) in a friction node as a commercial semi-synthetic gear oil (REF). Wear tests were performed on a block-on-ring model friction node stand using GBZ12 (CuSn12), BA1032 (CuAl10Fe3Mn2), and BA1054 (CuAl10Ni5Fe4) bronze samples. Glycerol–water-based oil (GWB) significantly reduced the wear of the samples by several times, compared to semi-synthetic oil (REF) and rapeseed oil-based oil (RSB). The (GWB) oil also provided a stable friction coefficient value at the lowest level of 0.05–0.06. The main disadvantage of the (RSB) oil was the temporary fluctuation of the friction coefficient value (increase above 0.1), which indicated the lack of stability of the boundary layer. The results highlight the potential of (GWB) oil in reducing wear and stabilizing friction under extreme conditions, supporting the shift toward sustainable lubricants in industrial applications.

This article defines the effect of surface roughness on a selection of tribological properties of systems withAlTiN coatings. Friction-wear tests were carried out on a tribological tester, which operates as a sphere anddisc assembly in a frictional, sliding motion. The tests were conducted under a load of 10 N over a frictiondistance of 1,000 m. Steel discs made of HS6-5-2C with an AlTiN coating and steel balls made of 100Cr6were used for the test Trials were carried out under lubrication conditions with polyalphaolefin oil PAO 8 andpolyalphaolefin oil containing 1.5% zinc dialkyldithiophosphate (ZDDP). The chemical composition of theAlTiN coating was studied using a scanning electron microscope, and the wear marks on the discs and sphereswere observed. The geometric structure of the samples was analysed before and after the geometric structureof the samples using a interferometer, and after tribological tests. Research has shown that surface roughnessaffects tribological properties. For samples with a higher surface roughness (Sa = 0.61 μm) – unpolished discs– lower linear wear values were obtained than for polished discs (Sa = 0.08 μm). After the introduction of thePAO 8 additive with ZDDP, a reduction in linear wear of 33% and 24% was observed for both polished andunpolished surfaces, respectively.

This paper examines the impact of incorporating the 1-Butyl-3-methylimidazolium hexafluorophosphate(BMIMPF6) ionic liquid into PAO 8 polyalphaolefin oil on the tribological characteristics of the steel-steelsystem lubricated with this oil. Friction-wear tests were carried out on a tribological tester operating as aball and disc assembly in a frictional motion. Tests were carried out with a load of 10 N over a slidingdistance of 1,000 m. 100Cr6 steel discs and balls were used in the tests. The tests were carried out underlubrication conditions with the BMIMPF6 ionic liquid, PAO 8 poly(α)olefin oil, PAO 8 poly(α)olefin oil withthe addition of 1% and 10% BMIMPF6 ionic liquid. Following the tribological tests, both discs and balls weresubjected to microscopic observation with a view to analysing the microstructure and geometric structure ofthe surface at the wear track. The study found that the quantity of ionic liquid incorporated into the PAO 8oil has a discernible influence on the tribological characteristics of 100Cr6 steel. Adding a lubricant with 1%of BMIMPF6 in PAO 8 to PAO 8 containing 10% of BMIMPF6 increased the coefficient of friction valueby approximately 26% and lowered disc wear by approximately 43%. In contrast, the analysis of ball wearrevealed that the lowest level of wear was observed in the 1% concentration of BMIMPF6 in PAO 8, whilethe highest level of wear was observed in PAO 8 oil.