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Corn oil biodiesel blends containing CuO nanoparticles were tested for their tribological properties in this research. The prepared biodiesel blends along with nanopowders are blended with 20W-40 lubricant. The aim was to explore the potential of these blends as lubricants in various mechanical systems. A pin-on-disk system was used to perform the tribological experiments, with each of the discs subjected to a different load. Including CuO nanoparticles into the biodiesel blends resulted in enhanced friction and wear properties. When compared to pure biodiesel, the addition of 100ppm CuO decreased the coefficient of friction by as much as 80% and the wear rate by up to 75%. These findings demonstrate the potential of using corn oil biodiesel blends with CuO nanoparticles as environmentally friendly lubricants in various industrial applications. [ABSTRACT FROM AUTHOR]

Potatoes are one of the most important agricultural products due to their great nutritional and industrial value. However, the mechanization of this crop is low in many countries. The main aim of this investigation was to characterize the Fianna potato variety. The potatoes were characterized morphologically (polar diameter, equatorial diameter, thickness, geometric diameter, arithmetic diameter, sphericity, and weight), mechanically (static friction coefficient, rolling angle, and axial compression), and by impact and firmness tests. The sample potatoes were distributed into four groups (S1, S2, S3, and S4) according to their size. A random complete blocks design was used to determine the mean values of their characteristics. The results of the physical characteristics showed a higher coefficient of variation in the S1 group. All values tended to decrease except sphericity. The results of the mechanical tests show that the coefficient of static friction increases as the size of the potato decreases, while the relationship of the rolling angle was the opposite. The axial compression results showed values that decreased from Group S1 to Group S4 except for Young's modulus, which ranged from 1.306 to 3.697 MPa in the four groups. Determining these data is necessary because they represent design parameters useful for the development of mechanical equipment. [ABSTRACT FROM AUTHOR]

Ceramics are considered to be candidate materials for galvanising pot bearing materials due to their excellent corrosion resistance in many molten metals. Galvanising pot roll bearings must have excellent wear resistance, and, therefore, it is important to understand the wear behaviour of prospective bearing materials. This study investigates the friction- and wear-resistant properties of select ceramics, namely, pure hBN, BN M26, AlN-BN, Macor, 3YSZ, Al2O3 and Si3N4. The ceramics were tested at different sliding speeds using a pin-on-disc device equipped with SiC pins. The lowest coefficient of friction (COF) achieved was below 0.1, and it was measured for pure hBN at a 3.14 m/min sliding speed. However, a wear scar analysis showed that the BN grades suffered from severe wear. The highest wear rate was obtained for BN M26 at a 9.42 m/min sliding speed and was equal to 17.1 × 10−6 mm3 N−1 m−1. It was shown that the wear coefficient of the tested ceramics varied exponentially with hardness. The lowest wear was observed on the 3YSZ, Al2O3 and Si3N4 ceramics, which showed no volume loss, and, for this reason, they can be potentially used as bearing materials in continuous galvanising lines. [ABSTRACT FROM AUTHOR]

In the current study, the friction and wear properties of Furcraea foetida fiber‐reinforced epoxy composites were investigated. This study evaluated the effect of Furcraea foetida fiber content on the tribological behavior of composites. A water‐retting method was employed to extract the fibers, and resin transfer molding was used to fabricate the composites. The frictional force, coefficient of friction (COF), and wear rate were measured under dry test conditions and various applied loads (80, 100, 120, and 140 N). Microstructural analysis was conducted using scanning electron microscopy to investigate the surface morphology and wear mechanisms of the composites. The results revealed that the composite with 50 vol% of fibers exhibits the lowest frictional force and COF in both normal and parallel orientations with overall average COF of 0.43 in normal orientation and 0.42 in parallel orientation. Moreover, the composite with 60 vol% demonstrates the best wear resistance with an overall average specific wear rate of 2.1982 × 10−5mm3/Nm in normal orientation and 4.3478 × (10−5) mm3/Nm in parallel orientation. Overall, this study provides valuable insights into the tribological behavior of Furcraea foetida fiber‐reinforced epoxy composites and identifies the optimal volume fractions for improved friction and wear performance. Highlights: Higher vol% yields denser composites with minimized voids.Normal fiber orientation shows maximum SWR of 10.0614 × (10−5) mm3/Nm.Optimal frictional force and COF in 50 vol% composite.Enhanced wear resistance observed in 60 vol% composite.Higher vol% increases interfacial bonding and wear resistance in composites. [ABSTRACT FROM AUTHOR]

One-step chromium incorporation into TiO2 films was performed by an electrochemical anodizing process, using HCl as anodizing base solution and K2Cr2O7 as chromium precursor salt. Due to the corrosion process that arises from the use of high concentrations of HCl, the preparation of two different electrolytes was considered in order to carry out the anodizing and doping: one with ethylene glycol and the other with glycerol. Energy dispersive spectroscopy confirmed the presence of chromium in the elemental composition of the synthesized films, which reached a maximum value of 1.42%. The FE-SEM analysis revealed that the presence of chromium modified the characteristic nanotubular morphology into compact nanometric grains. X-ray diffraction patterns demonstrated that chromium integration into the structure facilitated the transition from anatase to rutile after annealing at 700°C. The presence of chromium improved hardness, since the values obtained from the doped samples exceeded those obtained from titanium and TiO2 without doping. After annealing at 700°C, the sample with the highest amount of chromium reached a hardness value of 7.6 GPa. The microtribological analysis highlighted the improvement of the coefficient of friction for samples with chromium addition, as well as of film resistance to fracture during the tests. [ABSTRACT FROM AUTHOR]

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This paper presents the results of tests of EPAN coatings, a composite material based on carbon–carbon fibers. It uses fine molybdenum disulfide as the main lubricant and for binders, phenol, peroxide, and silicone resins. The tests were carried out on microarc oxidation (MAO) coatings. For comparison, the tribological characteristics of EPAN under friction on steels, as well as molybdenum disulfide composites are given. The friction coefficients of EPAN coatings on MAO coatings according to the "shaft–bushing" scheme do not exceed 0.05 at pressures of 10–20 kg/cm2 and shaft rotation speeds from 130 to 600 rpm. The advantage of such combinations of materials is the use of a light alloy, aluminum with MAO coating, for the counterbody to the EPAN coatings, which is important for space products. The creation and testing of solid lubricating coatings for modern space technology is a task of extreme importance, because in many developments of space products, low-temperature plastic lubricants continue to be used, which are operable up to subzero temperatures of –90 to –110°C. Such solutions require the use of thermal insulation and heating for mobile interfaces and friction units of machines, mechanisms, and devices. The result is a serious complication of structures and an increase in their weight. The tests of EPAN coatings on MAO coatings carried out in the work open new possibilities in the combination of materials for space technology. Having a coefficient of friction of 0.05 and high wear resistance, they allow you to create movable joints, first of all, sliding bearings, for operation on Earth sensing satellites, as well as mechanisms on the Moon. [ABSTRACT FROM AUTHOR]

The fretting wear and adhesive wear resistance of Al and Fe-based thin solid films deposited onto MDN121 steel are studied. Plasma-assisted cathodic arc evaporation technique (P-CAE) is used to develop AlCN/AlC and FeCrN monolayer coatings. The coatings and wear tracks are characterised by FESEM-EDS, nanoindentation, Raman spectroscopy, optical profiler, and confocal microscope. The results reveal that during fretting and adhesive wear, tracks are investigated using confocal microscopy and electron microscopy. When fretting wear occurs, the Coefficient of Friction (COF) dramatically decreases for AlCN/AlC thin solid films by 48.65% and for FeCrN thin solid films by 62.16% when compared to the substrate. FeCrN coating exhibits lower volumetric wear loss than AlCN/AlC coating. The wear surface morphology of both monolayer coverings against galling failure in the substrate exposes the abrasive form of the fretting wear process. Thin solid films of AlCN/AlC and FeCrN experience a COF reduction during adhesive wear of 40.89% and 56.22%, respectively, in comparison to the substrate. The FeCrN monolayer coating exhibits low friction and wear rate compared to AlCN/AlC monolayer coating. [ABSTRACT FROM AUTHOR]

The paper presents the results of mathematical modeling of tribosystems running-in processes when various factors are changed: design parameters of tribosystems, which are taken into account by the form factor; tribological properties of the lubricating medium; rheological properties of composite materials in the tribosystem; roughness of friction surfaces; load and sliding speed. By comparing the theoretically obtained results, by modeling according to the developed models, with experimental data, it was established that the mathematical model adequately reflects the running-in processes taking into account the changes in constructive, technological and operational factors. Applying the Cochrane criterion, it was established that the obtained experimental results are homogeneous and reproducible. The maximum value of the coefficient of variation of the values of the volumetric wear rate and the coefficient of friction is within the limits v = 12,3 - 26,5%. The value of the simulation error is within the limits v = 7,7 - 12,9%. A rating of factors that maximally affect the processes of running-in of tribosystems in the conditions of extreme lubrication has been obtained. In the first place is the roughness of the friction surfaces, the coefficient of variation v = 26,5%. In the second place – the load on the tribosystem during running-in, the coefficient of variation v = 20,8%. In third place is the value of sliding speed during running-in, the coefficient of variation v = 18,6%. The conclusion made must be taken into account when developing a rational program for running-in tribosystems in conditions of extreme lubrication. The methodical approach of applying the acoustic emission method in the study of tribosystem running-in processes is presented. It is proved in the work that in order to determine the volume rate of wear during tribosystem running-in, it is necessary to register and analyze the fourth cluster from the general acoustic emission signal. The sources of signal generation of the fourth cluster are microcutting and plastic deformation of protrusions of the roughness of the friction surface, which is characteristic of the first stages of running-in.

The tribological behavior of titanium dioxide (TiO2) filled with jute fiber reinforced interpenetrating polymer networks (IPNs) were studied by using a pin-on-disc wear test rig at dry slide conditions. During the study, 70 wt.% of epoxy and 30 wt.% of polyurethane have been chosen as the base matrix material. As well, various proportionate of titanium dioxide such as 0%, 3% and 5% have been utilized to fabricate the particulate reinforced IPN laminate. To do the wear analysis such as materials type (A), sliding speed (B) and applied loads (C) were kept as the influencing parameters whereas coefficient of friction (COF) and specific wear rate (SWR) have been seen as the outcome of the entire study. Taguchi technique was chosen to plan the entire experiments. Similarly, an orthogonal array and analysis of variance (ANOVA) was employed to examine the impact of process parameters on wear of the IPN laminate. Out of all, results show that, addition of particulate materials into the composite predominately increased the specific wear resistance of the IPN laminate significantly.

A technology has been developed for preparing a suspension and deposition of a coating to the surface of ultra-high molecular weight polyethylene (UHMWPE) samples. After deposition of a graphene oxide layer onto the sample surface, the sample was treated in helium plasma at low pressure to stabilize and crosslink the deposited layer. It has been experimentally shown that the deposition of a graphene oxide coating on the surface followed by UHMWPE plasma treatment reduces the dynamic coefficient of sliding friction by more than three times (from 0.092 to 0.027), but no significant increase in adhesion of graphene oxide layer due to plasma treatment was observed.

We performed a gas nitriding and quenching process (GNQP) on Ti–18 mass% Nb alloy to obtain a high damping capacity and wear resistance. GNQP was performed at temperatures of 1023, 1123, and 1223 K. The outermost surface of the GNQP specimen obtained at 1023 K mainly comprised TiO2, whereas that at 1223 K mainly comprised TiN. The surface and interior of the specimens exhibited higher hardness at 1223 K than that at 1023 K. Compared to the specimen obtained by solution–quenching (AQ), the unit volume of the α” martensite phase at a depth of 320 μm of the GNQP specimen obtained at 1023 K was similar, and that at 1223 K was higher. Such a difference can be related to the difference in the core hardness of the specimens. The wear amounts of all GNQP specimens were lower than those of the AQ specimen. The coefficient of friction of the GNQP specimen obtained at 1023 K was lower than that obtained at 1223 K. The surface constituent phase and surface roughness exhibited a strong influence on the wear at a load of 500 g. Meanwhile, the nitride layer and damping capacity were considered to be related to the wear at a load of 3000 g.

The study explored the viability of using waste plastic oil (PO) as an alternative lubricant to petroleum-based lubricants in industrial settings. To enhance the lubrication performance of the PO, this study incorporated cost-efficient, oleic acid-modified, graphene nano platelets [GNP (f)] and hexagonal boron nitride [hBN (f)] nano solid lubricant additives into the PO in various concentrations, forming functionalized nano lubricants. The PO and its functionalized nano lubricant’s rheological, dispersion stability, thermal degradation, friction, and wear performance were investigated. Results manifest that incorporating GNP (f) and hBN (f) into the PO significantly enhanced the viscosity and dispersion stability. In addition, it was seen that GNP (f) and hBN (f) nano lubricants lowered the coefficient of friction (COF) by 53% and 63.63% respectively, compared to the PO. However, the GNP (f) and hBN (f) nano lubricants demonstrated a 3.16% decrease and a 50.08% increase in wear volume relative to the PO. Overall, the GNP (f) and hBN (f) nano lubricants displayed a synergistic friction behavior, while they exhibited an antagonistic behavior pertaining to the wear volume. The study elucidated the mechanisms underlying friction and wear performance of the nano lubricants.

The purpose of this study is to examine the effect of different temperatures and sintering times on the microstructure, density, hardness, bending strength, coefficient of friction (COF), fracture toughness, and abrasion rate of Cf/Si3N4 fabricated via the spark plasma sintering (SPS) technique. For this target, the α phase of Si3N4 powder was prepared alongside sintering aids and carbon fiber. Next, five samples were sintered via SPS method at temperatures 1750 °C, 1800 °C, and 1850 °C, under the pressure of 70 MPa, and times of 10, 15, and 20 min. The obtained data illustrated that with an elevation of the sintering temperature from 1750 °C to 1850 °C, the density of the sintered body increased from 91.11 % to 93.03 %, and the hardness rose from 536 to 916 Vickers. Furthermore, upon prolonging the holding time from 10 min to 20 min, the density was enhanced from 93.03 % to 96.53 %, and hardness improved from 916 to 1433 Vickers. The results showed that with an elevation of temperature and time of sintering, the abrasion rate dropped from 14.4 × 10-7 to 4.4 × 10-7 g/N.m due to reducing the porosity of the sample. Finally, with a temperature rise from 1750 °C to 1850 °C, the bending strength of the samples decreased.

Determining an accurate state of lubrication is of utmost importance for the precise functionality of machine elements and to achieve elongated life and durability. In this work, a homogenized mixed-lubrication model is developed to study the effect of surface topographies on the coefficient of friction. Various measured real surface topographies are integrated in the model using the roughness homogenization method. The shear-thinning behavior of the lubricant is incorporated by employing the Eyring constitutive relation. Several Stribeck curves are generated to analyze the effect of roughness lays and root mean square (RMS) roughness on the coefficient of friction. The homogenized mixed lubrication model is validated against experimental rolling/sliding ball-on-disc results, and a good agreement between simulated and experimental coefficient of friction is found.

Background. Modern requirements for passenger cars include a number of main directions: efficient use of energy, improvement of environmental indicators, improvement of operational characteristics. The use of variator gearboxes has significantly improved the energy efficiency and environmental performance of the car due to optimal engine performance. However, the disadvantage of variators in comparison with manual transmissions is still insufficient efficiency, which does not allow competing with “mechanics” due to low performance characteristics. Since the variator is a friction mechanism, a way to increase the efficiency of its operation is to change the coefficient of friction in friction pairs. One of the options for such modernization is the creation of a regular microprofile on the surface of friction pulleys, namely– undulations. The actual contact spots formed by the undulation provide sufficient traction of the variator transmission and minimize power loss. The object of the study is the relationship between power indicators and the quality of the surface layer of friction elements of a continuously variable transmission. The subject of the study is an adequate assessment and provision of the power parameters of a continuously variable transmission, by ensuring the surface quality parameters of the drive pulley of the variator. The purpose of the study is to develop a technique for providing power indicators of a variator transmission by creating a wavy microprofile based on the mechanics of contact interaction. Materials and methods. The theoretical and experimental research carried out in the work is based on the study of literature, conducted research and the experience of practicing technologists. Results. The empirical dependence of the prediction of the coefficient of friction at normal wear depending on the parameters of surface quality is analyzed. It is shown that the parameters of the undulation of the surface have a greater influence on the coefficient of friction, and as a consequence, the traction ability of the transmission in the frictional interaction of parts, than the roughness parameters. Analytical dependences of determining the power on the output shaft of the variator and the efficiency of the variator depending on the height parameter of the waviness are proposed. Conclusions. Based on the conducted research and experiments, a mathematical model is proposed to ensure the power parameters of variators by forming a high-altitude waviness index. This will make it possible to predict and ensure the coefficient of friction of the friction pair at the stage of development work and drawing up the technological process of processing parts.

The influence of the central hole-edge condition on the hole expansion ratio (HER) of four automotive-grade steel sheets is experimentally investigated in this work. The punched hole shows inferior HER for all selected automotive-grade steel sheets than the wire-electrical discharge machined (WEDM) hole. The finite element simulation approach is used to determine the influence of the coefficient of friction and spring-back on HER. With an increased coefficient of friction, the punch force increases. Material near the inner edge of the central hole comes out in the direction of the sliding punch in the presence of friction. Spring-back has a small effect on HER, and its importance increases for lesser HER materials.

(1) Background: With the ever-increasing number of polymer materials and limited data on polymer gear calculations, designers are often required to perform extensive experimental testing in order to establish reliable operational data for specific gear applications. This research investigates the potential of a Polyvinyldene fluoride (PVDF) polymer material in gear applications, considering various loading conditions and different types of gear transmission configurations, including both self-mated mesh and steel/PVDF mesh. (2) Methods: PVDF gear samples were tested on a specially designed test rig that enables active torque control and temperature monitoring in order to obtain the necessary design parameters and failure modes. Each test for certain load conditions was repeated five times, and to fully investigate the potential of PVDF gear samples, comparative testing was performed for Polyoxymethylene (POM) gear. (3) Results: Tribological compatibility, tooth load capacity, and lifespan assessment, along with the types of failure, which, for some configurations, include several types of failures, such as wear and melting, were determined. Temperature monitoring data were used to estimate the coefficient of friction at the tooth contact of analyzed gear pairs, while optical methods were used to determine a wear coefficient. (4) Conclusions: The tribological compatibility of polymer gear pairs needs to be established in order to design a gear pair for a specific application. PVDF gear samples mated with steel gear showed similar lifespan properties compared to POM samples. Temperature monitoring and optical methods serve as a basis for the determination of the design parameters. PVDF is an appropriate material to use in gear applications, considering its comparable properties with POM. The particular significance of this research is reflected in the establishment of the design parameters of PVDF gear, as well as in the analysis of the potential of the PVDF material in gear applications, which gives exceptional significance to the current knowledge on polymer gears, considering that the PVDF material has not previously been analyzed in gear applications. [ABSTRACT FROM AUTHOR]

The slipperiness of ice is well known while, for ice skating, its mechanism still needs further investigation, where the complex interactions including the thermal conduction of the skate—meltwater—ice system, the ploughing and the frictional melting of ice to the friction force are still unclear. This study presents a theoretical framework and a simplified analytical solution to unveil the friction mechanism when a curved skate sliding on ice. The theory is validated by experiments and the effects of these various factors, including the sliding velocity, the ice temperature, the supporting weight, and the geometry of the skate blade to the friction are revealed in detail. This study finds that the contribution of friction force from the ploughing deformation through skate indentation and that from the fluid friction through the shear motion of the meltwater layer is comparable with each other, which thus clarifies how the ploughing deformation of the ice substrate together with its frictional melting regulates the friction during skating. [ABSTRACT FROM AUTHOR]

In this paper, the dry sliding wear behaviour of the polyester composite reinforced with iron slag as filler was studied experimentally. The Taguchi method-based experiments were carried on pin-on-disk wear test set-up. The control factors considered for studying wear rate were sliding velocity, slag percentage and normal load applied on the member with constant sliding distance. The output performance parameters considered were coefficient of friction and weight loss. From the analysis of variance (ANOVA), it was observed that coefficient of friction is significantly affected by normal load then followed by slag content and sliding velocity. Sliding velocity plays a vital role on the weight loss, then followed by slag content and normal load. The optimal factor combination obtained was sliding velocity = 50 cm/s, slag percentage = 30 % and normal load = 4 kg. The model was validated using the set of optimal factor combinations to conduct a confirmation experiment. [ABSTRACT FROM AUTHOR]

Stick-slip vibration is simultaneously influenced by several factors that share complicated coupling relationships. In this research, an experimental investigation was performed to analyze the evolution law of stick-slip characteristics at different working conditions using a tribometer. The results showed that the disc rotational speed and normal force had noticeable impact on both stick-slip vibration and coefficient of friction (COF). Then the Stribeck model, which can characterize COF characteristics in the stick-slip process, was employed and the parameters were identified to construct a dynamic relationship between working conditions and COF. Further, numerical simulations respectively considering and neglecting the dynamic relationship between working conditions and Stribeck model parameters were conducted via an established tribometer analytical model. It was found that the simulation results considering the influence of working conditions on Stribeck model parameters were in better agreement with the experimental results, as the stick-slip vibration depends on the combined effect of working conditions and Stribeck model parameters. Therefore, the dynamic relationship between working conditions and Stribeck model parameters is crucial to accurately reveal stick-slip characteristics. [ABSTRACT FROM AUTHOR]

In recent years, additive manufacturing technology, particularly in plastic component fabrication, has gained prominence. However, fundamental modelling of the influence of materials like ABS, PC, and PLA on tribological properties in fused deposition modeling (FDM) remains scarce, particularly in non-lubricated, oil-lubricated, and grease-lubricated modes. This experimental study systematically investigates the effects of material type, lubrication method, layer thickness, and infill density on FDM component tribology. A tribology analysis is conducted using a TRB3 tribometer. The results indicate a coefficient of friction (CoF) range between 0.04 and 0.2, generally increasing and decreasing with layer thickness and filler density. The lubrication impact hinges on the material surface texture. The study models the intricate relationships between these variables via full-factor analysis, showing a strong alignment between the modelled and measured friction coefficients (an average error of 3.83%). Validation tests on different materials affirm the model's reliability and applicability. [ABSTRACT FROM AUTHOR]

The importance of utilizing an optimal and efficient braking system is emphasized in this study. Braking system optimization and efficiency were practically determined through successive tests on the brake dynamometer, according to road safety regulations. Subsequently, the results were correlated with practical tests involving consecutive braking at different speeds, tracking both the time and distance of braking. The coefficient of friction (COF) was established for each braking instance by utilizing the braking force measured on the brake dynamometer. This paper aims to highlight the genuine impact of the braking system by measuring and establishing its braking efficiency depending on the car's speed, time, and distance of braking. [ABSTRACT FROM AUTHOR]

Surface texturing and protective coating are two prominent approaches adopted to improve wear and corrosion resistance of artificial bio-implants. This study depicts the combined effect of both these processes viz., picosecond laser induced texturing and subsequent pulsed laser deposition of zirconia coating on laser textured surface, in improving the surface properties of Ti6Al4V bio-alloy. The tribological properties were performed under dry sliding and simulated body fluid (SBF)-wet sliding conditions. The hierarchical grooved structure generated on sample surface was found to reduce the coefficient of friction of the surface while the sub-pattern embedded in these grooves trapped wear debris and inhibited abrasive and delamination wears. The electrochemical analysis performed in SBF environment revealed increased electrochemical potential for both grooved and zirconia coated grooved samples compared to pristine sample. The zirconia coated groove sample exhibited an anti-corrosion efficiency of 62% as against the pristine. This superior corrosion property is attributed to generation of laser induced titanium oxide layer and greater hardness of zirconia film on the sample. [ABSTRACT FROM AUTHOR]

Lubrication in cold rolling is a key aspect to ensure high quality of the rolled strips and the choice of a suitable lubricant surely has a remarkable influence on the contact conditions at the roll/strip interface. The present work proposes an original methodology based on inverse analysis to evaluate the friction conditions in the cold rolling process. Such a methodology was applied for the investigation of two different lubricants: a commercial semi-synthetic one and a natural-based one (able to reduce the environmental impact). Forces acting on work rolls were measured during the rolling operations in the two-stands reversing cold mill (Marcegaglia plant, Italy) and used as target value for tuning the unknown parameters (coefficients of friction, CoF, and roll's diameters, D) of the plane-strain analytical model through which each pass was modelled. In particular, an automatic optimization procedure, managed by the NSGA-II algorithm, was used for tuning the parameters CoF and D by iteratively changing their value and minimizing the discrepancy between the analytically calculated and the experimental forces. The optimization results allowed to evaluate the friction coefficients more efficiently than a laboratory test, since being directly calculated using data from the real production. Reliable values of the CoF could be thus determined: the inversely determined coefficients, when implemented in the proposed analytical model, led to a precise estimation of the rolling force (the discrepancy was below 10%). The Pareto designs revealed that the contact conditions at the roll/strip interface could be remarkably improved when adopting the natural-based lubricant (with an average reduction of the friction coefficient of 8%), the contact pressure being considerably reduced. Such a result is coherent with the reduction of rolls' wear when using the natural based lubricant and it is crucial in limiting the process-related costs. [ABSTRACT FROM AUTHOR]

Ensuring adequate reliability of the production process of packaging closures has made it necessary to study the effect of annealing and varnishing variants on the strength and structural properties of the stock material. As a test material, EN AW-5052-H28 aluminium alloy sheets with a thickness of 0.21 mm were used. The surface treatment of the test material involved varnishing the sheet metal surface using various varnishes and soaking the sheet metal. The coefficient of friction and the abrasion resistance of the coatings were determined using the T-21 ball-and-disc tribotester. The tested sheets were subjected to tribological analysis by the T-05 roller-block tribotester using countersamples made of Caldie and Sverker 21 tool steels. The results of the tests showed differences in mechanical and structural properties depending on the method of sample preparation. Based on the test results, significant differences in the adhesion of anti-wear coatings were found. The results revealed that the most favourable friction conditions are provided by the CrN coating. The (AlTi)N interlayer in the (AlTi)N/(AlCr)N coating adheres to the substrate over the entire tested area and no detachment from its surface was observed, which proves good bonding at the substrate/coating interface. The tested AlTiN/TiAlSiXN coating is characterised by a more homogeneous, compact microstructure compared to the (AlTi)N/(AlCr)N coating. [ABSTRACT FROM AUTHOR]

In this study, plastic oil (PO) as a potential lubricant was investigated. The base PO was incorporated with graphene nanoplatelets (GNP) and hexagonal boron nitride (hBN) nano additives in varying concentrations to form nano lubricants. Their viscosity, tribological, acidic/basic nature, thermal degradation and dispersion stability properties were investigated. It was observed that 1.5 wt% GNP and 1.0 wt% hBN added separately to the base PO, provided the lowest coefficient of friction (COF) and wear volume. Based on these lowest COF and wear volume insights, three nano lubricant mixtures were formulated by incorporating both GNP and hBN at different combinations using base PO. Positive synergistic behaviour was observed for COF (49%–60% reduced) and wear volume (90%–97% reduced) for two combination mixtures compared to the base PO. These improvements in the mixture were due to the polishing, mending mechanisms and tribofilm that protected the interacting surfaces. [ABSTRACT FROM AUTHOR]

Using an optical elastohydrodynamic lubrication (EHL) test rig, oil film thickness and the coefficient of friction (COF) were measured, and the influence of stearic acid additive on the EHL performance of mineral oil 2137 was investigated. The results showed that 2137 with 0.3 wt% stearic acid (denoted to as 2137s) achieved the same film thickness as 2137, while the COF of 2137s was significantly lower than that of 2137 when the contact was under conditions of a fully lubricant supply. Under conditions of limited lubricant supply, 2137 base oil was prone to oil starvation with the increase of entrainment velocity. On the other hand, 2137s significantly mitigated the oil starvation. This was attributed to the fact that lower surface energy by the adsorption of stearic acid results in discontinuous oil-droplet distribution on the lubrication track and, therefore, early pressure generation. Moreover, it is interesting to find that less 2137s supply quantity can produce higher film thickness when the contact is at high speeds, which is attributed to the fact that a smaller quantity of 2137s gives smaller droplets on the lubrication track, and the resultant small surface area–volume ratio presents oil more resistance to the centrifugal force and results in less oil escaping from the lubrication track. The addition of stearic acid reduced the average COF of 2137 mineral oil by about 13.3% [ABSTRACT FROM AUTHOR]