Search Results (244)

Oil additives are essential for improving anti-wear (AW) properties and durability of mechanical components. In this study, a novel ionic liquid based on phosphate ammonium salt (coded as IL-NPAS) was designed using organic synthesis methods. The high-level objective of this work is to enhance the wear resistance ability of oil-lubricated steels with low-cost additives in terms of materials and manufacturing methods. The IL-NPAS additive was incorporated at concentrations of 0.1 wt% and 0.5 wt% in 150 SN oil, which served as the base oil. Additionally, the commercial oil additive (coded as AW6110) was utilized as a reference to evaluate the effectiveness of the synthesized additive. The frictional behaviour was evaluated with an SRV tribometer at test temperatures of 25 °C and 100 °C. After that, SEM, 3D profilometry, XPS, and TOF-SIMS techniques were employed to show the wear modes and determine the chemical composition of the lubricating tribolayer. Noticeably, the formulated lubricant based on the 0.5 wt% IL-NPAS additive provided AW performance almost identical to the AW6110 additive. The results showed that the 0.5 wt% IL-NPAS additive reduced the coefficient of friction (COF) and improved AW properties by 34–36% and 80–90%, respectively, compared to the 150 SN base oil. Overall, this study holds significant promise for the development of low-cost lubricating oil additives. Full article

A series of poly(5-n-butyl-2-norbornene) oils with controlled molecular weights was synthesized via metathesis polymerization, fully hydrogenated, and characterized in terms of viscosity and tribological performance. In contrast to established lubricant base stocks—such as poly(α-olefins) and multiply alkylated cyclopentanes—these novel norbornene-based polymers remain underexplored, despite their promising anti-wear activity. Based on differential scanning calorimetry (DSC) data, all the synthesized products are amorphous compounds whose thermograms show a single glass transition temperature. The effect of molecular weight and temperature on the viscosity of poly(5-n-butyl-2-norbornene) oils was quantified over an extended temperature range, including extra-cold conditions down to −80 °C. The pour points of the oils were determined and can be as low as −66 °C, indicating excellent low-temperature fluidity. The tribological performance of the synthesized oils was evaluated using the four-ball test, with friction coefficient and wear scar diameter measured to assess anti-wear and antifriction properties. The tribological results were benchmarked against commercially available polyalphaolefin (PAO) oils (PAO-4, PAO-20, and PAO-80). Metathesis and hydrogenated poly(5-n-butyl-2-norbornene) oils outperform conventional PAOs by up to 67% in wear protection and 30% in friction reduction. These findings establish alicyclic molecular strain as a viable design parameter for next-generation lubricating oils, thereby expanding the toolbox for material development beyond conventional chemical functionalization. Full article

Polymer composite coatings are promising for tribological protection, with stable transfer films being key to their friction-reducing and anti-wear performance, yet the mechanism by which rare-earth compounds, known to enhance polymer tribological properties, regulate transfer film growth remains unclear. In this work, the tribological performance of phenolic resin (PF)-based coatings filled with lanthanum oxide (La₂O₃) and lanthanum fluoride (LaF₃) was systematically investigated. The results demonstrate that the friction coefficients of 5La₂O₃/PF and 3LaF₃/PF decrease to 0.024 and 0.031, representing a 79.66% and 73.95% reduction compared to pure PF, which compensates for the inadequacy of oil lubrication. Tribochemical analyses and characterizations of tribofilm structures confirm that complex tribochemical reactions involving rare-earth compounds occur, promoting the growth of a solid-lubricating tribofilm at the boundary lubrication interface. This work provides a theoretical foundation for the design of high-performance polymer lubricating coatings. Full article

M50 steel is a critical bearing material, yet its tribological properties may deteriorate in engineering applications. To reduce the frictional resistance between M50 steel and contact surfaces, this study utilized laser processing technology to fabricate square- and wave-shaped textures (with a depth of ~30 μm) in both linear and staggered arrangements. The tribological performance of these textured surfaces was evaluated under dry and oil-lubrication conditions. Experimental results demonstrated that under dry friction conditions, linearly arranged textures reduced frictional resistance, while staggered textures exhibited superior anti-wear performance. Under oil-lubrication conditions, both linear and staggered textures contributed to friction and wear reduction. Moreover, a synergistic effect was observed for the composite staggered pattern, which achieved the maximum reduction in friction coefficient by up to 8.92% and 8.23% under dry and oil-lubricated conditions, respectively. Full article

An operational test and degradation analysis of a hydraulic fluid based on synthetic esters was performed in three types of work machines. To enhance its performance, ZDDP anti-wear agents were added. Hydraulic fluids are susceptible to degradation by oxidation; therefore, to ensure the long service life of the equipment, it is essential to monitor their current condition through laboratory analyses during machine operation. Emission spectrometry was used to determine the presence of contaminants and the concentration of additive substances in the oil. Pollution was assessed by cleanliness code analysis according to ISO 4406-2021, alongside Total Acid Number (TAN) analysis and LNF analysis of wear and contamination in lubricants. The combination of cleanliness code analysis and LNF analysis of particle type and origin allows for monitoring not only the count but also the origin of contaminating metallic particles, which increases the probability of correct diagnostics and successful detection and resolution of wear problems. All three machines were still operational at the end of the test interval, meaning the tested hydraulic fluid is a suitable alternative to mineral variants. However, in all three pieces of equipment, it is necessary to replace the hydraulic fluid and flush the system before further operation. Furthermore, we recommend replacing the filter elements and inspecting the internal spaces of rotating parts with an increased potential for wear. From the oil’s perspective, it is advisable to add more anti-wear additives (ZDDP), which are depleted the fastest. Full article

Using femtosecond laser processing technology, various textures with different morphologies were fabricated on titanium alloy surfaces to investigate the impact of texture morphologies and parameters on friction and wear performance. This study provides insights for improving the friction and wear performance of joint interfaces and extending the lifespan of artificial joints. Reciprocating friction and wear experiments were conducted on a UMT-3 multifunctional tribometer under oil-starved lubrication conditions. The effects of surface textures with different morphologies and parameters on friction and wear performance were examined. Under identical experimental conditions, laser micro-textured specimens demonstrated improved tribological performance compared to un-textured specimens. With the same dimple depth and coverage area, the optimal texture parameters varied among different morphologies, providing the best reduction in friction and wear resistance. This study systematically evaluated the effects of three different texture geometries (circular, elliptical, and groove) on tribological properties. The experimental results showed that under the same conditions, the elliptical texture performed the best in reducing the friction coefficient and improving load-bearing capacity. Compared to non-textured surfaces, the wear amount was reduced by 52.94%, the average friction coefficient was lowered by 20.51%, and the wear depth decreased by 75.09%. Laser micro-texturing on the surface can effectively enhance the anti-wear and friction-reducing properties of materials used in artificial joints. Full article

This research reveals the anti-friction and anti-wear performance of lubricants using a castor oil base and a deep eutectic solvent (DES1) as an additive. To this end, DES1 was synthesized in a successful manner using DL-menthol and dodecanoic acid as components. Mass concentrations from 0.1 wt% up to 5 wt% of DES1 additives were chosen to formulate the lubricants. Friction experiments were conducted, yielding friction enhancements up to 4% compared to the castor oil base. Notably the greatest reduction was achieved for the lubricant with 0.1 wt% of DES1. In terms of the wear generated, the best anti-wear performance was achieved for the 0.5 wt% DES1 lubricant (with a wear reduction of 17%). Furthermore, by means of the profilometry of worn surfaces, it can be observed that the tribofilm formation of DES1 on steel surfaces is a potential lubrication mechanism. Full article

In this study, we investigated the tribological properties of various additives (lubricity, friction modifiers, anti-wear and extreme pressure) in a highly volatile paraffinic base oil formulated for stamping applications, using a newly developed methodology for tribological testing. The investigation focused on the short-term (10 cycles) and long-term (10,000 cycles) effects of the different additive mixtures on friction and wear behaviour. It was found that the performance of the additive mixtures evolves with sliding time, which is due to changes in contact conditions: the transfer of the Fe film from the steel sheet to the WC-Co surface increases the contact area, which in turn leads to a significant reduction in contact pressure and changes the activation of tribofilm formation. The presence of tribofilms influences the amount and size of the contact area and reduces the adhesion between the contact surfaces. Among the conventional additives, sulphurised additive mixtures show stable performance under both short and long-term conditions, while more aggressive chlorinated additive mixtures perform well in the short term, but their performance decreases with prolonged sliding. Importantly, the additives with a decreasing environmental impact outperformed the conventional additives under long-term conditions: the less harmful phosphorus-based mixture outperformed the sulphurised mixtures in terms of wear properties, while the performance of environmentally acceptable polyol ester was particularly encouraging, exhibiting the lowest friction coefficient (~0.11, compared with ~0.12 for S-oil and 0.14 for S-ester) and the second lowest wear coefficient (~1.1 × 10⁻¹ mm³/Nm compared with ~1.5 × 10⁻¹ mm³/Nm for S-ester). Overall, the polyol ester reduced the coefficient of friction by approximately 8 to 21% compared to sulphurised additive mixtures, and its wear coefficient was also about 27% lower. Full article

As a renewable fuel for diesel engines, biodiesel plays a significant role in improving the lubricating performance of low-sulfur diesel. The decline in lubricity of low-sulfur diesel can lead to increased friction and exacerbated wear on the surfaces of diesel engine friction pairs, whereas the addition of biodiesel can effectively mitigate such tribological issues. In this study, tribological performance tests of biodiesel-fueled engines were conducted, combined with molecular simulation methods. Using Materials Studio software, the adsorption behavior and dynamic processes of three typical fuel components: C₇H₁₆, C₁₁H₂₂O₂, and C₁₉H₃₆O₂, on the α-Fe (110) crystal surface were simulated. This systematically revealed the mechanism by which biodiesel improves friction and wear performance. The results indicate that biodiesel significantly enhances the lubricating properties of low-sulfur diesel. The carbonyl groups in biodiesel molecules exhibit high reactivity, demonstrating larger absolute values of adsorption energy and cohesive energy compared to alkane components, which indicates stronger surface adsorption capacity. This facilitates the formation of a stable and continuous lubricating film on metal surfaces, thereby providing anti-wear and friction-reducing effects, ultimately improving the wear resistance of key components in diesel engines. Full article

Due to their excellent mechanical stability, chemical stability, and environmentally friendly properties, ceramic materials have received extensive attention for years. Meanwhile, ionic liquids (ILs) have been found to effectively enhance tribological properties when applied as lubricants, which has become a distinctive example of their wide exploration. Here, three novel proton-type ionic liquids containing different polar groups were designed and synthesized as pure lubricants for use on different ceramic friction couples (silicon nitride–silicon nitride, silicon nitride–silicon carbide, and silicon nitride–zirconium oxide contacts), and their lubrication effect was evident. The results indicate that the adsorption behavior and frictional characteristics of different polar groups on a ceramic friction interface differ, largely depending on tribochemical reactions and the formation of a double electric layer on the interface between the ILs and ceramic substrates, without obvious corrosion during sliding. The friction coefficient is reduced by more than 80%, and this excellent anti-friction effect demonstrates that the constructed ionic liquid–ceramic interface tribological system shows good application potential. Based on the analyses of SEM, EDS, and XPS, the tribochemical reaction on the sliding asperity and the film-forming effect were identified as the dominant lubrication mechanisms. Here, the high lubricity and anti-wear performance of ILs containing phosphorus elements on different ceramic contacts is emphasized, enriching the promising application of high-performance ILs for macroscale, high-efficiency lubrication and low wear, which is of significance for engineering and practical applications. Full article

Atmospheric plasma spraying was used to create composite coatings employing mixed alloy matrices supplemented with carbon-based solid lubricants as feedstock materials. The current study’s goal was to examine the tribological properties of these coatings and explore the potential benefits of using CNTs as a nano-additive to minimize wear and friction while enhancing lubrication conditions in tribosystems such as piston ring–cylinder liner systems. Pin-on-disk measurements are used to correlate the chemical composition of feedstock materials with the friction coefficient and wear rate during coating operation. The enhanced behavior of the produced coatings is investigated. The anti-wear performance of Co-based cermet and metal alloys coatings, as well as the enhanced lubrication conditions during operation, are shown. In-depth discussion is provided regarding how the features of the feedstock powder affect the quality and performance of the produced coatings. The results showed that coatings based on the CoMo alloy exhibited an increase in wear due to CNT agglomeration. In contrast, CNT addition led to an improvement in bonding strength by up to 33%, a reduction in wear rate by up to 80%, and a decrease in the coefficient of friction from approximately 0.70 to 0.35 in CoNi cermet coatings. These findings demonstrate the role of CNTs in coating performance for demanding tribological applications. Full article

In this study, a green lubricating grease was prepared based on cellulose and epoxidized soybean oil (ESO). The cellulose extracted from the corn stover was functionalized using diphenylmethane diisocyanate (MDI), which enhances its compatibility and thickening ability in non-polar oil, and subsequently dispersed in ESO to form a stable gel-like bio-based grease. The functionalized surface of cellulose was characterized by FTIR, SEM, and XRD. And the rheological and tribological characteristics of the prepared bio-based grease were discussed. The superior lubricity and anti-wear properties of our bio-based grease are demonstrated by its lower friction and diminished wear relative to commercial lithium-based formulations. This work provides practical guidance for designing environmentally friendly grease for sustainable lubrication. Full article

Lubricating oil plays a critical role in protecting mechanical systems. Driven by sustainable development strategies, the development of high-performance, biocompatible green lubricants has become an urgent industry need. Biomass resources, characterized by wide distribution, renewability, and environmental friendliness, represent ideal raw materials for replacing petrochemical-based lubricants. In this study, renewable Xanthoceras sorbifolia oil was utilized as the feedstock. Branched modification was achieved via ring-opening esterification using 2-ethylhexanol (2-EH) as the modifier and tetrafluoroboric acid (HBF₄) as the catalyst. This epoxidation-branching modification process was synergistically combined with Nano-C₁₄MA/MMT treatment. This approach significantly reduced high-temperature kinematic viscosity loss while maintaining excellent low-temperature flow properties, resulting in an Xanthoceras sorbifolia oil-based lubricant with outstanding viscosity–temperature performance and low-temperature fluidity. At a Nano-C₁₄MA/MMT mass ratio of 0.3 wt% of the base oil, the lubricant demonstrated superior wide-temperature performance: KV₄₀ = 424.1 mm²/s, KV₁₀₀ = 50.8 mm²/s, VI = 180.8. The SP was reduced to −43 °C, exceeding the performance requirements of V-class environmentally friendly lubricants (e.g., synthetic ester oils). Furthermore, the coefficient of friction (COF) was 0.011 and the anti-wear scar diameter (AWSD) was 0.44 mm, indicating lubrication performance significantly superior to SN-class lubricants (specifications: COF < 0.12, AWSD < 0.50 mm). Full article

Carbide-bonded graphene (CBG) coating, with its unique 3D cross-linked network structure, shows significant potential for protecting silicon substrates. However, a comprehensive understanding of its macroscale tribological properties remains lacking. This study investigated the macroscale friction and wear behaviors of CBG-coated silicon wafers using reciprocating sliding tests against steel balls under various loads and sliding cycles. The CBG coating exhibited excellent friction-reduction and anti-wear performance, reducing the steady friction coefficient from 0.80 to 0.17 and wear rate by an order of magnitude compared to those of bare silicon. Higher loads slightly decreased both friction coefficients and wear rates, primarily due to the formation of denser tribofilms and transfer layers. Re-running experiments revealed three distinct wear stages—adhesive, abrasive, and accelerated substrate wear—driven by the evolution of tribofilms, transfer layers, and unabraded flat areas. Furthermore, comparative experiments confirmed that these “unabraded flat areas” on the wear track play a critical role in sustaining low friction and prolonging coating life. The findings identify CBG as a robust solid lubricant for high-contact-pressure applications and emphasize the influence of tribo-layer dynamics and wear debris behavior on coating performance. Full article

This study aimed to develop an experimental method for producing artificially aged oil with properties—such as coefficient of friction, average wear scar diameter, and antiwear additive content—similar to those of used oil contaminated with alternative fuel, sampled after 129 h of engine test bench operation. A design of experiment (DoE) methodology was applied to examine the effects of various parameters and identify optimal settings. Friction and wear tests were conducted using an Optimol SRV5 tribometer in a ball-on-disc configuration, while wear scars were analyzed with a Keyence VHX-1000 digital microscope. Oil analysis was conducted with an Anton Paar 3001 viscometer and a Bruker Invenio-S Fourier-transform infrared spectrometer. The DoE results showed that the heating duration had a negligible effect on oil degradation. Aging time primarily affected changes in the friction coefficient and average wear scar diameter, whereas aging temperature was the primary factor influencing the anti-wear additive content. Gaussian elimination identified the optimal aging parameters as 132.8 °C and 103.1 h. These results were confirmed through surface analysis using a ThermoFisher NexsaG2 X-ray photoelectron spectrometer, which showed that the tribofilm composition of the used oil most closely matched that of artificially aged oils prepared at 120 °C for 96 h and 140 °C for 120 h. The strong correlation between the predicted and experimentally confirmed conditions demonstrates the reliability of the proposed method for replicating realistic aging effects in lubricating oils. Full article