The establishment of environmentally friendly lubrication systems is of significant importance to the sustainable development. Here, we demonstrated an environmentally friendly approach, where superb ...lubricious carbon-based tribofilms formed in situ originating from base oil through tribochemical reactions, on the surfaces of catalytically active MoN-Ag film. We focused on the study of the tribological behavior of the MoN-Ag/oil solid-liquid system under varying loads. Through detailed characterization analysis of the carbon-based tribofilms, we elucidated the mechanism of friction reduction and wear resistance of the MoN-Ag film in the base oil, as well as the formation mechanism of carbon-based tribofilms. Furthermore, we provided a thermodynamic perspective to clarify the influence of load on the tribo-induced tribochemical reactions within the MoN-Ag/oil solid-liquid system.
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•Superb lubricious carbon-based tribofilms formed from base oil with MoN-Ag film through tribo-induced.•Effects of load on the tribological behavior of the MoN-Ag/oil solid-liquid system.•The mechanisms of friction reduction and wear resistance under varying loads are discussed.•The mechanism of tribochemical reactions was investigated from a thermodynamic perspective.
The tribological and anti-corrosion performances of four as-synthesized 5-phenyltetrazole ionic liquid (PTIL) lubricant additives for water were investigated. Research results suggested that an ...addition 3% of PTIL lubricant additive could greatly improve the tribological properties of water. Notably, the friction coefficient was reduced by about 80% and the wear volume by about 94% for the addition of 3% of tetrabutylphosphonium 5-phenyltetrazol-2-ide (PTP4444) in water. Further tested by CA, QCM, EDS, SEM and XPS showed that the exceptional tribological performances presented by PTILs were mainly due to the physical and chemical tribofilms generated during the rubbing procedure. Moreover, the synergistic effect of N-P elements also played a key role in the good tribological performances of PTP4444.
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•5-Phenyltetrazole ionic liquid lubricant additives were synthesized via simple acid-base neutralization.•The mean friction coefficient decreased significantly by 80% and the wear rate by 94%.•The morphological and elemental analysis of the formed tribofilms.•The physical and chemical tribofilms formed on the steel surfaces are responsible for the superior tribological performance.
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•A novel solvent-free covalent MXene nanofluids is proposed for application in lubrication.•The MXene nanofluids perform superior tribological performances under harsh conditions.•The ...MXene nanofluids exhibit a synergistic effect of solid lubricant and liquid lubricant.•The good lubrication is ascribed to the formation of thick tribofilms.
A sole liquid lubricant or solid lubricant cannot cater to the demands of high-efficiency lubrication performance. From the standpoint of fusion of solid and liquid lubrication, solvent-free nanofluids are expected to be promising lubricants. In this work, solvent-free covalent MXene nanofluids were synthesized by grafting MXene with organosilane (KH560) and polyether amine oligomer (M2070) via covalent linkage. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, thermogravimetric analysis and rheological characterizations demonstrated that the MXene nanofluids were successfully synthesized and presented macroscopic fluidity at room temperature. Importantly, when used as a lubricant, the nanofluids perform well in friction-reduction and anti-wear properties even at high velocity (50 Hz), elevated temperature (100 °C), and heavy load (1100 N). The excellent tribological properties are ascribed to the nanofluids integrating the advantages of significantly improved load-bearing capacity and lubrication performance of the core nanomaterials, as well as liquid-like fluidity and self-healing characteristics of the organic shell. Moreover, the formation of 120–180 nm thick tribofilm on the worn steel surface was identified, which is significant in improving the lubrication performance. The above results suggest that the solvent-free MXene nanofluids should be a quite excellent candidate lubricant for integrating the advantages of solid and liquid lubricants and provide theoretical guidance for structural design of high-performance solvent-free nanofluid lubricants.
Zinc dialkyldithiophosphate (ZDDP) anti-wear lubricant additive contributes to significant harmful emissions and its replacement has become a priority. In this study, green silica nanoparticles were ...synthesized and optimized for concentration to serve as hybrid additives alongside ZDDP in lubricants, aiming to mitigate environmental concerns. A combination of 0.5 wt% silica nanoparticles, 0.5 wt% oleic acid (OA), and 0.75 wt% ZDDP demonstrated notable improvements, reducing ZDDP usage by ∼25 % while achieving significant tribological enhancements. At room temperature, coefficient of friction (COF) was reduced by ∼60 %, and wear was reduced by ∼70 %, while at 100 °C, COF was reduced by ∼80 %, and wear was reduced by ∼96 %. Advanced characterization techniques such as FESEM with EDS mappings, EPMA, and TOF-SIMS were employed to elucidate the underlying mechanisms for observed reduction in friction and wear.
•A combination of silica nanoparticles and ZDDP is explored as hybrid additive to PAO4 oil.•Conventional ZDDP addition is reduced by 25 % in hybrid additive containing base oil.•Friction reduction of ∼ 60 %, and wear reduction of ∼ 70 % at room temperature using hybrid additive.•Friction reduction of ∼ 80 %, and wear reduction of ∼ 96 % at 100 °C using hybrid additive.•Plausible mechanisms of surface protection using the hybrid additive are proposed.
The paper analyses the influence of emulsion mist formation parameters and the nozzle distance from the tool–chip interface, on the droplet velocity at the nozzle outlet, on active medium atomization ...angle as well as on the diameter and number of droplets supplied to the cutting zone. The deformation coefficient of the droplets falling on the surface and the wetting angle have also been determined. In the work it has been proved that the strongest influence on the droplets diameter have the air flow and the distance of the nozzle from the cutting zone. It has been shown that larger angle of the stream splitting ensures that the droplets do not join each other in the air, and consequently assures small diameter on the surface. Additionally, the results show that the emulsion mass flow does not change the droplets diameters by more than 12%. It has been determined that smaller the droplets diameter is, higher content of active compounds in the tribofilms formed on the machined surface is present. In this way the paper presents the analysis and directions of MQCL adjustment trends needed to improve the machining performance.
•Analysis of tribofilm formation depending on the diameter and number of droplets.•The influence of mist formation conditions on the droplets diameter and the relative wetting surface.•Droplet diameter sizes and distribution depending on the input parameters of the emulsion mist formation.•Determination of the wetting angle and coefficient of droplet deformation on the surface.•Stream splitting angle and velocity at the nozzle outlet.
The novel solvent-free nanofluids (NFs) are prepared by assembling the hybrid Ti3C2Tx @SiCnws nanocores followed by grafting organosilane GPTES and polyether amine M2070. Then Ti3C2Tx @SiCnws NFs are ...incorporated into the PI/PTFE fabric liners composites (FC) along with tannic acid-PEI (TP) interfacial modification while the tribological performance of FC is systematically investigated. The results demonstrate that the tensile and interfacial strength of FC present effective growth resulting from tannic acid-PEI codeposition modification. Moreover, the addition of Ti3C2Tx @SiCnws NFs further enhances the thermal and mechanical properties of FC due to steric hindrance and entanglement of interfacial molecular chain. The tribological results prove that the improved interfacial adhesion, thermal properties and formation of load-bearing tribofilms are essential for enhanced tribological behaviors of FC.
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•Tannic acid-PEI co-deposition coating onto PI/PTFE fabric improves the interfacial adhesion between fabric and resin.•Ti3C2TX @SiCnws NFs are prepared by electrostatic assembly followed by attaching with organic shell.•Ti3C2Tx @SiCnws NFs promote the lubrication property of FC effectively.•Synergistic effect between Ti3C2Tx and SiCnws is recognized during friction procedure.
Herein, two types of tribocouple pairs based on polymer‐like carbon (PLC) films are designed through the in situ‐formed MXene coating. The in situ‐formed MXene coatings are synthesized via the in ...situ organic–inorganic chemical composite technique‐induced anionic polymers with different molecular weights (≈450 000 and ≈4 000 000, respectively). Next, the tribotesting condition is controlled in the ambient environment under different loads by bare and PLC‐coated bearing steel balls as counterbodies. During the whole sliding process, a lubricity state (friction coefficient is about 0.21 and wear rate is about 1.5 × 10−6 mm3 N−1 m−1) is realized on the self‐mated PLC system. Meanwhile, the contact surfaces are covered by graphitic 2D Ti3C2. Compared with the high‐molecular‐weight modifier system, most poly(acrylic acid)‐co‐MXenes grafted by the low‐molecular‐weight poly(acrylic acid) form far more sp
2‐C phases. Moreover, active groups are potentially involved in forming a tribofilm, which enhances the overall lubricity of MXenes during sliding. This verifies the key to achieving low friction and ultralow wear based on the formation of the nanostructured sliding interface upon MXenes and provides an expanded application of solid lubricants.
Herein, two tribocouple pairs based on polymer‐like carbon (PLC) films cooperate with MXenes through in situ the organic–inorganic chemical composite technique‐induced PAA with different molecular weights. Most PAA‐co‐MXenes grafted by low‐molecular‐weight PAA form far more sp
2‐C phases of graphitic 2D Ti3C2. Active groups are potentially involved in forming a tribofilm to improve the lubricity of MXenes during sliding.
Aluminium alloys are crucial in lightweighting equipment. However, their limited wear resistance hinders their further utilization. Herein, a gradient nanostructure layer incorporating α-Al2O3 ...particles is successfully fabricated on aluminium alloy 2024 using a novel method called strengthening grinding treatment (SGT). The tribological properties were investigated by a ball-on-disc tribometer. The results show that SGT effectively enhances the anti-wear performance. Compared to the untreated sample, the average friction coefficient and the wear rate of the SGT-treated sample decreased by 34.7 % and 90.1 %, respectively. The wear surface analysis demonstrates that the presence of α-Al2O3 in the gradient nanostructure effectively restricts shear deformation and crack generation. Additionally, the formation of a wear-resistant tribofilm composed of 'glaze' during friction contributes to further wear reduction.
The limited wear resistance of aluminum alloys hinders their application in lightweight equipment. Herein, we present the successful fabrication of a Ti-Al modified layer on the surface of aluminum ...alloy 2024 via surface mechanical attrition treatment (SMAT-Ti). Tribological assessments indicate an improvement in tribological performance. Specifically, the average friction coefficient and wear rate of the SMAT-Ti treated sample decreased by 49.1% and 81.9%, respectively, compared to untreated sample. Analysis of wear surfaces and molecular dynamics simulations demonstrate that the improvements observed can be attributed to the wear-resistant tribofilm formation. Furthermore, the integration of Ti particles beneath the subsurface facilitates the formation of HCP bands and dislocation locks. These microstructural changes obstruct frictional shear deformation and crack propagation, effectively reducing wear.
Efficiently reducing friction and wear in an environmentally friendly lubrication manner remains a challenging endeavor. Here, carbon-based tribofilms with excellent friction-reducing and anti-wear ...abilities was in-situ formed from the poly-α-olefin oil (PAO6) on the friction interfaces of MoN-Ag composite films. A series of MoN-Ag films were prepared by multi-target magnetron sputtering process. Then, X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Raman, and Fourier-transform infrared (FTIR) spectroscopy, etc. were employed to investigate the microstructures, surface morphologies, mechanical properties of the MoN-Ag films, as well as the tribological performance under the luberication of PAO6 oil. The results showed that the MoN-Ag film consists of γ-Mo2N and c-Ag. With the increase of Ag content, the surface roughness of the films stays increased, while the hardness and elastic modulus of the films initially increase and then decrease. When the content of Ag is 2.7 at.%, the film had the highest hardness (24.1 GPa) and elastic modulus (316.5 GPa), and the MoN-Ag/oil solid-liquid system exhibited the lowest average friction coefficient of 0.087 and the lowest wear rate of 5.8 × 10−7mm3N−1 m−1 after a long duration. The catalytic effect of Ag facilitated the degradation of PAO6 molecules on the friction interface, resulting in the in-situ reorganization and formation of amorphous carbon-based tribofilms with graphite-like structures.
In this paper, PVD technology was utilized to introduce Nano-Ag into MoN comosite films, preparing in a series of MoN-Ag composite films with varying Ag content. Then, the influences of Ag content on the microstructure, surface morphology, mechanical properties of the MoN-Ag films, as well as the tribological performance of these films in base oil, were investigated systematically. The catalytic effect of Ag in the solid-liquid lubrication system and the structure-activity relationship regarding the formation of carbon-based lubricating films from lubricating oil degradation were unequivocally determined. Furthermore, the study delved into the characterization and formation mechanism of in-situ generated lubricating carbon films at the friction interface, revealing the anti-friction and wear mechanisms of the solid-liquid lubrication system. Display omitted
•The MoN-Ag film had the best mechanical properties at Ag content is 2.7 at.%.•The excellent tribological behavior under base oil was achieved catalyzed by Ag.•Carbon-based tribofilms was in-situ formed on the friction interfaces of MoN-Ag films.•A long-term, stable TMN/PAO solid-liquid lubrication system is constructed under room temperature.
