Lubrication Science最新文献

The anti-emulsification property of lubricating oil is an important index to measure the quality of oil. In this paper, the behaviour of surfactants such as lubricating oil additives at the oil–water interface and the influence of the position of ethylene oxide (EO) and propylene oxide (PO) in the block polyether demulsifier on the demulsification effect were investigated by molecular simulation and experimental verification. The properties of seven lubricating oil additives with different functions and two pairs of isomers were investigated by molecular simulation, and their demulsification effects were verified by experiments. Some simulation results such as interface thickness and density distribution can accurately predict the experimental demulsification effect. Moreover, it was found that the position isomerism of surfactants affected the demulsification performance by changing the lipophilic balance and interface properties. The demulsification performance of sequenced copolymers is generally better than that of anti-sequenced copolymers. The accurate prediction of molecular dynamics simulation makes the selection of lubricating oil demulsifier more extensive and has practical application value.

This paper proposes an optimisation method for fabricating composite materials and functionally graded structures. Using the proposed method, 3D printing of copper (Cu)–polyethylene (PE) composite, Al₂O₃–ZrO₂ ceramic composite and functionally graded CuO foams are utilised. This work aims to advance the capabilities of additive manufacturing by leveraging nature-inspired approaches to create complex, tailored structures with enhanced performance across various industries. The major objective of the proposed method is to reduce the feed rate and increase the airflow rate and airflow temperature for the heat transfer process. Using the proposed technique in the advanced preparation conditions, Cu–PE composites with unreliable Cu substances are fabricated. The PE binder particle is melting as well as forming thick composites by means of soft surfaces. Using the proposed AHO approach, functionally graded materials with common distributions can be efficiently optimised. By then, the proposed model is implemented on the MATLAB platform, and its execution is calculated using the current procedures. The proposed technique displays superior outcomes in all existing methods like wild horse optimiser, particle swarm optimisation and heap-based optimiser. The proposed method shows a throughput of 57 mm³. The existing method shows the throughput of 32, 27 and 45 mm³. The results show that the proposed method has higher throughput compared with existing methods.

The present research analyses the power consumption (P _c) and surface roughness (R _a) in hard turning of high-strength low-alloy (HSLA) grade AISI 4140 steel using a recently developed AlTiSiN-coated carbide tool under different cooling-lubrication conditions (dry, flooded, nanofluid-MQL). The nanofluid was prepared by mixing the MWCNT nanoparticles with an eco-friendly automotive radiator coolant (base fluid). The cooling-lubrication performance is investigated briefly by comparing the machining responses like machined surface morphology, tool wear, cutting force and temperature. The experiments associated with 46 trials were performed by considering various machining variables, namely cutting speed, nose radius, depth of cut, feed and cooling-lubrication methods. From the perspective of predictive modelling and multi-response optimisation, response surface methodology has been employed to minimise power consumption and surface roughness. Thereafter, the predictive modelling and optimisation results are implemented for economic analysis and energy-saving carbon footprint evaluation. This innovative research also addresses comparative environmental sustainability evaluation in hard turning under different cooling-lubrication conditions using a life cycle assessment methodology for cleaner and safer production. Results indicate that cutting speed was the most influential item in power consumption enhancement. Furthermore, compared with dry and flooded turning, lower cutting force, reduced cutting temperature, shorter width of flank wear and better surface morphology were obtained under nanofluid-MQL machining. It has been observed that nanofluid-MQL machining outperformed sustainability improvement concerning techno-economically viable societal acceptable and environmental friendliness.

The tribological properties of lubricants containing the same additives often vary with varying hardness and composition of the frictional parts. This means that, in terms of the effectiveness of lubricant additives, most of current researches using GCr15 steel to assemble the frictional pair could not be directly cited by the moving parts made of other materials. Aiming at verifying if RNS-1A-PIBSA (referring to amino-functionalized silica nanoparticle [RNS-1A] after secondary surface-capping by polyisobutylene succinic anhydride [PIBSA]) is suitable for multiple frictional parts made of different materials with varying hardness and composition, herein we investigate its applicability an additive in poly-alpha-olefin 6 (PAO6) base oil to three types of sliding pairs constructed from GCr15 steel, #45 steel, and ductile iron with much different hardness and composition by SRV-5. A series of analyses of worn surface morphology and composition demonstrate that, independent of the composition and hardness of the frictional pairs, RNS-1A-PIBSA added in PAO6 base oil can form silica deposition film on the rubbed surfaces of the three kinds of sliding pairs, thereby effectively reducing friction and wear. Besides, we also examine the effect of RNS-1A-PIBSA on the thermal stability of the PAO6 base oil, and found the nano-additive RNS-1A-PIBSA can delay the thermal decomposition of PAO6 base oil to some extent, which is favourable for its application in lubrication engineering.

In this paper, the friction properties of the port pair with non-smooth surface in the pump were studied. The lubrication film was modelled and simulated to analyse dynamic pressure, velocity vector and friction coefficient. Tests were made for studying the effects of pit shape and revolution speed on friction properties of glass fibre epoxy resin (GFER) samples under seawater lubrication, with the wear of the surface and friction coefficient discussed. The results show that GFER is mainly manifested as adhesive and abrasive wear during the tests. The simulations and tests suggest that the hydrodynamic lubrication effect is improved by increasing revolution speed and using non-smooth surfaces, with the friction coefficient being decreased. Moreover, a roughness test was conducted, and it was found that the Ra value of the 316L sample decreased, whereas the Ra value of the GFER sample increased.

Discarded tempering lubricants retained significant reuse potential, making their recycling a vital step in reducing resource wastage and wastewater treatment costs in the strip steel industry. Hence, developing an accurate, rapid evaluation indicator for recycled fluid concentration was essential for facilitating this process. Research showed that among common evaluation indicators for metal fluids, three—electrical conductivity, refractive index and total base number (TBN)—due to their high linear correlation with tempering lubricant concentration (R ² > 0.995), could be utilised to monitor the dynamic changes in the concentration of tempering lubricants. Subsequent experiments on reused tempering lubricants revealed that electrical conductivity, significantly altered by iron powder (7%–24% variance), and refractive index, impacted by hydraulic oil (3% deviation), highlighted contaminant challenges; yet, filtration effectively mitigated iron powder's effect on TBN. Finally, A 17-day reused tempering lubricants simulation demonstrated consistent effectiveness of the three indicators in monitoring the need to update tempering lubricant concentration. However, in terms of sensitivity, precision, and particularly stability and relative mean deviation, the TBN concentration evaluation indicator outperformed, with TBN (3.38%) < Refractive Index (7.92%) < Electrical Conductivity (11.05%). This indicates the TBN method's superior stability over conductivity and refractive index methods, with its accuracy deviation below 2%, making it a stable, simple and reliable metric worthy of broader adoption.

Used lubricating oil is generated by various machinery after extended operation. It is also referred to as spent mobile oil. Extremely hazardous waste lubricating oil is detrimental to the environment because it produces oxidative products when additives break down. Used lubricating oil is classified as a hazardous waste substance and has a negative impact on the environment. Polychlorinated biphenyls (PCBs), carcinogenic substances and other impurities make lubricating oil poisonous and pose a serious threat to human health and the environment. Re-refining is considered the preferred technology for resource conservation, waste minimisation and reduced environmental hazards. The present study focuses on optimising the method of re-refining waste lubricating oil. The effects of various operating parameters such as refining time, refining temperature, solvent-to-used oil ratio and flocculant dosage have been extensively studied to maximise the percentage recovery of lubricating oil. Optimum process parameters are (i) a refining time of 80 min, (ii) a refining temperature of 48°C, (iii) solvent-to-waste oil ratio of 5:1 (w/w) and (iv) a flocculant dosage of 2 g/kg of solvent; the optimum yield was found to be 75% with the solvent extraction method and 78% with the extraction–flocculation method, respectively. The purity and physico-chemical properties of the recovered oil were thoroughly analysed using Fourier transform infrared spectroscopy and ASTM standard methods. It was concluded that refined oil can effectively reduce the ongoing oil crisis and create a clean, healthy environment.

The study involved the modification of a melamine sponge (SP) through the introduction of polydopamine (PDA) and octadecylamine (ODA), resulting in the creation of three distinct sponge types: PDA/ODA@SP, PDA@SP and ODA@SP. The successful modification of PDA and ODA onto the surface of the sponge was confirmed through the utilisation of scanning electron microscopy and x-ray photoelectron spectroscopy. Consequently, the resulting sponges exhibited a unique micro–nano composite structure. Wettability testing was conducted to assess the properties of the sponges, revealing that the PDA/ODA@SP sponge demonstrated hydrophobic superlipophilic characteristics. Moreover, a series of 10 repeated oil–water separation experiments indicated that the PDA/ODA@SP sponge achieved an impressive separation efficiency of up to 97%, demonstrating its exceptional oil–water separation capabilities and reusability. Additionally, investigations utilising soybean oil and engine oil demonstrated the composite sponge's superior absorption capabilities for fatty acids and hydrocarbons.

This article presents the preparation of environmentally friendly water-soluble lubricant additives. Adipic acid (AA), sebacic acid (SA) and dodecanedioic acid (DA) were individually subjected to esterification reactions with polyethylene glycol 1500 (PEG1500) to prepare a class of water-soluble polyether esters (AAPEE1500, SAPEE1500 and DAPEE1500) (referred to as XAPEE1500s) that exhibit excellent water solubility and do not contain environmentally harmful elements. First, the molecular structure characterisation and functional group analysis of these additives will be conducted using an infrared spectrometer and a nuclear magnetic resonance spectrometer. Subsequently, the frictional properties of the additives in the base liquid (deionised water) will be investigated using an SRV-V tribometer, Falex pin-on-disc tribometer and screw torque tester. The surface morphology of wear scars will be characterised and analysed using scanning electron microscopy (SEM) and a non-contact 3D profilometer. Finally, the lubrication mechanism of the DAPEE1500 additive will be analysed using X-ray photoelectron spectroscopy (XPS). The results indicate that the optimal lubrication performance is achieved when the added mass fraction of DAPEE1500 is at 3%. Compared with 0.5 wt% DAPEE1500, the average friction coefficient of 3 wt% DAPEE1500 decreased from 0.285 to 0.122, and the wear volume decreased from 25.52 × 10⁻⁵ μm³ to 10.96 × 10⁻⁵ μm³. The lubrication mechanism of polyether ester is the result of the combined action of its polar ester functional groups and long carboxylic acid chains in the structure. These polar functional groups can form a relatively firm adsorption film on the friction surface, while the long carboxylic acid chains act as a brush-like isolating layer, thus demonstrating superior anti-wear and anti-friction performance.

This article presents an experimental study about boundary slippage on the film thickness of hydrodynamic lubrication (HL) using a custom-made slider-on-disc bearing testing apparatus. The interfaces with different affinity were obtained by surface energy modification of sliders with various oleophobic coatings, which are characterised by their contact angle (CA) and contact angle hysteresis (CAH). To study the mechanism of interfacial slip on HL under different wettability constraints, the film thickness and velocity profiles under shear were measured using interference and fluorescence photobleached method, respectively. The results showed that the CAH could better characterise the influence of interface effect on the film thickness of HL, which was explained by the correlation between CAH and the interface potential barrier. Furthermore, it was found that the slip velocity increased with lubricant viscosity and shear rate, which can be explained by the spatial heterogeneity of the flow in conformal contact and the critical shear stress slip model.