Molecular Mechanism and Molecular Design of Lubricating Oil Antioxidants

To overcome the limitations of traditional experimental“trial and error”methods in lubricant additive design,a new molecular design method based on molecular structure parameters is established here.The molecular mechanism of the antioxidant reaction of hindered phenol,diphenylamine,and alkyl sulfide are studied via molecular simulations.Calculation results show that the strong electron-donating ability and high hydrogen-donating activity of the antioxidant molecule and the low hydrogen-abstracting activity of free radicals formed after dehydrogenation are the internal molecular causes of the shielding of phenol and diphenylamine from scavenging peroxy free radicals,and the strong electron-donating ability is the internal molecular cause of the high activity of thioether in decomposing alkyl hydrogen peroxide.Based on this antioxidant molecular mechanism,a molecular design rule of antioxidant is proposed,namely“high EHOMO,large Q(S),low bond dissociation energy BDE(O—H)and BDE(N—H)”.Two new antioxidants,PAS-I and PAS-II,are designed and prepared by chemical bonding of hindered phenol,diphenylamine,and sulfur atoms.Experimental results show that these antioxidants both have excellent antioxidant effects in lubricating oil,and that PAS-II is the superior antioxidant,consistent with theoretical predictions.

Identification of Lubricating Oil Additives Using XGBoost and Ant Colony Optimization Algorithms

To address the problem of identifying multiple types of additives in lubricating oil,a method based on midinfrared spectral band selection using the eXtreme Gradient Boosting(XGBoost)algorithm combined with the ant colony optimization(ACO)algorithm is proposed.The XGBoost algorithm was used to train and test three additives,T534(alkyl diphenylamine),T308(isooctyl acid thiophospholipid octadecylamine),and T306(trimethylphenol phosphate),separately,in order to screen for the optimal combination of spectral bands for each additive.The ACO algorithm was used to optimize the parameters of the XGBoost algorithm to improve the identification accuracy.During this process,the support vector machine(SVM)and hybrid bat algorithms(HBA)were included as a comparison,generating four models:ACO-XGBoost,ACO-SVM,HBA-XGboost,and HBA-SVM.The results showed that all four models could identify the three additives efficiently,with the ACO-XGBoost model achieving 100%recognition of all three additives.In addition,the generalizability of the ACO-XGBoost model was further demonstrated by predicting a lubricating oil containing the three additives prepared in our laboratory and a collected sample of commercial oil currently in use。

OBJECT-ORIENTED IMPLEMENTATION OF EXPERT SYSTEMS FOR ENGINE LUBRICATING OIL INSPECTION

The inspection of engine lubricating oil can give an indication of the internal condition of an engine. By means of the Object-Oriented Programming (OOP), an expert system is developed in this paper to computerize the inspection. The traditional components of an expert system, such us knowledge base, inference engine and user interface are reconstructed and integrated, based on the Microsoft Foundation Class (MFC) library. To testify the expert system, an inspection example is given at the end of this paper.

Predictive methods for density and refractive index of naphthenic lubricating oils during solvent extraction process

Lubricating oils are usually produced by solvent extraction to separate aromatics in order to achieve the desired specifications and better quality products.Among the different properties of lubricating oils,density and refractive index are some of the most important properties which can both be used for petroleum fluid characterization.Predictions of density and refractive index for naphthenic oils during solvent extraction by DMSO obtained by the pseudo-component approach and the quadratic correlation were both examined.The pseudo-component approach is a method to predict density and refractive index from composition while the latter merely relates density to refractive index.Results indicated that the predictions yielded by the pseudo-component method were in good agreement with experimental data for naphthenic oils.And the use of a function of refractive index(FRI_(20))as a pseudo-component property remarkably improved n_(20)predictions for the naphthenic mixtures.However,the density and refractive index predictions obtained by the quadratic correlation exhibited significantly higher de-viations for naphthenic oils than those for paraffinic oils.Thus a new modified correlation of the same functional form was proposed for naphthenic oils.The modification significantly improved predictions for naphthenic oils,which presented similar accuracy as the pseudo-component approach.And the previous correlation was still used for paraffinic oils.Additionally,effect of temperature on density and refractive index of naphthenic oils was examined.Results showed that the modified quadratic correlation was accurate for describing the relationship between density and refractive index of naphthenic oils at 20-90℃.The temperature dependence of density and refractive index for the raffinates and the extracts could be accurately described by the thermal coefficients for saturates and aromatics,respectively.Regarding the refractive index variation of the extracts with temperature,the empirical equation was proved to be a better option compared with the method using the thermal coefficient for aromatics.

Simulation of Solvent Extraction for Naphthenic Lubricating Base Oils

Solvent extraction is the process of separating aromatics from vacuum distillates for the production oflubricating base oils. In this study, the authors use dimethyl sulfoxide (DMSO) instead of furfural as solvent, in light of itshigher selectivity, to obtain extracts with a high aromatic content for naphthenic lubricating base oils. We systematicallyinvestigated effects of the solvent-to-oil (S/O) ratio and extraction temperature on the yield of the extract, efficiency ofaromatic removal, and composition of the extracts and raffinates. The results showed that the aromatic content of extractsfor naphthenic oils could reach a high value of about 80%. The solvent maintained a high selectivity for aromatics fornaphthenic oils even under a high S/O ratio and a high extraction temperature. Moreover, the efficiency of aromatic removalfor naphthenic lubricating base oils could be enhanced by increasing either the S/O ratio or the extraction temperature,although these measures had limited effects in practice. Following this, we used the non-random two-liquid (NRTL) modelbased on the pseudo-component approach to simulate the liquid-liquid equilibrium of the system of DMSO + naphtheniclubricating base oils, and determined the parameters of binary interaction through regression based on the data on phaseequilibrium. The modeling results showed that the predicted yield, content of the solvent, and composition of the raffinatesand extracts were in good agreement with those obtained in the experiments. This validates the reliability of the model usedto represent the DMSO + naphthenic lubricating base oil system. Both the experimental data and the method of simulationreported here can help optimize the extraction of naphthenic lubricating base oils, and provide a better understanding of thecorresponding process.

Alkyl-tetralin base oils synthesized from coal-based chemicals and evaluation of their lubricating properties

Naphthenic base oil is an important lubricating base oil and very scarce in the global petroleum resources.Herein,a series of alkylated tetralin fluids similar to naphthenic base oils were produced by the alkylation of tetralin and a-olefins(n-hexene,n-octene,n-decene)with ionic liquid Et_3NHCl/AlCl_(3)as the catalyst,where the applied raw materials are totally derived from the coal chemical industry.The product composition could be controlled by adjusting the feeding ratio of tetralin and olefin.The synthetic fluids were evaluated as lubricating base oils to reveal the structure-property correlations.Their principal physicochemical and tribological properties depend on the chain-length of a-olefins and the number of alkyl groups onto the aromatic rings.Bis-(octyl-or decyl-)alkyl tetralin exhibited good properties in terms of viscosity,thermo-oxidation stability and pour point,as well as friction-reducing and anti-wear performance,showing great potential for producing naphthenic base synthetic oils from coal-based chemicals.

Mechanism,Kinetics,and Thermodynamic Characteristics for the Demetallization of Used Lubricating Oil via Pyrolysis

This study analyzed the pyrolysis mechanism,developed a pyrolysis kinetic model,and determined the corresponding thermodynamic parameters for the removal of calcium from used lubricating oil using sulfurized calcium alkyl phenolate(T-115B)as a model compound.The pyrolysis process and products were evaluated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy.Visual inspection indicated that the removal of calcium from T-115B depended primarily on the destruction of micelles caused by the pyrolysis of compounds at high temperatures.The pyrolysis characteristics of T-115B at different heating rates were investigated by thermogravimetry and differential thermal analysis,which revealed two distinct pyrolysis phases.Thus,the pyrolysis mechanism can be described by a twostep model.The activation energy and thermodynamic parameters(ΔH,ΔG,andΔS)were determined by applying the Kissinger-Akahira-Sunose,Flynn-Wall-Ozawa,Friedman,and Starink methods;the average activation energies for T-115B pyrolysis obtained using these methods were 115.80,119.84,124.96,and 116.14 kJ/mol,respectively.Further,both stages of the pyrolysis reaction followed Fn mechanisms with n=1.39 in the first stage and n=0.86 in the second stage.This study provides reliable and effective pyrolysis models along with kinetic and thermodynamic parameters to facilitate the largescale industrial application of used lubricating oil.

Tribological effects of oxide based nanoparticles in lubricating oils

In order to enhance the tribological properties of lubricating oil, suitable surfactants such as Tween-20, Tween-60, Span-20 and Sodium sodecylbenzenesulfonate were selected and lubricating oils containing CeO2 and TiO2 nanoparticles were prepared. The morphology and size of CeO2 and TiO2 nanoparticles were examined with a transmission electron microscope （TEM）. The tribological properties of the oils were tested using an MRS-1J four-ball tribotester. The research results show that when the proportion by weight of CeO2 nanoparticles to TiO2 nanoparticles is 1：3, and the total weight fraction is 0.6%, the lubricating oil has optimal anti-wear and friction reducing properties. The addition of CeO2 nanoparticles reduces the required amount of TiO2 nanoparticles.

Synthetic polymers:A review of applications in drilling fluids

With the growth of deep drilling and the complexity of the well profile,the requirements for a more complete and efficient exploitation of productive formations increase,which increases the risk of various complications.Currently,reagents based on modified natural polymers(which are naturally occurring compounds)and synthetic polymers(SPs)which are polymeric compounds created industrially,are widely used to prevent emerging complications in the drilling process.However,compared to modified natural polymers,SPs form a family of high-molecular-weight compounds that are fully synthesized by undergoing chemical polymerization reactions.SPs provide substantial flexibility in their design.Moreover,their size and chemical composition can be adjusted to provide properties for nearly all the functional objectives of drilling fluids.They can be classified based on chemical ingredients,type of reaction,and their responses to heating.However,some of SPs,due to their structural characteristics,have a high cost,a poor temperature and salt resistance in drilling fluids,and degradation begins when the temperature reaches 130℃.These drawbacks prevent SP use in some medium and deep wells.Thus,this review addresses the historical development,the characteristics,manufacturing methods,classification,and the applications of SPs in drilling fluids.The contributions of SPs as additives to drilling fluids to enhance rheology,filtrate generation,carrying of cuttings,fluid lubricity,and clay/shale stability are explained in detail.The mechanisms,impacts,and advances achieved when SPs are added to drilling fluids are also described.The typical challenges encountered by SPs when deployed in drilling fluids and their advantages and drawbacks are also discussed.Economic issues also impact the applications of SPs in drilling fluids.Consequently,the cost of the most relevant SPs,and the monomers used in their synthesis,are assessed.Environmental impacts of SPs when deployed in drilling fluids,and their manufacturing processes are identified,together with advances in SP-treatment methods aimed at reducing those impacts.Recommendations for required future research addressing SP property and performance gaps are provided.

Grindability Evaluation of Ultrasonic Assisted Grinding of Silicon Nitride Ceramic Using Minimum Quantity Lubrication Based SiO_(2)Nanofluid

Minimum quantity Lubrication(MQL)is a sustainable lubrication system that is famous in many machining systems.It involve the spray of an infinitesimal amount of mist-like lubricants during machining processes.The MQL system is affirmed to exhibit an excellent machining performance,and it is highly economical.The nanofluids are understood to exhibit excellent lubricity and heat evacuation capability,compared to pure oil-based MQL system.Studies have shown that the surface quality and amount of energy expended in the grinding operations can be reduced considerably due to the positive effect of these nanofluids.This work presents an experimental study on the tribological performance of SiO_(2)nanofluid during grinding of Si_(3)N_(4)ceramic.The effect different grinding modes and lubrication systems during the grinding operation was also analyzed.Different concentrations of the SiO_(2)nanofluid was manufactured using canola,corn and sunflower oils.The quantitative evaluation of the grinding process was done based on the amount of grinding forces,specific grinding energy,frictional coefficient,and surface integrity.It was found that the canola oil exhibits optimal lubrication performance compared to corn oil,sunflower oil,and traditional lubrication systems.Additionally,the introduction of ultrasonic vibrations with the SiO_(2)nanofluid in MQL system was found to reduce the specific grinding energy,normal grinding forces,tangential grinding forces,and surface roughness by 65%,57%,65%,and 18%respectively.Finally,regression analysis was used to obtain an optimum parameter combinations.The observations from this work will aid the smooth transition towards ecofriendly and sustainable machining of engineering ceramics.

Versatile MXene Gels Assisted by Brief and Low‑Strength Centrifugation

Due to the mutual repulsion between their hydrophilic surface terminations and the high surface energy facilitating their ran-dom restacking,2D MXene nanosheets usually cannot self-assemble into 3D macroscopic gels with various applications in the absence of proper linking agents.In this work,a rapid spontaneous gelation of Ti3C2Tx MXene with a very low dispersion concentration of 0.5 mg mL^(-1) into multifunctional architectures under moderate centrifugation is illustrated.The as-prepared MXene gels exhibit reconfigurable internal structures and tunable rheological,tribological,electrochemical,infrared-emissive and photothermal-conversion properties based on the pH-induced changes in the surface chemistry of Ti_(3)C_(2)T_(x) nanosheets.By adopting a gel with optimized pH value,high lubrication,exceptional specific capacitances(~635 and~408 F g^(-1) at 5 and 100 mV s^(-1),respectively),long-term capacitance retention(~96.7%after 10,000 cycles)and high-precision screen-or extrusion-printing into different high-resolution anticounterfeiting patterns can be achieved,thus displaying extensive potential applications in the fields of semi-solid lubrication,control-lable devices,supercapacitors,information encryption and infrared camouflaging.

Silicone oil as a corneal lubricant to reduce corneal edema and improve visualization during

AIM:To evaluate the efficacy and safety of silicone oil(SO)as a corneal lubricant to improve visualization during vitrectomy.METHODS:Patients who underwent vitreoretinal surgery were divided into two groups.Group 1 was operated on with initial SO(Oxane 5700)as a corneal lubricant.Group 2 was operated on with initial lactated ringer’s solution(LRS)and then replaced with SO as required.Fundus clarity was scored during the surgery.Fluorescein staining was performed to determine the damage to corneal epithelium.RESULTS:Totally 114 eyes of 114 patients were included.Single SO use maintained a clear cornea and provided excellent visualization of surgical image.In group 1,the fundus clarity was grade 3 in 41/45 eyes and grade 2 in 4/45 eyes.In group 2,corneal edema frequently occurred after initial LRS use.The fundus clarity was grade 3 in 19/69 eyes,2 in 37/69 eyes and 1 in 13/69 eyes(P<0.05).SO was applied in 29 eyes of initial LRS use with subsequent corneal edema,which eliminated the corneal edema in 26 eyes.Corneal fluorescein staining score in group 1 was 0 in 28 eyes,1 in 11 eyes and 2 in 6 eyes,and 40,20 and 9,respectively,in group 2(all P>0.05).CONCLUSION:The use of SO as a corneal lubricant is effective and safe for preserving and improving corneal clarity and providing clear surgical field during vitrectomy.

Application of ultra-smooth composite diamond film coated WC-Co drawing dies under water-lubricating conditions

A specific revised HFCVD apparatus and a novel process combining HFCVD and polishing technique were presented to deposit the micro-and nano-crystalline multilayered ultra-smooth diamond（USCD） film on the interior-hole surface of WC-Co drawing dies with aperture ranging from d1.0 mm to 60 mm.Characterization results indicate that the surface roughness values（Ra） in the entry zone,drawing zone and bearing zone of as-fabricated USCD coated drawing die were measured as low as 25.7,23.3 and 25.5 nm,respectively.Furthermore,the friction properties of USCD films were examined in both dry sliding and water-lubricating conditions,and the results show that the USCD film presents much superior friction properties.Its friction coefficients against ball-bearing steel,copper and silicon nitride balls（d4 mm）,is always lower than that of microcrystalline diamond（MCD） or WC-Co sample,regardless of the lubricating condition.Meanwhile,it still presents competitive wear resistance with the MCD films.Finally,the working lifetime and performance of as-fabricated USCD coated drawing dies were examined under producing low-carbon steel pipes in dry-sliding and water-lubricating conditions.Under the water-lubricating drawing condition,its production significantly increases by about 20 times compared with the conventional WC-Co drawing dies.

Dynamic Response of IBM3370 Slider in High Density Recording Systems

A liquid lubricated head disk system is introduced. Subjected to high shear rate the rheology of the ultra thin film is different from that of the bulk continuum theory. The shear thinning effect is considered in setting up the mathematical model of the ultra thin film rheology. The Reynolds equation and the perturbation theory are employed to set up the static pressure distribution model and to deduce the dynamic pressure equation. The static and dynamic equations are solved by finite difference method. Based on the dynamic analysis the dynamic response of the slider is simulated and some valuable results are obtained about the static and dynamic characteristics of the liquid lubricated head disk systems.

Enhancing the Tribological Performance of Conductive Grease Through the Modification of Polypyrrole with Ionic Liquids

This study prepared four types of ionic liquid-modified polypyrrole(IL-modified PPy)as conductive additives and investigated their tribological performance and conductivity in polytetrafluoroethylene lubricating grease.The results indicated that IL-modified PPy effectively enhanced the anti-wear performance and conductivity of the base grease.Among the additives,1-octyl-3-methylimidazolium tetrafluoroborate([OMIm][BF4])modified PPy showed superior performance compared to the other three additives,with the best effect observed at a mass fraction of 0.5%.X-ray photoelectron spectroscopy analysis revealed that IL-modified PPy forms a stable friction chemical film during the friction process,effectively enhancing the lubrication performance and conductivity of the base grease.This indicates broad potential applications in the field of conductive lubrication.

Fluorographene with Narrow Lateral Size and Thickness Distributions Prepared for Enhancing Lubrication Performance of Bentonite Grease

Fluorographene(FG)with narrow lateral size and thickness distributions was prepared by a liquid-phase exfoliation method,based on liquid cascade centrifugation.The Rtec MFT-5000 tribo-meter was used to investigate the lubricating performance of bentonite grease enhanced by the as-prepared FG.The results showed that the coefficient of friction and the wear volume of bentonite grease with 0.3 wt%FG were decreased by 20.4%and 44.9%,respectively,as compared to those of the base grease.The main reason is that FG can promote the formation of the tribo-chemical reaction film consisting of complex carbon oxide,Fe_(2)O_(3)and FeF_(3)on the friction surface,which can remarkably improve the performance of friction reduction and prevent the appearance of severe wear.

Design and optimization of fluid lubricated bearings operated with extreme working performances——a comprehensive review

Fluid lubricated bearings have been widely adopted as support components for high-end equipment in metrology,semiconductor devices,aviation,strategic defense,ultraprecision manufacturing,medical treatment,and power generation.In all these applications,the equipment must deliver extreme working performances such as ultraprecise movement,ultrahigh rotation speed,ultraheavy bearing loads,ultrahigh environmental temperatures,strong radiation resistance,and high vacuum operation,which have challenged the design and optimization of reliable fluid lubricated bearings.Breakthrough of any related bottlenecks will promote the development course of high-end equipment.To promote the advancement of high-end equipment,this paper reviews the design and optimization of fluid lubricated bearings operated at typical extreme working performances,targeting the realization of extreme working performances,current challenges and solutions,underlying deficiencies,and promising developmental directions.This paper can guide the selection of suitable fluid lubricated bearings and optimize their structures to meet their required working performances.

MoS_(2)Lubricate‑Toughened MXene/ANF Composites for Multifunctional Electromagnetic Interference Shielding

The design and fabrication of high toughness electromagnetic interference(EMI)shielding composite films with diminished reflection are an imperative task to solve electromagnetic pollution problem.Ternary MXene/ANF(aramid nanofibers)–MoS_(2)composite films with nacre-like layered structure here are fabricated after the introduction of MoS_(2)into binary MXene/ANF composite system.The introduction of MoS_(2)fulfills an impressive“kill three birds with one stone”improvement effect:lubrication toughening mechanical performance,reduction in secondary reflection pollution of electromagnetic wave,and improvement in the performance of photothermal conversion.After the introduction of MoS_(2)into binary MXene/ANF(mass ratio of 50:50),the strain to failure and tensile strength increase from 22.1±1.7%and 105.7±6.4 MPa and to 25.8±0.7%and 167.3±9.1 MPa,respectively.The toughness elevates from 13.0±4.1 to 26.3±0.8 MJ m^(−3)(~102.3%)simultaneously.And the reflection shielding effectiveness(SE_(R))of MXene/ANF(mass ratio of 50:50)decreases~10.8%.EMI shielding effectiveness(EMI SE)elevates to 41.0 dB(8.2–12.4 GHz);After the introduction of MoS_(2)into binary MXene/ANF(mass ratio of 60:40),the strain to failure increases from 18.3±1.9%to 28.1±0.7%(~53.5%),the SE_(R)decreases~22.2%,and the corresponding EMI SE is 43.9 dB.The MoS_(2)also leads to a more efficient photothermal conversion performance(~45 to~55℃).Additionally,MXene/ANF–MoS_(2)composite films exhibit excellent electric heating performance,quick temperature elevation(15 s),excellent cycle stability(2,2.5,and 3 V),and long-term stability(2520 s).Combining with excellent mechanical performance with high MXene content,electric heating performance,and photothermal conversion performance,EMI shielding ternary MXene/ANF–MoS_(2)composite films could be applied in many industrial areas.This work broadens how to achieve a balance between mechanical properties and versatility of composites in the case of high-function fillers.

FlowBreakdown of Hybrid Nanofluid on a Rigid Surface with Power Law Fluid as Lubricated Layers

Thiswork investigates an oblique stagnation point flowof hybrid nanofluid over a rigid surface with power lawfluidas lubricated layers. Copper (Cu) and Silver (Ag) solid particles are used as hybrid particles acting in water H2O asa base fluid. The mathematical formulation of flow configuration is presented in terms of differential systemthat isnonlinear in nature. The thermal aspects of the flow field are also investigated by assuming the surface is a heatedsurface with a constant temperature T. Numerical solutions to the governing mathematical model are calculatedby the RK45 algorithm. The results based on the numerical solution against various flow and thermal controllingparameters are presented in terms of line graphs. The specific results depict that the heat flux increases over thelubricated-indexed parameter.

Rapidly determining kinematic viscosity of aviation lubricating oil 50-1-4Φ by mid-infrared spectrometry

This paper analyzed 11 lubricating oil 50-1-4Ф samples of different base oil content （standard oil） and 28 used oil samples by Fourier transform mid-infrared spectrometer （FTIR）. First, the absorption peak of 1 465 cm 1 was selected as the characteristic peak for determining their kinematic viscosities. And then correlation of the kinematic viscosity and the absorbance at characteristic peaks of corresponding infrared spectrum of standard oil and used oil samples was analyzed, re- spectively, and two regression equations were proposed. Finally, the regression equation of standard oil was corrected through other 20 new oil samples. The results show that determining kinematic viscosity of new lubricating oil 50-1-4Ф and the used one by FTIR is feasible and reliable.