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.

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.

Prediction of Density and Refractive Index of Lubricating Oils during Secondary Solvent Extraction Process by Furfural

To meet the requirements for high aromatic content and low polycyclic aromatic(PCA)concentration,eco-friendly aromatic-rich rubber extender oils are usually produced by two-stage solvent extraction processes with furfural.Among the different properties of rubber processing oils,density and refractive index are some of the most important properties related to their final quality.Two types of methods,including a pseudo-component approach by using mixing rules and several correlations,were used for calculation of density and refractive index at 20℃ of paraffinic furfural-extract oils and their secondary raffinates.Results indicated that similar accuracy was obtained for predicting the density and the refractive index of furfural+furfural-extract paraffinic oil systems.However,the quadratic correlation presents its advantage over the pseudo-component approach when the composition of oils is not available.Moreover,the quadratic correlation was also used for naphthenic lubricating oils during two-stage solvent extraction processes.The predictions showed much larger discrepancies with respect to experimental values than those of paraffinic lubricating oils,which indicated that the quadratic correlation was more suitable for paraffinic oils with a CN value of below 37%.

Compositionally Driven Viscometric Behaviors of Poly (Alkyl Methacrylates) in Lubricating Oils

Viscosity index (VI) and shear stability index (SSI) are standard methods used in the lubricant industry to determine temperature-viscosity dependency and resistance to product degradation, respectively. A variety of oil-soluble polymers, including poly(alkyl methacrylates) (PAMAs) are routinely used to control these properties in fully-formulated liquid lubricants. In this report, we use reversible addition-fragmentation chain transfer (RAFT) polymerization to precisely target identical degrees of polymerization in a family of PAMAs with varying lauryl, hexyl, butyl, ethyl, and methyl groups. Then, expanding on previous methodology reported in the literature, we establish structure property relationships for these PAMAs, specifically looking at how intrinsic viscosity [η] and Martin interaction parameters KM relate to VI and SSI characteristics. While the intrinsic viscosity [η] is associated with the volume of macromolecules at infinite dilution, the parameter KM reflects the hydrodynamic interactions of polymer chains at actual polymer concentrations in lubricating oils. In this paper, we show that the dependence of VI on the non-dimensional concentration c/c* (or c[η]) can be presented in a form of master curve with shift factors proportional to KM that decreases with increasing size of alkyl groups. This finding implies that even in the dilute regime, the coil-expansion theory used to explain the effect of macromolecules on VI should be complemented with the idea of hydrodynamic interactions between polymer molecules that can be controlled by the choice of alkyl chains in the family of PAMAs.

Study on application of CeO_2 and CaCO_3 nanoparticles in lubricating oils

The ceria （CeO2） nanoparticles and calcium carbonate （CaCO3） nanoparticles were chosen as additives of anti-wear and extreme pressure for lubricating oils, and the morphology and sizes of nanoparticles were examined using Transmission Electron Microscope （TEM）. The tribological performance of lubricating oils containing combined nanoparticles were determined by four-ball friction and wear tester, and the chemical composition of steel ball with worn surface were analyzed by X-ray Photoelectron Spectrurn（XPS）. The results showed that the lubricating oils containing combined nanoparticles had good anti-wear and friction reducing effects, and the tribological properties were optimal when WCeO2＋CaCO3=0.6%, WCeO2：WCaCO3=1：1. The extreme pressure value increased by 40.25%, the wear spot diameter reduced by 33.5%, and friction coefficient reduced by 32% compared with 40CD oil. The coordinated action of big and small particles made anti-wear and friction reducing effective. Tribological chemical reactions resulting from the friction surface formed metal calcium, metal cerium and oxides film, and they could fill up the concave surface and protect the worn surface.

Diester Derivatives from Chemically Modified Waste Cooking Oil as Substitute for Petroleum Based Lubricating Oils

In order to provide a new way for waste cooking oil(WCO) resource utilization, several diester derivatives were obtained from WCO through a three-step chemical modifications, viz.: transesterification, epoxidation and oxirane ring opening with carboxylic acids. The effects of the chain length of side chain groups on the viscosity, acid value, low temperature fluidity, thermo-oxidative stability, tribological properties and surface tension of diester derivatives were investigated. The results showed that increasing the chain length of side chain groups had a positive influence on the viscosity, viscosity index, acid value, pour point, friction coefficient and wear scar diameter along with a negative influence on the oxidation onset temperature, volatile loss, insoluble deposit, maximum non-seizure load and surface tension. These diester derivatives exhibited improved physicochemical and tribological properties that make themselves promising environmentally friendly biolubricant basestocks.

A Generalized Correlation for Characterization of Lubricating Base-oils from Their Viscosities

Lubricating mineral base oils are normally extracted from lube-oil cuts with furfural solvent.Aromatic content in the raffinate phase from extraction process is an essential parameter that affects the quality of the lubricating base-oils.For determination of aromatic content by the usual ASTM D3238 method,density,refractive index and molecular weight of the raffinate are required.In this work,a new generalized correlation is developed for de-termination the aromatic content by using only the measured viscosity of lubricating oil.With a mole fraction of aromatic compounds,the kinematic viscosity may be obtained at any temperature between 60-100°C along with their molecular weight and refractive index.

Tribological and economic evaluation of recycled mineral lubricating oils

Seven kinds of used mineral lubricating oils,including hydraulic oils,film bearing oils,steam turbine oil and gear oils,were recycled by reclamation and adding additives.Physical and chemical properties of the recycled oils were measured and their lubrication performances were evaluated by the original and modified four-ball testers.Worn surfaces were analyzed by energy dispersive X-ray spectroscopy and Raman microscope.The recycling costs of burning,re-refined and refortified were estimated.Results showed that physical and chemical properties of the refortified oils were improved effectively and became in the industrial access standard.With the different friction materials under different loads,refortified oils provided excellent lubrication performances,much better than those of fresh oils.Because of additives replenished,the different lubrication films could form on the worn surfaces.A rough financial calculation revealed that the refortification process could produce the most economic value among the three methods.

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.

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.

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。

Thermal oxidation of two aviation synthetic lubricant base oils

The thermal degradation of two synthetic lubricants base oils, poly-a-olefins （PAO） and di-esters （DE）, was investigated under oxidative pyrolysis condition and their properties were characterized in simulated ＂areo-engine＂ by comparing the thermal stability and identifying the products of thermal decomposition as a function of exposure temperature. The characterization of the products were performed by means of Fourier transform infrared spectrometry （FTIR）, gas chromatography/mass spectrometry （GC/MS） and viscosity experiments. The results show that PAO has the lower thermal stability, being degraded at 200℃ different from 300 ℃ for DE. Several by-products are identified during the thermal degradation of two lubricant base oils. The majority of PAO products consist of alkenes and olefins, while more oxygen-contained organic compounds are detected in DE samples based on GC/MS analysis. The related reaction mechanisms are discussed based on the experimental results.

Three-dimensional modeling of effect of surface intermetallic phase on surface defects of Al-Fe-Si aluminum foils during twin-roll casting

Scanning electron microscopy and X-ray energy dispersive spectrum analysis show that the clusters of intermetallic AlFeSi particle are distributed on or near the aluminum foil stock surfaces heterogeneously. 3D finite element modeling shows that these clusters of hard particles induce the fracture of the nano-scale lubricant oil film at first and further lead to severe deformation in the nearby aluminum foil substrate along the rolling direction. Consequently, the optical property in this region differs from that in the surroundings, resulting in surface defects.

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.

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.

Rapidly determining fuel pollution level of aviation lubricating oil 50-1-4Φby mid-infrared spectrometry

A series of aviation lubrication oil 50-1-4φ samples were prepared with different RP-3 content, and then these sam- ples were analyzed by Fourier transform mid-infrared spectrometer （FTIR）. The infrared region of 805--755 cm-1 was selected as quantitative area for determining fuel pollution level of aviation lubrication oil. Finally, correlation of the testing peak area and the fuel pollution level of corresponding samples were analyzed, and the regression equation was proposed. The results show that determining jet fuel pollution level of aviation lubricating oil by FTIR is feasible and reliable.

Tribological Performances of Fatty Acyl Amino Acids Used as Green Additives in Lubricating Oil

The friction and wear characteristics of lauroyl glutamine, lauroyl glycine and lauroyl alanine, used as green additives in HVI 350 mineral lubricating oil, were evaluated on a four-ball tribotester. The morphologies and chemical species of the worn surfaces were analyzed by scanning electron microscope （SEM） and X-ray photoelectron spectroscope （XPS）, respectively. The test results indicated that the three fatty acyl amino acids could effectively improve the anti-wear and friction-reducing abilities of the HVI 350 mineral oil. The improvement in anti-wear and friction-reducing abilities of the mineral oil by the related amino acids was mainly ascribed to the formation of a composite boundary lubrication film due to the adsorption of amino acids on the friction surfaces.

Nanosized copper powders prepared by gel-casting method and their application in lubricating oil

Nanosized copper powders were prepared by a gel-casting method using copper nitrate, acrylamide（AM） and N, N′-methylenebisacrylamide（MBAM） as the main raw materials. The as-prepared copper powders were characterized by X-ray diffractometry and scanning electron microscopy, and then added into a 48# industrial white oil. Dispersion and wear properties of the compounded lubricating oil were tested. The results show that the copper powders prepared are of high purity, fine dispersibility with mean particle size of about 60 nm and with a narrow particle size distribution. The nanosized copper powders can be well dispersed in the lubricating oil. The addition of the copper powders obviously improves the anti-wear properties of the lubricating oil owing to their good self-repairing performance. Compared with 48# industrial white lubricating oil, the friction coefficient of GCr15 steel with the compounded oil containing 0.6% copper powders reduces by 0.07 and nearly no wear chippings are found in the scratches of the friction counter parts.

Alkylation of naphthalene with n-butene catalyzed by liquid coordination complexes and its lubricating properties

With the development of coal chemical industry,large amounts of naphthalene and n-butene are produced,and converting them into high value-added products through alkylation has gained particular importance and interest.In this work,liquid coordination complexes(LCCs)were used as acid catalysts for the first time in the naphthalene alkylation reaction under mild conditions to obtain multibutylnaphthalenes with high yield.Various reaction conditions were thoroughly investigated.The LCC consisting of urea and AlCl_(3) showed excellent catalytic performance under optimal reaction conditions,giving 100%conversion of naphthalene and 99.66%selectivity towards multi-butylnaphthalenes.Combining the catalyst properties and catalytic results,a plausible reaction mechanism was proposed.The lubricating properties of the synthesized products were investigated for their potential application as lubricating base oils.The synthesized multi-butylnaphthalenes showed comparable physicochemical properties and tribological performances as the commercial cycloalkyl base oil.

CONSTITUTIVE EQUATION OF A NEW AVIATION LUBRICATING OIL

The traction of a new aviation lubricating oil was measured on a self-made test rig. The calculating formulae of the rheological parameters of the oil such as Erying stress, limiting shear stress and shear elastic modulus were obtained under the condition of the high shear strain rate in elastohydrodynamic lubrication（EHL）. The constitutive equation of this oil was determined and verified by test. The results of experiments show that the behavior of the new aviation lubricating oil behaves as visco-elastic fluid and the theoretical value agrees fairly well with the measured data, which implies that the constitutive equation of this oil is correct and feasible.