A comparative study between graphene oxide and diamond nanoparticles as water-based lubricating additives

The tribological properties of graphene oxide(GO) nanosheets and modified diamond(MD) nanoparticles with excellent water-solubility were investigated.GO nanosheets were synthesized using carbon fibers with a regular and uniform size,the lateral size being around 30 nm and the thickness being 2 or 3 nm,while MD nanoparticles were about 30 nm in the three dimensions.The friction properties of ceramics were improved by GO nanosheets or MD nanoparticles used as additives in water-based lubrication,though the effects of two nanoparticles were quite different.For GO nanosheets,the friction coefficient at the beginning decreased sharply from 0.6 to 0.1,as compared with the dionized water lubrication.At the same time,the running-in period was shortened from 2000 s to 250 s.A steady state characterized by ultralow friction(friction coefficient=0.01) was obtained after the running-in period.In the case of MD nanoparticles,the friction coefficient stayed at 0.1 without further decrease during the whole experiment.Based on the observation of wear scar and characterization of remains on the wear track,the positive effect of GO nanosheets was attributed to their lamellar structure and geometric size.MD nanoparticles reduced friction by forming the regularly grained surface on the mating surfaces,and prevented further reduction in steady-state friction coefficient owing to their larger size and hardness.In conclusion,GO nanosheets exhibited favorable potential as an effective additive for water-based lubrication.

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。

Synergistic Effect between Nano-ceramic Lubricating Additives and Electroless Deposited Ni-W-P Coating

The major solving ways for the material wear are surface modification and lubrication. Currently, the researches at home and abroad are all limited to the single study of either nano-lubricating oil additive or electroless deposited coating. The surface coating has high hardness and high wear resistance, however, the friction reduction performance of the coating with high hardness is not good, the thickness of the coating is limited, and the coating can not regenerate after wearing. The nano-lubricating additives have good tribological performance and self-repair function, but under heavy load, the self-repair rate to the worn surface with the nano-additives is smaller than the wearing rate of the friction pair. To solve the above problems, the Ni-W-P alloy coating and deposition process with excellent anti-wear, and suitable for industrial application were developed, the optimum bath composition and process can be obtained by studying the influence of the bath composition, temperature and PH value to the deposition rate and the plating solution stability. The tribological properties as well as anti-wear and friction reduction mechanism of wear self-repair nano-ceramic lubricating additives are also studied. The ring-block abrasion testing machine and energy dispersive spectrometer are used to explore the internal relation between the coating and the nano-lubricating oil additives, and the tribology mechanism, to seek the synergetic effect between the two. The test results show that the wear resistance of Ni-W-P alloy coating （with heat treatment and in oil with nano-ceramic additives） has increased hundreds times than 45 steel as the metal substrate in basic oil, the friction reduction performance is improved. This research breaks through the bottleneck of previous separate research of the above-mentioned two methods, and explores the combination use of the two methods in industrial field.

The Effect and Mechanism of Nano-Cu Lubricating Additives on the Electroless Deposited Ni-W-P Coating

The coating and deposition process with excellent anti wear and suitable for industrial application were developed, and the optimum bath composition and process were obtained by studying the influence of the bath composition, temperature and pH value on the deposition rate and the plating solution stability. Moreover, the tribological properties of nano-Cu lubricating additives and electroless deposited Ni-W-P coating as well as their synergistic effect are researched using ring-block abrasion testing machine and energy dispersive spectrometer. Research results show that Ni-W-P alloy coating and nano-Cu lubricating additive have excellent synergistic effect, e g, the wear resistance of Ni-W-P alloy coating （with heat treatment and the oil with nano-Cu additives） has increased hundreds times than 45 steel as the metal substrate with the basic oil, and zero wear is achieved, which breaks through the bottleneck of previous separate research of the above-mentioned two aspects.

Study on Tribological Behaviors of Boron-Nitrogen Modified Fatty Acid as Water-Based Lube Additives

A new type of boron-nitrogen modified fatty acid as water base lube additive was prepared and the chemical structure characterized by infrared spectrum.The tribological properties of the additive in water were evaluated by friction testers.The morphographies and tribochemical species of the worn surfaces were analyzed by means of X-ray Photoelectron Spectroscope(XPS).The results showed that the additive is excellent in increasing load-carrying capacity,anti-wear and friction-reducing abilities of water.The lubrication mechanism is inferred that a high strength adsorption film and a tribochemical reaction film are formed on the rubbing surfaces due to the carrier effect of the long chain fatty acid molecules,high reaction activities of nitrogen,electron-deficient orbit of boron and their synergisms.

Tribological behaviors of graphene oxide partly substituted with nano-SiO_(2) as lubricant additives in water for magnesium alloy/steel interfaces

Although graphene oxide(GO)has emerged as an excellent lubricant additive in water,there remain great challenges in their practical application due to high production costs.By taking into account the low cost and also its excellent tribological properties,it is likely that nano-SiO_(2)can be used as a lubricant additive to partially replace GO.Hence,this paper aims to explore the tribological properties of nano-SiO_(2)incorporated in GO nanofluids for partial GO replacement by investigating the friction coefficient and wear volume of the prepared SiO_(2)/GO hybrid nanofluids for magnesium alloy/steel sliding pairs.The experiments reveal that the SiO_(2)/GO hybrids retain low friction coefficients as compared to individual GO or SiO_(2)at all test conditions in this study.However,as for the bearing capacity test,all samples can provide a low wear volume under the loads of 1 and 3 N.With the increase of the normal load,there is considerable differences in the anti-wear behavior.Compared with that of individual GO nanofluids,the wear volume of the GO/SiO_(2)(mass ratio of 0.3:0.2)hybrid nanofluids was reduced by50.5%at 5 N and by 49.2%at 8 N.Furthermore,the wear volume of the GO/SiO_(2)(mass ratio of 0.3:0.2)hybrid nanofluids was reduced by46.3%under the rigorous conditions,as compared to individual GO nanofluids.The findings provide new insights into developing carbon nanomaterial-based hybrid nanofluids for magnesium alloy formation.

Preparation of nano-copper as lubrication oil additive

Nano-copper used as lubrication oil additive has good tribological property and active self-repairing effect for friction pairs. The reduction in liquid phase for preparing nano-additive is one of the most common method. Nano-copper was prepared by reduction in liquid phase. The different project and routine practice for preparing nano-copper were researched. The dispersion problem of nano-copper was investigated by surface treatment and high dispersion. The particles dimension, the dispersion stability and the purity of nano-copper were characterized by TEM and XRD. The conclusion indicates that the methods of the preparation and dispersion can obtain 20nm copper additive with good dispersion property in lubrication oil.

DEVELOPMENT OF A NEW GENERATION OF ADDITIVES FOR ALUMINIUM ROLLING LUBRICATION

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Preparation and Tribological Properties of Lanthanum-doped Muscovite Composite Particles as Lubricant Additives in Lithium Grease

Lanthanum-doped muscovite(MC) composite particles(hereinafter abbreviated as La-MC) were prepared by the mechanical solid-state-chemistry-reaction method, followed by surface modification with oleic acid. The microstructure of materials was characterized by SEM, XRD, EDS and FTIR. Furthermore, the friction-reduction and anti-wear properties of MC and La-MC as lubricant additives in lithium grease were evaluated using a four-ball friction and wear tester. The results showed that La(OH)_3 nanoparticles were coated on the surface of muscovite. Both MC and La-MC can effectively improve the friction-reduction and anti-wear properties of lithium grease and La-MC presents better tribological properties than MC. The excellent tribological properties of La-MC can be attributed to the formation of the adsorbed La-MC film and the chemical reaction film mainly composed of Fe_2O_3 and SiO_2 on the worn surface, as well as the catalysis of lanthanum element during the friction process.

Tribological Properties of Few-layer Graphene Oxide Sheets as Oil-Based Lubricant Additives

The performance of a lubricant largely depends on the additives it involves. However, currently used additives cause severe pollution if they are burned and exhausted. Therefore, it is necessary to develop a new generation of green additives. Graphene oxide（GO） consists of only C, H and O and thus is considered to be environmentally friendly. So the tribological properties of the few-layer GO sheet as an additive in hydrocarbon base oil are investigated systematically. It is found that, with the addition of GO sheets, both the coefficient of friction（COF） and wear are decreased and the working temperature range of the lubricant is expanded in the positive direction. Moreover, GO sheets has better performance under higher sliding speed and the optimized concentration of GO sheets is determined to be 0.5wt%. After rubbing, GO is detected on the wear scars through Raman spectroscopy. And it is believed that, during the rubbing, GO sheets adhere to the sliding surfaces, behaving like protective films and preventing the sliding surfaces from contacting with each other directly. This paper proves that the GO sheet is an effective lubricant additive, illuminates the lubrication mechanism, and provides some critical parameters for the practical application of GO sheets in lubrication.

Synthesis and Tribological Behaviour of 1,3,4-Thiadiazole Schiff Base Derivatives as Multifunctional Lubricant Additives

Six new 1,3,4-thiadiazole Schiff base derivatives were synthesized and characterized by IR spectroscopy and ~1H NMR spectrometry, and their anti-corrosion properties and thermal stability were investigated via thermogravimetric analysis(TGA) and copper strip corrosion test. The tribological behavior of the said Schiff base derivatives was evaluated on an Optimol SRV~?4 oscillating reciprocating friction and wear tester. The worn surfaces of the steel discs were investigated using a scanning electron microscope(SEM) and energy dispersive X-ray spectrometer(EDS). The test results indicated that these thiadiazole Schiff base derivatives possessed favourable thermal stability, corrosion inhibiting ability and the capability of improving the tribological characteristic of the base oil effectively. It is assumed that the adsorbed additives probably reacted with the steel surfaces during the friction process, resulting in the formation of a protective film composed of sulphates, sulphides and organic nitrogen compounds.

Comparison of Lubricities of Two Novel Benzotriazole Derivatives Used as Additives in Water-Glycol Hydraulic Fluid

Two kinds of benzotriazole derivatives with and without sulfur （abbreviated as BSC and BC, respectively,） were synthesized and their lubricating, anticorrosion and antirust properties were investigated, when they were used as additives in the water-glycol fluid. The morphology and chemical species of typical elements on the worn surface were examined by the scanning electron microscopy （SEM）, the energy dispersive spectrometry （EDS）, and the X-ray photoelectron spectroscopy （XPS） in order to reveal the tribological mechanisms. The results indicated that two synthesized additives could effectively improve the anti-wear, friction-reducing, load-carrying, anticorrosion, and antirnst properties of the base fluid. The surface analysis illustrated that stable nitrogen-containing absorption films generated by BC should be responsible for its facilitated anti-wear and friction-reducing performance, and the excellent lubricities of BSC should be attxibuted to the combined action of adsorption film and tribo-chemical film which were composed of iron oxides, iron sulfides and iron sulfates. The superior lubricating properties of BSC as compared to that of BC demonstrated the effectiveness of elemental sulfur in reducing friction and wear, especially under high loads. But corrosion wear is more obvious at a relative high concentration of elemental sulfur.

Plastic-elastic Model for Water-based Lubrication Considering Surface Force

Water-based lubrication is an effective method to achieve superlubricity,which implies a friction coefficient in the order of 10−3 or lower.Recent numerical,analytical,and experimental studies confirm that the surface force effect is crucial for realizing water-based superlubricity.To enhance the contribution of the surface force,soft and plastic materials can be utilized as friction pair materials because of their effect in increasing the contact area.A new numerical model of water-based lubrication that considers the surface force between plastic and elastic materials is developed in this study to investigate the effect of plastic flow in water-based lubrication.Considering the complexity of residual stress accumulation in lubrication problems,a simplified plastic model is proposed,which merely calculates the result of the dry contact solution and avoids repeated calculations of the plastic flow.The results of the two models show good agreement.Plastic deformation reduces the local contact pressure and enhances the function of the surface force,thus resulting in a lower friction coefficient.

Scalable preparation of functionalized graphite nanoplatelets via magnetic grinding as lubricity-enhanced additive

Graphite nanoplatelets were prepared by a novel magnetic-grinding method using self-made equipments. Under a variant magnetic field, magnetic needles collided at a high rotating speed and exfoliated pristine graphite into graphite nanoplatelets with high efficiency. The obtained graphite nanoplatelets are highly crystalline, and the thickness is less than 10 nm. Moreover, the surface area could reached 738.1 m^2/g with a grinding time of 4 h. Silanized graphite nanoplatelets can disperse well in SG 15W-40 engine oil and serve as lubricant additive. Tribological results indicate that the friction coefficient and wear-scar of the friction pairs are lower than 76% and 41%, respectively, by adding 1.5‰(mass fraction) of silanized graphite nanoplatelets. Notably, the functionalized graphite nanoplatelets can realize large-scale production and commercial application.

Multifunctional Lubricant Additive Improves Lubrication and Antioxidation Properties of Tung Oil

It is of considerable significance to develop efficient and environmentally friendly machinery lubricant additives because of the increasing depletion of petrochemical resources and severe environmental problems.Herein,we proposed a facile strategy to synthesize a multifunctional vegetable oil-based lubricant via the lignin derivative vanillin coupled to amine and diethyl phosphite to produce a lubricating additive with both extreme pressure and antioxidant properties.Compared with pure tung oil,the lubricating and antioxidant performance of tung oil is significantly improved after adding additives.Adding the 1.0 wt%additive to the tung oil reduced the friction wear coefficient and the volume,and the oxidation induction time was much longer than pure tung oil.

Study on Tribology Performance of Different Lubricant Additives under Atmospheric Pressure and High Vacuum Conditions

By using PAO-10 as the base oil, the tribological behavior of 11 additives under high vacuum condition was evaluated. By adopting some surface analytical instruments, such as scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and X-ray photoelectron spectroscopy(XPS), the tribological mechanisms of these additives were studied. In air, O_2 can react with metal to form metal oxide that can protect the surfaces of rubbing pair during the tribological tests. According to the theory of the competitive adsorption, the function of some active elements is weakened. In a vacuum environment, the additives contributed more to the lubrication performance. The sulfur-containing additives could react with Fe to produce Fe Sx and "M—C" bonds("M" represents metal). They both had contributions to the lubrication. As for the phosphorus-containing additives, they only generated the phosphates during the tests. When the sulfur and phosphorus-containing additives were applied, the generated phosphates and Fe Sx had the primary contribution to the lubrication performance during the tests.

Investigation of Antioxidative Properties of Multifunctional Additives of Alkyl Phenolate Type and Development of New Lubricant Compositions

The results of studies of the antioxidant properties of multifunctional alkylphenolate type additives indicate the calcium salts of condensation products of alkylphenols(C8-C12)with formaldehyde and the following amines:aminoacetic acid,benzotriazole,diethanolamine and boric acid,as well as their carbonated compounds.The determination of the antioxidant properties of the additives is tested on theАПСМ-1M apparatus.New lubricant compositions for diesel internal combustion engines oil meeting the required standards for these oils have been developed.The study of additives,which possess simultaneously detergent-dispersing,neutralizing,antioxidant anti-wear properties,revealed the dependence of antioxidant properties on their alkalinity.

Lubricating performances of graphene oxide and onion-like carbon as water-based lubricant additives for smooth and sand-blasted steel discs

Graphene oxide(GO)nanosheets and onion‐like carbon(OLC)nanoparticles were synthesized from natural graphite powder and candle soot,respectively,and characterized by transmission electron microscopy and Raman spectroscopy.The lubricating performances of GO and OLC as lubricant additives in water were comparatively evaluated using a ball‐on‐disc tribometer.The effects of sand blasting of a steel disc on its morphology and tribological property were evaluated.The results show that the two nanomaterials,GO and OLC,when used as lubricant additives in water effectively reduce the friction and wear of the sliding discs,which is independent of the disc surface treatment.On applying heavy loads,it is observed that GO exhibits superior friction‐reducing and anti‐wear abilities compared to those of OLC—a trace amount of GO can achieve a lubricating ability equivalent to that of an abundant amount of OLC.Furthermore,it is observed that sand blasting cannot improve the wear resistance of the treated steel disc,even though the hardness of the disc increased after the treatment.The possible anti‐wear and friction‐reducing mechanisms of the GO and OLC as lubricant additives in water are discussed based on results for the wear surfaces obtained by scanning electron microscopy,Raman spectroscopy,and X‐ray photoelectron spectroscopy。

Modified Vegetable Oil Based Additives as a Future Polymeric Material—Review

Polymeric materials from renewable resources have attracted a lot of attention in recent years. The development and utilization of vegetable oils for polymeric materials are currently in the spotlight of the polymer and chemical industry, as they are the largest renewable platform due to their universal wide availability, ingrained biodegradability, low cost, and excellent environmental aspects (i.e., low ecotoxicity and low toxicity toward humans). These excellent natural characteristics are now being taken advantage of in research and development, with vegetable oil derived polymers/polymeric materials/composites being used in numerous applications including paints and coatings, adhesives, and nanocomposites. The aim of this review paper is to give a fundamental description of the various vegetable oil applications in polymer materials and its recent developments. Particular emphasis will be placed on study and main application of triglyceride based additive for polymer and to give the reader an insight into the main developments is discussed.