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 electr...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.展开更多
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 comp...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.展开更多
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 co...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。展开更多
Increasing environmental concerns about limiting harmful emissions has necessitated sulfur-and phosphorus-free green lubricant additives.Although boron-containing compounds have been widely investigated as green lubri...Increasing environmental concerns about limiting harmful emissions has necessitated sulfur-and phosphorus-free green lubricant additives.Although boron-containing compounds have been widely investigated as green lubricant additives,their macromolecular analogs have been rarely considered yet to develop environmentally friendly lubricant additives.In this work,a series of boron-containing copolymers have been synthesized by free-radical copolymerization of stearyl methacrylate and isopropenyl boronic acid pinacol ester with different feeding ratios(S_(n)-r-B_(m),n=1,m=1/3,1,2,3,5,9).The resulting copolymers of S_(n)-r-B_(m)(n=1,m=1/3,1,2,3,5)are readily dispersed in the PAO-10 base oil and form micelle-like aggregates with hydrodynamic diameters ranging from 9.7 to 52 nm.SRV-IV oscillating reciprocating tribological tests on ball-on-flat steel pairs show that compared with the base oil of PAO-10,the friction coefficients and wear volumes of the base oil solutions of S_(n)-r-B_(m)decrease considerably up to 62%and 97%,respectively.Moreover,the base oil solution of S_(1)-r-B_(1)exhibits an excellent load-bearing capacity of(850±100)N.These superior lubricating properties are due to the formation of protective tribofilms comprising S_(n)-r-B_(m),boron oxide,and iron oxide compounds on the lubricated steel surface.Therefore,the boron-containing copolymers can be regarded as a novel class of environmentally friendly lubricating oil macroadditives for efficient friction and wear reduction without sulfur and phosphorus elements.展开更多
Graphene is a promising material as a lubricant additive for reducing friction and wear.Here,a dispersing method which combines chemical modification of graphene by octadecylamine and dicyclohexylcarbodiimide with a k...Graphene is a promising material as a lubricant additive for reducing friction and wear.Here,a dispersing method which combines chemical modification of graphene by octadecylamine and dicyclohexylcarbodiimide with a kind of effective dispersant has been successfully developed to achieve the remarkable dispersion stability of graphene in base oil.The stable dispersion time of modified graphene(0.5 wt%)with dispersant(1 wt%)in PAO-6 could be up to about 120 days,which was the longest time reported so far.At the same time,the lubricant exhibits a significant improvement of tribological performance for a steel ball to plate tribo-system with a normal load of 2 N.The coefficient of friction between sliding surfaces was~0.10 and the depth of wear track on plate was~21 nm,which decreased by about 44%and 90%when compared to pure PAO-6,respectively.Furthermore,the analysis of the lubricating mechanisms in regard to the sliding-induced formation of nanostructured tribo-film has been contacted by using Raman spectra and TEM.展开更多
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...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.展开更多
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 gener...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.展开更多
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 ...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.展开更多
Oleic acid surface-modified Cu nanoparticles with an average size of 20 nm were prepared by liquid phase reducing reaction. The tribological performance and mechanism of nanocopper as additive were studied by means of...Oleic acid surface-modified Cu nanoparticles with an average size of 20 nm were prepared by liquid phase reducing reaction. The tribological performance and mechanism of nanocopper as additive were studied by means of tribotester, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and nanoindentation instrument. The results indicate that the modified nanocopper additive can significantly improve the wear resistance and reduce friction coefficient of base oil. A copper protective film is formed and contributes to the excellent tribological properties of nanocopper additive. On the basis of the film forming mechanism, a new in-situ repair method was designed and used to repair wear-out-failure injection pump plunger and barrel. Furthermore, the current research progress of nanoparticles as green energy-saving lubricating oil additives were presented.展开更多
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.Herei...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.展开更多
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 ...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.展开更多
ZIF-8 is widely applied in lubrication,adsorption,and catalysis owing to its unique physicochemical properties.Previous experimental studies have demonstrated its feasibility as a lubricant additive.In the present wor...ZIF-8 is widely applied in lubrication,adsorption,and catalysis owing to its unique physicochemical properties.Previous experimental studies have demonstrated its feasibility as a lubricant additive.In the present work,the lubricating performance of ZIF-8 as an additive to lithiumbased grease is quantitatively and dynamically analyzed at the atomic scale using molecular dynamics simulations.Friction wear experiments are also conducted to elucidate the lubrication mechanism of ZIF-8.The simulation and experimental results indicate that the incorporation of ZIF-8 effectively enhances the antifriction and antiwear characteristics of lithium grease.The most significant improvement in the lubrication performance of the grease is obtained at a mass fraction of 2.0 wt.%ZIF-8,which reduces the friction factorof the grease by about 17.0%and the wear by40.0%.Furthermore,the molecular dynamics simulations reveal that ZIF-8 primarily functions as a ball bearing under low-load conditions.However,under high-load conditions,ZIF-8 undergoes significant deformation and primarily acts as a filler.This explains the experimentally observed significant reduction in friction coefficient after the addition of ZIF-8.The results of this study provide a theoretical foundation for the development of new environmentally friendly grease additives.展开更多
Herein,we have prepared SiO_(2)particles uploaded MXene nanosheets via in-situ hydrolysis of tetraetholothosilicate.Due to the large number of groups at the edges of MXene,SiO_(2)grows at the edges first,forming MXene...Herein,we have prepared SiO_(2)particles uploaded MXene nanosheets via in-situ hydrolysis of tetraetholothosilicate.Due to the large number of groups at the edges of MXene,SiO_(2)grows at the edges first,forming MXene@SiO_(2)composites with a unique core-rim structure.The tribological properties of MXene@SiO_(2)as lubricating additive in 500 SN are evaluated by SRV-5.The results show that MXene@SiO_(2)can reduce the friction coefficient of 500 SN from 0.572 to 0.108,the wear volume is reduced by 73.7%,and the load capacity is increased to 800 N.The superior lubricity of MXene@SiO_(2)is attributed to the synergistic effect of MXene and SiO_(2).The rolling friction caused by SiO_(2)not only improves the bearing capacity but also increases the interlayer distance of MXene,avoiding accumulation and making it more prone to interlayer slip.MXene@SiO_(2)is adsorbed on the friction interface to form a physical adsorption film and isolate the friction pair.In addition,the high temperature and high load induce the tribochemical reaction and form a chemical protection film during in the friction process.Ultimately,the presence of these protective films results in MXene@SiO_(2)having good lubricating properties.展开更多
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 spectros...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。展开更多
Tungsten film(W film) is deposited by using the ion beam assisted deposition(IBAD) on the 316 L substrate surface in this experiment. The micro structure and nano-hardness of the film are investigated by scanning elec...Tungsten film(W film) is deposited by using the ion beam assisted deposition(IBAD) on the 316 L substrate surface in this experiment. The micro structure and nano-hardness of the film are investigated by scanning electron microscopy(SEM) and nano-indentation tester. The tribological behavior of W film under lubrication by oil with ZDDP and MoDTC is evaluated by a SRV test machine. The tribo-film formed on the worn surfaces is investigated by X-ray photoelectron spectroscopy(XPS) to find out the tribological mechanisms between the W film and the two additional additives. The result shows that the W film lubricated by ZDDP and MoDTC-blended base oil has synergistic effects on the friction reduction property, while the anti-wear property is mainly caused by the hard surface of W film.展开更多
In this work,fatty acid and its derivatives were adopted as lubricity additives for low sulfur diesel.Tribological evaluation obtained from the High-Frequency Reciprocating Rig(HFRR)apparatus showed that the lubricati...In this work,fatty acid and its derivatives were adopted as lubricity additives for low sulfur diesel.Tribological evaluation obtained from the High-Frequency Reciprocating Rig(HFRR)apparatus showed that the lubricating performance of the additives increased in the following order:stearic acid>glycol monopalmitate>stearyl alcohol>ethyl palmitate>cetyl ethyl ether.The adsorption behavior of the additives on Fe(110)surface and Fe2O3(001)surface was investigated by molecular dynamics(MD)simulations to verify their lubricity performance.The results suggested that adsorption energies of the additives on Fe(110)surface are determined by the van der Waals forces,while adsorptions on Fe2O3(001)surface are significantly attributed to the electrostatic attractive forces.Higher values of adsorption energy of the additives on Fe2O3(001)surface indicate that the additive has more efficient lubricity enhancing properties.展开更多
Overbased lubricant detergents are important components in lubricating oil. Recently, a lot of papers about the synthesis mechanism, colloidal structure, acid neutralization and antifrictiorL properties of overbased d...Overbased lubricant detergents are important components in lubricating oil. Recently, a lot of papers about the synthesis mechanism, colloidal structure, acid neutralization and antifrictiorL properties of overbased detergents have been published with the development of experimental techniques, which can help us better understand the process of preparation and application of overbased detergents and propound new strategies for improving various performances of overbased detergents. In the future, the synthesis of environmentally friendly and multi-functional lubricant detergent using biodegradable vegetable oil instead of mineral oil as raw materials will be a primary objective for the colloidal lubricant detergent industry.This paper mainly presents the latest advances in the investigation of colloidal lubricant detergents.展开更多
To improve the properties of Babbitt alloys,Ni-coated-graphite-reinforced Babbitt metal composite specimens were prepared via selective laser melting(SLM),and the composites microstructures,mechanical properties,and t...To improve the properties of Babbitt alloys,Ni-coated-graphite-reinforced Babbitt metal composite specimens were prepared via selective laser melting(SLM),and the composites microstructures,mechanical properties,and tribological properties were studied through scanning electron microscopy(SEM),shear testing,and dry-sliding wear testing,respectively.The results showed that most of the nickel-coated graphite(NCGr)particles were distributed at the boundaries of laser beads in the cross section of the SLM composite specimens.Microcracks and microvoids formed at the boundaries of laser beads where NCGr particles accumulated.Both the shear strength and the friction coefficient of the SLM composite specimens decreased with increasing NCGr content.The shear strength and the friction coefficient of the SLM composite sample with 6 wt%NCGr were approximately 20%and 33%lower than those of the NCGr-free sample,respectively.The friction mechanism changed from plastic shaping furrow to brittle cutting with increasing NCGr content.A practical Babbitt material with a lower friction coefficient and sufficient strength can be obtained by controlling the NCGr particle dispersion;this can be achieved by choosing NCGr particles with a thicker Ni layer and precisely controlling the laser energy input during the SLM process.展开更多
Internal combustion engines′ fuel economy is an important role for engine designers,engine manufacturers over the past 30 years,especially passenger car motor oils.In heavy duty diesel engine,over the past 20 years,f...Internal combustion engines′ fuel economy is an important role for engine designers,engine manufacturers over the past 30 years,especially passenger car motor oils.In heavy duty diesel engine,over the past 20 years,fuel economy has in some cases been sacrificed for exhaust gas emission optimizations.Now,Heavy Duty Automotive and the related industries have strong interest in fuel economy and the lubricants.It is driven by competitive market forces as well as government mandates and new emission regulations.Japan was the first country in the world to establish and implement heavy duty trucks and buses fuel economy standards.Other countries also have followed either by establishing direct fuel economy standards or greenhouse gas(GHG) emissions standards which are directly tied to fuel economy.This paper is discussing that heavy duty diesel engine lubricants can contribute on fuel economy.The contribution of various aspects of engine oil formulations on fuel economy will be discussed such as lubricant viscosity grade,lubricant additives and friction modifiers.In this paper,the evaluation discussions are based on fuel economy measurements in some bench tests,standardized laboratory engine tests and field tests.展开更多
This study presents a nitrogen-doped microporous carbon nanospheres(N@MCNs)prepared by a facile polymerization–carbonization process using low-cost styrene.The N element in situ introduces polystyrene(PS)nanospheres ...This study presents a nitrogen-doped microporous carbon nanospheres(N@MCNs)prepared by a facile polymerization–carbonization process using low-cost styrene.The N element in situ introduces polystyrene(PS)nanospheres via emulsion polymerization of styrene with cyanuric chloride as crosslinking agent,and then carbonization obtains N@MCNs.The as-prepared carbon nanospheres possess the complete spherical structure and adjustable nitrogen amount by controlling the relative proportion of tetrachloromethane and cyanuric chloride.The friction performance of N@MCNs as lubricating oil additives was surveyed utilizing the friction experiment of ball-disc structure.The results showed that N@MCNs exhibit superb reduction performance of friction and wear.When the addition of N@MCNs was 0.06 wt%,the friction coefficient of PAO-10 decreased from 0.188 to 0.105,and the wear volume reduced by 94.4%.The width and depth of wear marks of N@MCNs decreased by 49.2% and 94.5%,respectively.The carrying capacity of load was rocketed from 100 to 400 N concurrently.Through the analysis of the lubrication mechanism,the result manifested that the prepared N@MCNs enter clearance of the friction pair,transform the sliding friction into the mixed friction of sliding and rolling,and repair the contact surface through the repair effect.Furthermore,the tribochemical reaction between nanoparticles and friction pairs forms a protective film containing nitride and metal oxides,which can avert direct contact with the matrix and improve the tribological properties.This experiment showed that nitrogen-doped polystyrene-based carbon nanospheres prepared by in-situ doping are the promising materials for wear resistance and reducing friction.This preparing method can be ulteriorly expanded to multi-element co-permeable materials.Nitrogen and boron co-doped carbon nanospheres(B,N@MCNs)were prepared by mixed carbonization of N-enriched PS and boric acid,and exhibited high load carrying capacity and good tribological properties.展开更多
文摘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.
文摘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.
基金the Beijing Natural Science Foundation(Grant No.2232066)the Open Project Foundation of State Key Laboratory of Solid Lubrication(Grant LSL-2212).
文摘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。
文摘Increasing environmental concerns about limiting harmful emissions has necessitated sulfur-and phosphorus-free green lubricant additives.Although boron-containing compounds have been widely investigated as green lubricant additives,their macromolecular analogs have been rarely considered yet to develop environmentally friendly lubricant additives.In this work,a series of boron-containing copolymers have been synthesized by free-radical copolymerization of stearyl methacrylate and isopropenyl boronic acid pinacol ester with different feeding ratios(S_(n)-r-B_(m),n=1,m=1/3,1,2,3,5,9).The resulting copolymers of S_(n)-r-B_(m)(n=1,m=1/3,1,2,3,5)are readily dispersed in the PAO-10 base oil and form micelle-like aggregates with hydrodynamic diameters ranging from 9.7 to 52 nm.SRV-IV oscillating reciprocating tribological tests on ball-on-flat steel pairs show that compared with the base oil of PAO-10,the friction coefficients and wear volumes of the base oil solutions of S_(n)-r-B_(m)decrease considerably up to 62%and 97%,respectively.Moreover,the base oil solution of S_(1)-r-B_(1)exhibits an excellent load-bearing capacity of(850±100)N.These superior lubricating properties are due to the formation of protective tribofilms comprising S_(n)-r-B_(m),boron oxide,and iron oxide compounds on the lubricated steel surface.Therefore,the boron-containing copolymers can be regarded as a novel class of environmentally friendly lubricating oil macroadditives for efficient friction and wear reduction without sulfur and phosphorus elements.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51527901 and 51335005)。
文摘Graphene is a promising material as a lubricant additive for reducing friction and wear.Here,a dispersing method which combines chemical modification of graphene by octadecylamine and dicyclohexylcarbodiimide with a kind of effective dispersant has been successfully developed to achieve the remarkable dispersion stability of graphene in base oil.The stable dispersion time of modified graphene(0.5 wt%)with dispersant(1 wt%)in PAO-6 could be up to about 120 days,which was the longest time reported so far.At the same time,the lubricant exhibits a significant improvement of tribological performance for a steel ball to plate tribo-system with a normal load of 2 N.The coefficient of friction between sliding surfaces was~0.10 and the depth of wear track on plate was~21 nm,which decreased by about 44%and 90%when compared to pure PAO-6,respectively.Furthermore,the analysis of the lubricating mechanisms in regard to the sliding-induced formation of nanostructured tribo-film has been contacted by using Raman spectra and TEM.
基金supported by the National Natural Science Foundation of China (No. 52001028)the Education Commission of Chongqing Municipality (No. KJQN20210141)the Chongqing Science and Technology Commission (Nos. cstc2020jcyj-msxmX0544 and cstc2019jcyj-msxm X0510)
文摘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.
基金Supported by National Natural Science Foundation of China(Grant Nos.51335005,51321092)National Key Basic Research Program of China(973 Program,Grant No.2013CB934200)the Foundation for the Supervisor of Beijing Excellent Doctoral Dissertation(Grant No.20111000305)
文摘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.
基金Project(ZR2011BL005)supported by the Natural Science Foundation of Shandong Province,China
文摘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.
文摘Oleic acid surface-modified Cu nanoparticles with an average size of 20 nm were prepared by liquid phase reducing reaction. The tribological performance and mechanism of nanocopper as additive were studied by means of tribotester, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and nanoindentation instrument. The results indicate that the modified nanocopper additive can significantly improve the wear resistance and reduce friction coefficient of base oil. A copper protective film is formed and contributes to the excellent tribological properties of nanocopper additive. On the basis of the film forming mechanism, a new in-situ repair method was designed and used to repair wear-out-failure injection pump plunger and barrel. Furthermore, the current research progress of nanoparticles as green energy-saving lubricating oil additives were presented.
基金Funding Statement:This work was supported by National Natural Science Foundation of China[No.31901260]Special Fund of Chinese Central Government for Basic Scientific Research Operations in Commonweal Research Institutes[No.CAFYBB2019SY037].
文摘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.
基金Financial support from the SINOPEC Research Program(No.ST13164-19]) is gratefully acknowledged
文摘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.
基金supported by the National Natural Science Foundation of China(52275178)the Fujian Industry University Cooperation Project(2020H6025)。
文摘ZIF-8 is widely applied in lubrication,adsorption,and catalysis owing to its unique physicochemical properties.Previous experimental studies have demonstrated its feasibility as a lubricant additive.In the present work,the lubricating performance of ZIF-8 as an additive to lithiumbased grease is quantitatively and dynamically analyzed at the atomic scale using molecular dynamics simulations.Friction wear experiments are also conducted to elucidate the lubrication mechanism of ZIF-8.The simulation and experimental results indicate that the incorporation of ZIF-8 effectively enhances the antifriction and antiwear characteristics of lithium grease.The most significant improvement in the lubrication performance of the grease is obtained at a mass fraction of 2.0 wt.%ZIF-8,which reduces the friction factorof the grease by about 17.0%and the wear by40.0%.Furthermore,the molecular dynamics simulations reveal that ZIF-8 primarily functions as a ball bearing under low-load conditions.However,under high-load conditions,ZIF-8 undergoes significant deformation and primarily acts as a filler.This explains the experimentally observed significant reduction in friction coefficient after the addition of ZIF-8.The results of this study provide a theoretical foundation for the development of new environmentally friendly grease additives.
基金supported by the National Natural Science Foundation of China(51972272,U21A2046)the Western Light Project of CAS(xbzg-zdsys-202118)the Research Fund of the State Key Laboratory of Solidification Processing(NPU),China(2023-TS-03).
文摘Herein,we have prepared SiO_(2)particles uploaded MXene nanosheets via in-situ hydrolysis of tetraetholothosilicate.Due to the large number of groups at the edges of MXene,SiO_(2)grows at the edges first,forming MXene@SiO_(2)composites with a unique core-rim structure.The tribological properties of MXene@SiO_(2)as lubricating additive in 500 SN are evaluated by SRV-5.The results show that MXene@SiO_(2)can reduce the friction coefficient of 500 SN from 0.572 to 0.108,the wear volume is reduced by 73.7%,and the load capacity is increased to 800 N.The superior lubricity of MXene@SiO_(2)is attributed to the synergistic effect of MXene and SiO_(2).The rolling friction caused by SiO_(2)not only improves the bearing capacity but also increases the interlayer distance of MXene,avoiding accumulation and making it more prone to interlayer slip.MXene@SiO_(2)is adsorbed on the friction interface to form a physical adsorption film and isolate the friction pair.In addition,the high temperature and high load induce the tribochemical reaction and form a chemical protection film during in the friction process.Ultimately,the presence of these protective films results in MXene@SiO_(2)having good lubricating properties.
基金financial support of the National Natural Science Foundation of China(No.21473061)the Guangdong Natural Science Funds for Distinguished Young Scholar(No.2015A030306026)the Science and Technology Planning Project of Guangzhou City(No.201707010055)
文摘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。
基金the Beijing Natural Science Foundation (3132023)the National Natural Science Foundation of China (51275494 and 51005218)+1 种基金the Fundamental Research Funds for the Central Universities (2652012115 and 2652013081)the Tribology Science Fund of State Key Laboratory of Tribology (SKLTKF13B10) for their financial support to this research
文摘Tungsten film(W film) is deposited by using the ion beam assisted deposition(IBAD) on the 316 L substrate surface in this experiment. The micro structure and nano-hardness of the film are investigated by scanning electron microscopy(SEM) and nano-indentation tester. The tribological behavior of W film under lubrication by oil with ZDDP and MoDTC is evaluated by a SRV test machine. The tribo-film formed on the worn surfaces is investigated by X-ray photoelectron spectroscopy(XPS) to find out the tribological mechanisms between the W film and the two additional additives. The result shows that the W film lubricated by ZDDP and MoDTC-blended base oil has synergistic effects on the friction reduction property, while the anti-wear property is mainly caused by the hard surface of W film.
基金financially supported by "the Fundamental Research Funds for the Central Universities,China"(11CX06036A)
文摘In this work,fatty acid and its derivatives were adopted as lubricity additives for low sulfur diesel.Tribological evaluation obtained from the High-Frequency Reciprocating Rig(HFRR)apparatus showed that the lubricating performance of the additives increased in the following order:stearic acid>glycol monopalmitate>stearyl alcohol>ethyl palmitate>cetyl ethyl ether.The adsorption behavior of the additives on Fe(110)surface and Fe2O3(001)surface was investigated by molecular dynamics(MD)simulations to verify their lubricity performance.The results suggested that adsorption energies of the additives on Fe(110)surface are determined by the van der Waals forces,while adsorptions on Fe2O3(001)surface are significantly attributed to the electrostatic attractive forces.Higher values of adsorption energy of the additives on Fe2O3(001)surface indicate that the additive has more efficient lubricity enhancing properties.
文摘Overbased lubricant detergents are important components in lubricating oil. Recently, a lot of papers about the synthesis mechanism, colloidal structure, acid neutralization and antifrictiorL properties of overbased detergents have been published with the development of experimental techniques, which can help us better understand the process of preparation and application of overbased detergents and propound new strategies for improving various performances of overbased detergents. In the future, the synthesis of environmentally friendly and multi-functional lubricant detergent using biodegradable vegetable oil instead of mineral oil as raw materials will be a primary objective for the colloidal lubricant detergent industry.This paper mainly presents the latest advances in the investigation of colloidal lubricant detergents.
基金financially supported by the Key-Area Research and Development Program of Guangdong Province,China(No.2019B90907002)the Scientific and Technological Innovation Foundation of Shunde Graduate School,University of Science and Technology Beijing(No.BK19BE026)。
文摘To improve the properties of Babbitt alloys,Ni-coated-graphite-reinforced Babbitt metal composite specimens were prepared via selective laser melting(SLM),and the composites microstructures,mechanical properties,and tribological properties were studied through scanning electron microscopy(SEM),shear testing,and dry-sliding wear testing,respectively.The results showed that most of the nickel-coated graphite(NCGr)particles were distributed at the boundaries of laser beads in the cross section of the SLM composite specimens.Microcracks and microvoids formed at the boundaries of laser beads where NCGr particles accumulated.Both the shear strength and the friction coefficient of the SLM composite specimens decreased with increasing NCGr content.The shear strength and the friction coefficient of the SLM composite sample with 6 wt%NCGr were approximately 20%and 33%lower than those of the NCGr-free sample,respectively.The friction mechanism changed from plastic shaping furrow to brittle cutting with increasing NCGr content.A practical Babbitt material with a lower friction coefficient and sufficient strength can be obtained by controlling the NCGr particle dispersion;this can be achieved by choosing NCGr particles with a thicker Ni layer and precisely controlling the laser energy input during the SLM process.
文摘Internal combustion engines′ fuel economy is an important role for engine designers,engine manufacturers over the past 30 years,especially passenger car motor oils.In heavy duty diesel engine,over the past 20 years,fuel economy has in some cases been sacrificed for exhaust gas emission optimizations.Now,Heavy Duty Automotive and the related industries have strong interest in fuel economy and the lubricants.It is driven by competitive market forces as well as government mandates and new emission regulations.Japan was the first country in the world to establish and implement heavy duty trucks and buses fuel economy standards.Other countries also have followed either by establishing direct fuel economy standards or greenhouse gas(GHG) emissions standards which are directly tied to fuel economy.This paper is discussing that heavy duty diesel engine lubricants can contribute on fuel economy.The contribution of various aspects of engine oil formulations on fuel economy will be discussed such as lubricant viscosity grade,lubricant additives and friction modifiers.In this paper,the evaluation discussions are based on fuel economy measurements in some bench tests,standardized laboratory engine tests and field tests.
基金supported by the National Natural Science Foundation of China(Nos.U21A2046 and 51972272)the Western Light Project of CAS(No.xbzg-zdsys-202118).
文摘This study presents a nitrogen-doped microporous carbon nanospheres(N@MCNs)prepared by a facile polymerization–carbonization process using low-cost styrene.The N element in situ introduces polystyrene(PS)nanospheres via emulsion polymerization of styrene with cyanuric chloride as crosslinking agent,and then carbonization obtains N@MCNs.The as-prepared carbon nanospheres possess the complete spherical structure and adjustable nitrogen amount by controlling the relative proportion of tetrachloromethane and cyanuric chloride.The friction performance of N@MCNs as lubricating oil additives was surveyed utilizing the friction experiment of ball-disc structure.The results showed that N@MCNs exhibit superb reduction performance of friction and wear.When the addition of N@MCNs was 0.06 wt%,the friction coefficient of PAO-10 decreased from 0.188 to 0.105,and the wear volume reduced by 94.4%.The width and depth of wear marks of N@MCNs decreased by 49.2% and 94.5%,respectively.The carrying capacity of load was rocketed from 100 to 400 N concurrently.Through the analysis of the lubrication mechanism,the result manifested that the prepared N@MCNs enter clearance of the friction pair,transform the sliding friction into the mixed friction of sliding and rolling,and repair the contact surface through the repair effect.Furthermore,the tribochemical reaction between nanoparticles and friction pairs forms a protective film containing nitride and metal oxides,which can avert direct contact with the matrix and improve the tribological properties.This experiment showed that nitrogen-doped polystyrene-based carbon nanospheres prepared by in-situ doping are the promising materials for wear resistance and reducing friction.This preparing method can be ulteriorly expanded to multi-element co-permeable materials.Nitrogen and boron co-doped carbon nanospheres(B,N@MCNs)were prepared by mixed carbonization of N-enriched PS and boric acid,and exhibited high load carrying capacity and good tribological properties.
