The emergence of vegetable oil as a promising alternative lubricant in the tribological application space has fueled research for making these oils as useful as mineral oils.Tribological modification of vegetable oil ...The emergence of vegetable oil as a promising alternative lubricant in the tribological application space has fueled research for making these oils as useful as mineral oils.Tribological modification of vegetable oil by the addition of TiO_(2)/gC_(3)N_(4)nanocomposite(as a nanoadditive)was studied here.The dispersion of the nanoadditive in the vegetable oil showed good oil dispersion stability without the addition of any surfactant.The tribological studies were conducted in a four-ball tester using ASTM standard D5183.In addition,the effect of temperature on tribological performance was also studied to understand the oxidation behavior of vegetable oil.The results showed a significant improvement in friction and wear properties of the optimized nano-oil.The mechanism behind the improvement in friction and wear properties is annotated in this paper.展开更多
The current work includes a numerical investigation of the effect of biodiesel blends with different aluminum oxide nanoparticle concentrations on the combustion process in the cylinder of a diesel engine.IC Engine Fl...The current work includes a numerical investigation of the effect of biodiesel blends with different aluminum oxide nanoparticle concentrations on the combustion process in the cylinder of a diesel engine.IC Engine Fluent,a specialist computational tool in the ANSYS software,was used to simulate internal combustion engine dynamics and combustion processes.Numerical analysis was carried out using biodiesel blends with three Al_(2)O_(3) nanoparticles in 50,100,and 150 ppm concentrations.The tested samples are called D100,B20,B20A50,B20A100,and B20A150 accordingly.The modeling runs were carried out at various engine loads of 0,100,and 200 Nm at a rated speed of 1800 rpm.The combustion characteristics are improved due to the catalytic effect and higher surface area of nano additives.The results showed the improvements in the combustion process as the result of nanoparticle addition,which led to the higher peak cylinder pressure.The increases in the peak cylinder pressures for B20A50,B20A100,and B20A150 about B20 were 3%,5%,and 8%,respectively,at load 200 Nm.The simulation found that the maximum temperature for biodiesel blends diesel was higher than pure diesel;this was due to higher hydrocarbon values of B20.Also,nano-additives caused a decrease in temperatures in the combustion of biofuels.展开更多
The microstructure and mechanical properties of ceramic coatings formed on 6063 aluminium alloy obtained in silicate-,borate- and aluminate-based electrolyte without and with nanoadditive Al2O3 and TiO2 by micro-arc o...The microstructure and mechanical properties of ceramic coatings formed on 6063 aluminium alloy obtained in silicate-,borate- and aluminate-based electrolyte without and with nanoadditive Al2O3 and TiO2 by micro-arc oxidation（MAO） were studied by scanning electron microscopy（SEM）,energy-dispersive X-ray spectroscopy（EDS）,X-ray diffraction（XRD）,microhardness and friction-abrasion tests,respectively.SEM results show that coatings with nanoadditive have less porosities than those without nanoadditive.XRD results reveal that nanoadditive-containing coatings contain more oxides compared with nanoadditive-free coatings in all cases,which are consistent with the EDS analysis.Mechanical properties tests show that nanoadditive Al2O3-containing coatings have higher microhardness values compared with the other coatings obtained in silicate-,borate- and aluminate-based electrolyte.On the other hand,nanoadditive has a positive effect on improving the wearing-resistance of MAO coatings in all cases.Furthermore,the borate-MAO coatings present an inferior anti-wearing property compared with the silicate- and aluminate-MAO coatings for both the nanoadditive-free and nanoadditive-containing coatings.展开更多
At present,achieving oil-based superlubricity depends on lubricating oil viscosity and rubbing pair materials excessively.Therefore,establishing a new route is of scientific significance and application value.Here,a n...At present,achieving oil-based superlubricity depends on lubricating oil viscosity and rubbing pair materials excessively.Therefore,establishing a new route is of scientific significance and application value.Here,a novel strategy,i.e.,the assembly of a dialkyl-dithiophosphoricmodified copper nanoparticle(DDP-Cu NP)lubricating additive and polyetheretherketone(PEEK)-GCr15 friction pairs,is reported to achieve oil-based superlubricity in polyalpha olefin oil(PAO40),a synthetic base oil with high viscosity.To our surprise,when the concentration of DDP-Cu is only 0.25 wt%,the lowest friction coefficient is 0.002,and the wear rate reaches 10^(-9) mm^(3)/(N·m)level(which is lower than that published in the literature by 1-2 orders).Furthermore,such superlubricity occurs without a runningin period and remains during the whole sliding process.These results are attributed mainly to the rolling effect of the spherical Cu NPs,the formation of a high-performance carbon-based tribofilm at the sliding counterface,and the in operando formation of some few(even mono)-layered graphene layers in the lubricant(the tribocatalytic effect of the DDP-Cu NPs).Specifically,DDP-Cu NPs perform in operando tribocatalysis to promote the decomposition of the PEEK matrix and PAO40 and generate some carbon species,including amorphous carbon and even graphene,all of which are responsible for the surprising oil-based superlubricity.The findings will contribute to enriching relevant tribological theory and promoting the exploration and application of oil-based superlubricity.展开更多
CeO_(2)nanoparticles are potential anti-wear additives because of their outstanding anti-wear and load-bearing capacity.However,the shear-sintering tribo-film formation mechanism of oxide nanoparticles limits the trib...CeO_(2)nanoparticles are potential anti-wear additives because of their outstanding anti-wear and load-bearing capacity.However,the shear-sintering tribo-film formation mechanism of oxide nanoparticles limits the tribo-film formation rate and thickness greatly.In this study,by compounding with zinc dioctyl dithiophosphate(ZDDP),ultra-fine CeO_(2)nanoparticles modified with oleylamine(OM)can quickly form 2μm ultra-thick tribo-film,which is 10-15 times thicker than that of ZDDP and CeO_(2),respectively.The ultra-thick tribo-film presents a nanocomposite structure with amorphous phosphate as binder and nano-CeO_(2)as filling phase,which leads to the highest loading capacity of composite additives.The results of adsorption experiments tested by dissipative quartz crystal microbalance(QCM-D)showed that the Ps value of additive has nothing to do with its equilibrium adsorption mass,but is directly proportional to its adsorption rate in 10 s.The compound additive of CeO_(2)and ZDDP presented the co-deposition mode of ZDDP monolayer rigid adsorption and CeO_(2)viscoelastic adsorption on the metal surface,which showed the highest adsorption rate in 10 s.It is found that the tribo-film must have high film forming rate and wear resistance at the same time in order to achieve super thickness.Cerium phosphate was formed from ZDDP and CeO,through tribochemistry reaction,which promotes the formation of an ultra-thick tribo-film with nanocomposite structure,which not only maintains the low friction characteristics of CeO,but also realizes high Pg and high load-carrying capacity.展开更多
Inorganic nanomaterials exhibit superior friction-reduction and anti-wear properties in oils. In this study, 2D layered α-zirconium phosphate (α-ZrP) nanosheets intercalated with different amines have been synthesiz...Inorganic nanomaterials exhibit superior friction-reduction and anti-wear properties in oils. In this study, 2D layered α-zirconium phosphate (α-ZrP) nanosheets intercalated with different amines have been synthesized to study their dispersion stabilities in lubricating oil and tribological applications. The intercalated amines should be sufficiently long and lipophilic to provide stabilization to α-ZrP nanosheets in mineral oil. The results of tribological tests illustrate that with the addition of well-dispersed nanosheets, the coefficient of friction (COF) and pin volume loss reduce by ~47% and 75%, respectively. The excellent dispersion stability enables the nanosheets to flow into the contact area at the beginning, and thereby protect the rubbing surface. A reduction in the van der Waals forces between the adjacent layers induced by the intercalated amines transforms the friction between adjacent layers from pin disk to sliding, leading to a decrease in the COF under hydrodynamic lubrication. The study provides a new method to enhance the tribological properties via tuning the dispersion stabilities of nanomaterials in oils.展开更多
基金The authors thank the Department of Science and Technology(DST)for the financial support to establish Nano Functional Materials Technology Centre(NFMTC)through SR/NM/NAT/02-2005 projectAlso,we would like to thank IIT Madras,Chennai,India.The SEM and Optical profilometry imaging have been carried out in Department of Metallurgical&Materials Engineering,IIT Madras.
文摘The emergence of vegetable oil as a promising alternative lubricant in the tribological application space has fueled research for making these oils as useful as mineral oils.Tribological modification of vegetable oil by the addition of TiO_(2)/gC_(3)N_(4)nanocomposite(as a nanoadditive)was studied here.The dispersion of the nanoadditive in the vegetable oil showed good oil dispersion stability without the addition of any surfactant.The tribological studies were conducted in a four-ball tester using ASTM standard D5183.In addition,the effect of temperature on tribological performance was also studied to understand the oxidation behavior of vegetable oil.The results showed a significant improvement in friction and wear properties of the optimized nano-oil.The mechanism behind the improvement in friction and wear properties is annotated in this paper.
文摘The current work includes a numerical investigation of the effect of biodiesel blends with different aluminum oxide nanoparticle concentrations on the combustion process in the cylinder of a diesel engine.IC Engine Fluent,a specialist computational tool in the ANSYS software,was used to simulate internal combustion engine dynamics and combustion processes.Numerical analysis was carried out using biodiesel blends with three Al_(2)O_(3) nanoparticles in 50,100,and 150 ppm concentrations.The tested samples are called D100,B20,B20A50,B20A100,and B20A150 accordingly.The modeling runs were carried out at various engine loads of 0,100,and 200 Nm at a rated speed of 1800 rpm.The combustion characteristics are improved due to the catalytic effect and higher surface area of nano additives.The results showed the improvements in the combustion process as the result of nanoparticle addition,which led to the higher peak cylinder pressure.The increases in the peak cylinder pressures for B20A50,B20A100,and B20A150 about B20 were 3%,5%,and 8%,respectively,at load 200 Nm.The simulation found that the maximum temperature for biodiesel blends diesel was higher than pure diesel;this was due to higher hydrocarbon values of B20.Also,nano-additives caused a decrease in temperatures in the combustion of biofuels.
基金Project(51371039)supported by the National Natural Science Foundation of China
文摘The microstructure and mechanical properties of ceramic coatings formed on 6063 aluminium alloy obtained in silicate-,borate- and aluminate-based electrolyte without and with nanoadditive Al2O3 and TiO2 by micro-arc oxidation（MAO） were studied by scanning electron microscopy（SEM）,energy-dispersive X-ray spectroscopy（EDS）,X-ray diffraction（XRD）,microhardness and friction-abrasion tests,respectively.SEM results show that coatings with nanoadditive have less porosities than those without nanoadditive.XRD results reveal that nanoadditive-containing coatings contain more oxides compared with nanoadditive-free coatings in all cases,which are consistent with the EDS analysis.Mechanical properties tests show that nanoadditive Al2O3-containing coatings have higher microhardness values compared with the other coatings obtained in silicate-,borate- and aluminate-based electrolyte.On the other hand,nanoadditive has a positive effect on improving the wearing-resistance of MAO coatings in all cases.Furthermore,the borate-MAO coatings present an inferior anti-wearing property compared with the silicate- and aluminate-MAO coatings for both the nanoadditive-free and nanoadditive-containing coatings.
基金the National Natural Science Foundation of China(Nos.52475186 and 52305189)the National Key R&D Program of China(No.2023YFB3812104)+1 种基金the National United Engineering Laboratory for Advanced Bearing Tribology(No.202305,Henan University of Science and Technology)the Tribology Science Fund of National and Local Joint Engineering Research Center of Advanced Carbon-Based Ceramics Preparation Technology(No.2024TJZX02,North Minzu University),and the Henan Province Science and Technology Key Project(No.232102230081).
文摘At present,achieving oil-based superlubricity depends on lubricating oil viscosity and rubbing pair materials excessively.Therefore,establishing a new route is of scientific significance and application value.Here,a novel strategy,i.e.,the assembly of a dialkyl-dithiophosphoricmodified copper nanoparticle(DDP-Cu NP)lubricating additive and polyetheretherketone(PEEK)-GCr15 friction pairs,is reported to achieve oil-based superlubricity in polyalpha olefin oil(PAO40),a synthetic base oil with high viscosity.To our surprise,when the concentration of DDP-Cu is only 0.25 wt%,the lowest friction coefficient is 0.002,and the wear rate reaches 10^(-9) mm^(3)/(N·m)level(which is lower than that published in the literature by 1-2 orders).Furthermore,such superlubricity occurs without a runningin period and remains during the whole sliding process.These results are attributed mainly to the rolling effect of the spherical Cu NPs,the formation of a high-performance carbon-based tribofilm at the sliding counterface,and the in operando formation of some few(even mono)-layered graphene layers in the lubricant(the tribocatalytic effect of the DDP-Cu NPs).Specifically,DDP-Cu NPs perform in operando tribocatalysis to promote the decomposition of the PEEK matrix and PAO40 and generate some carbon species,including amorphous carbon and even graphene,all of which are responsible for the surprising oil-based superlubricity.The findings will contribute to enriching relevant tribological theory and promoting the exploration and application of oil-based superlubricity.
基金We acknowledge the financial support provided by the National Natural Science Foundation of China(Nos.51875172 and 51775168)Scientific and Technological Innovation Team of Henan Province Universities(No.19IRTSTHN024)Zhongyuan Science and Technology Innovation Leadership Program(No.214200510024).
文摘CeO_(2)nanoparticles are potential anti-wear additives because of their outstanding anti-wear and load-bearing capacity.However,the shear-sintering tribo-film formation mechanism of oxide nanoparticles limits the tribo-film formation rate and thickness greatly.In this study,by compounding with zinc dioctyl dithiophosphate(ZDDP),ultra-fine CeO_(2)nanoparticles modified with oleylamine(OM)can quickly form 2μm ultra-thick tribo-film,which is 10-15 times thicker than that of ZDDP and CeO_(2),respectively.The ultra-thick tribo-film presents a nanocomposite structure with amorphous phosphate as binder and nano-CeO_(2)as filling phase,which leads to the highest loading capacity of composite additives.The results of adsorption experiments tested by dissipative quartz crystal microbalance(QCM-D)showed that the Ps value of additive has nothing to do with its equilibrium adsorption mass,but is directly proportional to its adsorption rate in 10 s.The compound additive of CeO_(2)and ZDDP presented the co-deposition mode of ZDDP monolayer rigid adsorption and CeO_(2)viscoelastic adsorption on the metal surface,which showed the highest adsorption rate in 10 s.It is found that the tribo-film must have high film forming rate and wear resistance at the same time in order to achieve super thickness.Cerium phosphate was formed from ZDDP and CeO,through tribochemistry reaction,which promotes the formation of an ultra-thick tribo-film with nanocomposite structure,which not only maintains the low friction characteristics of CeO,but also realizes high Pg and high load-carrying capacity.
基金This work was supported by the start-up funding from the Southern University of Science and Technology(SUSTech),"The Recruitment Program of Global Youth Experts of China"the Foundation of Shenzhen Science and Technology Innovation Committee(Grant Nos.JCYJ20160315164631204 and KQJSCX20170726145415637).
文摘Inorganic nanomaterials exhibit superior friction-reduction and anti-wear properties in oils. In this study, 2D layered α-zirconium phosphate (α-ZrP) nanosheets intercalated with different amines have been synthesized to study their dispersion stabilities in lubricating oil and tribological applications. The intercalated amines should be sufficiently long and lipophilic to provide stabilization to α-ZrP nanosheets in mineral oil. The results of tribological tests illustrate that with the addition of well-dispersed nanosheets, the coefficient of friction (COF) and pin volume loss reduce by ~47% and 75%, respectively. The excellent dispersion stability enables the nanosheets to flow into the contact area at the beginning, and thereby protect the rubbing surface. A reduction in the van der Waals forces between the adjacent layers induced by the intercalated amines transforms the friction between adjacent layers from pin disk to sliding, leading to a decrease in the COF under hydrodynamic lubrication. The study provides a new method to enhance the tribological properties via tuning the dispersion stabilities of nanomaterials in oils.
