Graphite nanosheets with the average thicknesses ranging from 24.4 to 48.9 nm were prepared with the use of expanded graphite as the raw material by sand milling in deionized water,anhydrous ethanol,glycerol,and 1,4-b...Graphite nanosheets with the average thicknesses ranging from 24.4 to 48.9 nm were prepared with the use of expanded graphite as the raw material by sand milling in deionized water,anhydrous ethanol,glycerol,and 1,4-butanediol,respectively.Anhydrous ethanol favored the formation of graphite nanosheets with a smaller average thickness.When the graphite nanosheets with the content of 2 wt%were added in lithium-based grease,the average friction coefficient decreased by 27%as compared with the pure lithium-based grease.The weld point and load wear index were 1.6 and 1.4 times those of the pure lithium-based grease,respectively.The tribological properties of the graphite nanosheet-containing lithium-based grease were comparable with those of the graphene-containing lithium-based grease.展开更多
Titanium complex greases were prepared by using naphthenic mineral oil and polydimethylsiloxane as the mixed base oil. The effect of polydimethylsiloxane molecular weight and polydimethylsiloxane content in mixed base...Titanium complex greases were prepared by using naphthenic mineral oil and polydimethylsiloxane as the mixed base oil. The effect of polydimethylsiloxane molecular weight and polydimethylsiloxane content in mixed base oil on the physicochemical and tribological properties of titanium complex greases was investigated.As compared to the sole mineral oil-based titanium complex grease, the use of polydimethylsiloxane(H201-350)as a co-base oil increased the dropping point from 310 to 329℃, decreased the oil separation from 3.7% to 2.3%,reduced the corrosion extent, and obviously improved the tribological properties. When the mixed oil-based titanium complex grease was used as a lubricant, lubricating films of polydimethylsiloxane were probably formed on the surfaces of friction pairs, giving good lubricating property.展开更多
Graphene as a lubricating additive holds great potential for industrial lubrication. However, its poor dispersity and compatibility with base oils and grease hinder maximizing performance. Here, the infuence of graphe...Graphene as a lubricating additive holds great potential for industrial lubrication. However, its poor dispersity and compatibility with base oils and grease hinder maximizing performance. Here, the infuence of graphene dispersion on the thickening efect and lubrication function is considered. A well-dispersed lubricant additive was obtained via trihexyl tetradecyl phosphonium bis(2-ethylhexyl) phosphate modifed graphene ([P_(66614)][DEHP]-G). Then lithium complex grease was prepared by saponifcation with 12-OH stearic acid, sebacic acid, and lithium hydroxide, using polyalphaolefn (PAO20) as base oil and the modifed-graphene as lubricating additive, with the original graphene as a comparison. The physicochemical properties and lubrication performance of the as-prepared greases were evaluated in detail. The results show that the as-prepared greases have high dropping point and colloidal stability. Furthermore, modifed-graphene lithium complex grease ofered the best friction reduction and anti-wear abilities, manifesting the reduction of friction coefcient and wear volume up to 18.84% and 67.34%, respectively. With base oil overfow and afux, well-dispersed [P_(66614)][DEHP]-G was readily adsorbed to the worn surfaces, resulting in the formation of a continuous and dense graphene deposition flm. The synergy of deposited graphene-flm, spilled oil, and adhesive grease greatly improves the lubrication function of grease. This research paves the way for modulating high-performance lithium complex grease to reduce the friction and wear of movable machinery.展开更多
In order to solve the hardening problem of complex calcium lubricating grease, the water absorption test of several calcium salts was carried out, and it was found that calcium 12-hydroxystearate did not absorb water,...In order to solve the hardening problem of complex calcium lubricating grease, the water absorption test of several calcium salts was carried out, and it was found that calcium 12-hydroxystearate did not absorb water, and calcium acetate, calcium phosphate and calcium borate had different degrees of water absorption. Calcium acetate has the highest water absorption rate, while calcium phosphate and calcium borate show comparable water absorption rates. Upon using the molecular simulation technology, it is found that in the complex calcium grease system, calcium phosphate and calcium borate tend to combine with water, which inhibits the water absorption of calcium acetate and alleviate the hardening problem.展开更多
Using 12-hydroxystearate, nonan-edioic acid and lithium hydroxide as thickener, refined mineral oil and synthetic oil as base oil, along with some structure improver, antioxidant and anti-wear extreme pressure additiv...Using 12-hydroxystearate, nonan-edioic acid and lithium hydroxide as thickener, refined mineral oil and synthetic oil as base oil, along with some structure improver, antioxidant and anti-wear extreme pressure additive, lithium complex grease was developed. The dropping point of the grease is 331℃, friction factor is 0.0250.026 under 1.0kN, especially above 220℃, its friction factor is 2/3 of those of urea-based greases and other high temperature greases. At the same time, it has good waterproof, anti-oxidation effect and anti-corrosion properties. The results of the field experiment proves that its working temperature is higher than 600℃, and it has reasonable working life in 800℃.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
Six kinds of alkylbenzene sulfonic acids were selected to prepare the sulfonates S1—S6. Among them, the sulfonates S3, S4, and S6 could be incorporated into lubricating grease with good performance in comparison with...Six kinds of alkylbenzene sulfonic acids were selected to prepare the sulfonates S1—S6. Among them, the sulfonates S3, S4, and S6 could be incorporated into lubricating grease with good performance in comparison with the grease produced from commercial sulfonates T106-1 and T106-2. The optimized conditions for synthesis of the sulfonates S3, S4, and S6 were explored by using different mass ratios of methanol, water and the type of copromoters. It was found out that the appropriate conditions for synthesis of the sulfonate S3 included a methanol to M(M is the total mass of alkylbenzene sulfonic acid and base oil) mass ratio of 16%, a water to M mass ratio of 4%, and a copromoter A to M mass ratio of 2%; the appropriate conditions for synthesis of the sulfonate S4 included a methanol to M mass ratio of 24%, a water to M mass ratio of 2%, a copromoter B to M mass ratio of 2%; and the optimized conditions for synthesis of the sulfonate S6 included a methanol/ M mass ratio of 8%, a water/M mass ratio of 4% and a copromoter B/M mass ratio of 2%. The new sulfonates S3, S4, and S6 produced under the optimized conditions exhibited higher TBN and better antiwear property in camparison with the previous products. Grease samples G9, G10, and G11 were prepared with new sulfonates S3, S4, and S6 successfully and exhibited improved water stability and high temperature performance.展开更多
A new category of lithium greases was synthesized by using poly-a-olefin(PAO8) and alkyl-tetralin as base oil, where the alkyl-tetralins were synthesized by the alkylation of tetralin and olefins. The influence of thi...A new category of lithium greases was synthesized by using poly-a-olefin(PAO8) and alkyl-tetralin as base oil, where the alkyl-tetralins were synthesized by the alkylation of tetralin and olefins. The influence of thickener concentration, alkyl-tetralin content and type of blend oils on the rheological and tribological performance of lithium grease was investigated. The microstructures of soap fibers were measured to reveal the structure-property correlations. The concentration of thickener and alkyl-tetralin content obviously affect the lubricating performance of lithium grease, while the molecular structure of alkyltetralin has no obvious impact on their properties. It was found that alkyl-tetralin could significantly enhance the thickening ability of PAO8 base oils, and decrease the amount of thickeners by 1.5%(mass).Lithium greases prepared using 20%(mass) alkyl-tetralin as co-base oil exhibited high colloidal stability,excellent rheological behaviors and tribological properties.展开更多
In this study,lithium complex grease(LCG)and polyurea grease(PUG)were synthesized using mineral oil(500 SN)and polyalphaolefin(PAO40)as base oil,adsorbed onto lithium complex soap and polyurea as thickeners,respective...In this study,lithium complex grease(LCG)and polyurea grease(PUG)were synthesized using mineral oil(500 SN)and polyalphaolefin(PAO40)as base oil,adsorbed onto lithium complex soap and polyurea as thickeners,respectively.The effects of grease formulation(thickener and base oil with different amounts(80,85,and 90 wt%)on the corrosion resistance and lubrication function were investigated in detail.The results have verified that the as-prepared greases have good anti-corrosion ability,ascribed to good salt-spray resistance and sealing function.Furthermore,the increase in the amount of base oil reduces the friction of the contact interface to some extent,whereas the wear resistance of these greases is not consistent with the friction reduction,because the thickener has a significant influence on the tribological property of greases,especially load-carrying capacity.PUG displays better physicochemical performance and lubrication function than LCG under the same conditions,mainly depending on the component/structure of polyurea thickener.The polyurea grease with 90 wt%PAO displays the best wear resistance owing to the synergistic lubrication of grease-film and tribochemical film,composed of Fe_(2)O_(3),FeO(OH),and nitrogen oxide.展开更多
An ionic liquid-polyaniline/tungsten disulfide(IL-PANI/WS_(2))composite was synthesized in 1-butyl-3-methylimidazole tetrafluoroborate(LB104)aqueous solution by in-situ polymerization and characterized by Fourier tran...An ionic liquid-polyaniline/tungsten disulfide(IL-PANI/WS_(2))composite was synthesized in 1-butyl-3-methylimidazole tetrafluoroborate(LB104)aqueous solution by in-situ polymerization and characterized by Fourier transform infrared spectroscopy.A current-carrying friction and wear tester was used to study the tribological properties of steel-steel and copper-copper friction pairs lubricated by an IL-PANI/WS_(2) lithium complex grease(LCG).After the experiment,scanning electron microscope was used to observe the surface morphology of the wear scar on the steel and copper plates,and X-ray photoelectron spectrometer was used to analyze the elemental composition of the wear scar surface.The results show that compared with greases containing IL-PANI and WS_(2),greases containing IL-PANI/WS_(2) exhibit better antiwear performance when lubricating steel-steel friction pairs and better tribological performance and electrical conductivity when lubricating copper-copper friction pairs.Therefore,it can be concluded that WS_(2) and IL-PANI have a synergistic effect.展开更多
In this study,we synthesized two types of calcium sulfonate complex greases(barium soap and calcium soap)and investigated their physical,rheological,and tribological properties in detail.The test results showed that t...In this study,we synthesized two types of calcium sulfonate complex greases(barium soap and calcium soap)and investigated their physical,rheological,and tribological properties in detail.The test results showed that the evolution of their linear viscoelasticity functions with frequency were quite similar to those of traditional lubricating greases.Moreover,these two calcium sulfonate complex greases had good friction-reducing and antiwear properties at room temperature and at 150°C.In addition,by adding an organic molybdenum compound(MoDTC)to the base greases,we obtained a very low friction coefficient(0.065)for one of the greases(calcium soap)at 400 N and 500 N(maximum Hertzian pressures of 3.47 GPa and 3.74 GPa,respectively)at 150°C.X-ray photoelectron spectroscopy(XPS)analysis showed that the tribofilm was composed of some complex oxide species and CaCO3 that had formed on the worn surface.展开更多
基金financially supported by Wuxi Municipal Bureau on Science and Technology,China(Wuxi 530 project,20130529010040)Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(SJCX180734)。
文摘Graphite nanosheets with the average thicknesses ranging from 24.4 to 48.9 nm were prepared with the use of expanded graphite as the raw material by sand milling in deionized water,anhydrous ethanol,glycerol,and 1,4-butanediol,respectively.Anhydrous ethanol favored the formation of graphite nanosheets with a smaller average thickness.When the graphite nanosheets with the content of 2 wt%were added in lithium-based grease,the average friction coefficient decreased by 27%as compared with the pure lithium-based grease.The weld point and load wear index were 1.6 and 1.4 times those of the pure lithium-based grease,respectively.The tribological properties of the graphite nanosheet-containing lithium-based grease were comparable with those of the graphene-containing lithium-based grease.
基金Supported by the National Natural Science Foundation of China(21506078,21506082)China Postdoctoral Science Foundation(2016M591786,2016M601739)
文摘Titanium complex greases were prepared by using naphthenic mineral oil and polydimethylsiloxane as the mixed base oil. The effect of polydimethylsiloxane molecular weight and polydimethylsiloxane content in mixed base oil on the physicochemical and tribological properties of titanium complex greases was investigated.As compared to the sole mineral oil-based titanium complex grease, the use of polydimethylsiloxane(H201-350)as a co-base oil increased the dropping point from 310 to 329℃, decreased the oil separation from 3.7% to 2.3%,reduced the corrosion extent, and obviously improved the tribological properties. When the mixed oil-based titanium complex grease was used as a lubricant, lubricating films of polydimethylsiloxane were probably formed on the surfaces of friction pairs, giving good lubricating property.
基金Supported by National Natural Science Foundation of China(Grant Nos.52075458 and U2141211).
文摘Graphene as a lubricating additive holds great potential for industrial lubrication. However, its poor dispersity and compatibility with base oils and grease hinder maximizing performance. Here, the infuence of graphene dispersion on the thickening efect and lubrication function is considered. A well-dispersed lubricant additive was obtained via trihexyl tetradecyl phosphonium bis(2-ethylhexyl) phosphate modifed graphene ([P_(66614)][DEHP]-G). Then lithium complex grease was prepared by saponifcation with 12-OH stearic acid, sebacic acid, and lithium hydroxide, using polyalphaolefn (PAO20) as base oil and the modifed-graphene as lubricating additive, with the original graphene as a comparison. The physicochemical properties and lubrication performance of the as-prepared greases were evaluated in detail. The results show that the as-prepared greases have high dropping point and colloidal stability. Furthermore, modifed-graphene lithium complex grease ofered the best friction reduction and anti-wear abilities, manifesting the reduction of friction coefcient and wear volume up to 18.84% and 67.34%, respectively. With base oil overfow and afux, well-dispersed [P_(66614)][DEHP]-G was readily adsorbed to the worn surfaces, resulting in the formation of a continuous and dense graphene deposition flm. The synergy of deposited graphene-flm, spilled oil, and adhesive grease greatly improves the lubrication function of grease. This research paves the way for modulating high-performance lithium complex grease to reduce the friction and wear of movable machinery.
文摘In order to solve the hardening problem of complex calcium lubricating grease, the water absorption test of several calcium salts was carried out, and it was found that calcium 12-hydroxystearate did not absorb water, and calcium acetate, calcium phosphate and calcium borate had different degrees of water absorption. Calcium acetate has the highest water absorption rate, while calcium phosphate and calcium borate show comparable water absorption rates. Upon using the molecular simulation technology, it is found that in the complex calcium grease system, calcium phosphate and calcium borate tend to combine with water, which inhibits the water absorption of calcium acetate and alleviate the hardening problem.
文摘Using 12-hydroxystearate, nonan-edioic acid and lithium hydroxide as thickener, refined mineral oil and synthetic oil as base oil, along with some structure improver, antioxidant and anti-wear extreme pressure additive, lithium complex grease was developed. The dropping point of the grease is 331℃, friction factor is 0.0250.026 under 1.0kN, especially above 220℃, its friction factor is 2/3 of those of urea-based greases and other high temperature greases. At the same time, it has good waterproof, anti-oxidation effect and anti-corrosion properties. The results of the field experiment proves that its working temperature is higher than 600℃, and it has reasonable working life in 800℃.
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.
文摘Six kinds of alkylbenzene sulfonic acids were selected to prepare the sulfonates S1—S6. Among them, the sulfonates S3, S4, and S6 could be incorporated into lubricating grease with good performance in comparison with the grease produced from commercial sulfonates T106-1 and T106-2. The optimized conditions for synthesis of the sulfonates S3, S4, and S6 were explored by using different mass ratios of methanol, water and the type of copromoters. It was found out that the appropriate conditions for synthesis of the sulfonate S3 included a methanol to M(M is the total mass of alkylbenzene sulfonic acid and base oil) mass ratio of 16%, a water to M mass ratio of 4%, and a copromoter A to M mass ratio of 2%; the appropriate conditions for synthesis of the sulfonate S4 included a methanol to M mass ratio of 24%, a water to M mass ratio of 2%, a copromoter B to M mass ratio of 2%; and the optimized conditions for synthesis of the sulfonate S6 included a methanol/ M mass ratio of 8%, a water/M mass ratio of 4% and a copromoter B/M mass ratio of 2%. The new sulfonates S3, S4, and S6 produced under the optimized conditions exhibited higher TBN and better antiwear property in camparison with the previous products. Grease samples G9, G10, and G11 were prepared with new sulfonates S3, S4, and S6 successfully and exhibited improved water stability and high temperature performance.
基金financially supported by the National Natural Science Foundation of China (U1910202, 21978194)the Key Research and Development Program of Shanxi Province (202102090301005)+1 种基金the Fund for Shanxi “1331 Project”the Shanxi Natural Science Foundation for Young Scientists (202103021223064)。
文摘A new category of lithium greases was synthesized by using poly-a-olefin(PAO8) and alkyl-tetralin as base oil, where the alkyl-tetralins were synthesized by the alkylation of tetralin and olefins. The influence of thickener concentration, alkyl-tetralin content and type of blend oils on the rheological and tribological performance of lithium grease was investigated. The microstructures of soap fibers were measured to reveal the structure-property correlations. The concentration of thickener and alkyl-tetralin content obviously affect the lubricating performance of lithium grease, while the molecular structure of alkyltetralin has no obvious impact on their properties. It was found that alkyl-tetralin could significantly enhance the thickening ability of PAO8 base oils, and decrease the amount of thickeners by 1.5%(mass).Lithium greases prepared using 20%(mass) alkyl-tetralin as co-base oil exhibited high colloidal stability,excellent rheological behaviors and tribological properties.
基金the financial support provided by the National Natural Science Foundation of China(No.51705435)Fundamental Research Funds for the Central Universities(2018GF05)Key Laboratory of Material Corrosion and Protection of Sichuan(2018CL14)。
文摘In this study,lithium complex grease(LCG)and polyurea grease(PUG)were synthesized using mineral oil(500 SN)and polyalphaolefin(PAO40)as base oil,adsorbed onto lithium complex soap and polyurea as thickeners,respectively.The effects of grease formulation(thickener and base oil with different amounts(80,85,and 90 wt%)on the corrosion resistance and lubrication function were investigated in detail.The results have verified that the as-prepared greases have good anti-corrosion ability,ascribed to good salt-spray resistance and sealing function.Furthermore,the increase in the amount of base oil reduces the friction of the contact interface to some extent,whereas the wear resistance of these greases is not consistent with the friction reduction,because the thickener has a significant influence on the tribological property of greases,especially load-carrying capacity.PUG displays better physicochemical performance and lubrication function than LCG under the same conditions,mainly depending on the component/structure of polyurea thickener.The polyurea grease with 90 wt%PAO displays the best wear resistance owing to the synergistic lubrication of grease-film and tribochemical film,composed of Fe_(2)O_(3),FeO(OH),and nitrogen oxide.
文摘An ionic liquid-polyaniline/tungsten disulfide(IL-PANI/WS_(2))composite was synthesized in 1-butyl-3-methylimidazole tetrafluoroborate(LB104)aqueous solution by in-situ polymerization and characterized by Fourier transform infrared spectroscopy.A current-carrying friction and wear tester was used to study the tribological properties of steel-steel and copper-copper friction pairs lubricated by an IL-PANI/WS_(2) lithium complex grease(LCG).After the experiment,scanning electron microscope was used to observe the surface morphology of the wear scar on the steel and copper plates,and X-ray photoelectron spectrometer was used to analyze the elemental composition of the wear scar surface.The results show that compared with greases containing IL-PANI and WS_(2),greases containing IL-PANI/WS_(2) exhibit better antiwear performance when lubricating steel-steel friction pairs and better tribological performance and electrical conductivity when lubricating copper-copper friction pairs.Therefore,it can be concluded that WS_(2) and IL-PANI have a synergistic effect.
基金supported by the open project of State Key Laboratory of Solid Lubrication,Lanzhou Institute of Chemical Physics,Chinese Academy of Sciences(1211)Natural Science foundation of Ningxia University(ZR1216).
文摘In this study,we synthesized two types of calcium sulfonate complex greases(barium soap and calcium soap)and investigated their physical,rheological,and tribological properties in detail.The test results showed that the evolution of their linear viscoelasticity functions with frequency were quite similar to those of traditional lubricating greases.Moreover,these two calcium sulfonate complex greases had good friction-reducing and antiwear properties at room temperature and at 150°C.In addition,by adding an organic molybdenum compound(MoDTC)to the base greases,we obtained a very low friction coefficient(0.065)for one of the greases(calcium soap)at 400 N and 500 N(maximum Hertzian pressures of 3.47 GPa and 3.74 GPa,respectively)at 150°C.X-ray photoelectron spectroscopy(XPS)analysis showed that the tribofilm was composed of some complex oxide species and CaCO3 that had formed on the worn surface.
