This work investigated the temperature changes inside the bulk of lubricating greases under controlled high-shear stress conditions(250-500 s-1).For this purpose,a newly developed temperature-measuring cell called Cal...This work investigated the temperature changes inside the bulk of lubricating greases under controlled high-shear stress conditions(250-500 s-1).For this purpose,a newly developed temperature-measuring cell called Calidus was successfully tested.The temperature changes(ΔT)have been related to the greases'components(thickener,base oil-type,and composition)and the structural degradation of the lubricating greases.Furthermore,a theoretical approach was proposed for calculating the internal temperature change of lubricating greases during shear stress.All greases showed an internal temperature profile characterised by a sudden rise inΔT within the first 4 h from starting the test and subsequentΔT decay until it reaches the steady state value.Furthermore,it was found that greases C1 and C5,formulated with lithium and calcium soap,respectively,with different soap content(16.1 wt%and 9.7 wt%,respectively),but the same base castor oil,showed the highest value of the maximumΔT,c.a.3.2 K,and the most drastic drop ofΔT.These greases showed both the highest specific densities and heat capacities.In addition,they showed the lowest ratio of expended energies(Rtee),which means more structural degradation in the stressed grease.On the contrary,the grease C3,with 13 wt%of Li-soap but the lowest base oil's viscosity,showed the lowest maximumΔT and the temperature profile was characterised by a moderate variation ofΔT along the test.The biogenic grease B3 developed a low-temperature change in the group of pure bio-genic greases close to grease C3.展开更多
This study investigates the development of novel montmorillonite/castor oil blends to formulate sustainable lubricating greases to promote the replacement of petrochemicals industry-derived materials by substances obt...This study investigates the development of novel montmorillonite/castor oil blends to formulate sustainable lubricating greases to promote the replacement of petrochemicals industry-derived materials by substances obtained from renewable sources.Specifically,the effect of the thickener concentration on the rheological,chemical,thermal,tribological properties,and atomic force microscopy(AFM)microstructure of these systems were studied.The results showed that the C20A nanoclay content could be used to modulate the viscosity values,the linear viscoelastic functions,and tribological properties of these montmorillonite dispersions.In general,these gel-like dispersions exhibited remarkable lubricant properties;the samples showed values of the friction coefficient and wear scars similar or lower than those obtained with model bentonite grease.展开更多
3-(5-(2.4-dichlorophyenyl)-4.5-dihydro-1H-pyrazol-3-yl)-4hydroxy-1-methylquinolin(1H)-one, 5-((4-hydroxy-8-methyl-2-oxo-1.2-dihydroquinolin-3-yl)methylene)-1-phenyl-2-hioxodihydropyrimidine-4.6(1H.5H)-dione, and 1-but...3-(5-(2.4-dichlorophyenyl)-4.5-dihydro-1H-pyrazol-3-yl)-4hydroxy-1-methylquinolin(1H)-one, 5-((4-hydroxy-8-methyl-2-oxo-1.2-dihydroquinolin-3-yl)methylene)-1-phenyl-2-hioxodihydropyrimidine-4.6(1H.5H)-dione, and 1-butyl-4-hydroxy-3-(5-styryl-4.5-dihydro-1H-pyrazol-3yl)quinolin-2(1H)-one were synthesized and characterized by spectroscopy analysis. These compounds are designated I, II and III, respectively. The antioxidants efficiency of the synthesized compounds in lubricating greases had been investigated using ASTM d-942 and ASTM d-664. The obtained data showed that the total acid number and oxygen pressure drop of these compounds in lubricating greases decrease in the order: Comp.III. < Comp.I. < Comp.II. The antioxidant efficiency of the prepared quinolinones derivatives was discussed. Acceptable correlations were obtained between the obtained oxidation inhibition and the calculated quantum chemical parameters.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
In order to investigate the influening factors of organic modification procedure and find out connections between organic modification and the properties of bentonite greases, organic montmorillonite(OMMT) thickeners ...In order to investigate the influening factors of organic modification procedure and find out connections between organic modification and the properties of bentonite greases, organic montmorillonite(OMMT) thickeners with different surfactant dosages and constituents were synthesized through intercalation reaction between sodium montmorillonite(NaM MT) and quaternary ammonium surfactants in aqueous solvents. The lubricating greases were prepared with the resulting organoclays, while the penetration and oil separation of lubricating greases were evaluated, respectively. The surface modification process of montmorillonite(MMT) was analyzed and the thickening mechanism of OMMT was discussed in this study. The experimental results showed that, with an increasing amount of surfactant, the basal spacing between the clay platelets was increasing and the structure of modifier molecules layer in the interlayer was changing from lateral bilayer to paraffin-type bilayer. The optimal properties of lubricating greases were achieved, when the structure of surfactant molecules loaded in the interlayer was the paraffin-type monolayer, which meant that the dosage of modifier was equal to 120—140 mmol/(100g). Meanwhile, it was found that the thickening performance, colloid stability, anti-wear and friction-reducing performance of lubricating greases were improved, when the surfactants were mixed with octadecyl trimethyl ammonium chloride(OTAC) and hexadecyl trimethyl ammonium chloride(HTAC). And the optimum mole ratio of two surfactants is was 1:1.展开更多
文摘This work investigated the temperature changes inside the bulk of lubricating greases under controlled high-shear stress conditions(250-500 s-1).For this purpose,a newly developed temperature-measuring cell called Calidus was successfully tested.The temperature changes(ΔT)have been related to the greases'components(thickener,base oil-type,and composition)and the structural degradation of the lubricating greases.Furthermore,a theoretical approach was proposed for calculating the internal temperature change of lubricating greases during shear stress.All greases showed an internal temperature profile characterised by a sudden rise inΔT within the first 4 h from starting the test and subsequentΔT decay until it reaches the steady state value.Furthermore,it was found that greases C1 and C5,formulated with lithium and calcium soap,respectively,with different soap content(16.1 wt%and 9.7 wt%,respectively),but the same base castor oil,showed the highest value of the maximumΔT,c.a.3.2 K,and the most drastic drop ofΔT.These greases showed both the highest specific densities and heat capacities.In addition,they showed the lowest ratio of expended energies(Rtee),which means more structural degradation in the stressed grease.On the contrary,the grease C3,with 13 wt%of Li-soap but the lowest base oil's viscosity,showed the lowest maximumΔT and the temperature profile was characterised by a moderate variation ofΔT along the test.The biogenic grease B3 developed a low-temperature change in the group of pure bio-genic greases close to grease C3.
文摘This study investigates the development of novel montmorillonite/castor oil blends to formulate sustainable lubricating greases to promote the replacement of petrochemicals industry-derived materials by substances obtained from renewable sources.Specifically,the effect of the thickener concentration on the rheological,chemical,thermal,tribological properties,and atomic force microscopy(AFM)microstructure of these systems were studied.The results showed that the C20A nanoclay content could be used to modulate the viscosity values,the linear viscoelastic functions,and tribological properties of these montmorillonite dispersions.In general,these gel-like dispersions exhibited remarkable lubricant properties;the samples showed values of the friction coefficient and wear scars similar or lower than those obtained with model bentonite grease.
文摘3-(5-(2.4-dichlorophyenyl)-4.5-dihydro-1H-pyrazol-3-yl)-4hydroxy-1-methylquinolin(1H)-one, 5-((4-hydroxy-8-methyl-2-oxo-1.2-dihydroquinolin-3-yl)methylene)-1-phenyl-2-hioxodihydropyrimidine-4.6(1H.5H)-dione, and 1-butyl-4-hydroxy-3-(5-styryl-4.5-dihydro-1H-pyrazol-3yl)quinolin-2(1H)-one were synthesized and characterized by spectroscopy analysis. These compounds are designated I, II and III, respectively. The antioxidants efficiency of the synthesized compounds in lubricating greases had been investigated using ASTM d-942 and ASTM d-664. The obtained data showed that the total acid number and oxygen pressure drop of these compounds in lubricating greases decrease in the order: Comp.III. < Comp.I. < Comp.II. The antioxidant efficiency of the prepared quinolinones derivatives was discussed. Acceptable correlations were obtained between the obtained oxidation inhibition and the calculated quantum chemical parameters.
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.
基金financially supported by the Chongqing Construction Project of Innovation Teams in Colleges and Universities-Petroleum Products Application Engineering and Technology(Project No.KJTD201342)the Chongqing Project of Innovation Research by Postgraduates(Project No.CYB16130)
文摘In order to investigate the influening factors of organic modification procedure and find out connections between organic modification and the properties of bentonite greases, organic montmorillonite(OMMT) thickeners with different surfactant dosages and constituents were synthesized through intercalation reaction between sodium montmorillonite(NaM MT) and quaternary ammonium surfactants in aqueous solvents. The lubricating greases were prepared with the resulting organoclays, while the penetration and oil separation of lubricating greases were evaluated, respectively. The surface modification process of montmorillonite(MMT) was analyzed and the thickening mechanism of OMMT was discussed in this study. The experimental results showed that, with an increasing amount of surfactant, the basal spacing between the clay platelets was increasing and the structure of modifier molecules layer in the interlayer was changing from lateral bilayer to paraffin-type bilayer. The optimal properties of lubricating greases were achieved, when the structure of surfactant molecules loaded in the interlayer was the paraffin-type monolayer, which meant that the dosage of modifier was equal to 120—140 mmol/(100g). Meanwhile, it was found that the thickening performance, colloid stability, anti-wear and friction-reducing performance of lubricating greases were improved, when the surfactants were mixed with octadecyl trimethyl ammonium chloride(OTAC) and hexadecyl trimethyl ammonium chloride(HTAC). And the optimum mole ratio of two surfactants is was 1:1.
