High-performance organic friction modifiers(OFMs)added to lubricating oils are crucial for reducing energy loss and carbon footprint.To establish a new class of OFMs,we measured the friction and wear properties of N-(...High-performance organic friction modifiers(OFMs)added to lubricating oils are crucial for reducing energy loss and carbon footprint.To establish a new class of OFMs,we measured the friction and wear properties of N-(2,2,6,6-tetramethyl-1-oxyl-4-piperidinyl)dodecaneamide referred to as C12Amide-TEMPO.The effect of its head group chemistry,which is characterized by a rigid six-membered ring sandwiched by an amide group and a terminal free oxygen radical,was also investigated with both experiments and quantum mechanical(QM)calculations.The measurement results show that C12Amide-TEMPO outperforms the conventional OFMs of glyceryl monooleate(GMO)and stearic acid,particularly for load-carrying capacity,wear reduction,and stability of friction over time.The friction and wear reduction effect of C12Amide-TEMPO is also greatly superior to those of C12Ester-TEMPO and C12Amino-TEMPO,in which ester and amino groups replace the amide group,highlighting the critical role of the amide group.The QM calculation results suggest that,in contrast to C12Ester-TEMPO,C12Amino-TEMPO,and the conventional OFMs of GMO and stearic acid,C12Amide-TEMPO can form effective boundary films on iron oxide surfaces with a unique double-layer structure:a strong surface adsorption layer owing to the chemical interactions of the amide oxygen and free radical with iron oxide surfaces,and an upper layer owing to the interlayer hydrogen-bonding between the amide hydrogen and free radical or between the amide hydrogen and oxygen.Moreover,the intralayer hydrogen-bonding in each of the two layers is also possible.We suggest that in addition to strong surface adsorption,the interlayer and intralayer hydrogen-bonding also increases the strength of the boundary films by enhancing the cohesion strength,thereby resulting in the high tribological performance of C12Amide-TEMPO.The findings in this study are expected to provide new hints for the optimal molecular design of OFMs.展开更多
Novel Ni-PSF@PAO40 microcapsules(NPPMS)with high stability were prepared by using a combined processing method of electroless nickel plating and solvent volatilization.The results indicate that Ni is completely assemb...Novel Ni-PSF@PAO40 microcapsules(NPPMS)with high stability were prepared by using a combined processing method of electroless nickel plating and solvent volatilization.The results indicate that Ni is completely assembled on the surfaces of PSF/PAO40 microcapsules with the encapsulation capacity of NPPMS achieved at 50%.Organic solvents immersion shows that NPPMS have an excellent chemical stability.Macro thermal stability tests reveal that the softening temperature of NPPMS is increased up to over 400℃ while it becomes lower than 200℃ for PSF/PAO40 microcapsules.Furthermore,NPPMS were embedded into polyamide 6(PA6)to prepare PA6/NPPMS composites.The cross-sectional morphology shows that NPPMS are intact in PA6 matrices.The microhardness of PA6 is effectively improved with the incorporation of NPPMS.As compared with neat PA6,the coefficient of friction(COF)for PA6/NPPMS composites with 10%NPPMS could be reduced by 87.7%(from 0.49 to 0.06)and the wear rate could be decreased by 96.8%(from 1.29×10^(-5) to 4.15×10^(-7) mm^(3)/(N·m)).Further studies confirmed that increasing test loads and test temperatures was beneficial to improve the lubrication performance of NPPMS despite the opposite trend occurred when increasing the sliding speeds.It has been demonstrated that synergistic effects between PAO40 and Ni layer play an important role in improving the tribological properties of PA6.Therefore,NPPMS significantly improve the ability of microcapsules to resist a harsh environment,which has important scientific significance for expanding the use of microcapsules more practically in self-lubricating composites.展开更多
Friction and wear are ubiquitous,from nano-electro-mechanical systems in biomedicine to large-scale integrated electric propulsion in aircraft carriers.Applications of nanomaterials as lubricating oil additives have a...Friction and wear are ubiquitous,from nano-electro-mechanical systems in biomedicine to large-scale integrated electric propulsion in aircraft carriers.Applications of nanomaterials as lubricating oil additives have achieved great advances,which are of great significance to control friction and wear.This review focuses on the applications of nanomaterials in lubricating oil and comprehensively compares their tribological characteristics as lubricating oil additives.Statistical analysis of tribology data is provided and discussed accordingly;moreover,the interaction between nanomaterials and sliding surface,lubricating oil,other additives,and synergistic lubrication in nanocomposites are systematically elaborated.Finally,suggestions for future research on nanomaterials as lubricating oil additives are proposed.Hence,this review will promote a better fundamental understanding of nanomaterials for lubricating oil application and help to achieve the superior design of nanoadditives with outstanding tribological performances.展开更多
基金JSPS KAKENHI Grant(Nos.19K21915 and 21H01238)JST Adaptable and Seamless Technology Transfer Program through Target-driven R&D(No.JPMJTM19FN)NSK Foundation for Mechatronics Technology Advancement.We thank Dr.Kin-ichi OYAMA(Research Center for Materials Science,Nagoya University)for mass spectrometry analysis of the synthesized OFMs and associate professor Takayuki TOKOROYAMA(Graduate School of Engineering,Nagoya University)for the help with wear scar measurements.Jinchi HOU is grateful for the financial support from the China Scholarship Council(No.202006030017).
文摘High-performance organic friction modifiers(OFMs)added to lubricating oils are crucial for reducing energy loss and carbon footprint.To establish a new class of OFMs,we measured the friction and wear properties of N-(2,2,6,6-tetramethyl-1-oxyl-4-piperidinyl)dodecaneamide referred to as C12Amide-TEMPO.The effect of its head group chemistry,which is characterized by a rigid six-membered ring sandwiched by an amide group and a terminal free oxygen radical,was also investigated with both experiments and quantum mechanical(QM)calculations.The measurement results show that C12Amide-TEMPO outperforms the conventional OFMs of glyceryl monooleate(GMO)and stearic acid,particularly for load-carrying capacity,wear reduction,and stability of friction over time.The friction and wear reduction effect of C12Amide-TEMPO is also greatly superior to those of C12Ester-TEMPO and C12Amino-TEMPO,in which ester and amino groups replace the amide group,highlighting the critical role of the amide group.The QM calculation results suggest that,in contrast to C12Ester-TEMPO,C12Amino-TEMPO,and the conventional OFMs of GMO and stearic acid,C12Amide-TEMPO can form effective boundary films on iron oxide surfaces with a unique double-layer structure:a strong surface adsorption layer owing to the chemical interactions of the amide oxygen and free radical with iron oxide surfaces,and an upper layer owing to the interlayer hydrogen-bonding between the amide hydrogen and free radical or between the amide hydrogen and oxygen.Moreover,the intralayer hydrogen-bonding in each of the two layers is also possible.We suggest that in addition to strong surface adsorption,the interlayer and intralayer hydrogen-bonding also increases the strength of the boundary films by enhancing the cohesion strength,thereby resulting in the high tribological performance of C12Amide-TEMPO.The findings in this study are expected to provide new hints for the optimal molecular design of OFMs.
基金This work was supported by the Doctoral Fund Project of Yanshan University(No.BL18057)Aviation Scientific Fund Project(No.20200045099001)Aviation Scientific Fund Project(No.20184599001).
文摘Novel Ni-PSF@PAO40 microcapsules(NPPMS)with high stability were prepared by using a combined processing method of electroless nickel plating and solvent volatilization.The results indicate that Ni is completely assembled on the surfaces of PSF/PAO40 microcapsules with the encapsulation capacity of NPPMS achieved at 50%.Organic solvents immersion shows that NPPMS have an excellent chemical stability.Macro thermal stability tests reveal that the softening temperature of NPPMS is increased up to over 400℃ while it becomes lower than 200℃ for PSF/PAO40 microcapsules.Furthermore,NPPMS were embedded into polyamide 6(PA6)to prepare PA6/NPPMS composites.The cross-sectional morphology shows that NPPMS are intact in PA6 matrices.The microhardness of PA6 is effectively improved with the incorporation of NPPMS.As compared with neat PA6,the coefficient of friction(COF)for PA6/NPPMS composites with 10%NPPMS could be reduced by 87.7%(from 0.49 to 0.06)and the wear rate could be decreased by 96.8%(from 1.29×10^(-5) to 4.15×10^(-7) mm^(3)/(N·m)).Further studies confirmed that increasing test loads and test temperatures was beneficial to improve the lubrication performance of NPPMS despite the opposite trend occurred when increasing the sliding speeds.It has been demonstrated that synergistic effects between PAO40 and Ni layer play an important role in improving the tribological properties of PA6.Therefore,NPPMS significantly improve the ability of microcapsules to resist a harsh environment,which has important scientific significance for expanding the use of microcapsules more practically in self-lubricating composites.
基金supported by the National Key R&D Program of China(No.2018YFB2000301)the National Natural Science Foundation of China(No.51905385).
文摘Friction and wear are ubiquitous,from nano-electro-mechanical systems in biomedicine to large-scale integrated electric propulsion in aircraft carriers.Applications of nanomaterials as lubricating oil additives have achieved great advances,which are of great significance to control friction and wear.This review focuses on the applications of nanomaterials in lubricating oil and comprehensively compares their tribological characteristics as lubricating oil additives.Statistical analysis of tribology data is provided and discussed accordingly;moreover,the interaction between nanomaterials and sliding surface,lubricating oil,other additives,and synergistic lubrication in nanocomposites are systematically elaborated.Finally,suggestions for future research on nanomaterials as lubricating oil additives are proposed.Hence,this review will promote a better fundamental understanding of nanomaterials for lubricating oil application and help to achieve the superior design of nanoadditives with outstanding tribological performances.
