Superlubricating materials can greatly reduce the energy consumed and economic losses by unnecessary friction.However,a long pre-running-in period is indispensable for achieving superlubricity;this leads to severe wea...Superlubricating materials can greatly reduce the energy consumed and economic losses by unnecessary friction.However,a long pre-running-in period is indispensable for achieving superlubricity;this leads to severe wear on the surface of friction pairs and has become one of the important factors in the wear of superlubricating materials.In this study,a polyethylene glycol-tannic acid complex green liquid lubricant(PEG10000-TA)was designed to achieve macroscale superlubricity with an ultrashort running-in period of 9 s under a contact pressure of up to 410 MPa,and the wear rate was only 1.19×10^(–8)mm^(3)·N^(−1)·m^(−1).This is the shortest running-in time required to achieve superlubricity in Si_(3)N_(4)/glass(SiO_(2)).The results show that the strong hydrogen bonds between PEG and TA molecules can significantly reduce the time required for the tribochemical reaction,allowing the lubricating material to reach the state of superlubrication rapidly.Furthermore,the strong hydrogen bond can share a large load while fixing free water molecules in the contact zone to reduce shear interaction.These findings will help advance the use of liquid superlubricity technology in industrial and biomedical.展开更多
Two-dimensional compounds combining group IV A element and group V A element were determined to integrate the advantages of the two groups.As a typical 2D group IV–V material,SiP has been widely used in photodetectio...Two-dimensional compounds combining group IV A element and group V A element were determined to integrate the advantages of the two groups.As a typical 2D group IV–V material,SiP has been widely used in photodetection and photocatalysis due to its high carrier mobility,appropriate bandgap,high thermal stability,and low interlayer cleavage energy.However,its adhesion and friction properties have not been extensively grasped.Here,large-size and high-quality SiP crystals were obtained by using the flux method.SiP nanosheets were prepared by using mechanical exfoliation.The layer-dependent and velocity-dependent nanotribological properties of SiP nanosheets were systematically investigated.The results indicate the friction force of SiP nanosheets decreases with the increase in layer number and reaches saturation after five layers.The coefficient of friction of multilayer SiP is 0.018.The mean friction force,frictional vibrations,and the friction strengthening effect can be affected by sliding velocity.Specially,the mean friction force increases with the logarithm of sliding velocity at nm/s scale,which is dominated by atomic stick-slip.The influence of frequency on frictional vibration is greater than speed due to the different influences on the change in contact quality.The friction strengthening saturation distance increases with the increase in speed for thick SiP nanosheets.These results provide an approach for manipulating the nanofriction properties of SiP and serve as a theoretical basis for the application of SiP in solid lubrication and microelectromechanical systems.展开更多
基金the National Natural Science Foundation of China(U21A2046,51905518)the Program for Taishan Scholars of Shandong Province(TS20190965)+4 种基金the National Key R&D Program of China(2020YFF0304600)the Innovation Leading Talents Program of Qingdao(19-3-2-23-zhc)in Chinathe Key Research Program of the Chinese Academy of Sciences(XDPB24)the Western Light Project of CAS(xbzg-zdsys-202118)the LICP Cooperation Foundation for Young Scholars(HZJJ21-03)for providing financial support.
文摘Superlubricating materials can greatly reduce the energy consumed and economic losses by unnecessary friction.However,a long pre-running-in period is indispensable for achieving superlubricity;this leads to severe wear on the surface of friction pairs and has become one of the important factors in the wear of superlubricating materials.In this study,a polyethylene glycol-tannic acid complex green liquid lubricant(PEG10000-TA)was designed to achieve macroscale superlubricity with an ultrashort running-in period of 9 s under a contact pressure of up to 410 MPa,and the wear rate was only 1.19×10^(–8)mm^(3)·N^(−1)·m^(−1).This is the shortest running-in time required to achieve superlubricity in Si_(3)N_(4)/glass(SiO_(2)).The results show that the strong hydrogen bonds between PEG and TA molecules can significantly reduce the time required for the tribochemical reaction,allowing the lubricating material to reach the state of superlubrication rapidly.Furthermore,the strong hydrogen bond can share a large load while fixing free water molecules in the contact zone to reduce shear interaction.These findings will help advance the use of liquid superlubricity technology in industrial and biomedical.
基金Thanks for the financial support of the Program for Taishan Scholars of Shandong Province(No.ts20190965)the National Key R&D Program of China(No.2020YFF0304600)+2 种基金the National Natural Science Foundation of China(No.51905518)the Key Research Program of the Chinese Academy of Sciences(No.XDPB24)the Innovation Leading Talents Program of Qingdao(No.19-3-2-23-zhc)in China.
文摘Two-dimensional compounds combining group IV A element and group V A element were determined to integrate the advantages of the two groups.As a typical 2D group IV–V material,SiP has been widely used in photodetection and photocatalysis due to its high carrier mobility,appropriate bandgap,high thermal stability,and low interlayer cleavage energy.However,its adhesion and friction properties have not been extensively grasped.Here,large-size and high-quality SiP crystals were obtained by using the flux method.SiP nanosheets were prepared by using mechanical exfoliation.The layer-dependent and velocity-dependent nanotribological properties of SiP nanosheets were systematically investigated.The results indicate the friction force of SiP nanosheets decreases with the increase in layer number and reaches saturation after five layers.The coefficient of friction of multilayer SiP is 0.018.The mean friction force,frictional vibrations,and the friction strengthening effect can be affected by sliding velocity.Specially,the mean friction force increases with the logarithm of sliding velocity at nm/s scale,which is dominated by atomic stick-slip.The influence of frequency on frictional vibration is greater than speed due to the different influences on the change in contact quality.The friction strengthening saturation distance increases with the increase in speed for thick SiP nanosheets.These results provide an approach for manipulating the nanofriction properties of SiP and serve as a theoretical basis for the application of SiP in solid lubrication and microelectromechanical systems.