Tribological Properties Of Interlayer Graphene Oxide/binary Ionic Liquid Lubrication Film

Single-crystal silicon?Si?which is the main structural material of micro-electro-mechanical systems?MEMS?,has large surface adhesion force and micro friction,and it will seriously restrict the development of MEMS.Reducing the adhesion,friction and improving anti-wear performances of Si surface is an important method to solve this problem.In this paper,an interlayer graphene oxide/binary ionic liquid lubricating film was designed on the Si substrate,containing a connecting layer of N-aminoethyl-3-aminopropyl trimethoxysilane?DA?,an intermediate reinforcing layer of Graphene oxide?GO?and a shear lubricant layers of 1-carboxyethyl-3-methylimidazole chloride?[CMIM]Cl?and 1-dodecyl-3-methylimidazole hexafluorophosphate?[DMIM]PF₆?.The molecular dynamics simulation method was used to study the structural characteristics of the lubricating film system,and a lubricating film system with optimal coverage,grafting position,and adsorption ratio was determined.The wetting characteristics of the surface of the lubricating film system were further discussed.The results showed that when the coverage rates of GO,upper layer DA,and[CMIM]Cl are 50%,50%,and 100%,respectively the replacement positions of GO and upper layer DA are at the linear of the smallest cell and at the positions of four vertices;and When the ratio of the number of molecules of[CMIM]Cl to[DMIM]PF₆is 1:1,a film structure with stable structure can be obtained.In the analysis of the wetting performance,the calculation of the radial distribution function of the surface revealed that the surface of the interlayer graphene oxide/binary ionic liquid lubricating film exhibited the weakest hydrogen bonding effect,making it less hydrophilic and showing a larger table,observed contact angle,with low adhesion performance.In this paper,an interlayer graphene oxide/binary ionic liquid lubricating film system was successfully prepared on the Si substrate using molecular self-assembly technology and spray coating.The surface morphology of the lubricating film system was characterized by atomic force microscope?AFM?,and the surface morphology and parameters of each film were obtained.The wetting performance of the lubricating film system was characterized by a contact angle measuring instrument,and the change law of the contact angle of each film was obtained.Furthermore,the chemical composition of each thin film was characterized by total reflection Fourier transform infrared spectrometer?ATR-FTIR?and X-ray diffractometer?XPS?,and the changes of chemical elements and chemical bonds of each thin film were obtained.The adhesion and nano friction coefficient of the lubricating film system were measured by AFM,and the macro-tribological characteristics of the lubricating film system were investigated by the micro-friction and wear testing machine,the super-depth microscope,and a scanning electron microscope.The tribological properties of the lubricating film system were studied from the macro and micro perspectives,and the mechanism of the synergistic effect of the base DA,GO,[CMIM]Cl and[DMIM]PF₆ on reducing the surface friction coefficient and extending the wear time was explored.The results show that,the interlayer graphene oxide/binary ionic liquid lubricating film had the lowest adhesion force and micro/macro friction coefficient.Under 400m N load and 0.5Hz macro test conditions,in the experimental time of 2486 seconds,friction failure phenomenon was no abrasion observed,showing good anti-friction and anti-wear performance.Furthermore,the interlayer graphene oxide/binary ionic liquid lubricating film can be used as an effective lubricating film.At the same time,it provides theoretical basis and experimental guidance for the effective application of graphene oxide-ionic liquid composite lubricating film in the field of MEMS lubrication.