Micro Synergistic Friction Behavior Of Mussel Adhesive Protein And Graphene

Graphene,a two-dimensional material composed of carbon atoms,has the potential to be used as a solid lubricant in micro-nano electromechanical systems.Graphene has a lower coefficient of friction under some conditions,which is called superlubricity.However,how to achieve superlubricity through simple and fast methods remains to be studied.On the other hand,although graphene has a very strong anti-wear ability,the anti-wear ability of the edge is relatively weak,which limits the application of graphene as a wear-resistant coating.In this paper,a mussel adhesive protein-graphene coating is prepared.The friction and abrasion properties of this coating are studied,and the mechanism of how the protein influences the tribological behavior of graphene is explained using molecular dynamics simulation.The major contents of this paper can be concluded as follows:(1)Preparation and characterization of mussel adhesive proteingraphene coating.The mussel adhesive protein layer is prepared on the silica substrate by immersion,and then graphene is transferred onto the protein by mechanical exfoliation.The thickness,roughness and chemical composition of the coating are characterized by atomic force microscope,Raman spectroscopy,infrared spectroscopy and other means.(2)Study on the microscopic friction properties of mussel adhesivegraphene coating.The atomic force microscope is used to study the microfriction properties of the coatings,and the effects of graphene thickness,loading method,load,scan speed,and protein degradation on the friction properties are compared.It is found that mussel adhesive protein decreases the friction of graphene,and the influence is more significant when applying large load with high scan speed on few-layer graphene,but the protein will degrade over time and the influence will vanish.Simulations show that the friction decrease effect of the protein is due to the enhanced adhesion between graphene and the substrate.(3)Wear resistance of mussel adhesive protein-graphene coating.The atomic force microscope is used to study the anti-wear properties of the coating.It is found that the protein can increase the anti-wear ability of the edges of graphene by about 60 %,and has no negative effect on the antiwear ability of the center of the sheet.Simulations show that the effect of protein on the wear resistance ability of graphene is also due to the enhanced adhesion.