Research On Interface Properties And Electronic Structure Of Graphene/Al Composites By First-principles Calculation

Graphene has much higher physical and mechanical properties than traditional materials,and it is an ideal reinforcing material.It has been proved that it can significantly enhance the properties of composite materials as a reinforcement body.Graphene/Al composites have high specific strength,excellent ductility,and good machine performance,which are significantly improved compared to traditional Al-based composites.At present,the experimental research of graphene/Al composites is mainly in the fields of tissue characterization and performance research.However,the research on the interface bonding mechanism of composite materials is not systematically studied due to the characteristics of graphene and equipment.The first-principles study in the field of composite material interface bonding,bonding type,interface electronic structure and other fields is not limited by materials and instruments,and makes up for the lack of testing.In this paper,the first-principles study of the interface stability,energy size,and electronic structure of the graphene/Al composite phase interface was conducted.Graphene/Al composites have graphene,Al,Si and 4H-SiC phases.The energy calculation results for multi-layer graphene show that the total energy of double-layer graphene is arranged in order of AB stacking,and the three-layer graphene is arranged in ABA stacking order.The energies of the three defects of single vacancy defects,double vacancy defects and topological defects of graphene are discussed.When the defect type is a topological defect,the defect formation energy is minimal;the introduction of defects can improve the non-metallicity of graphene,and the defect is to graphene.Pinning effect.The results of surface energy calculations for multiple low-index surfaces of Al,Si and 4H-SiC phases obtained from graphene/Al composites show that the surfaces with the lowest surface energy are Al(111)and Si(011),respectively.For the 0.6363 J/m~2,1.0556 J/m~2;4H-SiC non-polar surfaces,the lowest surface energy of the SiC(11(?)0)surface;Polar surface neutral and non-polar surface SiC(0001)-Si termination,The surface energy of the surface Si atom containing only one unsaturated bond is the lowest.The first-principle principle was used to study the stability and electronic structure of the interface between pure Al/graphene/pure Al doped with alloying elements.For the Al/Graphene/Al interface model,the interfacial bonding between different layers of graphene and different graphene-Al hardly affects the interfacial bonding strength.The combination of the interface separation work and the interfacial separation determine that the interfacial bonding mechanism is a weak interaction(physics adsorption)or mechanical bonding;the interface stability of Al/defective graphene/Al interface is improved compared to pure aluminum,and the interface separation work size is increased to-1.1764 J/m~2.The introduction of Si and Mg alloy elements respectively improves the interface separation work.There is an electronic interaction between the dopant atoms and graphene,and the binding mechanism of Si,Mg atoms and graphene is a strong interaction(chemisorption).This paper studies the interfacial properties of graphene/Al composites.The Si/monolayer graphene/Si interface has an interfacial separation work of 0.0278 J/m~2,and there is a small amount of charge transfer between Si and C.The interface separation of SiC(11(?)0)/graphene(0001)/SiC(11(?)0)at SiC/single-layer graphene/SiC interface has a higher work value of 0.0132 J/m~2.SiC(11(?)0)/Graphene(0001)/SiC(11(?)0)interface The first layer of Si atoms and graphene undergo a stronger charge transfer between the graphene and C and graphene than at the interface.The bonding mechanism is mainly covalent bonding of Si atoms in SiC and graphene C atoms.For the Al/Graphene/Si interface,the interface separation power of Al(111)/monolayer graphene/Al(111)interface is 0.191 J/m~2;Al(111)/double-vacancy defect graphene/Al(111)The interface separation power of the interface is 1.7695 J/m~2.At the Al(111)/double-vacancy-deficient graphene/Al(111)interface,there is an overlap of electron clouds between C atom and Al atom,C atom and Si atom.The overlap between C atom and Al atom is strong,indicating that The interface of the bond.The differential density map shows that the introduction of defects destroys the perfect structure of graphene itself,which can increase the amount of charge transfer between graphene and Al,Si,thereby increasing the interface bonding strength.