Effect of vacancy defects of graphene on the interfacial bonding and strengthening mechanism of graphene/Al composite

The structure and properties of the graphene-Al interface change significantly when defects are present in graphene. However, the effect of defects on interfacial bonding lacks quantitative assessment, and the results of theoretical studies are also difficult to guide the design of interface structures. In this paper, the interfacial structure of graphene-Al with different vacancy defect types has been investigated by first-principle calculations, and the interfacial bonding was calculated by quantifying the interfacial shear strength. The interfacial shear strengths of defect-free, single-vacancy, and double-vacancy were 0.02 GPa, 6.8 GPa, and 8.5 GPa, respectively. Based on the first-principles data and the differential idea, the calculation model of shear strength of graphene-Al interface with different defect contents was established. The role of vacancy defects on the enhancement of graphene-Al interfacial bonding was elucidated. A method to estimate the shear strength of graphene-Al direct bonding interface based on Raman characterization of graphene defects was proposed. The influence of graphene defects on graphene strengthening efficiency was clarified, and an apparent strengthening model applicable to directly bonded interfacial graphene/aluminum composites was established. The model was validated by graphene/Al composites with directly bonding interface.