The mechanical behavior and collapse of graphene-assembled hollow nanospheres under compression

Recently, much interest has been attracted in the graphene-assembled hollow nanospheres (GAHNs) because of outstanding multi-functional properties. This paper systematically explores the compressive mechanical behaviors and gas bearing capability of GAHNs by a coarse-grained molecular dynamics (CGMD) simulation combining with in-situ compressive test. It was found that the GAHNs possess excellent compressive elasticity (experimentally recoverable strain can reach similar to 58%). Under large compressive strain (>90%), the GAHNs also display obvious plastic deformation owing to inter-layer slippage between graphene nanosheets. In addition, the morphology of force measurement tip (FMT) plays critical roles on the compressive failure modes of GAHNs. When FMT is sharp, it can pierce through the shell of GAHN, whereas the blunt one compels GAHN to collapse. The thermal expansion process of GAHNs was investigated by CGMD simulation. With the increase of ambient temperature, the internal pressure of GAHN increased until a crack appears. To further understand this expansion failure, an in-situ scratching experiment was designed and the tearing strength of shell of GAHN was estimated to be similar to 748 MPa. This work provides an in-depth understanding on intrinsic mechanical properties of GAHNs and broadens their potential applications. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

Graphene-assembled hollow nanospheres (GAHNs) have attracted much interest due to their outstanding multi-functional properties, including excellent compressive elasticity and plastic deformation characteristics. The morphology of force measurement tip plays a critical role in the compressive failure modes of GAHNs. With the increase of ambient temperature, the internal pressure of GAHN increases until a crack appears.