Micromechanical properties of pyrolytic carbon with interlayer crosslink

Pyrolytic carbon (PyC) materials are laminar deposits formed from the high-temperature pyrolytic reaction of volatile hydrocarbons. The outstanding mechanical performance of PyC renders it attractive as interfacial materials in aerospace applications and thermonuclear fusion. But the deposition process of PyC under extreme conditions in particular makes it challenging to achieve large-sized specimens used in further cognition on processing-microstructure-property relationship for PyC materials. Toward recent molecular insights into the initial formation of PyC [Carbon 148 (2019) 307-316], we herein performed molecular dynamics simulations to investigate the micromechanical properties of PyC with the consideration of interlayer crosslinks. Under out-of-plane uniaxial tension, moderate numbers of interlayer crosslinks can significantly enhance the mechanical properties of PyC. Meanwhile, the increase of interlayer crosslinks will improve the energy dissipation through local and multilayer delamination and tearing. Interlayer crosslinks can provide strong junctions between adjacent layers to bear out-of-plane shear deformation effectively. While under in-plane tension or shearing, the mechanical properties of PyC are weakened due to intralayer pore defects introduced by interlayer crosslinks. Moreover, tension-compression asymmetry of PyC is found at nanoscale. Graphene layers with interlayer crosslinks experience kink-like puckering deformation in the in-plane compression, while they only straighten in the in-plane stretching before failure. (C) 2020 Elsevier Ltd. All rights reserved.