Theoretical strength and rubber-like behaviour in micro-sized pyrolytic carbon
X Zhang and L Zhong and A Mateos and A Kudo and A Vyatskikh and HJ Gao and JR Greer and XY Li, NATURE NANOTECHNOLOGY, 14, 762-+ (2019).
The creation of materials with a combination of high strength, substantial deformability and ductility, large elastic limit and low density represents a long-standing challenge, because these properties are, in general, mutually exclusive. Using a combination of two-photon lithography and high-temperature pyrolysis, we have created micro-sized pyrolytic carbon with a tensile strength of 1.60 +/- 0.55 GPa, a compressive strength approaching the theoretical limit of similar to 13.7 GPa, a substantial elastic limit of 20-30% and a low density of similar to 1.4 g cm(-3). This corresponds to a specific compressive strength of 9.79 GPa cm(3) g(-1), a value that surpasses that of nearly all existing structural materials. Pillars with diameters below 2.3 mu m exhibit rubber-like behaviour and sustain a compressive strain of similar to 50% without catastrophic failure; larger ones exhibit brittle fracture at a strain of similar to 20%. Large-scale atomistic simulations reveal that this combination of beneficial mechanical properties is enabled by the local deformation of 1 nm curled graphene fragments within the pyrolytic carbon microstructure, the interactions among neighbouring fragments and the presence of covalent carbon-carbon bonds.
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