Effective composites/Lasagna noodles

stiff direction

cross-section of ruffled, compliant part of graphite ribbon (mimics matrix)

cross-section of central, stiff part of graphite ribbon (mimics carbon fiber)

one "noodle" within effective composite crystal

The schematic illustrates one design for a curved graphite crystal that will mimic a carbon-carbon composite, a class of materials frequently used in disc brakes for jumbo jets[19].  The structure is composed of alternating stripes of flat and wavy graphite.  While the flat stripes are expected to have the high stiffness of conventional graphite, the wavy stripes will be much more compliant.  The principle that a stiff material can mimic a soft, flexible material has been demonstrated experimentally with silicon:  Wavy films of elastomeric silicon have been synthesized[20]

In principle, this kind of material can be synthesized with a low density of graphene edges. Raman spectroscopy data show that the origami variant of curved kish routinely has a low edge density, much like HOPG.  Sufficiently low edge density will make highly oriented, high strength graphite gas-tight and useful for high pressure hydrogen storage tanks.  Reduced edge density will also make this effective composite oxidation resistant.  Wavy graphite will still be vulnerable to oxidation at the defects of intrinsic curvature.  For demanding applications, these graphene defects may be replaced with hexagonal boron nitride by a substitution reaction[16,17].

The SEM micrographs show   we can make objects somewhat similar to this "lasagna noodle" structure, already.  This cactus-like structure is easy to produce, appearing spontaneously when thin graphene deposits are swiftly cooled.  For more careful control of the shape of curved graphite materials, a general-purpose electrostatic patterning technique is called for.

This medium-scale view of a "cactus", one of many dendritic structures produced already, shows we can produce graphene surfaces with alternately wavy and spiky striations. 

 

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Dendrites like these are visible in profile on the cactus page.