There is already a precedent for welding graphene molecules
together on a small scale. Carbon nanotubes have been welded at 800
degrees C under 1.25 MeV electron irradiation[9].
The use of molten metal for graphite welding may permit the joining of much
larger carbon pieces without the use of an unusually powerful TEM.
The joined graphite pieces may be withdrawn from the melt.
This procedure may be applied to numerous separate graphite pieces to produce seamless
oriented graphite objects that are too large or convoluted to precipitate as
single pieces.
Graphene precipitation slows as exposed graphene edges are
joined seamlessly. Further precipitation requires the nucleation of
fresh crystals.
Graphite precipitating from the melt will extend the already
existing graphene edges. The melt surface will align the growing
graphene layers so that they meet in between the original pieces.
Immerse the separate pieces part-way into molten metal (iron,
nickel, etc.) already nearly saturated with carbon. Exploit the
anisotropy of graphite to wet the pieces as far as the highest pair of
graphene edges, no farther.
Start with separate pieces of highly oriented graphite in close
proximity, but not necessarily well aligned.
This thumbnail image from the
origami page shows a rift in a curved kish graphite shell. It is
striking, because it is rare. Except when samples are violently cooled
and stressed at the same time--by splat cooling--it
appears nearly impossible to preserve a rupture in a melt-grown graphite
shell. This does not mean it is difficult to tear kish graphite.
On the contrary, it is trivially easy to pinch several lumps of melt from a
sample through the application of electrostatic stress. In spite of
this rough treatment, the final product is routinely an origami graphite shell with no
obvious damage. Evidently rifts in kish graphite swiftly heal.
These observations suggest a procedure for welding separate graphite crystals
together:
