Half a croissant, on a plate, with a sign in front of it saying '50c'
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Reversible Pencil-Knife

Graphite at one end, pencil at the other
  [vote for,

A pure graphite pencil which has a diamond blade at the other end. This is made by taking a hexagonal column of graphite and applying extreme pressure and heat to half of it along a transverse axis, squashing it and converting it to diamond. This enables one end to be used as a very durable, sharp blade and the other as a writing implement. Alternatively, the blade can be used as a pen by drawing blood and writing with it. It needs to be held with some kind of spongy protective holder when written or drawn with.

I have a question. If the pressure in forming such a device is applied as a gradient, are there intermediate graphite/carbon allotropes and if so, what are they like?

Obviously you'd throw it away when you ran out of graphite.

nineteenthly, Jan 08 2017

https://www.newscie...s-hardest-material/ [hippo, Jan 09 2017]


       If you break it in half you can sharpen the pencil.
whatrock, Jan 08 2017

       Hardness and durability are different things.
Voice, Jan 08 2017

       I don't think there is a smooth transition. The heat/pressure will make a fracture gap.   

       Maybe if the intervening Carbon continuum was all different C containing molecules, just like the Metamorphosis print, then you could get something that stuck to graphite and transition to something that stuck to/into diamond. All solidified with pressure and heat.   

       Also thanks I will look into the canadian programme Continuum.
wjt, Jan 09 2017

       Is there a reason why there can't be bits of graphite embedded in diamond or vice versa? What happens with black diamonds?
nineteenthly, Jan 09 2017

       Diamond would make a fairly crappy knife blade. It's way too brittle (as well as not being heat-resistant, etc.)
hippo, Jan 09 2017

       And what would you sharpen it with?
Ian Tindale, Jan 09 2017

       Wurtzite boron nitride, of course (see link)
hippo, Jan 09 2017

       Well, make the knife out of that, then.   

       And the pencil, somehow.
Ian Tindale, Jan 09 2017


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