On 20 jaan, 19:43, Matt Browne SFW <matt.h.bro...@[EMAIL PROTECTED]
>
wrote:
> On Jan 18, 9:10 pm, bealoid <sig...@[EMAIL PROTECTED]
> wrote:
>
> > I read many books which mention nano-engineered structure made from
> > diamond.
>
> > I know diamond is hard, but I thought it was brittle.
>
> > Would a nano-engineered diamond be any less brittle?
>
> > Would diamond be a suitable material for a set of bicycle gears?
>
> I've read in some article that a Los Alamos National Laboratory
> research project has made a super-hard phase of carbon by applying
> pressure to carbon nanotubes. The material was at least as hard as
> cubic diamond and retained its properties at room temperature even
> when the pressure was removed.
>
No wonder, because diamond itself also retains its properties at room
temperature, and even on moderate heating, when pressure is removed.
Consider glass and fibreglass plastic. Glass is brittle - a crack in
glass easily propagates, so a small force is enough to drive a crack
all through. But in fibreglass plastic, snapping one fibre will not
cause a crack to propagate through all the fibres.
So, an idea of strengthening diamond would be to create a dense tangle
of diamond fibres, which are welded together just hard enough that
they do not easily slip apart like graphite planes do, but not so
thoroughly annealed as to allow free crack propagation.
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