How do robotic surgeons work? Do diamonds melt? What is heartburn? Can fish see colours, and what should anglers wear? What is brain plasticity? What would happen if an egg were dropped into boiling oil? What causes blushing? Why does holding the antenna of an AM radio improve reception?
Good questions. Diamond is a network solid and melting has no meaning for it. I mean there are no constituent atoms/molecule but only one big molecule of carbons atoms. Since the C-C bonds are very strong, it requires very high energy to break them and if it occurs; that is no longer diamond but gaseous carbon atoms.
"Diamond is a network solid and melting has no meaning for it. "
Interesting; thanks for the reference bored chemist. chris, Wed, 9th Oct 2013
Ok, I've read that and I am quite surprised; I'd always thought that diamond did not melt. That's a learning point for me for today! chris, Wed, 9th Oct 2013
I agree that at the right temperature and pressure diamond (or almost anything) can be transformed into a liquid, but I'm not sure if I would call it melting. Certainly the liquid would not be diamond, just some form of liquid carbon, even though it could return to diamond form if cooled at the right rate.
" Certainly the liquid would not be diamond, just some form of liquid carbon, even though it could return to diamond form if cooled at the right rate."
If, at a specific pressure and temperature, diamond becomes liquid in a condition of thermodynamic aequilibrium (as you say, if cooling the liquid a little it becomes a diamond again) then it's exactly "melting". If it's not an aequilibrium condition and you can't reverse the conditions to obtain a diamond again, it's not properly a melting.
Does Graphite melt? its the same question.. and the premise of liquid diamond and liquid graphite being different would be interesting to understand.
Does Graphite melt?
The main components of the diamond is carbon, is non-metallic elements.
Diamonds will burn if there's air present, but you can remove the air and replace it by something less reactive easily enough.