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Carbon Nanotubes Harder Than Diamond
purduephotog writes "CDAC has announced the formation of a new form of hexagonal packed carbon similiar to diamond. Carbon nanotubes are compressed at 75 GPa and quenched. The new material is conclusively different via Raman Spectroscopy and both cracked and indented the diamond anvil used in its creation. CDAC is also known to have created via CVD the hardest diamond to date."
This might be good for new machining tools?
I wonder what the optical properties are, and what the maximum size of these is?
Is it really hard to speak out Random Access Memory?
Or Central Processing Unit?
Its CVD. Like CAD or CNC.
Acronyms stop being acronyms if the majority of peoply using them dont even know the original meaning without thinking a moment.
HI O WISE PRINCE. WHT TOOK U SO DAM LONG?
CVD isn't an acronym, it's an initialism. Acronyms must be pronounceable as words. NATO, RAM...
Acronyms don't degrade the language, they enhance it. They become words. Initialisms degrade it.
On the other hand, it's definitional that overuse of acronyms degrades language.... that's the only meaning overuse could have for acronyms. The question is whether many people actually do overuse acronyms. I doubt it. It's mainly an initialism/acronym stew that causes trouble.
These are the types of advances we need to make the space elevator a reality. Either using nanotubes like this in a matrix, or more mind-boggingly, create wires of them.
Going up!
...or maybe not.
Now we have drills to carve parts from synthetic diamonds. Very tiny drills, for very tiny machined parts. This nanotech is starting to get good.
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make install -not war
For humans, J. Storrs-Hall (of sci.nanotech fame) proposed a space railway that could be built sooner and more cheaply than a space elevator. It's a linear induction motor laid along a 300km-long track, 100km above the ground, where the atmosphere is thin enough to take a few orbits to decay your orbit. You drive your spaceship up a ramp to one end, and the motor accelerates you along the railway at about 10G for about 90 seconds, putting you in a slightly elliptical orbit with an apogee on the other side of the Earth. When you hit apogee, you do a burn to get into a higher orbit.
Relatively little radiation because you cross the Van Allen belts much faster. You get to LEO without burning any of your own fuel, which is a big energy win. The railway is low enough that orbits still decay slowly, so there's no space junk to worry about at that altitude.
The structure is a collection of A-frames, built like a radio tower. Like the space elevator, only a tiny fraction of the height is subjected to significant weather. The structure is under compression, not tension, which widens the choice of materials. According to Storrs-Hall, existing synthetic diamond would be suitable.
WWJD for a Klondike Bar?
Thats why you should define it once they use the acronym from then on out.
for example:
Oh my god(OMG) it's 6:30pm on a friday. Why am I still here. OMG my boss just gave me more stuff to do.
500 dollar reward for tip(s) leading to the arrest of the person(s) who stole my sig.
Carborundum is not as hard as diamond on the Mohs scale, SiC comes in at about 9.3, a little harder than corundum (aluminium oxide)
Boron nitride is damn near as hard as diamond, somewhere at about 9.8. Theoretically carbon nitride, C3N4 should be harder than diamond but getting sp3 bonding going in the structure is very tricky. I think very small amounts have been made. If the theory is correct then carbon nitride would be about 12 on the Mohs scale.
So wait, you have a large bit of material placing pressure on a smaller piece of harder material, ad infinitum...
Won't that just leave you with a series of bisected samples, each harder than the last?
No, due to the cell geometry. The face contacting the softer material is large, and the face contacting the harder material is smaller. As force is constant (not pressure), you end up with less pressure on the weaker face, and more (though hopefully less than your intermediate material's inelastic deformation pressure) on the harder face.
This lets you apply huge pressures to a very small sample, between two diamond faces. My understanding is that they handle the edges by using a metal gasket, which is allowed to deform inelastically to transfer force to a side housing with more surface area (think "o-ring seal").
Diamond anvil cells were big news when they came out because they were so _small_. You could hold them in-hand or put them on a lab bench and apply pressure by turning screws, whereas past high-pressure machines had been huge monstrosities. And with the diamond anvils as windows, you can even to spectrographic measurements of samples as they're being compressed (though the diamond's absorption bands interfere, and the faces can warp under very high pressure). Very nifty gadgets.