Sciencemadness Discussion Board - in which way could diamond powder/dust be turned solid

in which way could diamond powder/dust be turned solid

13enigma - 10-8-2017 at 16:46

I see online that diamond powder is sold. Which is pretty much just carbon. But how could the powder form be reverted back into solid. I realize that it will not be "beautiful engagement ring diamonds" but I was curious behind this chemical process and physical change

Chemetix - 10-8-2017 at 23:50

One technique can be attributed to a Ferris Bueller.

https://www.youtube.com/watch?v=O42K4EwVssQ

Otherwise the principle is sound. Extreme pressure and heat is used.
Iirc, the modern synthetic approach also uses an electrical field and some water during the process.

13enigma - 11-8-2017 at 09:45

An electrical field and water?
Like electrolysis??

DFliyerz - 11-8-2017 at 10:07

I've heard that sodium nickelate has been used to recrystallize diamonds. http://www.sciencedirect.com/science/article/pii/09259635949...

13enigma - 11-8-2017 at 10:36

Yeah this idea is very interesting. I saw videos of salt being crystallized into a diamond shaped figure. I was interested in doing this with the diamonds powders I have now. I understand that carbon is different from NaCl. But the idea was there

Chemetix - 11-8-2017 at 15:00

I understand the the electric field is used to orient the di-poles of the forming carbon lattice so to maintain the diamond structure, water I think acts as a sort of solvent, probably for the electrons to move around bit before forming the c-c bond. The use of electrical charge is about where the similarity to electrolysis ends.

The rest is some pretty exotic hardware of extreme hydraulic presses with heated cores and some very specifically engineered dies for the gem formation. A backyarder $5 budget isn't going to consolidate diamond powder to any quantity.

Implosive forming using HE shaped charges or explosive lenses might get a few lumps to stick together. You might need an outer shell of, say, salt to act as a buffer to the expansion phase of the shock; to keep the formed diamond from being ripped apart again.... just a thought bubble at this stage.

Melgar - 11-8-2017 at 21:19

The short answer is that you can't. Unlike many other materials, you can't melt down diamonds and combine them to make larger ones. It's sort of like wood in that respect. You can glue together sawdust to get particle board, but it won't have nearly the strength as regular wood.

edit: You can get 2-3 carat rough industrial diamonds for $10-$20 on eBay. If a diamond is below gemstone quality, its price is dramatically lower:

https://www.ebay.com/sch/i.html?_from=R40&_sacat=0&L...

Usually the auctions, as opposed to the "Buy it Now" listings are cheaper, if you don't mind waiting.

[Edited on 8/12/17 by Melgar]

13enigma - 12-8-2017 at 12:24

So, you're saying that a diamond powder similar, to saw dust, can not be clumped back together to form a bigger solid?
How?
I see that carbon powder like graphite can be turned back into solid. I've seen 99% Graphene crucibles too. Correct me if I'm wrong on this.
Thanks

ELRIC - 12-8-2017 at 17:36

Quote: Originally posted by 13enigma

So, you're saying that a diamond powder similar, to saw dust, can not be clumped back together to form a bigger solid?
How?
I see that carbon powder like graphite can be turned back into solid. I've seen 99% Graphene crucibles too. Correct me if I'm wrong on this.
Thanks

You do know that you're "carbon powder" is in fact a solid. Just like the NaCl you

likely have in you're kitchen is a solid. I'm with Melgar on this one. If it were not

so, wouldn't the value of diamonds drop like a rock (pun intended)

13enigma - 12-8-2017 at 17:55

I know it's a solid.
I just meant that the powder would need to agglomerate into a bigger cohesive solid

elementcollector1 - 12-8-2017 at 17:59

Quote: Originally posted by 13enigma

Please research the difference between a sintered product and a solid one.

unionised - 13-8-2017 at 04:14

In principle it's perfectly simple; you melt the diamond powder the let it cool down and set into a single diamond.
However the temperatures and pressures required make it practically impossible.

LD5050 - 13-8-2017 at 06:52

Just curious but exactly what are the temps and pressures needed?

Assured Fish - 13-8-2017 at 12:44

@LD5050 Straight from the wiki. https://en.wikipedia.org/wiki/Synthetic_diamond

Norton and Carborundum companies to further develop diamond synthesis. They were able to heat carbon to about 3,000 °C (5,430 °F) under a pressure of 3.5 gigapascals (510,000 psi) for a few seconds.

I would assume the process of fusing smaller diamonds would follow along the same lines.

However i recently found the following which seems to suggest that the guys at the carnegie institute in washington manage to succeed at much lower pressures.
The idea follows the same general anvil process however instead of using graphite as there carbon source they use methane and pass an ionized hydrogen plasma through it.
I don't have any info as to the exact design of this process however.
http://cen.acs.org/articles/90/i11/Carbon-Goes-Deep.html
https://www.youtube.com/watch?v=A4_l3pKhaJo

13enigma - 15-8-2017 at 13:41

Quote: Originally posted by unionised

In principle it's perfectly simple; you melt the diamond powder the let it cool down and set into a single diamond.
However the temperatures and pressures required make it practically impossible.

Yeah, in principle it sounds so simple. But so much difficult to do. I'm convinced that an amateur hobbyist chemist ad myself can't do it with regular tools. I'm gonna need industrial equipment with safety precautions in a lab.
But I saw a video of a guy making salt crystals in diamond shape with water and some other inorganic salts. That's is not possible to do with Diamond powders right? I'm assuming because of their difference in elemental status

Assured Fish - 15-8-2017 at 21:00

@13enigma it fucken took you long enough.

Quote:

But I saw a video of a guy making salt crystals in diamond shape with water and some other inorganic salts. That's is not possible to do with Diamond powders right? I'm assuming because of their difference in elemental status

You astound me with your complete lack of knowledge on the subject of chemistry.
NaCl is an ionic salt that is highly soluble in a range of solvents, therefore it can be recrystallized.
Diamonds are an allotrope of carbon.
Carbon is pretty much insoluble in just about everything (atleast i cannot think of anything it is soluble in).
Diamonds despite there appearance are not the same as crystals, it is fucken imperative that you get this through your thick skull.

If you have any legitimate passion for chemistry then i implore you to please go pick up a basic high school chemistry textbook and read it front to back before you even attempt to think about trying to conduct any amateur chemistry.
Now let this insanity be over.

j_sum1 - 15-8-2017 at 21:27

Agreed, AF. This line of questioning is at the extreme basic end of chemistry and displays a fundamental misunderstanding of some elementary principles. I have to wonder what the specific interest in diamonds is given the lack of knowledge here.

So... here are some basics. Bonding.

There exist several main mechanisms by which atoms may be bonded together. Here is an oversimplified summary.

Ionic -- a bond between a non-metalic element and a metallic element.
In this mechanism the metallic atom loses an electron and thereby becomes positively charged. At this point it is called an ion: specifically, a cation.
The non-metallic atom gains that electron and becomes a negatively charged ion: an anion.
The positive and negative ions then stack together in a regular lattice and are held in stable configuration by electrostatic attraction. This is known as a crystal of an ionic solid.

Metallic -- a bond between (usually identical) metal atoms.
In this mechanism all of the atoms involved lose electrons. The lost electrons are delocalised -- that is, free to move and not associated with any one particular atom. There is of course an electrostatic force of attraction between the positive cations and the mobile electrons. The system arranges in a stable configuration where the cations stack together in a crystal lattice and the electrons move freely through that lattice. The phrase generally employed to describe this is, "positive ions in a sea of electrons."

Covalent -- this is bonding between non-metallic elements (although there are many exceptions). In this configuration the atoms share electrons. In a normal atom the electrons occupy orbitals and essentially form a stable standing-wave shape centred around the nucleus of that atom. In a covalent bond the outermost or valence electrons form an orbital that is centred around the nucleus of two atoms. This turns out to be a very stable configuration since all the atoms involved can achieve a state where they effectively have a full outer shell.

Covalent bonding can give rise to two distinct structures: molecules and networks.
In a molecule a small number of atoms are attached to one another and the whole structure is free to operate as one unit.
In a network there is a rigid three dimensional network of bonded atoms. These forms some of the hardest and strongest materials known. Diamond is one of these.

All this should be taken with a grain of NaCl. there are no hard and fast boundaries between any of the categories I have mentioned. But this should at least answer your question. The situation has nothing to do with the "elemental status" of diamond. Rather it has everything to do with the type of bonding involved. And covalent bonding is the strongest bonding there is.

I concur with AF. it is time to get out a secondary school textbook and read the first few chapters.

diddi - 15-8-2017 at 21:58

I suggest rubbing the diamonds together rapidly. the resulting heat from friction will fuse them together and maintain the crystal structure because they are bonded along the opposing faces.

[Edited on 16-8-2017 by diddi]

plastics - 15-8-2017 at 23:06

Stop feeding this troll

It is this sort of mind numbing tat that makes me want to switch off

Even the tongue-in-cheek replies of my more erudite colleagues are a massive turn off

physics inclination - 16-8-2017 at 07:30

This is kind of a joke/"out-there" suggestion, but what if you tried detonating a shaped charge (no copper penetrator or anything, just explosive) onto graphite or diamond powder, where the "focus" of the blast is right on the powder?
That would be 1) certainly able to generate pressures high enough, or probably even higher than a solid lab apparatus and 2) somewhat accessible and relevant to users of this forum

edit: also keep in mind that this would (if it works at all) only produce lower-quality "sintered" diamond crystals rather than high-quality high-strength "cast" or "forged" diamond crystals--to use the analogy to how metal crystalline structures form differently depending on how they're made

[Edited on 8-16-2017 by physics inclination]

[Edited on 8-16-2017 by physics inclination]

phlogiston - 16-8-2017 at 10:46

physics inclination, that does actually work. It has been the subject of serious research, no joke.
One can use explosives to make (very, very small) diamonds. Oxygen-deficient explosions of TNT have been shown to produce 'nano-diamonds' (just 10's of nm in size, but definately diamond phase).
I am too lazy to look up the papers right now, but no doubt google will easily find them.

Did mythbusters not also have an episode where they made diamonds large enough to be visible with explosive compression?

physics inclination - 16-8-2017 at 13:33

Quote: Originally posted by phlogiston

Did mythbusters not also have an episode where they made diamonds large enough to be visible with explosive compression?

Found it yes

https://www.youtube.com/watch?v=0mWQUvxcANE

clearly_not_atara - 16-8-2017 at 14:42

Could you do CVD onto a surface covered in diamond powder and thereby bind them together?

j_sum1 - 16-8-2017 at 16:21

Quote: Originally posted by clearly_not_atara

Could you do CVD onto a surface covered in diamond powder and thereby bind them together?

If you are going to sinter diamond particles then you have an alignment problem. You might get a cohesive mass (if you are clever) but you won't get a single crystal unless you are above recrystallisation temperature for long enough time. IOW, diamond dust is going to be a poor starting material if you want large diamonds.

elementcollector1 - 17-8-2017 at 08:43

Come to think of it, why not just mix the diamond dust with a resin binder and create a 'druzy' that way? It'd still be gorgeous, and you wouldn't have to worry about high-tech methods to improve the diamonds' size.

Melgar - 17-8-2017 at 22:58

Quote: Originally posted by j_sum1

Actually... if growing diamonds via CVD, you do need diamond seed crystals, and dust can be used for this purpose. CVD takes place at low pressures, and moderate temperatures, at least for the solid diamond.

Assured Fish - 17-8-2017 at 23:23

Wait, i just realized that the process that the carnegie institute uses is just the CVD process.
So then the CVD grown diamonds are in fact genuine diamonds, in that the bonds have been formed.

I guess this means diamonds in the near future are gonna begin to be almost worthless (hyperbolically talking).
Possibly worth less than platinum group metals and also gold.
Rightfully so if you ask me.

MrHomeScientist - 18-8-2017 at 06:36

They already are worthless; the diamond cartels create artificial scarcity to drive up prices. There's vaults full of diamonds, and they release small amounts at a time to keep up demand. Buy moissanite instead!

Melgar - 18-8-2017 at 12:56

Quote: Originally posted by MrHomeScientist

They already are worthless; the diamond cartels create artificial scarcity to drive up prices. There's vaults full of diamonds, and they release small amounts at a time to keep up demand. Buy moissanite instead!

If you think diamonds are a scam, "moissanite" ie, "optical-grade silicon carbide cut into gemstone shapes" is even worse. Typical markup on a diamond is 10-25%. Typical markup on "moissanite" is something like 500%.

The artificial scarcity thing was true for a while in the 1990s, but isn't true anymore. What happened was that De Beers inadvertently created huge incentives for "blood diamond" mining, then had to reverse course due to extremely bad PR. They went from controlling about 90% of the world's diamond supplies to about a third. De Beers is actually the good guy now, believe it or not, and pays for medicine and education and such in countries like Namibia and Botswana.

Quote: Originally posted by Assured Fish

Wait, i just realized that the process that the carnegie institute uses is just the CVD process.
So then the CVD grown diamonds are in fact genuine diamonds, in that the bonds have been formed.

I guess this means diamonds in the near future are gonna begin to be almost worthless (hyperbolically talking).
Possibly worth less than platinum group metals and also gold.
Rightfully so if you ask me.

Eh, CVD is only more economical than mining diamonds for diamonds under 1 carat or so. As the surface area to volume ratio decreases, the process becomes slower and slower, and it's already really slow and energy intensive.

They also have a certification process for diamonds that can detect CVD and "enhanced" diamonds (where they take yellowish-brown diamonds and treat them to make them a nicer color) and anyone who buys diamonds makes sure the certificates are in order already. I don't foresee the market for natural diamonds ever going away, especially considering the demand in Asia, but consider how many cool new technologies are becoming available for sale lately, and diamonds hardly seem worth their steep price.

clearly_not_atara - 18-8-2017 at 14:24

I think the real "killer app" for CVD diamond is using diamond as a coating for other less durable gemstones. Opal is much prettier than diamond, but if you wear them every day they'll get dull and scratched. But diamond-coated opal could really last a lifetime.

As for ultrahard clear stones to be worn as status symbols, go for the meteoric minerals like stishovite. That's a cool story IMO. "Hey I got you this space crystal".

Melgar - 20-8-2017 at 05:52

The trouble with applying diamond as a coating is that its crystal structure is totally different from most minerals, which are oxides. It's actually a crystal held together with covalent bonds, which AFAIK is something that only occurs in carbon and silicon, and possibly germanium (which is practically a metal, in any case). Alumina / corundum / ruby / sapphire is hard enough for all practical purposes, much easier to synthesize, is an oxide like virtually every other gemstone, and is the reason that we can build things out of aluminum without them undergoing magnesium-like reactions when they catch on fire.

Most stishovite isn't actually from asteroids or meteors, it's obtained from ordinary quartz, by dissolving the quartz away with hydrofluoric acid. It actually forms under similar conditions as diamonds do, and is found in kimberlite pipes like diamonds are.

Meteoric iron fragments are pretty cheap though. There was this huge iron meteor that exploded over China hundreds of years ago. I guess there aren't too many employment opportunities in that part of the country because people use metal detectors to find the fragments, and they turn up on eBay all the time for really cheap.