FAQ
It is currently Mon Sep 25, 2017 10:16 pm


Author Message
Ascended
Post  Post subject: Diamonds  |  Posted: Fri Oct 19, 2012 6:26 pm
User avatar

Joined: Sat Sep 29, 2012 6:59 pm
Posts: 221
Location: Over the hills and far away

Offline
I'm posting this straight into pseudoscience because it sounds a bit fishy to me but thought I'd ask anyway, I recently read an article about the possibility to reconstitute the carbon atoms of graphite into a crystalline structure to make an artificial diamond, but without the high pressures normally required, instead using only heat and a relatively low heat of only 1200 degress centigrade. So could this actually be in any way possible or is it just nonsense?

_________________
Success consists of going from failure to failure without loss of enthusiasm


Top
marnixR
Post  Post subject: Re: Diamonds  |  Posted: Fri Oct 19, 2012 6:33 pm
User avatar

Joined: Thu Aug 04, 2011 8:35 pm
Posts: 4851
Location: Cardiff, Wales

Offline
well, there IS something like chemical vapour deposition, which appears to fall in the category of manufacture you're referring to

you don't happen to have a link to the article, or failing that, a reference of where it was published ?

_________________
"Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
"Someone is WRONG on the internet" (xkcd)


Top
Ascended
Post  Post subject: Re: Diamonds  |  Posted: Fri Oct 19, 2012 10:01 pm
User avatar

Joined: Sat Sep 29, 2012 6:59 pm
Posts: 221
Location: Over the hills and far away

Offline
Maddeningly I don't for life of me remember the magazine the article was in as I was at the hospital the and flicking through several car, travel, DIY and even women's magazines whilst waiting. I didn't have time to read the whole article neither but remember thinking that can't be right or everybody would making diamonds, as I was under the impression at least, high pressures are a necessity.

From reading the wiki page I would imagine even if it was some how possible without the pressure you'd still need some way to break the bonding in the graphite before the heat could even take any effect, also I would think making the carbon crystallize to any significant would also be problematic. All that said, if it some how is possible it would certainly make for an interesting project.

_________________
Success consists of going from failure to failure without loss of enthusiasm


Top
marnixR
Post  Post subject: Re: Diamonds  |  Posted: Sat Oct 20, 2012 7:25 am
User avatar

Joined: Thu Aug 04, 2011 8:35 pm
Posts: 4851
Location: Cardiff, Wales

Offline
besides, the high pressure method of making industrial diamonds is described as the cheap method
meaning that the other methods won't be the type you do in your backyard

_________________
"Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
"Someone is WRONG on the internet" (xkcd)


Top
jimmydasaint
Post  Post subject: Re: Diamonds  |  Posted: Sun Oct 28, 2012 11:47 am
User avatar

Joined: Fri Aug 12, 2011 4:53 pm
Posts: 380
Location: Farnham Royal, Bucks

Offline
It sounds like chemical vapour deposition with relatively low pressures:

Quote:
Chemical vapor depositionChemical vapor deposition is a method by which diamond can be grown from a hydrocarbon gas mixture. Since the early 1980s, this method has been the subject of intensive worldwide research. Whereas the mass-production of high-quality diamond crystals make the HPHT process the more suitable choice for industrial applications, the flexibility and simplicity of CVD setups explain the popularity of CVD growth in laboratory research. The advantages of CVD diamond growth include the ability to grow diamond over large areas and on various substrates, and the fine control over the chemical impurities and thus properties of the diamond produced. Unlike HPHT, CVD process does not require high pressures, as the growth typically occurs at pressures under 27 kPa.[36][45]

The CVD growth involves substrate preparation, feeding varying amounts of gases into a chamber and energizing them. The substrate preparation includes choosing an appropriate material and its crystallographic orientation; cleaning it, often with a diamond powder to abrade a non-diamond substrate; and optimizing the substrate temperature (about 800 °C) during the growth through a series of test runs. The gases always include a carbon source, typically methane, and hydrogen with a typical ratio of 1:99. Hydrogen is essential because it selectively etches off non-diamond carbon. The gases are ionized into chemically active radicals in the growth chamber using microwave power, a hot filament, an arc discharge, a welding torch, a laser, an electron beam, or other means.

During the growth, the chamber materials are etched off by the plasma and can incorporate into the growing diamond. In particular, CVD diamond is often contaminated by silicon originating from the silica windows of the growth chamber or from the silicon substrate.[46] Therefore, silica windows are either avoided or moved away from the substrate. Boron-containing species in the chamber, even at very low trace levels, also make it unsuitable for the growth of pure diamond.[36][45][47]



http://en.wikipedia.org/wiki/Synthetic_diamond

The heat required is about the heat from a bunsen burner in a school lab. What surprises me is that the suggested pressure is less than atmospheric pressure. I always thought atmospheric pressure was about 101 kPa...?

_________________
Barbarus hic ego sum quia non intelligor illis (I am a barbarian to those who do not know me) Ovid


Top
Ascended
Post  Post subject: Re: Diamonds  |  Posted: Tue Dec 04, 2012 12:34 pm
User avatar

Joined: Sat Sep 29, 2012 6:59 pm
Posts: 221
Location: Over the hills and far away

Offline
That almost sounds to easy, ready to make diamonds anyone?

_________________
Success consists of going from failure to failure without loss of enthusiasm


Top
marnixR
Post  Post subject: Re: Diamonds  |  Posted: Tue Dec 04, 2012 8:21 pm
User avatar

Joined: Thu Aug 04, 2011 8:35 pm
Posts: 4851
Location: Cardiff, Wales

Offline
hmmm ... there must be a catch somewhere
if something seems too good to be true, it usually means it is

_________________
"Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
"Someone is WRONG on the internet" (xkcd)


Top
Ophiolite
Post  Post subject: Re: Diamonds  |  Posted: Thu Dec 06, 2012 7:22 am
Original Member
Original Member

Joined: Mon Aug 08, 2011 12:00 pm
Posts: 261

Offline
I'm not clear what application they are targeting.

Is the substrate meant to be part of the final product, or is it simply a surface on which the diamond can grow? If the latter, what do they plan to do with the diamond 'flake' that is produced? If the former how are they binding the diamond to the substrate?

I have some background in formation of polycrystalline diamond compacts in the drilling industry (at high pressure and temperature) and I am perplexed by what they are doing here.


Top
marnixR
Post  Post subject: Re: Diamonds  |  Posted: Thu Dec 06, 2012 7:52 am
User avatar

Joined: Thu Aug 04, 2011 8:35 pm
Posts: 4851
Location: Cardiff, Wales

Offline
Ophiolite wrote:
I have some background in formation of polycrystalline diamond compacts in the drilling industry (at high pressure and temperature) and I am perplexed by what they are doing here.


are you referring to chemical vapour deposition method of jimmydasaint's ?

_________________
"Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
"Someone is WRONG on the internet" (xkcd)


Top
Ascended
Post  Post subject: Re: Diamonds  |  Posted: Thu Dec 06, 2012 7:29 pm
User avatar

Joined: Sat Sep 29, 2012 6:59 pm
Posts: 221
Location: Over the hills and far away

Offline
Be interesting to know how large a diamond this method could actually produce and if any impurities or inclusions could be successfully kept out.

_________________
Success consists of going from failure to failure without loss of enthusiasm


Top
Ophiolite
Post  Post subject: Re: Diamonds  |  Posted: Thu Dec 06, 2012 11:16 pm
Original Member
Original Member

Joined: Mon Aug 08, 2011 12:00 pm
Posts: 261

Offline
marnixR wrote:
Ophiolite wrote:
I have some background in formation of polycrystalline diamond compacts in the drilling industry (at high pressure and temperature) and I am perplexed by what they are doing here.


are you referring to chemical vapour deposition method of jimmydasaint's ?

Yes.


Top
Display posts from previous:  Sort by  
Print view

Who is online
Users browsing this forum: No registered users and 0 guests
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
Jump to:   


Delete all board cookies | The team | All times are UTC


This free forum is proudly hosted by ProphpBB | phpBB software | Report Abuse | Privacy