3
$\begingroup$

I want to make a diamond at home using chemical vapor deposition (CVD).

  1. If I use a metal chamber filled with methane and hydrogen gas and heated with a microwave oven oscillator element, will the gas explode?

  2. What is the ratio of methane and hydrogen for the diamond to be able grow?

$\endgroup$
  • 1
    $\begingroup$ You can't do that at home. Think of something more realistic, like a nuclear reactor. $\endgroup$ – Ivan Neretin May 4 at 12:55
6
$\begingroup$

The easiest way to grow diamond through chemical vapor deposition (CVD) is on a heated filament, which just takes a few watts.

You'd need a low-pressure chamber (~30 torr, or ~0.04 atm) with gas-tight fittings for electricity, feed-gas of ~1% $\ce{CH4}$ and ~99% $\ce{H2}$ and $\ce{Cu}$, $\ce{Ti}$, $\ce{W}$ or $\ce{Ta}$ filaments. Since this is a flow-though reactor, you'll also need to dispose of the flammable feed-gas without letting it accumulate near the vacuum pump.

N.B. This is not a simple project one could do at home, since you'd need vacuum equipment, pressure regulators, high-pressure bottles* of these highly flammable gases, and a vacuum-vessel which could implode. If you can get a knowledgeable instructor involved who has access to laboratory facilities and a thorough understanding of safety procedures, though, it's not impossible to accomplish.

* One of the greatest dangers would be a gas bottle falling, taking off like a rocket and leaving explosive gas in its wake!

$\endgroup$
  • $\begingroup$ Logically for a 2 gram diamond I need the equivalent weight of carboon in the methane gas, theoretically I don't have to feed the gas constantly into the chamber, only to feed it once along with the hydrogen gas and let it react with the graphite seed, is this true? $\endgroup$ – Oliver May 5 at 16:25
  • $\begingroup$ Probably not true, because, apparently, the process requires a constant ratio of methane to hydrogen. Of course, this could be subject to experiment... $\endgroup$ – DrMoishe Pippik May 5 at 18:15
  • $\begingroup$ What is the purpose of hydrogen in the reaction, why can't I use only methane, or instead of methane only carbon dioxide witch doesn't explode, as far as I know real diamonds are made of CO2 $\endgroup$ – Oliver May 11 at 20:52
  • $\begingroup$ There are many allotropes of carbon, e.g. graphite and diamond. See en.wikipedia.org/wiki/Allotropes_of_carbon .Did the reference above give any information why H2 helps diamond form rather than something else? This may have been determined empirically or from some theoretical basis. $\endgroup$ – DrMoishe Pippik May 12 at 1:53

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.