41–50 of 58 posts
I stopped reading at: "composed of carbon atoms joined in a pattern that makes the material extremely tough and impervious to even the smallest atom, helium." Is helium really smaller than hydrogen?
Oddly enough yes Helium has a smaller atomic radius because the additional proton and electron complete that first electron shell and get pulled closer to the nucleus.
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In theory any molecule that looks like a graphite layer should be enough. In practice there are plenty of concerns about the stability of the ones that aren't rolled into tubes (and some concern about those later ones too). The result is, you'll see plenty of calculations telling it's possible. But it is probably not.
It definitely is with a tapered cable. The only question is if it could be done practically and if it would actually be worth the hassle. The self support length is for a cylinder of the material, with a cone there isn't a limit to the maximum self support length as the base just gets as wide as necessary to support the rest of it. But with graphene it's close enough that just a 10 to 1 difference in the cross-sectio…
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It should burn with all the side products of most artificial carbon chains (aromatics and poisonous carbon oxides). Those aren't hard to deal with, but don't expect it to burn cleanly. It should also be hard to burn. It will probably require some water vapor to burn at all, and do it slowly.
I'm not sure I understand how you arrived at your first point. It seems to me that at a suitable temperature and oxygen content atmosphere, it should burn about as clean as natural gas. Why would you expect otherwise? I also do not understand your second point. Surely, it is oxygen that is the missing ingredient in the burn rather than water vapor. What does water vapor provide to increase the rate of combustion?
With enough temperature and a high oxygen pressure, graphene will burn cleanly. But also will your furnace, and my bet is that both will do so at roughly the same temperature and pressure.
About the second point, oxygen does not react well with graphite because it's entire surface does not let its electrons go very easily. Graphene has similar properties. Water does catalyze the burning of graphite, it may very well do that to graphene too.
I stopped reading at: "composed of carbon atoms joined in a pattern that makes the material extremely tough and impervious to even the smallest atom, helium." Is helium really smaller than hydrogen?
Well, I'm not a physicist, but hydrogen gas is two atoms compared to 1 atom for helium gas.
hydrogen gas is two atoms
I stopped reading at: "composed of carbon atoms joined in a pattern that makes the material extremely tough and impervious to even the smallest atom, helium." Is helium really smaller than hydrogen?
Oddly enough yes Helium has a smaller atomic radius because the additional proton and electron complete that first electron shell and get pulled closer to the nucleus.
Earlier quoted context omitted.
It should burn pretty cleanly (as it's just carbon), but who knows what it would be mixed with in an actual application. Could be mixed with all kinds of plastics and resins that are nasty when burnt.
Graphite is "just carbon" too, but you cannot simply burn it by putting a lit flame to it -- it's simply not hot enough to combust it. To put it in perspective, graphite is frequently used as a crucible to melt aluminum in. Aluminum won't melt in your home fireplace (it's not hot enough), but graphite crucible will easily hold molten aluminum without combusting itself.
One of the applications for graphene membranes that I am watching for are large scale desalination plants. It has been shown to work for small membranes and if you had enough surface area you could build a desalinator that was using not much more energy than the energy to pump the water around.
It looks like maybe a factor of 3 or so energy efficiency improvement is available for desalination. Current efficient processes are around 3kWh/m³†. The thermodynamic limit is about 1kWh/m³‡. That can be improved a little if you pump more seawater, there is a tradeoff there. Treatment of fresh water is around 1kWh/m³, so it gets into the ballpark for freshwater treatment, though I presume some of the freshwater trea…
https://electrek.co/2017/11/16/cheapest-electricity-on-the-p...
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How large is the "crowd" in the field (companies, research labs, conferences) ?
EU's biggest research initiative is the Graphene Flagship - https://en.wikipedia.org/wiki/Graphene_Flagship Major Conferences - Graphene Week, Mobile World Congress (Barcelona + SF), National Graphene Association (inaugural conference was Oct 2017) Major universities in the US - UT Austin, UPenn, MIT, Stanford, Rice, Berkeley. Lot of activity in Korea, Japan, and China Companies - Various companies on growth side. Lo…
All I can really remember from my thesis was I had a throwaway line describing graphene as a single layer of hybridized SP2 Bonded carbon atoms and examiner spent what felt like 15 mins of my allotted defense time grilling me about it (in reality it was probably only 1 or 2 mins but I was so freaking nervous at the time felt like it was dragging on forever)...
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Oddly enough yes Helium has a smaller atomic radius because the additional proton and electron complete that first electron shell and get pulled closer to the nucleus.
Helium is a strange bird. Every other element in liquid form will freeze if you drop the temperature enough, except Helium. You must greatly pressurize Helium for it to freeze. It is worth pointing out that while the atomic radius of Helium is smaller than Hydrogen, Helium is still the heavier element. It’s small radius and tendency to remain a gas or liquid makes it very useful in testing for leaks or as a purging g…
For leak testing, it can be better than helium because the molecule is lighter. This raises the speed for any given temperature, and thus increases the rates of diffusion and effusion.
A downside is that hydrogen can burrow right into solid metal, one atom (proton) at a time, and then merge back into diatomic molecules. This creates a sort of internal pressure in the material, making it brittle. Hydrogen embrittlement is a significant problem, particularly with titanium.