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Large Sheets of Carbon Nanotubes Produced
StCredZero brings news that scientists have developed sheets of nanotubes that measure up to three feet by six feet, and they promise "slabs 100 square feet in area as soon as this summer." The developers see uses for the sheets in electromagnetic shields and airplane construction, and according to the Next Big Future blog, the sheets could also impact the development of solar sails.
"The sheets, which the company can produce on its single machine at a rate of one per day, are composed of a series of nanotubes each about a millimeter long, overlapping each other randomly to form a thin mat. The tensile strength of the mat ranges from 200 to 500 megapascals--a measure of how tough it is to break. A sheet of aluminum of equivalent thickness, for comparison, has a strength of 500 megapascals. If Nanocomp takes further steps to align the nanotubes, the strength jumps to 1,200 megapascals."
Rudimentary quantum computing can be done with the ballistic nature of how electrons flow through a sheet of graphene, or in this case, a carbon nanotube. Expect to see computing related articles.
If you don't understand what it mean to say that electrons move in a "ballistic" manner through these nanotubes, imagine that cool trick your math teach showed you in high school with marbles and pegs making a bell curve. Now imagine being able to change the outcome by removing a lot of peg, and then making your computer understand the results.
(First off I work in this area) I know one we have tried purchasing these sheets in the past a couple time and have not been able to. They might be able to make them but the availability is still very low for any research or products.
If this stuff is as strong as aluminum, why aren't we using it to actually build things like cars and buildings?
Because they are just learning how to create and manipulate such materials? Your question is like a bronze age smith who knows that small bits of iron can be found and worked saying "How come we haven't replaced bronze with this stuff yet?" It's an engineering challenge is all. As production techniques improve it will be easier and cheaper to make.
Also, note that it's just the tensile strength that is comparable to aluminum. They said nothing about it's shear strength or rigidity.
to replace my tinfoil hat...
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Maybe the carbon nanotube sheets are made out of, oh, I don't know, carbon? Seems to me there's no shortage of that stuff..
Anthropic principle: We see the universe the way it is because if it were different we would not be here to see it.
One good reason is that aluminum is a limited resource. Although there's lots of it around, current estimates show that it will only last for about 200 more years ( source).
I don't have a copy of that book, so can't read it in context, but I still have to call bullshit on this.
Aluminum (Aluminium for you Brits) is the most abundant metal in the Earth's crust. While smelting it is energy intensive, recycling it is significantly less so. There is so much that has already been used, and available for recycling, I can't see us running out in the next couple of centuries, if ever.
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People. Carbon nanotubes are made out of people.
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Don't blame me, I voted for Baltar.
For bikes, aluminum frames are certainly stiffer, but they're substantially less shock absorbing.
One of the reasons carbon fiber is used is the ability to choose different properties on different axes. Many cyclists want a frame that absorbs road vibration (longitudinally flexible) while being as stiff as possible laterally to transmit pedaling force efficiently and maneuver aggressively.
tensile strength != toughness. And, unfortunately, aluminum is not particularly ductile. At least, not when compared to, say, steel.
But aluminum does have a very good strength to weight ratio. Also, it doesn't rust. Instead it forms an oxide layer which prevents further oxidation.
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