Could metal become obsolete?

[Junghalli]

Some of you may be familiar with carbon nanotubes. Those little strings of bonded carbon atoms that are stronger than diamond. So basically when/if it becomes economical to produce you'd essentially have superstrength plastic.
So, when this stuff hits the mass market what will the effects be? What would it be good for? Could it actually make iron and steel obsolete?

[Darth Wong]

That is the most retarded question I've heard in a long time. Really strong strings are about to make metal obsolete? Puh-lease.

[Setesh]

They won't make metal obsolete, but they might replace kevlar in the body armor market.

[ntstlkr]

Really now, if you give it a little consideration....just because we can build a hammer out of something doesn't really mean we should right? Of course metals are going to be used for all those things that it makes more sense to stay with traditional materials. That doesn't mean that uses won't be found for the new stuff, but that cost, expediency, and just plain "good enough" will be what prevails.

Take the hammer example. Sure we could manufacture one made out of titanium right? But what would be the point? It's still a hammer and what really would be the advantage of using a relatively expensive material and manufacturing process to fabricate what essentually remains a hand tool.

For all that steel, iron, and aluminum might seem rather "dated" compared to the newer exotic (and not so exotic but still more expensive or time consuming in manufacturing), but they still retain the properties we need for the things we use them for.

I've seen some recent articles on the material you'r posting about, and sure it does promise to ADD to our arsenal of materials that can be used to make things out of, but that in no way means it will replace the rest. It's just another thing we can use, thats all.

Ceramics, plastics, you name it, at one time or another they have all gone through the "makes everything before it obsolete" phase, but in truth, all any material does is find its way into uses (replacing those where it can do better, but not exclusively) that match its properties. A thousand years from now (if we haven't succumbed to some vast Fundie inspired regression or we haven't destroyed ourselves) we'll still be using plain 'ol mundane steel, iron, aluminum, and what not.

[Junghalli]

They won't make metal obsolete, but they might replace kevlar in the body armor market.

Thanks for the feedback. I didn't think it would make metals obsolete, just throwing that out there as an extreme possibility. What about vehicles? It seems to me like it'd be a good material to make aircraft or spacecraft out of.

[Setesh]

Thanks for the feedback. I didn't think it would make metals obsolete, just throwing that out there as an extreme possibility. What about vehicles? It seems to me like it'd be a good material to make aircraft or spacecraft out of.

Not likely, its to expensive to produce compared to aluminum

[tharkûn]

Really strong strings are about to make metal obsolete?

Really strong strings is a bad description. Ridiciously strong little rods would be better.

The idea that it will replace metal is still idiotic. If nothing else carbon nanotubes have a few more oxidizer problems than some of your more resistent metals (and that is ignoring costs).

[SirNitram]

They won't make metal obsolete, but they might replace kevlar in the body armor market.

Thanks for the feedback. I didn't think it would make metals obsolete, just throwing that out there as an extreme possibility. What about vehicles? It seems to me like it'd be a good material to make aircraft or spacecraft out of.

You are aware you need a rigid body for the frame and skin, yes? One which will soak up radiation in the case of a spacecraft?

[ntstlkr]

Oh sure, body panels for cars. Although it took composite awhile to get through delaminating issues when used in aircraft components, it probably has a future there too.

Those are pretty easy to see. Will they be able to make a flexable version? Dunno at this point, but if they develope different "types" you could possible see it used in things as pedestrian as car tires, or bicycle frames. Laptop cases, etc, etc..

[Darth Wong]

Really strong strings are about to make metal obsolete?

Really strong strings is a bad description. Ridiciously strong little rods would be better.

Not really, because these things won't have any rigidity to speak of. A rod generally has decent rigidity and can handle axial compressive loading. A string (and a carbon nanotube) will not.

[tharkûn]

You are aware you need a rigid body for the frame and skin, yes? One which will soak up radiation in the case of a spacecraft?

You can make quite rigid nanotube structures. As far as radiation, umm pure carbon ain't exactly bad, if you really need more than is required for the frame you can likely use HDPE or some other filler.

Those are pretty easy to see. Will they be able to make a flexable version? Dunno at this point, but if they develope different "types" you could possible see it used in things as pedestrian as car tires, or bicycle frames. Laptop cases, etc, etc..

Depending upon how you bind the tubes they can be rigid or flexible. The big problem is that fabrication costs are sky high and material costs are still in neverneverland (for the less impressive varieties of low purity you are still paying $30 a gram - the good stuff starts in around $150 a gram).

[Broomstick]

They won't make metal obsolete, but they might replace kevlar in the body armor market.

Thanks for the feedback. I didn't think it would make metals obsolete, just throwing that out there as an extreme possibility. What about vehicles? It seems to me like it'd be a good material to make aircraft or spacecraft out of.

Depends on the property of the materials. I mean, composites were supposed to be the be-all and end-all of aerospace design but they still use lots of metal in airplanes - not just aluminum but stuff like steel and copper and lead and probably stuff I'm not aware of. Why? Because each of those metals have their own properties which makes them more suited to a particular job than other materials.

The stuff used to build aircraft needs compressive strength in some places, and the exact opposite in others. In some places it must be rigid, in others flexible.

Then there's cost - aircraft are already expensive. Even if a material is ideal cost alone might lead to using a second choice. For example, back when just about all airplanes were cloth-covered using silk would have been ideal, as it is strong and light but it was just too expensive - so they used cotton instead. (Nowadays "ragwings" use synthetics). If your carbon wonder-tubes are too expensive to produce in quantity aerospace will stick current materials except where absolutely necessary.

[GrandMasterTerwynn]

You are aware you need a rigid body for the frame and skin, yes? One which will soak up radiation in the case of a spacecraft?

You can make quite rigid nanotube structures. As far as radiation, umm pure carbon ain't exactly bad, if you really need more than is required for the frame you can likely use HDPE or some other filler.

How do you make rigid nanotube structures? From what little I've read, it looks like the way that would be done is by coating the nanotubes in a thin film of some other material, creating a composite. And, as you mentioned, it looks like the methods for doing so would be extremely expensive.

And while pure carbon isn't bad for radiation, it isn't the best either. The graphite control rods in nuclear reactors serve to slow the neutrons down. Unless I'm mistaken, one wants something that absorbs various forms of radiation. Though one could concievably accomplish this by building a spaceship's water tanks just under its hypothetical composite hull. Slow down particle radiation through the composite, so it won't penetrate the water tanks so deeply.

[tharkûn]

How do you make rigid nanotube structures? From what little I've read, it looks like the way that would be done is by coating the nanotubes in a thin film of some other material, creating a composite. And, as you mentioned, it looks like the methods for doing so would be extremely expensive.

Silicating the tubes will make them rigid, that is still a quite expensive technique at present. If you really want to burn money you build a lattice with fuse T-Junctions so the material becomes anisotropic (basicly use an AFM to position the tubes then jump pass an electrical current over the junction at phenomenally high voltage).

Remember though that nanotubes are just rolled graphite sheets, much of their flexibility comes from their dimensions rather than their chemical structures. Metal wiskers of a similar scale are quite flexible as well.

And while pure carbon isn't bad for radiation, it isn't the best either. The graphite control rods in nuclear reactors serve to slow the neutrons down. Unless I'm mistaken, one wants something that absorbs various forms of radiation.

Space does not have abundant neutron radiation. Most of the nasty staff up there is charged and will be absorbed by carbon. If memory serves the ISS uses polyetheylene, which is just carbon and hydrogen, to soak most of it up.

Not really, because these things won't have any rigidity to speak of. A rod generally has decent rigidity and can handle axial compressive loading. A string (and a carbon nanotube) will not.

The literature reports ~100 GPa axial compressive strengths, I thought that was actually on the high end.

To echo Broom, cost is going to be an overriding concern. For many aircraft components titanium would be superior to aluminium; it doesn't get used (outside of military birds and other really high end performance birds) because titanium is much more expensive. Currently the production and fabrication costs for nanotubes make titanium look cheap. For the foreseeable future I see no possible way for nanotubes to compete in the bulk markets.

[aerius]

I very much doubt it'll displace metals. If you could make it for cheap it can replace carbon fibre and some plastics in certain applications, but it's not going to make inroads on metals. The first place you'll likely see it if it becomes widely available & affordable is in tennis rackets and golf clubs. They're usually the early adopters of new & fancy materials.

[Centurian99]

And while pure carbon isn't bad for radiation, it isn't the best either. The graphite control rods in nuclear reactors serve to slow the neutrons down. Unless I'm mistaken, one wants something that absorbs various forms of radiation. Though one could concievably accomplish this by building a spaceship's water tanks just under its hypothetical composite hull. Slow down particle radiation through the composite, so it won't penetrate the water tanks so deeply.

John G. Hemry uses that method in his "Space JAG" novels. The space between the outer and inner hulls was filled with water (actually, it was filled with lots of hexagonal cells of water, so that the loss of one or a few due to enemy fire/accident/whatever wouldn't be catestrophic.

[SyntaxVorlon]

Yeah of course bucky fiber will replace metal, just like metal replaced stone, nope you don't see any form of rock or nonmetallic mineral in use today.

[aerius]

Yeah of course bucky fiber will replace metal, just like metal replaced stone, nope you don't see any form of rock or nonmetallic mineral in use today.

I take it you haven't seen a brick or concrete building lately? Right now I'm also eating from a ceramic plate which qualifies as a non-metallic mineral. And if you go to the local garden centre you'll find lots of clay pots.

[Shroom Man 777]

Dude, he was being sarcastic.

And from my layman's point of view, I say no. Everybody's making metal now. It's easy, it's cheap. How about nanotubes? It's not easy and it ain't cheap. So even if nanotubes becomes the shit, lots of folks will still prefer metals. And I don't think this nanotube stuff is some wonder-thing that's got absolutely zero weaknesses and is uber in everything.

[Sea Skimmer]

Yeah of course bucky fiber will replace metal, just like metal replaced stone, nope you don't see any form of rock or nonmetallic mineral in use today.

Remember that other horrendously obsolete material, wood? I don’t know what those early people where thinking, building houses and furniture out of giant flammable weeds, what stupidity.

[Broomstick]

For that matter, we're still building airplanes out of wood. I mean brand new ones, not just maintaining antiques.

[wilfulton]

I'm going out on a limb because that's typically where you find the fruit.

Aren't metals supposed to be 1000 to 10,000 times stronger than they actually are, something to do with the grain boundries between individual crystals. Does anyone else know anything about this, or did I just happen to overhear someone talking out of their ass?

BTW, carbon nanotubes seem wonderful and all, but I doubt they could ever replace a good pocket knife, something I typically carry everywhere I go, because you never know when you need a knife.

[tharkûn]

Aren't metals supposed to be 1000 to 10,000 times stronger than they actually are, something to do with the grain boundries between individual crystals. Does anyone else know anything about this, or did I just happen to overhear someone talking out of their ass?

No metals are as strong as they are supposed to be. If you had a perfect matrix of perfect covalent bonds most metals would indeed be stronger (don't know the numbers off the top of my head). The reason they aren't is because they have defects. Rather than a nice orderly array of atoms you have places where one atom is just a little out of alinement, were there is a hole, where there is an extra atom, etc. While such defects do result in higher energy states (why the shouldn't exist) they also increase entropy (why they do exist).

The most common defects in metals are dislocations where one layer has slightly more or fewer atoms than one beside it. It becomes quite easy to move the dislocation through the sample (barring intersecting dislocation and the accompying work hardening) which makes it more flexible, malleable, and ductile.

You cannot make defect free metal. The entropy requirements entail having some defects. Ultrapure defect-free silicon has less than one defect in 10^9 atoms, if memory serves; that a huge amount of time, energy, and effort (not to mention pitching loads of "bad" Si).

Carbon nanotubes are very close to defect free in most cases because there are so few possible defects with small energy costs. Vacancies break up the pi conjugation, dislocations break up the pi conjugation and create bond angle stress, substitution is only possible with Boron (everything else in the universe is too large or has an incompatible number of electrons), and pentagon-heptagon defects just have lousy energies and kinetics.