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Ancient Swords Made of Carbon Nanotubes
brian0918 writes "Nature reports that researchers at Dresden University believe that sabres from Damascus dating back to 900 AD were formed with help from carbon nanotubes. From the article: 'Sabres from Damascus are made from a type of steel called wootz. But the secret of the swords' manufacture was lost in the eighteenth century.' At high temperatures, impurities in the metal 'could have catalyzed the growth of nanotubes from carbon in the burning wood and leaves used to make the wootz, Paufler suggests. These tubes could then have filled with cementite to produce the wires in the patterned blades, he says.'"
So swords are a series of tubes too?
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But I didn't know it was called "wootz". That's almost too good to be true. Next we'll find out the it's made of pwned ore.
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This, for instance, tells the story of old Damascan warriors that would run around slaying their enemies, and at each kill would shout a prayer of "W00Tz" to their ancient sword gods to thank them for their glorious victory.
... I've heard so far.
From my understanding the steel was hammered into very very thin sheets- of approximate shape- and then bundled. 30 to 50 of these sheets were then dipped in an carbon-iron fluxed solution at high temperature which was then 'wicked' between the plates by capillary action. Cooled and drop forged by any number of techinques the steel was work hardened and quenched, and provided the best of both world- steel's strength and hardness (sharpness), and the raw iron's fibrous flexibility.
As you know raw iron (no carbon) has packed fibres- you can see them as they rust away- but I have no idea if the fibres are that small...
Anyway... interesting theory.
Since the secret of manufacturing was lost in the 18th century, it would make sense that they were still made during 1500-1600. How would their properties in manufacturing compare to the folding method of the Japanese katana? Would the nanotubes be present in the katana as well, or was this unique to Damascus?
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This just in: carbon nanotubes found in Amiga computers! Also, carbon nanotubes made of vibrating strings!
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Maybe I'm mis-reading your post, but it sounds like you're thinking of pattern welding. The true damascus steel was produced in a different way from pattern welding. Because the of the similar appearance of the two steels, pattern welded blades are just called damascus steel nowadays.
Neal Stephenson mentions this in the Baroque Cycle. He talks about how the little eggs of steel were forged in India and hammered out to make watered steel, then sold to the asian market. I assume he is talking about the same thing? I believe he even used the word "wootz", but I can't recall.
By these guys?
Or has their worked been made suspect or not confirmed?
Scientific American reported over a year ago that a metallurgist and a blacksmith managed to reproduce Damascus steel. The secret was in the Wootz. Wootz is a lump of iron that was produced at the mine, then exported. The folks in India didn't know how to make it into Damascus steel, the folks in Damascus did, but the process only worked with a wootz from one particular mine in India. The mine in India played out several hundred years ago. That's why the secret died, after being a state secret for over 1000 years. It stopped working.
According to the team SA reported on, the secret is in a small amount of molybdenum. the process of manufacture used up to 50 forgings, and used acids to etch designs into the blade. The forgings cause microscopically fine strands of molybdenum to be located throughout the steel, breaking up the crystaline structure, and with it the fracture points. This also caused the famous 'watermarks' that all true Damascus steel has.
As some nanotubes result from almost any coking process, there would be nanotubes in there, (vanishingly small quantities), but the strength would come from other things.
I understand that it is now possible to buy a new Damascus steel sword again, but the price is very high. (it always was.) A flying car might be cheaper.
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The making of Damascus steel was lost around 1750, but rediscovered around 2000. There's a nice article on the rediscovery referenced from one of the wikipedia pages.
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Scientific American published the secret of Damascus steel back in 2000:
h art/classes/down_loads/damascus.pdf
http://www.mines.edu/Academic/met/pe/faculty/eber
As with most things in material science, the "secret" came down to the impurities.
The article concludes that there was never a "lost technique", it was merely a fluke that the source of their iron contained just the right type of impurities in the right amounts, to result in the incredible Damascus steel. Once that source was exhausted, the "technique" no longer seemed to work, and the "secret" was henceforth considered lost.
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Almost every post on slashdot has an overlord joke with a +5 Funny rating. I'm waiting for the day when its not funny any more...
Maybe it's time for MythBusters to RE-revisit cutting a sword with a sword...
I, for one, do not welcome our eventual humorless overlords.
simple - the slashdot mod system is broken, funny posts get no positive karma. Thus, kind moderators will often mod a funny post as informative or insightful, so that the poster gets the karma.
this can really fuck you over, by the way, if you tell a controversial joke... get modded +5 funny, then get a -1, troll, and another funny, and another troll. When a moderation war kicks in, you keep losing karma from the -1 troll's and gain no positive karma from the +1 funny's. Eventually you could end up with a +5 post that cost you an assload of karma.
Sometimes Scientific American is just like /. - dupes and all.
Back in the 70's SA ran a similar article on Damascus steel. The authors (iircc, one was from Stanford) attributed the steel's property both to the impurities which this article talks about and to the heating/cooling cycles that gave the steel its strength. The article referenced an ancient blacksmith's poem that described the various colors the steel had to take as it was heated and cooled. Since the poet didn't have a Pantone color palette available, he compared the colors to the sun and moon at various times of the day and year. Heaven help the color-blind or weak memoried blacksmith.
One last point that I remember from the article was a discussion of the quenching fluids. For the final quenching, the poem describes killing a slave by driving the steel into his chest. The authors, noting the current shortage of slaves, concluded that a saline solution held at 98 degrees Fahrenheit was the salient factor in the quenching fluid.
I was wondering where the tem 'w00t' came from, lol. Obviously they took that from the Damascans as well as the Carbon swords from the Phantasy Star series on good old Sega Genesis. Must be the basis for a +1 sword in D&D too. So what's Drizzt Du Erden's +5 scimitar based on in reality you ask? Well that's simple, it's a carbon nanotube enhanced, antimatter bladed, quantum slash enhanced, electric current carrying, Ruby on Rails using blade :)
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I find it hard to believe that a normal furnace is hot enough to produce carbon nanotubes. Currently CNTs have to be manufactured using plasma torches. in a normal furnace, there will be too many defects in the CNTs for them to be of any use.
I'm waiting for the day when its not funny any more...
You missed it already. See, it gets not-funny after awhile, and then using it becomes the joke itself and so it is made funny again, only to eventually be over-used and become not funny again. Repeat until the sun goes nova.
As the Slashdot Faq says: Note that being moderated Funny doesn't help your karma. You have to be smart, not just a smart-ass.
If you want to give someone Karma and the post doesn't fit into the Insightful or Interesting category, use +1 Underrated.
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Either that, or he's confused about basic smithing. The basic idea behind a sword is that you beat the shit out of the edge while it's cooling to form hard, brittle martensite while the rest of the body forms as soft pearlite to avoid cracking. Then there's the L6 bainite supersword, which is just nuts.
>> simple - the slashdot mod system is broken, funny posts get no positive karma.
> That's not a bug, it's a feature.
The way it is implimented, it is a bug.
It has only happend to me once, and only by 1 point, but it is annoying to lose Karma for a post that has a flat or net positive moderation.
+Funny should only be zeroed to the degree that the final score is the same as the starting score.
If you want to give someone Karma and the post doesn't fit into the Insightful or Interesting category, use +1 Underrated.
And if you want to unjustifiably mod someone down because you disagree with them, and not have the moderation reviewed in metamoderation, use -1 Overrated.
Which is probably not what it was intended for.
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While later Japanese swords were made by forging different metals together, very early swords were not--they were forged from a solid piece of steel. The steel was beaten flat and folded over itself several times, but it was not to impart mechanical qualities--it was to mix the carbon evenly throughout the impure metal. (Later this was accomplished through better steel manufacturing, so the folding was replaced by the multi-part welding of of different alloys as described.)
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Once the sword was shaped it was quenched. However since they wanted different properties on the edge vs. the spine, they needed to cool the different parts at different rates. This was accomplished by painting the sword with varying thicknesses of clay--thick on the back for a slow quench (resulting in soft but springy steel) and thin on the edge for a fast quench (resulting in hard but brittle martensite). This differential cooling also caused some of the curvature. It also allowed a sword maker to impart a "signature" of sorts, by painting patterns into the clay. This manifests itself in the subtle wavy reflective pattern seen along the cutting edge of many katanas, called the hamon.
Finally to address the GP, the original pattern that is now called Damascus had nothing to do with folding the blade. If you look at an original Damascus blade the pattern is not alligned to the edge but runs throughout the blade. It has more to do with the steel composition and how it was forged.
Sources for more info:
http://en.wikipedia.org/w/index.php?title=Katana&
http://www.mines.edu/Academic/met/pe/faculty/ eberhart/classes/down_loads/damascus.pdf (PDF)
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An ideal sword would be both flexible and sharp, and a number of cultures have achieved this goal via pattern welding (welding alternating thin layers of hard and soft steel), most famously the Japanese katana, but this technology was well known in the ancient world, and is evident in recovered Viking swords, Indonesian kris, and as far back as Roman times (for use in decorative steel artifacts). Its use can also be found in a few modern knives (see Swedish Mora).
This differs from the damascus technique, which was rediscovered in the 1980's by Alfred Pendray and John Verhoeven. They didn't mention nanotubes, just the necessity of small Vanadium impurities in the ore. This explains the 'lost technology' of damascus steel very well, ie. when the original ore deposits containing said impurities were exhausted, the technique simply did not work anymore.
An ancient Damascan sword?
... and then they built the supercollider.
the comment settings page, where you can assign -6 to Funny comments and never have to have your reading interrupted by them again!
In fact, your explanation of the process is a tad wrong... here comes an explanation closer to reality
For simple carbon steels, beating the shit out of the edge just gives it its basic shape (it will be refined later at the polish stage). The formation of bainite, martensite and pearlite is caused by the cooling rate. Thus they come from the quenching and subsequent tempering of the blade. The tempering is mainly there to relieve the internal stresses caused by the structure reorganisation triggerred by the quench (and reduce the hardness by a few Rockwell points). Basically (very simplified), a fast cooling rate will give you pearlite while a slower cooling rate will give you martensite and if you keep it a long time at the correct temperature, you'll end up with bainite.
A prime example of that concept is the way japanese swords are made (oversimplified once more, as this is not a smithing forum).
After you've given a basic edge shape to the blade, you apply clay on the edge (and a bit on the spine, too) then you bring the whole blade to non-magnetic temperature and you quench it. Three things can happen at that point:
- the blade curves towards the back (due to the different cooling rates) and the crystalline structure changes (martensite and friends under the clay, pearlite where there is no clay)
- the blade curves towards the edge (can happen with 5160 quenched in oil), it's a miss
- the blade cracks due to the stress (you used the wrong quenching medium for your alloy or heated the blade too much)
If the blade survived, you can then temper it by bringing it back to a certain temperature (depending on the alloy) so the internal stresses are relieved and the surface crystalline structure can change a bit too (if the temp is in the correct range). After that, the smith gives the a very rough polish before sending it to a real polisher.I do agree about the L6 bainite swords by HC, they are amazing ;) L6 in itself is just a tooling alloy (used for saw blades, IIRC), the properties of the L6 swords come from the controlled temperatures of the salt baths used by Howard. He is keeping the blades at a very precise temperature range for a certain amount of time to maximise the reorganisation of the crystalline structure to bainite. I don't haved the temperature graphs for various structures handy, but they're quite easy to find on the web ;)
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I think Verhoeven got it right. Read all about it at http://www.tms.org/pubs/journals/JOM/9809/Verhoeve n-9809.html.
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The thing about muslim swords and european armours is a different story altogether, and it's about the shape of the sword rather than the metal.
Let's focus on two aspects:
1. The edge. There are two basic moves for _cutting_ with a sword:
A) draw cut. No, it's not the Iai maneuver, but dragging the edge along as you cut. Sorta like what most people do when they cut a slice of bread or of salami with a knife. Curved swords are ideal for draw cuts, straight swords suck for it.
Draw cuts are deadly against unarmoured opponents, and can cut through flesh like a hot knife through butter. Draw cuts, on the other hand suck against metal armour. Even the cheapest chain hauberk makes a scimitar or katana completely useless.
B) hard square hits, much like with an axe or mace. Here you don't draw the edge to slice, but just hit hard and let the kinetic energy drive the edge into the opponent. Straight swords are perfect for it, curved swords much less so.
This hacking move is actually very nice against armour, especially chain. Even if it doesn't penetrate, you're being bludgeoned with a 3 pound steel bar with a very narrow edge. Even the maille and the padding under it can only spread it over so much surface. So even if it doesn't penetrate, it can break a rib or two, or crack a skull.
2. The tip. Here we actually have three cases, if we also include the katana.
a) straight sword, tappered tip. (I.e., the european swords.) A straight sword is ideal for piercing _accuracy_ and strength since it's basically a short spear. (See for example the later estoc which was basically more of a short spear than a sword by now.) You can aim pretty well and put all your strength behind that tip, because the force goes along the axis of that bar.
b) curved sword, tappered tip. (I.e., the muslim swords that you mentioned.) Again this becomes a lot less useful against armoured opponents, since you have neither the accuracy (e.g., for thrusting between two plates) nor as much strength in a strictly piercing hit.
c) curved tip. (E.g., the Japanese Katana or the Chinese Dao.) This is a special kind of tip that is outright useless at piercing against an armoured opponent, but great at cutting. The most fearsome cuts with a katana are done with the tip. It's a tip that emphasizes not only cutting power, but range. (Your outer range with the weapon is also the range at which you are the deadliest.) The range fits well with the Samurai techniques which emphasise, basically, striking first over defense. (By comparison, in european fencing _the_ focus was defense, and harming the opponent was second priority.)
Unfortunately this too is useless against metal armour, which is why the Katana became _the_ symbol of the Samurai only after firearms made armour obsolete. (Much like the Rapier and the Smallsword in Europe.) Prior to that, the bow and spear were the preferred weapons.
So to make a long story short: the reason the muslims had trouble against the crusaders was because the turkish/arabic curved swords sucked against heavily armoured opponents.
Basically, unrelated, this is why it gets on my nerves to hear so many manga fans repeat stuff like that the european swords were crap and only used because of some religious reasons. For the fighting style they were used in, and the reality of European warfare at the time, a straight sword was actually a great weapon.
And it's also worth remembering that it wasn't just the Europeans, but also, for example, the Chinese that favoured the longsword. While the curved-tip Dao (broadsword) was the weapon given to common troops, the nobles and elites used the Jian (straight longsword) as a more effective weapon in the hands of a highly trained elite. And as a status symbol.
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