Ancient Swords Made of Carbon Nanotubes 293
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.'"
Nice history lesson... (Score:2, Informative)
Re:I'm very interested in word origins (Score:5, Informative)
Wikipedia says "the word wootz may have been a mistranscription of wook, an anglicised version of ukku, the word for steel in many south Indian languages."
So probably WoW wasn't responsible for this word, but maybe a type of back pain related to a sedentary lifestyle, will be called "pwned spine".
Re:I'm very interested in word origins (Score:5, Informative)
Re:Well, that's certainly the most interesting the (Score:5, Informative)
Re:Katana comparison (Score:5, Informative)
Most Japanese swords created before higher quality iron began being imported in large quantities from other countries were made from volcanic black sand (which is high in iron oxide). The sand was smelted with rice stalks and the resulting block of iron was broken into pieces and sorted by color (carbon content).
These different carbon content metals were formed into billets and used to make the different parts of the blade since katana blades were not traditionally made in one piece. They were usually made in anything from two pieces (core/edge and outer casing) to five pieces (back ridge, both sides, core, and edge - in this case usually made of harder iron recycled from old pots) with some being made in even more pieces.
Incidentally, this is also what caused them to be curved since the different metals cooled at different temps. Unfortunately, it also meant that tempering the sword was a very delicate time because if the sword had any non-minor defects or was cooled improperly, the blade would literally rend itself apart.
So, to answer your question, they were two completely different processes.
Re:Katana comparison (Score:5, Informative)
Again, I only have a passing knowledge of this. Interestingly, blue and white steels are used in modern Japanese woodworking chisels and planes. Here's are brief explanation of the types of steel used - http://www.woodworking-forum.com/woodworking/Whit
Old News (Score:5, Informative)
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.
Nice article on rediscovery (Score:5, Informative)
Re:Katana comparison (Score:2, Informative)
Re:Wootz? (Score:5, Informative)
Damascus secret rediscovered! (Score:5, Informative)
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.
Re:Old News (Score:5, Informative)
WTF are you talking about? (Score:2, Informative)
The wikipedia article says that Damascus steel was rediscovered in the 1980's, but I got to meet an ABS Master Bladesmith (there's less than 100 of them) several years ago (around 2001) and had the chance to heft in my hand what he said was the first hunk of real raw damascus steel that his friend (an ABS Master) had given to anyone since rediscovering the process.
So, from what I understand, we already know how to recreate the original style of Damascus steel aka wootz.
Not really news... (Score:2, Informative)
Re:Locking up Jefferson. (Score:1, Informative)
Re:informative (Score:5, Informative)
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.
Scientific American Version 1.0 (Score:5, Informative)
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.
Re:Wootz? (Score:5, Informative)
Wootz is an entirely different animal. The technique was lost because it depended upon certain ores with trace impurities which dried up in the 1700s or so. The carbon would clump together which formed the distinctive banding.
Summary: pattern-welded = 2 different ores folded in alternating layers form a pattern, wootz = forging process and chemical composition of ore results in macroscopic pattern-forming carbon lamellae
Re:Well, that's certainly the most interesting the (Score:5, Informative)
Re:Wootz? (Score:5, Informative)
Pattern-Welded is actually a weaker sum of the metals that went into it's production. Molecular cohesion just does not happen, the metals aren't being smelted or wrought together in a way that is conducive to improving the strength of iron. No matter if it's 2 steels being sandwiched (which is basically the process used when going for aesthetics alone) or even if it's a tool steel being etched by laser or in an acid bath; which is also done.
Damascene steel on the other hand, is extremely strong. It can hold an edge while still maintaining flexibility. The silica content as well as the amount of tungsten present in the sand from which the iron was extracted is a synergistic combination. Silica providing flexibility (I'm hacking a metallurgical textbook in half to get where I'm going, forgive me), with the tungsten giving the steel a little UMMF that none other had at the time--bands of tungsten carbide. In itself completely inflexible but present as it is in most blades it actually is given alot of room to move.....by the silica.
Similar qualities are present in the tungsten rich sands of some Japanese waters. However not in the same manner, the Japanese had an ingenious forging method, sometimes referred to as the 1000-leaf method by those speaking of it in English.
REAL Damascus steel is still legendary not only among sword and knive enthusiasts, but amont metallurgists as well. It is for all intensive purposes a wonder-metal, even by today's standards. In today's day of Titanium, Monel, Inconel and Carpenter-20, Damascus is still something people in the field whistle about.
That is not entirely correct (Score:5, Informative)
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/ [mines.edu] eberhart/classes/down_loads/damascus.pdf (PDF)
Re:Locking up Jefferson. (Score:5, Informative)
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 [thegearjunkie.com]).
This differs from the damascus technique [iastate.edu], 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.
Re:I'm very interested in word origins (Score:5, Informative)
Oops.
In my haste to offer you a good-natured ribbing, I sort of glossed over the part where you explained how you're not a retard.
I guess that makes me the retard today.
Re:Well, that's certainly the most interesting the (Score:5, Informative)
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 ;)
Re:Wootz? (Score:2, Informative)
Re:Wootz? (Score:3, Informative)
You just revealed how little - back when I was a metallugist we called them crystals, grains, unit cells all kinds of things but molecules don't make sense in that metallic context, and things can be joined together by forge welding.
As for it being a magical wonder metal - well it was a way of getting a very good material out of two crappy ones that is an example given to students but don't get all mystical on us. Bands of high carbon material with a lot of different metal carbides and a structure that gives a lot of strength layered between bands of soft relatively pure iron that could absorb a lot of impact energy is a simple description of the material that makes up a damascas sword - and yes we can make better materials more easily now - and no - people have not forgotten how it is made even if they can't get the same ore.
I'm going to be pedantic here. (Score:5, Informative)
The Right of Congress to make laws regarding Intellectual Property is in the Body of the Constitution Proper. In Article 1, "The legislative powers of Congress", Section 8: Congress (and only congress) shall have the power to "To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries;"
Actually, that's a completely different story (Score:5, Informative)
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.