Skip to comments.Sharpest cut from nanotube sword-Carbon nanotech may have given swords of Damascus their edge
Posted on 11/16/2006 1:26:06 PM PST by FLOutdoorsman
Think carbon nanotubes are new-fangled? Think again. The Crusaders felt the might of the tube when they fought against the Muslims and their distinctive, patterned Damascus blades.
Sabres from Damascus, now in Syria, date back as far as 900 AD. Strong and sharp, they are made from a type of steel called wootz.
Their blades bear a banded pattern thought to have been created as the sword was annealed and forged. But the secret of the swords' manufacture was lost in the eighteenth century.
Materials researcher Peter Paufler and his colleagues at Dresden University, Germany, have taken electron-microscope pictures of the swords and found that wootz has a microstructure of nano-metre-sized tubes, just like carbon nanotubes used in modern technologies for their lightweight strength.
The tubes were only revealed after a piece of sword was dissolved in hydrochloric acid to remove another microstructure in the swords: nanowires of the mineral cementite.
Wootz's ingredients include iron ores from India that contain transition-metal impurities. It was thought that these impurities helped cementite wires to form, but it wasn't clear how. Paufler thinks carbon nanotubes could be the missing piece of the puzzle.
At high temperatures, the impurities in the Indian ores could have catalysed 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.
But his suggestion isn't necessarily rock solid. Steel expert John Verhoeven, of Iowa State University in Ames, suggests Paufler is seeing something else. Cementite can itself exist as rods, he notes, so there might not be any carbon nanotubes in the rod-like structure.
Another potential problem is that TEM equipment sometimes contains nanotubes, says physicist Alex Zettl of the University of California, Berkeley. Paufler admits it is difficult to exclude the problem but says that, having studied the swords with a range of different equipment, he is convinced that the tubes he sees are from the swords.
If Paufler is right, nanotube researchers do not mind being pre-empted by Indian steel-makers. "The important fact is that nanotubes were serving some very useful purpose even before they were discovered," says chemist Andrei Khlobystov of the University of Nottingham, UK. "This should inspire us to look for new practical applications of these remarkable nanostructures."
The next step, says Paufler, will be to take the latest carbon nanotube knowledge and work with bladesmiths to try and recreate the lost process.
I used "Damascus."
Damascus steel made for some very beautiful swords - I remember seeing some knives purportedly made by the same process and wanting to buy one. There was a tale - probably apocryphal - of Richard I meeting one of Saladin's subordinates. To demonstrate the strength of his sword, Richard arose and hacked a block of wood apart. Saladin's emissary responded by demonstrating the subtlety of his sword - tossing a silk pillow in the air and letting it fall on the edge of his Damascus steel, which sliced it apart.
Great...so now we have it...greatest invention out of muzzie-land is the sword...I guess that's why head severing is a priority there.
There is a wonderful, if imaginative, description of the creation of wootz in the middle book of Neal Stephenson's Baroque Cycle, "Confusion", in which the author claims that wootz was the creation of a caste of Hindoos who sold the eggs of steel to swordsmiths.
It wasn't a Muslim invention - that "wootz" steel was entirely Hindu, and in fact Damascus swords always depended on South-Indian steel.
Much like many other Muslim ideas, like Arabic numbers, the zero and probably algebra, it came from India.
Others came via China. The Muslim center of gravity in the Middle East made them brokers of technology and ideas across Eurasia.
Stephenson is not all that wrong.