As Predicted, Buckytubes in Damascus Steel
16th Nov 2006, 22:44 GMT
Damascus steel swords have been famed for centuries for their toughness and sharp edge. Four years ago, I suggested on the sci.nanotech newsgroup that these swords might gain their properties from nanotubes. According to this article, the buckytubes have now been found. Part of my post: So if nanotubes can be formed in the presence of carbon and iron in a reducing (opposite of oxidizing) atmosphere at atmospheric pressure, is it possible that they could be formed in a blacksmith's forge and be deposited on the piece of metal being worked? A forge definitely has a reducing atmosphere! Then if the metal were folded repeatedly, as in the Samurai or Damascus swords, the buckytubes would be incorporated into the blade. Such swords are legendary for their strength, flexibility, and sharpness. A heavy dose of buckytubes could supply all three qualities, if they were incorporated into the metal and also stuck out at the edge of the blade. This assumes that buckytubes could occur in the first place, and further assumes they could be sufficiently bonded to the metal, which probably implies that they'd have to be pretty long. (OTOH, we know steel likes to bond to carbon atoms -- can anyone tell me about graphite/steel mixtures? Of course buckytubes are more strained than sheet graphite, which perhaps makes their electrons more accessible.) This is very testable--just stick a good Samurai or Damascus blade under an atomic force microscope, and look for the long tubular objects. Now, from the article reporting the find: Peter Paufler of the Technical University of Dresden, Germany, and colleagues studied samples of a 17th-century sword under an electron microscope and found clear evidence of carbon nanotubes and even nanowires. The researchers think that the sophisticated process of forging and annealing the steel formed the nanotubes and the nanowires, and could explain the amazing mechanical properties of the swords (Nature, vol 444, p 286). Nanotechnologists like to cite examples of nanotechnology having been practiced long ago. For example, Chinese ink uses carbon nanoparticles, and red stained glass uses gold nanoparticles. But I think this example is cooler than either of them. Blacksmiths were actually making buckytubes in their forges, and giving their weapons a molecular edge (no pun intended). UPDATE: This article explains that fullerene formation in metal has been known for a decade or more. You just heat and cool it a few times, and the carbon atoms link into buckytubes and other fullerenes all by themselves. So I don't know whether the buckytubes in Damascus steel condensed from the combustion products of the forge, as I suspected, or formed within the bulk of the metal, as in Robert Job's process. Chris Phoenix Tags: nanotechnology nanotech nano science technology ethics weblog blog