A Damascene sword from the 17th century: the unusual sharpness and durability of these weapons is the result of early nanotechnology. Photo: Alexander Dietsch
Read The legendary Damascus steel owes its extraordinary properties to nanotechnology. Structures made of carbon nanotubes and iron carbide filaments enclosed in them gave the steel, from which the Arabs already made swords for the fight against the Crusaders, its particular strength. This is what Marianne Reibold from the University of Dresden and her colleagues found out when investigating an old sword. Using a high-resolution transmission electron microscope, the researchers studied a sword of the 17th-century Persian blacksmith Assad Ullah. The forging technique of the Persians from this period was a complicated thermomechanical treatment of the steel, in which the forging was repeatedly brought to certain temperatures, forged, and cooled again. The exact procedure for this has been forgotten since the 18th century.

Reibold and her colleagues assume that the blacksmiths eventually created nanostructures by tediously trying different methods that made up the secret of their special strength. The cyclic heating and shaping of the steel promotes the formation of carbon nanotubes, which in turn contribute to the formation of the microscopically thin filaments of iron carbide, the researchers suspect.

For the production of Damascus steel, so-called Wootz was imported from India. This steel contained a high proportion of carbon, which caused a great deal of damage to European forging, because at high temperatures it forms iron carbide. This compound is very hard and wear-resistant, but makes the forged brittle and poorly moldable. For a long time, the Europeans remained mystified how the weaponsmiths of the Orient could produce their high-quality swords.

Marianne Reibold (Dresden University of Technology) et al .: Nature, Vol. 444, p. 286 ddp / science.de? Sabine Keuter advertisement

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