Medieval blacksmiths used nanotechnology

In medieval times, crusading Christian knights cut a swathe through the Middle East in an attempt to reclaim Jerusalem from the Muslims. The Muslims in turn cut through the invaders using a very special type of sword, which quickly gained a mythical reputation among the Europeans. These 'Damascus blades' were extraordinarily strong, but still flexible enough to bend from hilt to tip. And they were reputedly so sharp that they could cleave a silk scarf floating to the ground, just as readily as a knight's body...

Two years ago, Marianne Reibold and colleagues from the University of Dresden uncovered the extraordinary secret of Damascus steel - carbon nanotubes. The smiths of old were inadvertently using nanotechnology...

Reibold's team solved this paradox by analysing a Damascus sabre created by the famous blacksmith Assad Ullah in the seventeenth century, and graciously donated by the Berne Historical Museum in Switzerland. They dissolved part of the weapon in hydrochloric acid and studied it under an electron microscope. Amazingly, they found that the steel contained carbon nanotubes, each one just slightly larger than half a nanometre...

It isn't clear how ancient blacksmiths produced these nanotubes, but the researchers believe that the key to this process lay with small traces of metals in the wootz including vanadium, chromium, manganese, cobalt and nickel. Alternating hot and cold phases during manufacture caused these impurities to segregate out into planes. From there, they would have acted as catalysts for the formation of the carbon nanotubes, which in turn would have promoted the formation of the cementite nanowires. These structures formed along the planes set out by the impurities, explaining the characteristic wavy bands, or damask (see image at top), that patterns Damascus blades.

By gradually refining their blade-making skills, these blacksmiths of centuries past were using nanotechnology at least 400 years before it became the scientific buzzword of the twenty-first century. The ore used to produce wootz came from Indian mines that were depleted in the eighteenth century. As the particular combination of metal impurities became unavailable, the ability to manufacture Damascus swords was lost...

More info at the link. (image credit here)