High-tech in ancient armories
In its day, Damascus steel was a fearsome high-tech material. The blades of Muslim warriors demonstrated the superior art of oriental blacksmiths to western crusaders. The weapons of that time even contained the most modern nanostructures of today.
Ancient knowledge is often of a different kind. It is the result of a long, evolving process of trial, error and success. For example, an ancient or medieval blacksmith might have tried various ores, irons, steels, and mixtures in search of a recipe for the best sword blade. Often the result was good only to be melted down again immediately. But sometimes it was actually a little better than the usual products. So the blacksmith continued to research in this direction and collected his knowledge, which he passed on to the following generation. In those days, science was not infrequently a side activity for zealous craftsmen.
The approach may have been slow and didn't always bring the desired success, but sometimes it delivered quite astonishing results. Such as the Damascus steel, which probably owes its name to the main center of oriental trade at the time, the city of Damascus. Without knowing what was going on inside their steel, the gunsmiths found they needed a specific Indian steel that contained a very high carbon content of up to two percent.
But only in one of two phases, so that a not too hot-forged sword was hard and tough at the same time. On the battlefields in the fight against the crusaders with their uncompetitive steels, the Damascene sabers fulfilled their gruesome purpose - and disappeared in the 18th century. Century practically from the arsenal of the still steel-hungry war industry: the Indian ore mines were exhausted. Knowing how was no longer enough without additional knowing why.
Today's full-time researchers struggle for that knowledge. Often enough, they even approach their goal from the theoretical side, which describes the why, in order to reach the how as directly as possible. This also applies to the effort to subsequently decipher the secret of Damascus steel. With the analytical methods of materials science, they have already found out that small "impurities" in the steel with the elements vanadium, chromium, manganese, cob alt and nickel have made their contribution, as well as the beautifully curved band structures of iron carbide (Fe) called cementite 3C). Cementite nanowires have even been discovered in the blades.
Now scientists led by Peter Paufler from the Technical University of Dresden are adding another ingredient to the recipe: carbon nanotubes. In a sample from the 17th century, the researchers recognized these tiny structures under the electron microscope, which had only been officially discovered a few years ago. However, not in earthly steel, but in cosmic clouds and later in chemical laboratories. The fact that Persian blacksmiths unknowingly produced nanotubes more than 400 years ago seems like an anachronism that makes you smile. Apparently, sometimes high-tech is just old hat.
The nanotubes in the saber can only be seen after a special acid treatment. These are multi-walled specimens that should have high tensile strength. Because of this property, nanotubes are now mixed into plastics, giving them greater stability - essentially the same job they may have performed in weapons. There they may also have served to protect the cementite nanowires that encased them like a shell.
A close look at the old blade brings the materials researchers one step closer to their ultimate goal: the ability to forge Damascus steel again. But then hardly to form deadly swords out of it, but rather because of the aesthetic band structures. And because old and new knowledge come together beautifully in the fire of the forge.
