Carbon nanotechnology in an 17th century Damascus sword

The Damascus swords of the Middle East were legendarily sharp, strong and flexible. Now, an analysis of one of these weapons under an electron microscope reveals that the key to its properties is nanotechnology, inadvertently used by blacksmiths centuries before modern science.

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 a swathe 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.

A piece of Damascus steel shows the characteristic wavy 'damask' pattern. These superlative weapons gave the Muslims a great advantage, and their blacksmiths carefully guarded the secret to their manufacture. The secret died eventually died out in the eighteenth century and no European smith was able to reproduce their method.

Now, Marianne Riebold and colleagues from the University of Dresden have uncovered the startling origins of Damascus steel using a technique unavailable to the sword-makers of old – electron microscopy.

Damascus blades were forged from small cakes of steel from India called ‘wootz’. All steel is made by allowing iron with carbon to harden the resulting metal. The problem with steel manufacture is that high carbon contents of 1-2% certainly make the material harder, but also render it brittle.

This is useless for sword steel since the blade would shatter upon impact with a shield or another sword. Wootz, with its especially high carbon content of about 1.5%, should have been useless for sword-making. Nonetheless, the resulting sabres showed a seemingly impossible combination of hardness and malleability.

A carbon nanotubeRiebold’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 (see left), each one just slightly larger than half a nanometre. Ten million could fit side by side on the head of a thumbtack.

Carbon nanotubes are cylinders made of hexagonally-arranged carbon atoms. They are among the strongest materials known and have great elasticity and tensile strength. In Riebold’s analysis, the nanotubes were protecting nanowires of cementite (Fe3C), a hard and brittle compound formed by the iron and carbon of the steel.

Here is the answer to the steel’s special properties – it is a composite material at a nanometre level. The malleability of the carbon nanotubes makes up for the brittle nature of the cementite formed by the high-carbon wootz cakes.

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.

Now, thanks to modern science, we may eventually be able how to replicate these superb weapons and more importantly, the unique steel they were shaped from.

Reibold, Paufler, Levin, Kochman, Patzke & Meyer. 2006. Nature 444: 286.

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17 Responses

  1. i think This will clear the misconception that muslims are Looters And Invaders.If any one read the muslim history U will Find That Foundation of Modern Chemistry Was Laid By The JABER-Bin-Hayan.Algorithms was invented By An Musa-Al-Khawarzim and So-on But I will also Not Forget That The Modern Inventions Are Created Mostly By The Westerns.

  2. Especially since the Damascus sword was used to *repel* invaders :-)

    Rashid makes a good point about the contribution of many other cultures to modern science, which is too often seen as an endeavour of white middle-class people.

    However, I think it’s interesting to ask why the modern contribution of Islam to science is currently much lower than the strong contributions it made earlier in history, as described in Rashid’s post (This is what I understand – feel free to correct/explain further).

  3. Rashid:

    That’s why it’s so sad that this culture that produced so much in the way of math, science, and technology in the past is now disabled by courting the disciples of degeneration and destruction.

    And, living in the middle of the USA, I have never heard anyone state that Muslims are all looters and invaders, though I’m sure some have existed (as is true for any people group, unfortunately.) Nor do I, being a diehard Christian, believe that myself. I really don’t think you’d find a lot of people outside of the Middle East who do believe that.

  4. Okay people. If you want to have a conversation about the role of Islam in science, and how that has changed throughout history, fine by me.

    But this is not the place for a debate about the merits of different religions and people’s attitudes towards them. Asserting that non-Muslims believe Muslims to be ‘looters and invaders’ is not on and saying that an entire culture is ‘courting the disciples of degeneration and destruction’ is not acceptable.

    Plus it sounds naff.

    I can really do without people sparking up a religious flame-war on my site.

  5. Damascus blades are made up of nanotubes

  6. Quote,”we may eventually be able how to replicate these superb weapons and more importantly, the unique steel they were shaped from” end quote.

    I hate to put a fly in the ointment so to say, but Wootz has been recreated and used for a few years now. I have not made it, but have forged the steel.

    Alfred Pendray, a noted Bladesmith teamed up with
    Dr.John Verhoeven in the early 1980′s and recreated Wootz steel.

    Wootz is a crucible steel. meaning it was smelted with iron and other elements in a sealed crucible. now I do not know the complete process .

    I just wanted people to know that it has been done again useing old world and new world methods. Do a google search on these smiths and you will see Wootz again in ways not seen in hundreds of years.

    The smiths are as follows: Alfred Pendray, Ric Furrer, Ulrich Hennicke. that is just a few of the outstanding smiths doing this. Here is a link showing a process by which one of the aforementioned smiths made wootz, then forged it into middle eastern type weapons.
    http://forums.dfoggknives.com/index.php?showtopic=7058

    anyway this has ben my two cents worth, thanks for your time.

    Kenneth

  7. Thanks Kenneth. Now, I’d be happy to change the last sentence, but just wanted to check something.

    My understanding is that despite having modern wootz, we still can’t produce swords of the same quality as the Damascus blades of old, either because the method of working the steel was lost, or the wootz we have isn’t quite the same in terms of its contents.

    Anyone care to chip in?

  8. I am not sure how ot answer this. I have held some new Wootz weapons. cut with them, abused them. and they held up great. Now to say are they the same? cant be as we are not useing the minerals from southern india. If we(smiths) had acess to some i am sure we could make Wootz that would be inspected and be EXACTLY the same.

    Barring that we can use minerals that would be as close as possible. If you want to know the low down on modern wootz , my cash would be on the afore mentioned smith Ric Furrer. He is in india now! as we speak learning. and he has been on a indo-persion kick as of late. but to sum up the question is it the same? for all intents and purposes it is. cuts the same take a heck of a beating. i will try to dig through my stored papers on it and leave some more decisive info.

    thanks for your time.

    Kenneth P.S. sorry for the crappy punctuation, it is really late and i am tired.

  9. Hello All,
    I search the web now and again for subjects I like and found this site. I have corresponded with the Dresden scientists and, though I am not an expert on nano tech and do not have access to modern microscopes like they have, I see no reason to doubt the findings. What those findings mean is another matter for debate. I do not know if nano-tubes are found in all high carbon steels and I do not know how they form or even if they are present in the raw materials (charcoal for instance).
    I am a fan of Buckminster Fuller and the intriguing geometry of carbon structures in general, but as to how the tubes will effect the performance of the steel or how they got there I am not able to say.

    As to my trip to India:
    I returned two weeks ago and can say with some certainty that there is no wootz being made there today. I spoke to several Lohar (blacksmiths who make swords) and many museums and collectors and none could show me any modern work made from modern made wootz ingots. There are some blades with wootz-like patterns, but they are mostly forged from mill balls or ball-bearings and are therefor…different and not wootz.

    The group I was traveling with had some basic analytical equipment and were able to do Vickers hardness testing on old blades and we did find that the wootz blades were usually harder than the bloomery iron/steel blades (not made by the crucible steel method) made from the same time period and the wootz armor was about as hard as the wootz blades
    SO
    All things being equal (which they rarely are) the wootz blades were “better” than the blommery blades (non crucible steel). Anecdotal evidence from he collectors also led to that conclusion, however, myth and legend are to be referenced, but not relied on as evidence in the true sense of the word.

    All things considered the swords did what swords were made to do and armor did what armor was made to do and this is why it was used for such a long period of time.
    Nano is hot now and history is interesting so I do not mind science articles like this being produced—every test yields information..what is done with that information is up to the reader.

    Yours,
    Ric

    Ric Furrer
    Sturgeon Bay, WI
    Door County Forgeworks

  10. If I was a European I would be
    shocked.
    But I’m not so I found this article interesting along with another article on this very sub. at Nanowerk

  11. Iron has been forged for lifetimes and the experience passed on to the next generation. Thats a long time to explore combinations and sources of ores, mining techniques and the combination of gasses and fluxes used in the forge. Everything is not as it appears to the modern mind. There should be more than one way to make wootz steel. Sometimes it is a matter of finding how some of the methods used in the ancient past could have been done with materials made only by modern processes. The question becomes how do you make a cast iron perform like a tool steel. Where do you find the materials other than vanadium to have the wire like composite form. I am wondering if Mr. Furrer found plant substances or pigments that would also form the other wootz composite. I have been working on what that might be for the past 20 years. Sorry about being vague.

  12. Do you think that it would be posible to make a sword out of other metles like for instence tunksten and carbite. Also steel and tunksten.

  13. Thankyou for all of your insights. I am creating a presentation on Damascus Steel Blades in an Engineering Class and am very impressed on how strong and hard these blades are.

    I do have a question for anyone who can answer it. I was reading that the blades were curved because the steel when cooled would tighten or shrink on the backbone of the sword, pulling the blade edge tight and creating a slight curve. thus making the sword able to keep its sharpness longer and making it stronger. Is this that I had read true or false? And could someone explain what happens exactly be it true or false.
    Thankyou.

  14. In indonesia ( java, bali, sulawesi and other place ) we found same metal pattern like damascus steel. For example in keris ( traditional weapon from java, bali and other ) we find that pattern. In java they call it “pamor”. This for example :
    http://tbn0.google.com/images?q=tbn:Q15KH81u2XscVM:http://old.blades.free.fr/keris/introduction/wilah/picpamor/draw/pamor_pic2.gif
    http://tbn0.google.com/images?q=tbn:HZ3Hp8GI_PXmRM:http://pachome1.pacific.net.sg/~dspf/nigirid2.jpg
    http://tbn0.google.com/images?q=tbn:b-q7GbUEPZhdbM:http://luciusmonkey.tripod.com/keris.jpg

    This weapon produce by “empu” ( smith who make “keris” ). But there are rare “empu” who have knowledge, ability and accessibility in some “keris” material. As we know, keris ( now ) made from three kind of steel material. There are :
    1. Iron.
    2. Carbon Steel.
    3. Meteorit Stone.
    This kind of weapon and ability still exist in surakarta ( central java ), yogyakarta ( java ) and bali.
    Some art collector can identify which “keris” that produce before 19th century. They check it in metalurgy laboratory, and they found some characteristic about keris before 19th century, there are :
    1. Keris made from original iron ore or iron sand and meteorit stone.
    2. That method produce unpure iron metal. Who has many kind of metal in some compotition like titanium, cobalt, alumunium.
    3. Keris more light but strong and sharp. Maybe there is titanium characteristic.
    4. To make this pattern, after forging metal, they put the keris in high acid liquid ( maybe HCl ).

    Although we know that keris has strength like damascus sword, i still don’t know are there nanotube in it.

  15. The damascus swords were made from a specific quality of ore, the source of which has been traced by me. Inetersted parties may call me for samples of the ore from me.

  16. In japan,high strength steel parts of car was very expensive a few years ago.
    But durable tool steel “SLD MAGIC” for stamping die use was developed by Hitachi Metals.Because of rigid high strength steel,die life becomes shorter and vehicle parts becomes more expensive.But engineers can keep die lifespan from becaming short by using this tool steel.
    Hitachi is also a famous maker of samurai sword raw material.

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