A new album titled Nanotechnology Pictures was added to Photo Gallery. If you want to share interesting pictures of Nanotechnology materials, products, carbon nanotubes, or pictures regarding nano processes, you can share in the album. The link for the album is http://www.drcetiner.org/photo_gallery/main.php?g2_itemId=19631
Carbon nanotubes (CNTs) are an allotrope of carbon. They take the form of cylindrical carbon molecules and have novel properties that make them potentially useful in a wide variety of applications in nanotechnology, electronics, optics and other fields of materials science. They exhibit extraordinary strength and unique electrical properties, and are efficient conductors of heat. Inorganic nanotubes have also been synthesized.
Nanotubes are members of the fullerene structural family, which also includes buckyballs. Whereas buckyballs are spherical in shape, a nanotube is cylindrical, with at least one end typically capped with a hemisphere of the buckyball structure. Their name is derived from their size, since the diameter of a nanotube is on the order of a few nanometers (approximately 50,000 times smaller than the width of a human hair), while they can be up to several millimeters in length. There are two main types of nanotubes: single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs).
The nature of the bonding of a nanotube is described by applied quantum chemistry, specifically, orbital hybridization. Nanotubes are composed entirely of sp2 bonds, similar to those of graphite. This bonding structure, which is stronger than the sp3 bonds found in diamond, provides the molecules with their unique strength. Nanotubes naturally align themselves into “ropes” held together by Van der Waals forces. Under high pressure, nanotubes can merge together, trading some sp2 bonds for sp3 bonds, giving great possibility for producing strong, unlimited-length wires through high-pressure nanotube linking.
Carbon nanotubes are no longer the proud boast of 21st century materials scientists. It appears their discovery was unwittingly pre-empted by mediaeval Muslim sword-smiths whose tough Damascus blades taught the Crusaders the true meaning of cold steel when they fought over the Holy Land.
Peter Paufler and colleagues at Dresden’s Technical University discovered carbon nanotubes in the microstructure of a 17th century Damascus sabre. Intriguingly, the nanotubes could have encapsulated iron-carbide nanowires that might give clues to the mechanical strength and sharpness of these swords.
To Europeans, Damascus steel blades seemed magical. Not only could they cut a piece of silk in half as it fell to the floor, they could cleave rocks and their own swords without losing sharpness. The problem facing sword smiths was how to produce steel that was both hard and malleable. Too much carbon and the steel is hard and brittle; too little and it is too soft and malleable to hold an edge when sharpened. Damascus steel blades were forged out of small pure cakes of steel containing around 1.6–1.7 per cent carbon, called wootz. Produced in India, wootz cakes were shipped to Damascus where expert sword smiths fashioned them into blades.
Steel that contains this amount of carbon forms plates of cementite (Fe3C) which, on its own, makes the steel brittle. However, during the forging process at around 800oC, small amounts of ‘impurities’ were added containing many first-row transition elements (such as V, Cr, Mn, Co, and Ni), tungsten, and some rare-earths. which together had the effect of forming the cementite into bands. This gave the blades great strength, malleability, and a distinctive wavy-band pattern known as a damask. The skill had been lost by the 18th century, when supplies of these ores and impurities ran out.
Micro-structural examination of the bands had previously shown they contained nanowires of Fe3C. Now, Paufler’s team has uncovered the presence of carbon nanotubes by exposing a small piece of a blade to corrosion by hydrofluoric acid, and examining the effects under a high resolution scanning electron microscope. In some remnants the researchers saw evidence of incompletely dissolved Fe3C nanowires, suggesting the nanotubes could have encapsulated the nanowires. This would not only have given the blades their renowned strength and sharpness, but also their characteristic banding pattern. ‘The nanotubes probably came from the addition of mandatory organic ingredients we know were added during wootz production, such as wood from the tree Cassia auriculata and leaves from Coltropis gigantean,’ said Paufler. ‘So, by empirically optimising their blade-treatment procedures, these craftsmen made nanotubes more than 400 years ago.’
Lionel Milgrom
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According to news, SR12 Million was donated for Nanotechnology Center in our University. You can read the news as follows:-
RIYADH, 25 November 2006 — Custodian of the Two Holy Mosques King Abdullah donated SR36 million to the three leading universities in the Kingdom for research studies in nanotechnology, Higher Education Minister Khaled Al-Anqari said in a statement to the Saudi Press Agency yesterday.
The minister’s statement said, “King Abdullah donated a sum of SR36 million from his personal account for the completion of equipping the sophisticated nanotechnology laboratories at King Abdul Aziz University, King Saud University and King Fahd University for Petroleum and Minerals at the rate of SR12 million for each.”
Al-Anqari said the facilities would serve as the nucleus for the establishment of advanced institutes of nanotechnology in the three universities where Saudi experts will be trained in this new branch of science.
These institutes will chalk out programs for their partnership and cooperation with international institutes in the field besides attracting international experts and researchers.
Taken from Arabnews: http://www.arabnews.com/?page=1§ion=0&article=82773&d=25&m=11&y=2006
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.
New studies of Damascus swords are revealing that the legendary blades contain nanowires, carbon nanotubes, and other extremely small, intricate structures that might explain their unique features.
Damascus swords, first made in the eighth century A.D., are renowned for their complex surface patterns and sharpness. According to legend, the blades can cut a piece of silk in half as it falls to the ground and maintain their edge after cleaving through stone, metal, or even other swords.
But since the techniques for making these swords have been lost for hundreds of years, no one is sure exactly why these swords are so exceptional.
Now studies of the swords’ molecular structure are uncovering the tiny structures that may explain these properties.
Peter Paufler, a crystallographer at Technical University in Dresden, Germany, and his colleagues had previously found tiny nanowires and nanotubes when they used an electron microscope to examine samples from a Damascus blade made in the 17th century.
Today in the journal Nature, the teams reports that it has also discovered carbon nanotubes in the sword—the first nanotubes ever found in steel, Paufler says.
Figure Nanotubes
The nanotubes, which are remarkably strong, run through the blade’s softer steel, likely making it more resilient. (Related: “Nano-Switches Could Yield Even Smaller Gadgets” [August 16, 2005].)
“It is a general principle of nature,” Paufler said. “Materials that are softer, you can strengthen by including harder wires.”
Secret Techniques
Some of the nanowires Paufler and his team had previously found were made of an extremely hard iron-based mineral called cementite.
In the new research, the team discovered that carbon nanotubes encase some cementite nanowires, protecting them.
These nanotube-nanowire bundles may give the swords their special properties, Paufler says.
The bundles run parallel to the blade’s surface and may help larger particles of cementite arrange in layers. These hard layers, which have softer steel in between, could help explain how the steel remains strong yet flexible.
This combination of strength and flexibility makes the steel ideal for forging swords.
The blades were generally made from metal ingots prepared in India using special recipes, which probably put just the right amount of carbon and other impurities into the iron (India map).
By following these recipes and following specific forging techniques, “craftsmen ended up making nanotubes more than 400 years ago,” Paufler and his colleagues write.
When these blades were nearly finished, blacksmiths would etch them with acid. This brought out the wavy light and dark lines that make Damascus swords easy to recognize.
But it could also give the swords their sharpness, Paufler says. Because carbon nanotubes are resistant to acid, they would protect the nanowires, he theorizes.
After etching, many of these nanostructures could stick out from the blade’s edge, giving it tiny saw-like teeth.
Skeptical Smiths
The techniques for making the steel were lost around A.D. 1700. But many researchers are studying how to recreate the blades—even though metallurgical experts warn that the blades, though exceptional for their time, are far outperformed by modern steels.
While some scientists have claimed success, others dispute that the reproductions are truly the same as the originals.
And many experts doubt that the new findings will clear things up.
John Verhoeven, a metallurgist at Iowa State University at Ames who has worked on reproducing the Damascus sword-making techniques, is skeptical that Paufler and his colleagues have cracked the secret of Damascus blades.
“I don’t think that [the nanowires] are anything unusual,” Verhoeven said. “I think those structures would be found in normal steels.”
The Damascus sword is also an example of how unexpected nanosize structures can show up in materials—and sometimes give them surprising properties, experts say.
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