Iron pillar of Delhi
The Iron pillar in Delhi (India) is one of the oldest monuments of metal worldwide. She has been about 700 to 1000 years in the Qutb complex in the south of the city; but its history goes back even further: it is sometimes referred to as Ashoka Pillar, but a Sanskrit inscription with the name Chandra and the naming of the Hindu god Vishnu she puts in the time of the Gupta emperor Chandragupta II.
Description
The Iron pillar is 98 % pure wrought iron, is 7.21 m high (of which 1.12 m in the soil), 6.5 t and has at its lower end with a diameter of 42 cm which is slightly on the upward direction about 30 cm decreases. At its head is a sleek, multi- structured and 1.75 m high capital, which formerly by a wheel ( chakra ), an attribute of Vishnu, or a standing or kneeling Garuda figure may have been crowned, the latest in the Islamic period was melted.
Production
The Iron pillar is 98 % wrought iron of pure quality, a sign of the strong expertise that had gained the early Indian iron smiths in the extraction and processing of iron. Because of their high resistance to weathering and lack of corrosion in the past 1600 years, it has attracted the interest of archaeologists and metallurgists (see below). The Iron Pillar was probably not molded, but is produced by the method of hammer welding. The temperatures required of about 1200 ° C can be achieved by burning charcoal under continuous supply of oxygen.
History
The Iron Pillar was probably commissioned by the Gupta emperor Chandragupta II (r. 375-414 AD), who was known as Vikramaditya and was considered a great devotee of the Hindu god Vishnu, in the heyday of the Gupta dynasty built - this interpretation is based on the inscription and on analyzes of old gold coins from the Gupta Empire.
The column with the chakra idol on its tip was originally set up at a place that Vishnupadagiri ( " hill with footprint of Vishnu " ) was called. This place was equated with the cave temples of Udayagiri near Sanchi. A ( later? ) Mounted on the pillar inscription states that it was erected in honor of the Hindu god Vishnu. Furthermore, the heroism and the quality of a king known as Chandra are praised, which is equated by the recent archaeological research with Chandragupta II.
Vishnupadagiri lies on the Tropic of Cancer and was therefore in the Gupta era possibly an astronomical observatory. At the original location of the iron pillar in Vishnupadagiri the pillars shadow fell once in the early morning during the summer solstice ( June 21) in the direction of the foot of Anantasayain Vishnu. The creation and development of Udayagiri was apparently accompanied by a highly developed astronomical knowledge, which is why Udayagiri and in particular the Iron Pillar are persuasive evidence for the astronomical knowledge in ancient India around 400 AD.
If the original site Udayagiri agree, the column must (probably in the early 13th century Qutb -ud -Din Aibak and his son and successor Iltutmish ) in the Middle Ages as a trophy in the former Hindu temple in the area of the 8th century by the have been spent Tomara Rajput, founded in the 12th century and enlarged by the Chauhans fortress " Lal Kot ". Temple and fortress were destroyed at the end of the 12th century by Qutb -ud -Din Aibak to build at this point the mosque tower Qutub Minar and Quwwat -ul -Islam, the Mosque. The Iron Pillar was erected in the courtyard.
Metallurgical investigations
Claim metallurgists from the IIT Kanpur that a thin layer of " Misawite " - has kept the Iron Pillar against corrosion - a special lattice structure of iron hydroxide. In their view, the protective layer spread within three years after the establishment of the column and is growing slowly since then. This information was erroneously attributed by the media in circulation, based on an article in the journal Current Science. In this article it is mentioned that the protective film (according to R. Balasubramaniam of IIT Kanpur ) in the 1600s was only 1/ 20 mm thick. In another report, the Current Science Balasubramaniam is believed that the protective film is catalyzed by the presence of a high phosphorus content in iron - the phosphorus content in the iron of the pillar is one percent as opposed to 0.05 percent in the present iron.
There are three known procedures that explain the protective layer, two of which are explained below:
According to a statement by the high phosphorus content could result from the way how the early Indians manufactured iron by reducing iron ore using charcoal as a reducing agent in iron with low carbon content at a stable rate of reduction. Modern blast furnaces used coke instead of charcoal and limestone addition in order to produce steel later with the hot metal can. In modern process the majority of the phosphor is removed with the slag resulting from the limestone. Because no lime has been used in ancient blast, was a higher amount of phosphorus contained in the material.
A further possibility is that the column can resist the grate due to its thickness, which allows the sun, during the day, the column of heating so that the entire rain or dew evaporates from its surface. The accumulated heat could also keep the surface in this way dry at night.
For a detailed account of all relevant theories on the corrosion resistance of the pillar in Delhi, the article by Balasubramaniam in Corrosion Science can serve as the source.
In the 1920s, it was claimed that the iron produced was similar to the iron of the Iron pillar in Mirjati near Jamshedpur. Further research of the National Metallurgical Laboratory at ( tribal associated) Advasi - iron did not confirm this claim.
Others
In popular belief, it is claimed that one who stands with his back against the iron pillar, it includes backward with the hands and the fingertips touch each other, should have much luck. After various damage but a fence around the Iron Pillar was erected in 1997.