The Iron Pillar in Delhi has attracted the attention of archaeologists and metallurgists from all over the world for years. This marvelous structure has withstood corrosion for the last 1600 years, despite harsh weather conditions. The pillar is a testament to the high level of skill achieved by ancient Indian architects in the extraction and processing of iron. Made up of 98% wrought iron of pure quality, it is 23 feet 8 inches high and has a diameter of 16 inches.
Experts at the IIT Kanpur ( Indian Institute of Technology, Kanpur) resolved the mystery behind the 1600-year-old iron pillar in the year 2002*. Metallurgists at IIT Kanpur have discovered that a thin layer of 'miswrite'-a compound of iron, oxygen, and hydrogen- has protected the cast iron pillar from rust. The protective film took form within three years after the erection of the pillar and has been growing ever so slowly since then. After 1600 years, the film has grown just one-twentieth of a millimeter thick. The protective layer was formed with the presence of a high amount of phosphorus that acted as a catalyst. It was a unique iron-making process practiced by ancient ironsmiths in India who reduced iron into steel in one step by mixing it with charcoal. Modern blast furnaces, on the other hand, use limestone in place of charcoal yielding molten slag and pig iron that is later converted into steel. In the process, most phosphorus content is carried away by the slag.
The pillar, almost seven meters high and weighing more than six tonnes, was erected by Chandragupta II Vikramaditya (375-414 CE) of the Gupta dynasty that ruled northern India during 320-540 CE.
The Iron Pillar of Delhi Photos
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| The Iron Pillar of Delhi |
The Iron Pillar at Delhi (Birla Academy Monographs on the Cultural, Scientific, and Technological Heritage of India, No. 1) Hardcover – Import, 1 December 1995
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