Centuries-old Indian Pillar Gives Model for Nuclear Storage

Iron Asoka pillar protected from rust by ancient Indian metallurgy with high phosphorous content...

Published: 10-Oct-2004

lign=justify>Kanpur, Oct 9 (IANS) Metallurgists here believe the metallurgy behind a 1,600-year-old iron pillar in New Delhi that has never corroded could be used to develop containers for storing nuclear materials.

According to the Current Science journal, experts at the Indian Institute of Technology here have found that a thin layer of "misawite" - a compound of iron, oxygen and hydrogen - protected the cast iron Asoka pillar near the historic Qutub Minar from rust for centuries.

The metallurgy could be used to develop a model for containers used to store nuclear materials, they said.

"The protective film had formed due to the presence of high amounts of phosphorous in the iron - as much as one percent, against less than 0.05 percent in today's iron," said R. Balasubramaniam, a professor at the Indian Institute of Technology.

The high phosphorous content was a result of the unique iron-making process practiced by ancient Indians, he said.

The reduced iron ore was converted into steel in one step by mixing it with charcoal, whereas modern blast furnaces use limestone in place of charcoal, he said.

Calling the pillar "a living testimony to the skill of metallurgists of ancient India", Balasubramaniam said a new "kinetic scheme" had now been developed by his group for predicting growth of the protective film that prevents rusting of iron.

This could be useful for modelling long-term corrosion behaviour of nuclear storage containers.

The pillar, over seven metres high and weighing more than six tonnes, was erected by Kumara Gupta of the Gupta dynasty that ruled northern India in AD 320-540.

According to the metallurgists, the protective film that took form within three years after erection of the pillar has been growing ever so slowly, that even after 1,600 years, the film is just one-20th of a millimetre thick.

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