Posted on 03/13/2005 1:55:06 PM PST by blam
Mystery of Delhi's Iron Pillar unraveled
Press Trust Of India
Thursday, July 18, 2002
New Delhi, July 18: Experts at the Indian Instituteof Technology have resolved the mystery behind the 1,600-year-old iron pillar in Delhi, which has never corroded despite the capital's harsh weather.
Metallurgists at Kanpur IIT have discovered that a thin layer of "misawite", a compound of iron, oxygen and hydrogen, has protected the cast iron pillar from rust.
The protective film took form within three years after erection of the pillar and has been growing ever so slowly since then. After 1,600 years, the film has grown just one-twentieth of a millimeter thick, according to R. Balasubramaniam of the IIT.
In a report published in the journal Current Science Balasubramanian says, the protective film was formed catalytically by the presence of high amounts of phosphorous in the iron—as much as one per cent against less than 0.05 per cent in today's iron.
The high phosphorous content is a result of the unique iron-making process practiced by ancient Indians, who reduced iron ore 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 modern process most phosphorous is carried away by the slag.
The pillar—over seven metres high and weighing more than six tonnes—was erected by Kumara Gupta of Gupta dynasty that ruled northern India in AD 320-540.
Stating that the pillar is "a living testimony to the skill of metallurgists of ancient India", Balasubramaniam said the "kinetic scheme" that his group developed for predicting growth of the protective film may be useful for modeling long-term corrosion behaviour of containers for nuclear storage applications.
. Have you ever been to the Ornamental Metal Museum in Memphis, Tn?
Yes, several times, went to see Jim Wallace.
I got my start from knowing Alex Bealer, a great guy
and the man who did the most to bring blacksmithing
back in this country.
I helped found ABANA, and was a member of Tullie Smith
Blacksmith Guild and the Alabama Forge Council.
I did some knife making a long time ago, do you know
Jim Batson, Cleston Sinyard?
Went to the knife show here in Atlanta last year, sure
are some talented folks doing great work now.
Thanx for the info.Phosphorus is the key.I've heard of this pillar before,and the non-corrosive properties were mentioned but no explanation as to why.Mystery solved.
Me too [*LOL*].
If I remember the stories correctly, the people were fully aware of the problem because they had this stuff raining on them continually. I think that the company eventually put a clear coating over the exposed Cor-Ten. The coating made the steel appear to be just what was orginally designed, but it prevented further oxidation and the subsequent rain of rust particles.
Bill
I got a similiar story from my father. He was a coal miner. He said that he once had a copper coal chisel that had been made by a Cherokee Indian miner. He told me that the process had involved p*ssing on it during the tempering process.
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Gods |
Just updating the GGG info, not sending a general distribution. |
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