Mystery of Delhi's Iron Pillar unraveled

Press Trust of India ^ | Sunday, July 21, 2002 | Editorial Staff

[vannrox]

Nation

Monday, July 22, 2002

Mystery of Delhi's Iron Pillar unraveled

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.

[RightWhale]

One of the major buildings in downtown Pittsburgh was made of something like this. It was born rusted but wouldn't rust further. Particles of rust flaked off and got in the eyes of pedestrians, so there were or are complaints.

[AdmSmith]

Misawite is probably a local name, you will get better results if you search for Ferroxyhyte or Feroxyhite i.e. the common name for δ-FeOOH. (δ is the Greek letter delta)

[mugs99]

Is this just ancient "rust blueing" as on fine, vintage firearms?

That, and they probably used a little copper in their brine when they wraped it.

[skepsel]

"Rust Bluing" ? Is that anything like case hardening steel in an oil bath?

[skepsel]

Maybe it was covered in "Motel of the Mysteries"?

[William Terrell]

Maybe a mispelling of miascite

(n.) A granitoid rock containing feldspar, biotite, elaeolite, and sodalite

[gcruse]

540 AD is the date of the cataclismic start of the worldwide Dark Ages. (I wonder if they are related?)

Possibly.  Things rust more slowly in the dark, due to slowing interstitial migration of oxygen ions through the iron molecular lattice.  And yes, I am a metallurgist.  I mean, no I'm not.

[gcruse]

I loved that book.

[PoorMuttly]

Rust blueing is simply letting the metal get a fine coating of rust, "carding" it off gently, then repeating until a brown finish is there...and it seems to resist more rust somehow. Well, more or less. Looks nice, though.

[PoorMuttly]

Fascinating stuff.

[aruanan]

Rust blueing is simply letting the metal get a fine coating of rust, "carding" it off gently, then repeating until a brown finish is there...and it seems to resist more rust somehow. Well, more or less. Looks nice, though.

Wish I could do this on my truck.

[PoorMuttly]

It seems to have worked pretty well, but would certainly take a long time to do on a truck, and I'm not sure the effect of rusting it would be good for the rest of it! You'd really have to love your truck to do all that work, or have no other life worth attending to!

It may have been popularized by the "Brown Bess" in more modern times, but was used by some knights on their chain mail....the Black Knight sort of thing.

Modern finishes are a great improvement, but it certainly is perhaps the best looking firearms finish there is.

[Casloy]

Why is a two year old article breaking news?

[mugs99]

Fascinating stuff

It sure is. My neighbor was a machinist at RCBS and restored antique firearms for a hobby.
I bought a Kentucky flintlock kit and he browned it for me. It is beautiful!

[SunkenCiv]

Just updating the GGG information, not sending a general distribution.

Please ping me to other topics which are appropriate for the GGG list. Thanks.

Please FREEPMAIL me if you want on, off, or alter the "Gods, Graves, Glyphs" PING list --
Archaeology/Anthropology/Ancient Cultures/Artifacts/Antiquities, etc.
The GGG Digest -- Gods, Graves, Glyphs (alpha order)

[Cultural Jihad]

[vannrox]

THE IRON pillar near Qutub Minar at New Delhi is in the news, thanks to the research by Prof. R. Balasubramaniam of IIT, Kanpur and his team of metallurgists. The pillar is said to be 1,600 years old.

A protective layer of `misawite' — a compound made up of iron, oxygen and hydrogen on the steel pillar, which is said to contain phosphorus - is claimed as the reason for the non-corrosive existence.

The ab-initio layer of misawite is supposed to have developed three years after the pillar was erected. It is claimed that the layer has increased in thickness ever since. In a millennium and a half, it is calculated that this layer has grown to a thickness of 50 micron.

Presence of Phosphorus in this ancient iron — about one per cent — is due to the smelting process of iron ore using charcoal, discovered then, in this country. The pillar is dated back to the Gupta Dynasty between 320 A D and 540 A D. In comparison, modern day smelting process yields steel with only 0.05 per cent of phosphorus in it.

Dr Baldev Raj, director, Materials, Chemical and Reprocessing Groups, Indira Gandhi Centre for Atomic Research, Kalpakkam feels that this claim could be `one' of the reasons for the eternal appearance of the pillar — it needs to be confirmed. Development of such a coat at room temperature is questionable, according to him. He mentions that discoloration or multi-coloration has occurred on the outer surface of the pillar — patches of brown, blue, green and light brown are visible to his eyes. He uses a graphical display to pinpoint differing electrical potential — from the top to the bottom at different points — on the outer surface of the pillar in issue. If this is so, the layer of `misowite' which is said to be evenly spread needs to be debated. With differing potential difference along the outer surface, can a layer such as this, be even? He agrees to a suggestion that this product of technology in metallurgy cannot be a custom made one to be unique. Baldev Raj is involved in producing corrosion resistive containers for irradiating substances used in nuclear plants. For the 500 mega watt fast breeder reactor at Kalpakkam, corrosion resistant stainless steel is under study to replace carbon steel pipes. Corrosion conditions at the outer surface of materials are often totally different to that of the bulk of material, says Baldev Raj.

In this context, nano materials, where the grain size of the particle is 100 nano metres or less, can be interesting. It is well known that the physical properties of nano materials correspond neither to those of the free atoms and molecules that make up the particle, nor to those of the bulk solid of the same composition. Material made of nano powder exhibits much harder property against deformation too.

This awakens one to study nano powder of metals like steel — perhaps with phosphorus molecules — to nano-coat the surface of a steel column. This may be a solution to delay corrosion of steel. A hypothetical — almost bordering on fantasy — postulate is, whether any similar process was used on this iron pillar of Gupta period.B. G. Prakash

[Aliska]

A google search on the term 'misawite' yields only two hits

I just tried it and got pages and pages of hits on "misawite".

[chuknospam]

Neat

[BureaucratusMaximus]

Its really embarrassing when my iron pillar becomes unraveled.

That is all.

(cmon...someone had to say it)