iron piller

The iron pillar of Delhi, India, is a 7 m (23 ft) high pillar in the Qutb complex, notable for the composition of the metals used in its construction.
The pillar, which weighs more than six tons, is said to have been fashioned at the time of Chandragupta Vikramaditya (375–413) of the Gupta Empire,[1] though other authorities give dates as early as 912 BCE.[2] The pillar initially stood in the center of a Jain temple complex housing twenty-seven temples that were destroyed by Qutb-ud-din Aybak, and their material was used in building the Quwwat-ul-Islam mosque and the Qutub Minar complex where the pillar stands today.[3]
The pillar has attracted the attention of archaeologists and metallurgists and has been called "a testament to the skill of ancient Indian blacksmiths" because of its high resistance to corrosion,[4] due to both the Delhi environment providing alternate wetting and drying conditions, and iron with high phosphorus content conferring protection by the formation of an even layer of crystalline iron hydrogen phosphate.[5]
The name of the city of Delhi is thought to be based on a legend associated with the pillar (see History of Delhi).
Contents [hide]
1 Description
2 Scientific analysis
3 See also
4 References
5 Further reading
6 External links
[edit]Description



Detail showing the inscription


The Iron pillar stands within the courtyard of Quwwat-ul-Islam Mosque


Text and translation of the inscription in English at the site
The height of the pillar, from the top of its capital to the bottom of its base, is 23 ft 8 in (7.21 m), 3 ft 8 in (1.12 m) of which is below ground. Its bell pattern capital is 3 ft 6 in (1.07 m) in height, and its bulb-shaped base is 2 ft 4 in (0.71 m) high. The base rests on a grid of iron bars soldered with lead into the upper layer of the dressed stone pavement. The pillar's lower diameter is 16.4 in (420 mm), and its upper diameter 12.05 in (306 mm). The bell pattern capital is 3 ft 6 in (1.07 m) high. It is estimated to weigh more than six tons.[6]
The pillar was erected by Chandragupta Vikramaditya (375 CE–414 CE), (interpretation based on analysis of archer-type Gupta gold coins) of the Gupta dynasty that ruled northern India 320–540.[7] The pillar, with the statue of Chakra at the top, was originally located at a place called Vishnupadagiri (meaning "hill with footprint of Lord Vishnu").[8] This has been identified as modern Udayagiri, situated in the vicinity of Vidisha, Madhya Pradesh. There are several aspects to the original site of the pillar at Udayagiri. Vishnupadagiri is located on the Tropic of Cancer and, therefore, was a centre of astronomical studies during the Gupta period. The iron pillar served as a sundial when it was originally at Vishnupadagiri. The early-morning shadow of the iron pillar fell in the direction of the foot of Anantasayin Vishnu (in one of the panels at Udayagiri) only around the summer solstice (June 21). The Udayagiri site in general, and the iron pillar location in particular, are evidence for the astronomical knowledge that existed in Gupta India.
The pillar bears a Sanskrit inscription in Brahmi script,[9] which states that it was erected as a standard in honour of Lord Vishnu. It also praises the valor and qualities of a king referred to simply as Chandra, who has been identified with the Gupta King Chandragupta Vikramaditya (375-413). The inscription reads (in the translation given in the tablets erected by Pandit Banke Rai in 1903):
He, on whose arm fame was inscribed by the sword, when, in battle in the Vanga countries (Bengal), he kneaded (and turned) back with (his) breast the enemies who, uniting together, came against (him);-he, by whom, having crossed in warfare the seven mouths of the (river) Sindhu, the Vahlikas were conquered;-he, by the breezes of whose prowess the southern ocean is even still perfumed;-
(Line 3.)-He, the remnant of the great zeal of whose energy, which utterly destroyed (his) enemies, like (the remnant of the great glowing heat) of a burned-out fire in a great forest, even now leaves not the earth; though he, the king, as if wearied, has quit this earth, and has gone to the other world, moving in (bodily) from to the land (of paradise) won by (the merit of his) actions, (but) remaining on (this) earth by (the memory of his) fame;-
(L. 5.)-By him, the king,-who attained sole supreme sovereignty in the world, acquired by his own arm and (enjoyed) for a very long time; (and) who, having the name of Chandra, carried a beauty of countenance like (the beauty of) the full-moon,-having in faith fixed his mind upon (the god) Vishnu, this lofty standard of the divine Vishnu was set up on the hill (called) Vishnupada.
It is believed by some that the pillar was installed in its current location by Vigraha Raja, the ruling Tomar king.[10] One of the inscriptions on the iron pillar from A.D. 1052 mentions Tomara king Anangpal II.[11]
A fence was erected around the pillar in 1997 in response to damage caused by visitors. There is a popular tradition that it was considered good luck if one could stand with one's back to the pillar and make one's hands meet behind it.
[edit]Scientific analysis

The pillar was manufactured by forge welding and is composed of 98% pure wrought iron, is 7.21 m (23 feet 8 inches) high, with 93 cm (36.6 inches) buried below the present floor level,[12] and has a diameter of 41 cm (16 inches) at the bottom, which tapers towards the upper end.


Details of the top of iron pillar, Qutub Minar, Delhi.
In a report published in the journal Current Science, R. Balasubramaniam of the IIT Kanpur explains how the pillar's resistance to corrosion is due to a passive protective film at the iron-rust interface. The presence of second-phase particles (slag and unreduced iron oxides) in the microstructure of the iron, that of high amounts of phosphorus in the metal, and the alternate wetting and drying existing under atmospheric conditions are the three main factors in the three-stage formation of that protective passive film.[13]
Lepidocrocite and goethite are the first amorphous iron oxyhydroxides that appear upon oxidation of iron. High corrosion rates are initially observed. Then, an essential chemical reaction intervenes: slag and unreduced iron oxides (second phase particles) in the iron microstructure alter the polarization characteristics and enrich the metal–scale interface with phosphorus, thus indirectly promoting passivation of the iron[14] (cessation of rusting activity). The second-phase particles act as a cathode, and the metal itself serves as anode, for a mini-galvanic corrosion reaction during environment exposure. Part of the initial iron oxyhydroxides is also transformed into magnetite, which somewhat slows down the process of corrosion. The ongoing reduction of lepidocrocite and the diffusion of oxygen and complementary corrosion through the cracks and pores in the rust still contribute to the corrosion mechanism from atmospheric conditions.
The next main agent to intervene in protection from oxidation is phosphorus, enhanced at the metal–scale interface by the same chemical interaction previously described between the slags and the metal. The ancient Indian smiths did not add lime to their furnaces. The use of limestone as in modern blast furnaces yields pig iron that is later converted into steel; in the process, most phosphorus is carried away by the slag.[15] The absence of lime in the slag and the deliberate use of specific quantities of wood with high phosphorus content (for example, Cassia auriculata) during the smelting induces a higher phosphorus content (> 0.1%, average 0.25%) than in modern iron produced in blast furnaces (usually less than 0.05%). One analysis gives 0.10% in the slags for 0.18% in the iron itself. This high phosphorus content and particular repartition are essential catalysts in the formation of a passive protective film of misawite (d-FeOOH), an amorphous iron oxyhydroxide that forms a barrier by adhering next to the interface between metal and rust. Misawite, the initial corrosion-resistance agent, was thus named because of the pioneering studies of Misawa and co-workers on the effects of phosphorus and copper and those of alternating atmospheric conditions in rust formation.[16]
The most critical corrosion-resistance agent is iron hydrogen phosphate hydrate (FePO4-H3PO4-4H2O) under its crystalline form and building up as a thin layer next to the interface between metal and rust. Rust initially contains iron oxide/oxyhydroxides in their amorphous forms. Due to the initial corrosion of metal, there is more phosphorus at the metal–scale interface than in the bulk of the metal. Alternate environmental wetting and drying cycles provide the moisture for phosphoric-acid formation. Over time, the amorphous phosphate is precipitated into its crystalline form (the latter being therefore an indicator of old age, as this precipitation is a rather slow happening). The crystalline phosphate eventually forms a continuous layer next to the metal, which results in an excellent corrosion resistance layer.[5] In 1,600 years, the film has grown just one-twentieth of a millimetre thick.[14]
Balasubramaniam states that the pillar is "a living testimony to the skill of metallurgists of ancient India". An interview with Balasubramaniam and his work can be seen in the 2005 article by Veazy.[17] Further research published in 2009 showed that corrosion has developed evenly over the surface of the pillar.[18]
It was claimed in the 1920s that iron manufactured in Mirjati near Jamshedpur is similar to the iron of the Delhi pillar.[19] Further work on Adivasi (tribal) iron by the National Metallurgical Laboratory in the 1960s did not verify this claim
Standing at the center of the Quwwatul Mosque the Iron Pillar is one of Delhi's most curious structures. Dating back to 4th century A.D., the pillar bears an inscription which states that it was erected as a flagstaff in honour of the Hindu god, Vishnu, and in the memory of the Gupta King Chandragupta II (375-413). How the pillar moved to its present location remains a mystery. The pillar also highlights ancient India's achievements in metallurgy. The pillar is made of 98 per cent wrought iron and has stood 1,600 years without rusting or decomposing.



The Iron Pillar from Delhi
7.3 m tall, with one meter below the ground; the diameter is 48 centimeters at the foot, tapering to 29 cm at the top, just below the base of the wonderfully crafted capital; it weighs approximately 6.5 tones, and was manufactured by forged welding.

Enigma of the Iron Pillar

B.N. Goswamy

The sight is so familiar: each time you are in the vicinity of the Qutab Minar in Delhi, you find groups of tourists gathered around a tall, sleekly tapering iron pillar in that complex, one person from the group standing with his or her back firmly against it, and trying to make the fingers of the two hands touch while holding the pillar in embrace. Very few succeed but, almost always, there is a feeling of merriment around, since terms are set within the group and each person is 'tested', as it were, for fidelity or truthfulness or loyalty, even longevity, it could be anything. When a person fails to make the contact between the fingers of the two hands wrapped around the pillar, squeals of delight go up. This has gone on for years, certainly ever since tourist guides came into being.





The Iron Pillar at Delhi seen through an arch.




The Iron Pillar dates from Gupta King,
who ruled from 375 - 413 AD

Barely anyone from these thronging groups of tourists, however, cares to find out the history of this pillar, or knows that it has been something of a riddle for people—historians, archaeologists, palaeographers, metallurgists, etc—for close to a century and a half. The pillar is now located in Delhi, although one knows almost for certain that it was moved to that place from somewhere in Madhya Pradesh about a thousand years ago. But, somehow, in my own mind, it has come to be associated also with Shimla. For that is where I have been hearing of it mostly of late.
When I was there last year, at the Indian Institute of Advanced Study(IIAS), a series of lectures on the Iron Pillar were being delivered by a visiting scholar, a well-known metallurgist, Prof R. Balasubramaniam of the IIT, Kanpur. This year again, when I was in Shimla, the pillar came up, for the institute had brought out a finely detailed publication based on that series of lectures, under the title, "The Delhi Iron Pillar: New Insights." Like last year, however, a debate about the points made in the book ensued again, for there were, and are, scholars at the institute who hold other opinions on the points raised in the book. Each serious study that appears—and Professor Balasubramaniam's is certainly one—adds to the scholarship on this theme, and extends the field further. But nothing, it seems, is finally settled.



Inscription on the rust resilient Iron Pillar from Delhi

Some physical facts about the pillar are reasonably well-established: it is 7.3 metres tall, with one metre below the ground; the diameter is 48 centimetres at the foot, tapering to 29 cm at the top, just below the base of the wonderfully crafted capital; it weighs approximately 6.5 tonnes, and was manufactured by forged welding. But, this said, nearly everything else about the pillar is surrounded by acute controversy: For whom was it made? Exactly when? Where did it originally stand before it was moved to Delhi? What is the true import of the long inscription in Brahmi characters engraved upon it? Who placed the later inscriptions on it, and when? Who had the pillar moved to its present location, and why? What exact processes were followed in forging it into shape at that early a point of time, the 4th/5th century AD? Above all, from the scientists' point of view, what is the secret, the great mystery, behind the fact of its being virtually non-rusting? There seems to be no end to the questions.

Take the case of the Brahmi inscription alone. Readings of this six-line, three-stanza inscription in Sanskrit verse vary considerably, the one most often published being that by Fleet, who translated it in 1888. It speaks, in very poetic terms, of the powerful, all-conquering monarch who had the pillar made: "He on whose arm fame was inscribed by the sword, when in battle in the Vanga countries, he kneaded (and turned) back with (his) breast the enemies who, uniting together, came against him; … he, by the breezes of whose prowess the southern ocean is even still perfumed." But, this eloquent panegyric apart, when it comes to identifying the king with clarity, and giving further details about the erection of the pillar, the inscription suddenly leaves some questions unanswered: obviously, not for those who lived in those early times, but for later generations, for whom so much information was lost in the centuries that have gone by.

Thus, the verse concludes with the words: "He who, having the name of Chandra, carried a beauty of countenance like (the beauty of) the full moon, having in faith fixed his mind upon (the God) Vishnu, (had) this lofty standard of the divine Vishnu set up on the hill (called) Vishnupada." But who exactly was king Chandra remains a puzzle. On other grounds, historical or palaeographic, it can be concluded that the pillar belongs to the Gupta period, but, from among the imperial Guptas, who is it that is referred to here simply by the name of 'Chandra': Chandragupta I, Chandragupta II, also celebrated as Vikramaditya, or, as some firmly believe, Samudragupta? Again, the Guptas were known to have been devotees of Lord Vishnu, but where was this hill called 'Vishnupada' located?

Questions like these are, however, only a relatively simple sample of the issues that centre on the great pillar. There are others, very complex ones, that have engaged the minds of scholars. Prof Balasubramaniam addresses them in his inquiry without once losing sight of the sheer elegance of the pillar, especially of its exquisitely made capital atop which a figure of Garuda, the ' Sun-bird ', who is the vahana of Vishnu, or a chakra, the discus that is his emblem, might once have stood. There are long and detailed chapters on the structural features of the pillar, the methodology of its manufacture, a general inquiry into other large iron objects in ancient India, including the iron pillars in Dhar and Mandu in Madhya Pradesh, Mount Abu in Rajasthan, the Kodachadri Hill in Karnataka. But, understandably, the most densely argued chapter is on the corrosion-resistant nature of this iron pillar, the P-content and the S-content of the low carbon mild steel of which it is made, the process of rust protection, the colour of whatever rust there is, spectroscopic analyses, are all themes, something that has led to its being widely regarded as a 'miracle' of technology, given the times in which the pillar was forged and erected.

With all this, however, will the whole clutch of issues addressed in the book get finally settled, one might ask? I doubt it. But then this is the way it should be; this is how scholarship proceeds.

Corrosion, of a different kind
I was very taken up with a saying of the Buddha, cited from the Dhammapada, which serves as an epigraph at the beginning of the book. This is how it runs:
"As rust, sprung from iron, eats itself away when arisen, even so his own deeds lead the transgressor to states of woe…."



Source: http://www.tribuneindia.com/2002/20020714/spectrum/art.htm
Mystery of Delhi's Iron Pillar unraveled

New Delhi, July 18: Experts at the Indian Institute of 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.