<abstract xmlns="http://www.w3.org/1999/xhtml"><p>This investigation deals with the chemical composition and microstructural analysis of the iron object, a spear excavated from Sanur, Tamil Nadu- a megalithic site dated 300 B.C. to 50 A.D. Phase analysis and microstructural examination were carried using XRD, optical and variable pressure scanning electron microscope (VP-SEM). Optical micrograph shows the equiaxed grain structure along with the Newman bands. Formation of Newman bands suggests that the original artifact was forged at high temperature followed by cooling, although not so rapid to produce the marked hardening. The absence of carbides at the grain boundary, within the grains and lower value of micro-hardness indicates that the iron spear was not subjected to the carburizing treatment. Results of corrosion characterization revealed that deterioration of excavated iron artifact is associated with the presence of chlorine in corrosion products. However, <italic>compact nature of the outer rust (goethite) was helpful in protecting the object. The formation of goethite [ ∝-FeOOH] layer may prevent the iron matrix suffering from attacks by other environmental factors due to its good continuity. In addition, less aerated environment of storage and no history of any cleaning of object were also helpful in preventing the iron spear from further deterioration.</italic></p></abstract>

This investigation deals with the chemical composition and microstructural analysis of the iron object, a spear excavated from Sanur, Tamil Nadu- a megalithic site dated 300 B.C. to 50 A.D. Phase analysis and microstructural examination were carried using XRD, optical and variable pressure scanning electron microscope (VP-SEM). Optical micrograph shows the equiaxed grain structure along with the Newman bands. Formation of Newman bands suggests that the original artifact was forged at high temperature followed by cooling, although not so rapid to produce the marked hardening. The absence of carbides at the grain boundary, within the grains and lower value of micro-hardness indicates that the iron spear was not subjected to the carburizing treatment. Results of corrosion characterization revealed that deterioration of excavated iron artifact is associated with the presence of chlorine in corrosion products. However, compact nature of the outer rust (goethite) was helpful in protecting the object. The formation of goethite [ ∝-FeOOH] layer may prevent the iron matrix suffering from attacks by other environmental factors due to its good continuity. In addition, less aerated environment of storage and no history of any cleaning of object were also helpful in preventing the iron spear from further deterioration.

Characterization of Corrosion Behavior of Archaeological Iron Spear from Sanur (300 BC – 50 AD) – A Megalithic Site in Southern India

National Research Laboratory for Conservation of Cultural Property

Acta Chemica Malaysia

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

This investigation deals with the chemical composition and microstructural analysis of the iron object, a spear excavated from Sanur, Tamil Nadu- a megalithic...

Characterization of Corrosion Behavior of Archaeological Iron Spear from Sanur (300 BC – 50 AD) – A Megalithic Site in Southern India

Published Online: Feb 24, 2020

Page range: 21 - 28

DOI: https://doi.org/10.2478/acmy-2019-0003

Keywords
Megalithic iron, Sanur, Slag inclusion, Goethite, Carburization

© 2019 Vandana Singh et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Characterization of Corrosion Behavior of Archaeological Iron Spear from Sanur (300 BC – 50 AD) – A Megalithic Site in Southern India

Published Online: Feb 24, 2020

Page range: 21 - 28

DOI: https://doi.org/10.2478/acmy-2019-0003

KeywordsMegalithic iron, Sanur, Slag inclusion, Goethite, Carburization

© 2019 Vandana Singh et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
Megalithic iron, Sanur, Slag inclusion, Goethite, Carburization