Over the last 40 years, there has been a discernible increase in the number of scholars who have focused their research on early industrial organizations, a fi eld of study that has come to be known as Archaeotechnology. Archaeologists have conducted fi eldwork geared to the study of ancient technologies in a cultural context and have drawn on the laboratory analyses developed by materials scientists as one portion of their interpretive program. Papers for this department are solicited and/or reviewed by Michael Notis, a professor and director of the Archaeometallurgy Laboratory (www.Lehigh.edu/~inarcmet) at Lehigh University.In this article, metallurgical aspects of a 17th century forge-welded iron cannon at Thanjavur are addressed, including an analysis of manufacturing methodology based on careful observation of its constructional details. Microstructural examination of iron from the cannon reveals that the iron was extracted from ore by the direct process. Thus, the cannon was fabricated by forge welding and not by casting. Electrochemical polarization studies indicate that the corrosion rate of the cannon iron can be compared to that of 0.05% carbon mild steel under complete immersion conditions. However, the atmospheric corrosion resistance of the cannon is far superior to that of modern steel and can be attributed to the formation of an adherent protective passive fi lm. It is concluded that this cannon constitutes a marvel of medieval Indian metallurgical skill.

Anodic polarization and caustic cracking tests were carried out on a mild steel in a 20% NaOH caustic solution at 120°C, with and without prior electrochemical conditioning and imposed electrochemical potential. The results presented here suggest that the anodic polarization behavior of the mild steel specimens that were not subjected to prior conditioning is different from those subjected to prior cathodic conditioning. This difference in anodic polarization has implications on caustic cracking susceptibility of mild steel. Imposed potential slow strain rate ͑SSR͒ testing was used to study caustic cracking behavior of specimens with and without prior electrochemical conditioning and imposed electrochemical potential during SSR testing. Specimens tested with prior conditioning as well as imposed electrochemical potential showed extended range of strain rates where caustic cracking is observed. This has been related to the quasi-passivity and the presence of activated iron on the surface of test specimens as a result of prior conditioning.

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Coating of an organo-silane (Bis-1,2-(TriethoxySilyl)Ethane (BTSE)) has been observed to improve the corrosion resistance of magnesium alloy AZ91D. Three different types of surface preparations have been employed before condensing the silane coating on to the substrate. Corrosion resistance was investigated using electrochemical impedance spectroscopy (EIS). A specific alkali treatment of the substrate prior to the coating has been found to improve the corrosion resistance of the coated alloy, which has been attributed to the ability of the treatment in facilitating the condensation of a relatively compact siloxane film.

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