Portable Raman study on the conservation state of four CorTen steel-based sculptures by Eduardo Chillida impacted by urban atmospheres

• Published in: Journal of Raman spectroscopy Vol. 43; no. 8; pp. 1111 - 1117
• Main Authors: Aramendia, J., Gomez-Nubla, L., Castro, K., Martinez-Arkarazo, I., Vega, D., Sanz López de Heredia, A., García Ibáñez de Opakua, A., Madariaga, J. M.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01-08-2012; Wiley Subscription Services, Inc
• Subjects: Atmospheric corrosion; corrosion; CorTen steel; mobile equipment; Raman spectroscopy; Rusting; sculpture; Sculptures; Statuary; Steels; Weathering; Weathering steels
• ISSN: 0377-0486; 1097-4555
• DOI: 10.1002/jrs.3158

Weathering steel, and particularly CorTen steel, is a very used material for modern artworks exhibited outdoors. One of the characteristic that makes this material so attractive to artists is the property to develop a protective rust layer composed by iron oxides which preserves its metallic core from atmospheric corrosion. This study was conducted to evaluate the conservation state of four CorTen sculptures by Eduardo Chillida, located in different places of Bilbao city (north of Spain) and affected by different factors (environmental among others) by using Raman spectroscopy. Measurements were performed in situ with a handheld Raman spectrometer mounted on a tripod with x–y–z axes motorization at the micron level. The most common oxyhydroxides detected were lepidocrocite (γ‐FeO(OH)), goethite (α‐FeO(OH)), hematite ( ‐Fe2O3) and magnetite (Fe3O4), being goethite the most stable phase. All the iron oxyhydroxides were identified in all of the studied sculptures but their relative amounts were different for each sculpture. The consequences of the marine aerosols exposure in the steel surface were also studied, detecting limonite (FeO(OH)·nH2O) and akaganeite (β‐FeO(OH)). The results confirmed that the evolution of the rust layer present on the analyzed weathering steels is different, depending both on the exposure and the particular type of the steel. Copyright © 2012 John Wiley & Sons, Ltd.
The evolution of the rust layer present on the weathering steels is different, depending both on the exposure and the particular type of the steel. The evolution of four CorTen sculptures has been analyzed with portable Raman spectroscopy demonstrating that different factors could decrease the protective function of the rust layer.