Non-destructive analysis of cultural heritage artefacts from Andalusia, Spain, by X-ray diffraction with Göbel mirrors

Abstract

The characterization of the phases present in artefacts has been normally carried out using XRD (Bragg–Brentano geometry) that requires sampling from artworks, being a destructive technique. However, X-ray diffraction with Göbel mirrors permits directly to study rough artefacts without sampling. Grazing incidence attachments can be used to characterize as much the superficial layer as the underlying ones in flat samples to obtain information about the depth profile of some samples. The combination of Göbel mirrors and measure at low fixed incidence angles allow to obtain information about the depth profile of bent samples. This work reports the alteration processes on the surface of the following cultural heritage artefacts: a rivet and a nail extracted from Pardon Gateway, located in the North façade of Mosque-Cathedral of Cordoba; a Roman arrow and a button from a Roman jacket obtained from an excavation in Baena (Cordoba); organ pipe from Cathedral of Zaragoza; lead seals from Seville City Hall collection. The main objective of this paper is the study through a totally non-destructive analytical method, X-ray diffraction with Göbel mirrors, of the superficial alteration of some metallic artefacts from cultural heritage. This knowledge allows us the election of appropriate methods to carry out the restoration of these artefacts.