Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Characterisation of corrosion products on metal threads and accelerated corrosion tests

Various corrosion morphologies have been observed on metal threads. The corrosion products were found to be mainly sulphur compounds with only relatively few and patchy chlorine containing products. The copper content in the corrosion products and in the surface regions of the metal filaments were always relatively higher than that measured in the bulk material, indicating copper ion surface migration. X-ray Photoelectron Spectroscopy (XPS) analysis of corroded metal threads showed the presence of chlorine and sulfide and to a lower extent sulfate. X-ray Diffraction (XRD) was employed for the first time to analyse the corrosion products on historic metal threads. Various corrosion crystals were identified, including digenite, chlorargyrite and acanthite.

Accelerated tarnishing studies of copper and silver foils, based on the thermal and photo-degradation of associated silk and wool, produced a variety of corrosion morphologies. Degradation of wool was found to cause higher levels of visible corrosion than silk. A greater variety of corrosion levels were observed due to the photodegradation of differently dyed wool and silk, compared to thermal degradation of differently dyed fibres. XPS of the accelerated tarnished silver and copper indicated that the main corrosion products were sulfide with some sulfate observed on copper coupons.

Reported by

The University of Manchester
School of Materials
United Kingdom