'Corrosion of silver alloys in sulphide environments'

PAPER, RSC ADVANCES 6, ROYAL SOCIETY OF CHEMISTRY

• I. Tissot*^a, O.C. Monteiro^b, M.A. Barreiros^c, v. Corregidor^d, J. Correia^b, M.F. Guerra^e. 2016. Corrosion of silver alloys in sulphide environments: a multi-analytical approach to surface characterization. RSC Advances, 6, 51856-51863.
  
  Corrosion of silver alloys in sulphide environments: a multianalytical approach for surface characterisation
  
  ^{* Corresponding author
  a Laboratory LIBPhys, NOVA University Lisbon // Archeofactu  b Center of Chemistry and Biochemistry, Faculty of Sciences, UL
  c National Laboratory of Energy and Geology, LEN/UES  d Institute of Plasma and Nuclear Fusion, IST/Technological and Nuclear Campus, UL
  e ArchAm – UMR 8096 CNRS, MAE, France}

^{Abstract
Sterling silver samples, prepared to simulate cultural heritage surfaces, were subjected to accelerated ageing tests through exposure to sulphide containing environments. Data obtained by X-ray diffraction, ultraviolet-visible spectrophotometry, contact angle goniometry, ellipsometry and scanning electron microscopy revealed, contrarily to what has been suggested, that the colour of corroded surfaces is related to the thickness of the corrosion layer and to the multi-layer structure of various corrosion products. At the early stages of corrosion, Cu prevails over the Ag compounds. In subsequent stages, AgCuS complexes were also detected. Ag₂S is the prevailing corrosion product after longer periods of time.The colour of the layer-by-layer film developed on Ag-Cu alloys in sulphide environments varies with its thickness and composition.}