APPLICATION OF ELECTROCHEMICAL TECHNIQUES FORTHE STUDY OF CORROSION PROTECTION OF BRONZEMONUMENTS UNDER URBAN ATMOSPHERIC EXPOSURE

摘要

The use of non-destructive electrochemical techniques for 'in situ' analysis is an innovatingcontribution to conservation of metallic sculptures. For the last five years we have been contributing to aninterdisciplinary integration of historical and aesthetic aspects of conservation and restoration withscientific methodology on corrosion. Since then, conservation of valuable bronze sculptures wastechnically supported by open circuit potential measurements of the metal and its patina (Pourbaixtechnique). Evolution with time of the protectiveness of different colour patinas and also scientificselection criteria on the best procedures for sculptures conservation at 2 years' interval was provided. Thistool showed evidence of patina alteration with time and further localised corrosion resistance which wasvalid for the whole structure. Another electrochemical technique, based on 'in situ' current measurementsfor a given potential is being experienced to evaluate patina protectiveness variation on localised areas ofbronze monuments. Surface analysis (SEM/EDX, X-ray diffraction) of tiny carefully scrapped samples ofdifferent colour patinas complemented this study of the effect of atmospheric agents on patinaprotectiveness. Localised interventions must thus consider the type and magnitude of exposure toatmospheric agents and the corresponding microclimate.