Nanoscale aspects of corrosion on cultural heritage metals

Abstract

Metallic artefacts are an important part of the cultural heritage and must be protected for the future generations. Unfortunately, classical metal protection methods used for example in industry, can in most of cases not be used in the context of the conservation of cultural heritage because artefacts must not be aesthetically modified and any protection treatment must be potentially removable without any damage to the artefact. For that reason, to set up efficient conservation strategies, it is necessary to understand and model the long term corrosion mechanisms. In addition to environmental monitoring and empirical approaches, the fine understanding of the corrosion systems, based on the use of multiscale characterisation techniques and methodologies is a key issue to understand the mechanisms and evaluate the degradation rates. This chapter reviews the cases for which investigations at nano scales are necessary to understand and model in a reliable way the corrosion behaviour of different metals (ferrous alloys and bronzes). Nanoscale investigation, also allows scientists to understand the way intentional patinas were made on ancient bronzes. Lastly, an example of the use of nanotechnology to set up an adapted and innovative protective treatment is given.