Corrosion processes in the development of thin tarnish films

Corrosion processes in thin films at the molecular level are investigated. Corrosion of thin films in two key areas is studied: (a) at the composition and structure of the thin-film corrosion layer; and (b) the processes of microcell corrosion that account for film growth from 2 nm to 20 nm. The electrochemical and chemical processes that occur in the development of thin tarnish layers and corrosion products during atmospheric exposures are discussed. The processes are illustrated by the behavior of copper in moist air containing low concentrations of sulfur dioxide. Corrosion science principles for bulk electrolytes are applied to the corrosion processes in thin films of electrolyte.>