Corrosion experiments on copper in different groundwaters

A series of projects on copper corrosion has been performed at Studsvik on commission by SKI. The work has been focused on general and localised corrosion of copper in the repository environment. The work comprised a thorough compilation and up-date of literature data. A selection of a 'working environment', defining the chemical parameters and their ranges of variation was made from literature and discussions with SKI and later on used as a fundament for planning of experiments. Especially the importance of highly saline solutions and solutions containing sulphide was tested by thermodynamical calculations and laboratory experiments. Some of the results are highlighted here. At simultaneous presence of sulphide and chloride a very complicated surface film is formed on the copper surface. In some cases of environment also the growth of copper containing whiskers was observed on top of the surface film. As whiskers could indicate an underlying localized attack on the copper metal, specific care was taken to find evidence of such attacks. The nature of layers and whiskers was investigated by applying SEM-EDS, XRD and Raman Spectroscopy