Characterization of the corrosion layer of copper-nickel alloys in a synthetic sweat medium by FTMS and LAMMA laser microprobes

This study conducted with FTMS and LAMMA laser microprobes has made it possible to characterize the corrosion layer formed on the surface of copper-nickel alloys. This was done after 6 weeks of immersion in synthetic sweat. The experimental results show that the corrosion layer is essentially composed of copper-based species, the nature of which is determined by the alloy composition. We show the formation of copper trihydroxy-chloride for alloys with a high copper content as well as copper (I) oxide doped with chloride anions for alloys with a high nickel content. We also highlighted the selective corrosion of nickel. This characterization of the corrosion layer as well as the selectivity of the corrosion process permit us to explain the evolution of the quantity of nickel released, which is necessary in turn to estimate the allergenic power of these alloys during their immersion in synthetic sweat. (C) 1998 Elsevier Science B.V.