Early stages of dezincification of α brass immersed in 4%NaCl solution

Abstract

AbstractFilms formed on 70–30 brass surfaces in 4%NaCl solution were analysed after short periods of immersion using X-ray photoelectron and Auger electron spectroscopy surface analytical techniques. The electrolyte was simultaneously analysed by atomic absorption. Divalent copper (in the form of CuCl2) was detected on the outside of the surfacefilm after immersion for 2 min. The presence of copper metal and cu2+ on the surface supports the view that a disproportionation reaction had occurred in the film. In addition, copper dissolved as CuCl-2 while dissolution of zinc is suspected to have occurred through HZnO-2 and ZnCl2, with the latter formed by galvanic reaction. Solution analysis during these early stages revealed a copper/zinc ratio which increased with increasing immersion time. This result, together with the surface analysis in tlte initial stages of immersion, supports the simultaneous dissolution theory.