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

ISSN： 0007-0599

Source： British Corrosion Journal, Vol.32, Iss.1, 1997-01, pp. : 57-62

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Abstract

Films 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.