Comparison of the spontaneous and anodic processes during dissolution of brass

Thr results of investigations on spontaneous dissolution of alpha, beta', g amma and epsilon -brasses in non-complexing, oxidant free acid solutions (2 .0 M H2SO4) have been compared with literature results of anodic dissolutio n of these alloys. In anodic process the Cu-enriched intermediate phases ar e created while during spontaneous process dezincification leads to the cre ation of a layer of pure copper. Occurrence of Cu-rich intermediate phases has not been seen during spontaneous dissolution of beta' and gamma -brasse s. As a result of a consecutive reaction, however. copper hydride is create d. It appears that the spontaneous dissolution of brasses is related to the mechanism of creation and growth of a new copper phase. It seems that the main difference between those two processes consists in the appearance of h ydrogen ions reduction, which is absent during anodic dissolution. It has b een suggested, that reduction of the hydrogen ions is responsible for the c hange of the mechanism, of brass dissolution, from the anodic to spontaneou s one. (C) 2001 Elsevier Science Ltd. All rights reserved.