Analytical Study of CuZn 30 and CuZn 39 Brass Surfaces in 3% NaCl Solution Under Polarization

The main objective of the investigation is to identify the role of beta phase on the corrosion behavior of CuZn alloys in chloride solution. The experimental study was based on the characterization and identification of the anodized brass films formed on the surface of two alloys: CuZn30 and CuZn39, abbreviated by CuZn alpha and CuZn alpha beta. Oxidation was carried out at different potentials chosen from the anodic polarization curves recorded beforehand with the two alloys. The main analysis techniques are AFM, SEM, EDS and XRD. Results indicate that the corrosion mechanism is similar for both alpha and alpha beta brasses and followed the same succession of steps. Nevertheless, the rate of dezincification is higher in the case of CuZn alpha beta: the surface of the attack is larger, and different plugs could be created at the same potential. Therefore, the composition of the protective layer is more diverse than that of CuZn alpha, while much more varied oxide and hydroxide species are likely to be formed.