Kinetics and Mechanism of β-Brass Dealloying in Aqueous 0.5 M Sodium Chloride Solution Derived from Combined Scanning Tunneling Microscopy and Electrochemical Data

• Autores: Morales, J.; Esparza, P.; González, S.; Vázquez, L.; Salvarezza, Roberto Carlos; Arvia, Alejandro Jorge
• Año de publicación: 1996
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Ciencias Exactas; Química; Scanning tunneling microscopy; β-Brass Dealloying; Electrochemical Data
• Institución: Universidad Nacional de La Plata

Scanning tunneling microscopy (STM) combined with conventional electrochemical techniques was used to determine the kinetics and mechanism of β-brass dealloying in aqueous neutral solutions containing NaCl. In the potential range where selective dissolution of Zn occurs, electrochemical data suggest that the corrosion process is controlled by surface diffusion of Cu atoms. STM imaging of β-brass after dealloying shows the development of an irregular surface which attains a stationary regime. The irregular surface topography consists of faceted islands with atomically smooth terraces. For a constant dealloying time, the extent of faceting increases as the potential is moved positively, and at a constant applied potential it increases with electrodissolution time. The proportionality ξ ∝ Lα was established, where ξ is the interface width related to L, the sample size. The exponent R is related to the degree of surface disorder. The value of R derived from STM is in the range 0.7 ≤ α ≤ 0.8, i.e. close to the predictions of aggregation models including surface diffusion.
Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas