INVESTIGADORES
CERE silvia
artículos
Título:
Copper and brass aged at open circuit potential in slightly alkaline solutions
Autor/es:
R.A. PROCACCINI,; M. VÁZQUEZ; S. CERÉ
Revista:
ELECTROCHIMICA ACTA
Editorial:
Elsevier
Referencias:
Año: 2009 vol. 54 p. 7324 - 7329
ISSN:
0013-4686
Resumen:
Surface oxide films were grown on 99.99% copper and
brass (copperzinc alloy, Cu77Zn21Al2) in
0.1 mol L−1
borax solution at open
circuit potential and were characterized using various experimental
techniques. The composition of the passive films
formed in situ on the different materials was studied
using differential reflectance spectroscopy. The
thickness of the oxide layers on copper and brass was
compared by chronopotentiometric curves and potentiodynamic
reductions. The electrical properties
of each oxide were analyzed by means of
electrochemical impedance spectroscopy. Their influence on
the oxygen reduction reaction was also investigated
using voltammetry hydrodynamic tools such as the
rotating disk electrode. The results show that the
incorporation of Zn to Cu in brass changes the composition
and the thickness of the surface film. The films grown
on brass tend to be thicker but less resistive
and Zn compounds incorporate to the film. This is supported
by results from reflectance and impedance
spectroscopy. The kinetics of oxygen reduction is
strongly inhibited on oxidized electrodes, particularly
in the case of brass. The global number of exchanged
electrons remains close to four and seems to be
independent
of the presence of surface oxides.