INVESTIGADORES
ELSNER Cecilia Ines
congresos y reuniones científicas
Título:
Study of the corrosion behavior of the electrogalvanized steel/Cr(III) and Zr conversion layer/paint system by electrochemical and visual methods.
Autor/es:
F.M. QUEIROZ; P.R. SERÉ; C.I. ELSNER; A.R. DI SARLI; C. R. TOMACHUK; ISOLDA COSTA
Lugar:
Pisa
Reunión:
Congreso; European Corrosion Congress (EUROCORR 2014); 2014
Institución organizadora:
EUROCORR
Resumen:
Finding environmentally friendly conversion layers
with the same performance of those previously existing has been the great
challenge for researchers of the surface treatment field. Successful examples
are the Cr(III)-based pretreatments, which used to replace the Cr(VI) ones are,
so far, the best alternative. In the last years, studies in nanotechnology are
increasing and nanoparticulate systems based on silica, titanium and zirconium
have been evaluated. In this work, the corrosion behavior of an electrogalvanised-zirconium
conversion treatment-paint system was characterized by evaluating not only the
open corrosion
potential (OCP) and electrochemical impedance spectroscopy (EIS) evolution as a
function of the exposure time but also the samples performance subjected to
accelerated corrosion tests. All the electrogalvanised steel sheets were
obtained by using an alkaline free-cyanide bath. After this, they were immersed
in a nanoparticulate system containing Cr(III)-based salts and zirconium.
Finally, part of these samples was covered with a solvent-based paint, and the
remaining with a waterborne-paint. After curing, the samples were exposed to
salt spray or humid chamber. Periodic inspections for measuring the treated
samples? OCP and EIS were performed. Moreover, visual observations to detect
and photographically record the eventual appearance of corrosion and/or
blistering were also carried out. In order to compare the corrosion performance
of the new system, samples pretreated with trivalent chromium or hexavalent
chromium were also evaluated. The experimental results allowed to infer that
the electrogalvanised-nanoparticulate conversion layer-paint system afforded a
corrosion protection higher than that of the Cr(III) or Cr(VI) pretreated and
painted samples, and therefore, that the new pretreatment is a promising
alternative to the Cr(VI) one.