At. Shawaqfeh et Re. Baltus, GROWTH-KINETICS AND MORPHOLOGY OF POROUS ANODIC ALUMINA FILMS FORMED USING PHOSPHORIC-ACID, Journal of the Electrochemical Society, 145(8), 1998, pp. 2699-2706
Citations number
19
Categorie Soggetti
Electrochemistry,"Materials Science, Coatings & Films
The growth kinetics of porous alumina films formed by anodic oxidation
of aluminum in phosphoric acid under galvanostatic conditions was stu
died. Scanning electron microscope measurements, Faraday's law, and ox
ide film mass measurements was used to analyze the growth kinetics and
obtain film growth rates, pore density, and porosity. Current efficie
ncy was also determined from these measurements. The effect of current
density and solution temperature on the oxide film growth rate and mo
rphology was examined. The rate of growth of the alumina film was foun
d to increase with an increase in current density. The rate of growth
was observed to increase with temperature at low current densities (7.
5 mA/cm(2)), but was found to exhibit a maximum as temperature was var
ied at high current densities (17.5 mA/cm(2)). The pore density was fo
und to decrease with an increase in current density and with a decreas
e in temperature. The porosity and the average cross-sectional pore ar
ea of the films were found to increase with anodization time and decre
ase with an increase of current density and temperature. These results
can be explained by considering the interplay between film growth and
oxide dissolution that controls the resulting film morphology. The un
derstanding of the effect of process variables on film morphology that
is gained by this study provides the information that is needed to pr
epare alumina films with well-defined and well-characterized morpholog
y.