No abstract

No abstract

No abstract

The growth kinetics o f porous alumina films formed b y anodic oxidation o f aluminum i n phosphoric acid under galvanostatic conditions was studied. Scanning electron microscope measurements, Faraday's law, and oxide film mass measurements was used t o analyze the growth kinetics and obtain film growth rates, pore density, and porosity. Current efficiency was also determined from these measurements. The effect o f current density and solution temperature on the oxide film growth rate and morphology was examined. The rate o f growth o f the alumina film was found t o increase with an increase i n current density. The rate o f growth was observed t o increase with temperature at low current densities (7.5 mA/cmZ), but was found t o exhibit a maximum as temperature was varied at high current densities (17.5 mA/cm2). The pore density was found t o decrease with an increase i n current density and with a decrease i n temperature. The porosity and the average cross-sectional pore area o f the films were found t o increase with anodization time and decrease with an increase o f current density and temperature. These results can be explained b y considering the interplay between film growth and oxide dissolution that controls the resulting film morphology. The understanding o f the effect o f process variables on film morphology that is gained b y this study provides the information that is needed t o prepare alumina films with well-defined and well-characterized morphology.

No abstract