IN-SITU MONITORING OF ANODIC-OXIDATION OF ALUMINUM USING A QUARTZ-CRYSTAL MICROBALANCE - ESTIMATION OF THE WATER-CONTENT FROM AN ISOTOPIC EFFECT

Anodic oxidation of aluminum was studied by use of a quartz crystal mi crobalance (QCM) in an attempt to estimate the content of incorporated water molecules in growing oxide films. In situ QCM analysis both in aqueous (H2O) and deuterium oxide (D2O) solutions indicated that the M -eq (mass change responsible for the passage of an equivalent of charg e) obtained in tetramethylammonium hydrogen phthalate aqueous solution was different from that obtainrd in deuterium oxide solution while th e M-eq obtained in ammonium adipate solutions did not show any differe nce. From the difference in the M-eq values, the number of incorporate d water molecules (per 1 mole of Al2O3) was estimated to be 0 and 1.3 in ammonium adipate and teramethylammonium hydrogen phthalate solution s, respectively. The numbers are in good agreement with that obtained by STEM, EDX analysis. It is demonstrated that the QCM method can be a powerful tool for measuring water content the growing oxide film unde r completely in situ and real-time conditions.