Abstract
The growth kinetics of anodic oxide films on some valve metals under open circuit conditions have been studied using potential and capacitance measurements. The corrosion potential and the reciprocal capacitance of tantalum, niobium, zirconium, hafnium, I aluminium, and molybdenum electrodes werefound to increase linearly with logarithm of time in various electrolytes, indicating oxide growth according to a direct logarithmic law. Equations describing the oxide growth have been theoretically derived by assuming that the oxides grow via a solid state mechanism under the influence of a strong electric field. The estimated field strength values are of the order of a few megavolts per centimetre, which could reasonably produce the required ionic migration.
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