Abstract
An electronic balance was used to investigate the time-variation of the amount of hydrogen gas evolved during anodic dissolution of iron corresponding to electric charges of 5.0 C at 20 mA/cm2 current density. The electrodes were made of commercial type iron of 99.5% purity. The corrosive solutions were a chloride-sulfate mixed bath of pH 8.0(0.5 M NH4Cl - 0.5 M Na2SO4 - 0.1 M H3BO3 - 0.1 M Na2B4O7).
Use of an electronic balance enabled in situ measurements of the buoyancy attributable to the hydrogen gas bubble formed during the pitting corrosion of the iron. Measurements also elucidated the induction period from the beginning of electrolysis until hydrogen gas formation. The results indicate that a strongly corrosive solution formed progressively in the pits brought about chemical dissolution of iron followed by hydrogen gas evolution.
