The Difference Effect and Anodic Behavior of Hafnium Dissolving in Hydrofluoric Acid
Crystal bar hafnium dissolving in hydrofluoric acid and in hydrofluoric-hydrochloric acid mixtures exhibited a positive difference effect similar to that previously observed for zirconium dissolving in hydrofluoric acid. The effect was so pronounced as to completely overbalance the hydrogen volume developed by the internal polarization current and to reduce the rate of self-dissolution by an additional 1·5-3 mm 3/cm 2 min of H 2. The effect was accompanied by a strong shift of the potential of the hafnium electrode toward noble values. Similar potential changes were observed upon the addition of noble metal salts to the acid mixture. The results of the difference effect studies together with rate measurements in hydrofluoric-hydrochloric acid mixtures appear to confirm previous conclusions with regard to the high rate of dissolution of Hf (no anodic current) namely that the dissolution rate is brought about by direct chemical action of molecular HF. A possible explanation is given for the slight increase of metal dissolution and of K in the presence of HCl additions. © 1963 Pergamon Press Ltd.
W. J. James et al., "The Difference Effect and Anodic Behavior of Hafnium Dissolving in Hydrofluoric Acid," Corrosion Science, Elsevier, Jan 1963.
The definitive version is available at http://dx.doi.org/10.1016/S0010-938X(63)80032-3
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© 1963 Elsevier, All rights reserved.