FLUCTUATIONS OF PERMEATION RATE THROUGH AN IRON MEMBRANE INDUCED BY HYDROGEN BUBBLES

Using the electrochemical permeation technique, we have recorded fluct uations of the concentration of absorbed hydrogen in an Armco iron mem brane during cathodic hydrogen charging in acidic solution. The fluctu ations coincide quite closely with the dynamics of hydrogen bubbles at the cathode surface, which were followed both visually and by recordi ng cathode-potential and ohmic-resistance fluctuations. The local flux of hydrogen into the iron membrane gradually decreases when there is an attached bubble growing and quickly increases when the bubble depar ts. An excellent correlation was found between the fluctuations of the concentration of absorbed hydrogen in the first layers of metal and t he fluctuations of the cathode potential.