Effect of hydrogen on impedance of the passivating film on iron

The role of H in the passivating films that form on metals has been the subject of much speculation as relating to the structure, composition and other properties of the film. In previous work it was reported that H present in the passive film increases the susceptibility to pitting. The resistance to corrosion depends on the electrical properties of the film because the breakdown involves the electronic of the film because the breakdown involves the electronic and ionic transport in the film. However, the relationship between H in the passive film and the electrical properties has not yet been clarified. Hydrogen injection into the passive film of Fe has been carried out by using a permeation technique. Before and after H injection the electrical impedance of the passive film has been measured and the result is discussed in relation to the valence change of the metal ions by the protons inserted into the film. Graphs. 19 ref.--AA