抄録
In order to clarify the role of the bound water in the passive film to the stability of AISI 304 stainless steel in chloride media, precise measurements of the induction period of pitting and the frequency of the anodic current fluctuation were made, and the effect of desorption of the bound water from the passive film with heat treatment and dioxane treatment on the induction period and the anodic current fluctuation was investigated. From the results it was deduced that the passive film has two different kinds of bound water depending upon the condition under which the film is formed. These two kinds of water are characterized as follows; (1) The bound water in the passive film formed under the passivation conditions at low temperature or at low potential (the first kind of bound water) is easily dehydrated by dioxane solvent, and is active to chloride ions as well as to film formation. (2) The bound water formed at high temperature or for long time of passivation (the second kind of bound water) is not easily transferred to dioxane media. It is substantially incorporated in the passive film. (3) The first kind of bound water has the tendency to change into the second kind of bound water.
