P. Manolatos et al., THE ELECTROCHEMICAL PERMEATION OF HYDROGEN IN STEELS WITHOUT PALLADIUM COATING .1. INTERPRETATION DIFFICULTIES, Corrosion science, 37(11), 1995, pp. 1773-1783
There is no general agreement on the experimental conditions used in t
he hydrogen electrochemical permeation method. Particulary, the necess
ity of a palladium coating on steel is not yet recognized. To answer s
ome questions concerning the boundary conditions, experiments were car
ried out on pure iron and low alloyed steels without palladium coating
. It is shown clearly that in this case surface phenomena are not cont
rolled. Especially, the passivation layer on the exit side induces var
iation of the hydrogen concentration on this side with time. Consequen
tly no quantitative evaluation can be made for diffusion parameters, a
s long as the mathematical model issued from the usual stationary boun
dary conditions is used.