A pressure modulation method to study surface effects in hydrogen permeation through iron base alloys

In this work, we present a pressure modulation method developed to study su rface effects in hydrogen permeation through iron base alloys. The techniqu e involves the generation of a sinusoidal hydrogen pressure on the input si de of a permeation membrane and the measurement of the corresponding sinuso idal hydrogen flow, as an electrochemical current, at the exit side of the membrane. The obtained transfer function depends on both the bulk propertie s of the permeation membrane and the surface effects at the input and exit sides. By choosing appropriate membrane thickness and material, surface eff ects are rate determining and can be characterised. Studies of the effect o f different Pd films electrodeposited on the input side of the permeation m embrane show that there is a finite resistance for the transfer of hydrogen across the hydrogen/palladium interface. (C) 1999 Elsevier Science Ltd. Al l rights reserved.