A study of transport of hydrogen in self-stressed metals by a one-port transfer function

Experimental conditions for studying the transport of hydrogen in self-stressed metals by the one-port transfer function (TF) have been proposed. In contrast to the conditions applied typically in studies of bounded diffusion of hydrogen in a metal membrane specimen by electrochemical impedance spectroscopy (EIS), the concentration of hydrogen is maintained at both sides of the specimen close to the same value. Thus, the transport of hydrogen is close to equilibrium, as in EIS studies of restricted diffusion. Although its features are apparently the same as those of the typical impedance spectrum of bounded diffusion, the TF spectrum depends also on the elastic properties of the specimen. Hence, the diffusion coefficient of hydrogen and the bulk elastic modulus of the metal matrix can be determined simultaneously. Also, the dependence of both parameters on the concentration of hydrogen in the matrix may be studied. (C) 2002 Elsevier Science B.V. All rights reserved.