Second International Conference on Ultra High Purity Base Metals
UHPM - 95

J. Phys. IV France 05 (1995) C7-409-C7-415
DOI: 10.1051/jp4:1995750

Use of Pure Metals to Analyse Hydrogen Electrochemical Permeation in Steels

P. Manolatos^{1, 2}, J. Le Coze³, C. Duret-Thual⁴ and M. Jérome<sup>1

1</sup>  Laboratoire C.F.H., Ecole Centrale de Paris, Grande Voie des Vignes, 92295 Châtenay-Malabry cedex, France
²  E.C., Joint Research Centre, P.O. Box 2, 1755 ZG Petten, The Netherlands
³  Ecole des Mines de Saint-Etienne, 158 cours Fauriel, 42023 Saint-Etienne cedex 2, France
⁴  IRSID-Unieux, BP. 01, 42490 Fraisses, France

Abstract
The electrochemical permeation method is often used to study hydrogen diffusion and trapping in steels ; unfortunately, there is great scatter in the experimental results. To identify the reason for this scattering, experiments were carried out usiug pure iron and pure palladium specimens. It is clearly shown that on the iron samples, surface phenomena are not controlled. In particular, the passive layer on the exit side induces variation of the hydrogen concentration on this side with time. On palladium samples, such phenomena can be controlled and stationary conditions as well as good reproducibility can be obtained. The use of a palladium coating on the exit side of ferrous samples can help to better control the surface phenomena during permeation experiments and so to obtain meaningful measurements.

© EDP Sciences 1995