Characterization of isolated hydrogen traps by hydrogen permeation experiments

Abstract

The present work analyzes hydrogen permeation through a slab sample containing isolated hydrogen traps. The analysis is based on a flux continuity model that considers both the absorption and desorption processes. An analytical solution in series is derived for a dilute system with a low trap coverage fraction. According to this solution, we are able to characterize isolated hydrogen traps using only hydrogen permeation tests on two groups of samples with each group having different thicknesses. One group of samples, serving as a reference, is made of a pure matrix material without any hydrogen traps, while the other group of samples is made of the same matrix material with traps. The proposed multisample method is demonstrated by numerical calculations and plots, from which we determine the hydrogen diffusion coefficient, the desorption rate, the absorption parameter, the trap density, and the trap enthalpy from the permeation data of the steady flux and the time lag. The maximum error caused by the numerical calculations is less than 7%.