Effect of initial hydrogen distribution on the parameter extraction of the thermal desorption spectra: A finite element study

The main objective of this study was to clarify whether the commonly encountered inhomogeneous hydrogen distribution in thermal desorption tests, resulting from unsat-urated hydrogen charging and hydrogen release during specimen transfer, could affect the desorption curves and parameter determination. The transient hydrogen distributions in the specimen, both in normal lattice sites and trap sites, during absorption, air exposure, and thermal aging were simulated using finite element method based on the Oriani's local equilibrium theory. Results indicated the significant effect of initial inhomogeneous hydrogen distribution on the transient hydrogen distribution and the desorption spectra. This effect could result in both the shift of peak temperature and the artifact in desorption curves, depending on the trap binding energy. The effect of testing parameters and trap parameters on the validity of Kissinger's theory was also discussed. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.