Study of Hydrogen Sorption/Desorption Effect on Austenitic Iron-Based Alloys

Surface Interaction Studied by Cyclic Voltammetry on 304L Stainless Steel and Invar

Master thesis (2019)

Authors

K.S. Encalada Flores Mechanical Engineering

Contributors

A.J. Bottger (OLD) MSE-1 (supervisor 1)
V. Popovich (OLD) MSE-5 (coach)
R. Kortlever Large Scale Energy Storage - Mechanical, Maritime and Materials Engineering (coach)
Faculty
Mechanical Engineering
Copyright: © 2019 Katherine Stephanie Encalada Flores
Cyclic voltammetry Hydrogen adsorption Austenitic iron-based alloys
More Info
expand_more

Published Date

28-10-2019

Language

English

Reuse Rights

Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.

Faculty

Mechanical Engineering

Abstract

The so-called “hydrogen economy” became one of the scientific targets among the different renewable energies alternatives, as a result of the efforts to transition from fossil fuels to environmentally-friendly energy sources. In this context, various options to transport and store hydrogen are being explored. Gaztransport & Technigaz (GTT) company, intending to be part of this challenge, is exploring the possibility to transport liquid hydrogen (LH2) in pre-existent ship’s containers initially designed for liquid natural gas (LNG) transportation. This project is about the study of the surface effect of the interaction between hydrogen with iron-based alloys in the case of 304L stainless steel (uncoated and coated with TiO2) and Invar alloy.The methodology consisted of electrochemical induced hydrogen evolution on an iron-based austenitic metal cathode taking advantage of the intermediate adsorbates (atomic hydrogen) generated during the reaction to study the electrochemical adsorption efficiency. Characterisation of the materials, by techniques like XRF, XRD, optical microscopy, and SEM, is conducted before and after hydrogen exposureso that it was possible to evaluate the effect of hydrogen ingress.The results showed that the chemistry of the surfaces is irreversible changed after the electrochemical induced hydrogen sorption/desorption process due to the formation of oxides. The amounts of hydrogen desorbed were quantified after different H2 loading times. In all cases, the amount of hydrogen desorbed showed a maximum after which the hydrogen desorbed decreased significantly. The maximum for uncoated 304L stainless steel was after 24 h, 90 min for the coated 304L, and 2 hfor Invar. The welds are the most vulnerable sections to hydrogen ingress in both cases. XRD results before hydrogen exposure revealed that 304L consists of an austenitic matrix with around 5% of ferrite. An increment of the austenitic volume fraction of 2.2% was observed after the H2 sorption/desorption process. Invar is a purely austenitic phase, and no changes in the phase composition were observed after the H2 sorption/desorption process.