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

Study of Hydrogen Sorption/Desorption Effect on Austenitic Iron-Based Alloys: Surface Interaction Studied by Cyclic Voltammetry on 304L Stainless Steel and Invar

Encalada Flores, Katherine Stephanie (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Materials Science and Engineering)

Bottger, Amarante (mentor)
Popovich, Vera (graduation committee)
Kortlever, Ruud (graduation committee)

Delft University of Technology

Mechanical Engineering

2019-10-28

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.

Hydrogen adsorption
Austenitic iron-based alloys
Cyclic voltammetry

http://resolver.tudelft.nl/uuid:32242c29-753c-412f-ae6a-d08c673f9920

Student theses

master thesis

© 2019 Katherine Stephanie Encalada Flores