Possible origin and roles of nano-porosity in ZrO2 scales for hydrogen pick-up in Zr alloys
Artikel i vetenskaplig tidskrift, 2017

A mechanistic understanding of Wagnerian build-up and subsequent non-Wagnerian break-down of barrier oxide upon oxidation of zirconium alloys by water is reiterated. Hydrogen assisted build-up of nano-porosity is addressed. Growth of sub-nanometer wide stalactitic pores owing to increasing aggregation of neutral oxygen vacancies offering a means to permeate hydrogen into the alloy is explored by density functional theory. The Wagnerian channel utilizes charge separation allowing charged oxygen vacancies and electrons to move separately from nominal anode to nominal cathode. This process becomes increasingly controlled by the charging of the barrier oxide resulting in sub-parabolic rate law for oxide growth. The break-down of the barrier oxide is understood to be preceded by avalanching hydrogen pick-up in the alloy. Pore mediated diffusion allows water to effectively short circuit the barrier oxide.

Hydrogen pick-up

Zirconium oxidation

Porosity

DFT

Nucleation

Oxygen vacancy

Författare

Mikaela Lindgren

Chalmers, Kemi och kemiteknik, Energi och material, Oorganisk miljökemi

Christine Geers

Chalmers, Kemi och kemiteknik, Energi och material, Oorganisk miljökemi

Itai Panas

Chalmers, Kemi och kemiteknik, Energi och material, Oorganisk miljökemi

Journal of Nuclear Materials

0022-3115 (ISSN)

Vol. 492 22-31

Ämneskategorier

Oorganisk kemi

DOI

10.1016/j.jnucmat.2017.05.017

Mer information

Skapat

2017-10-08