A thermodynamic approach of the mechano-chemical coupling during the oxidation of uranium dioxide

TL;DR

This paper develops a thermodynamic model to analyze the mechano-chemical coupling during uranium dioxide oxidation, highlighting how mechanical stresses influence oxidation and potential cracking, supported by simulations.

Contribution

It introduces a thermodynamic framework integrating mechanical stresses into oxidation modeling, specifically applied to uranium dioxide.

Findings

Compression stress field near the internal interface is consistent with experimental observations.

Mechanical stresses significantly influence oxidation processes and cracking.

The model successfully simulates oxidation behavior in uranium dioxide.

Abstract

The aim of the present work is to introduce a thermodynamic model to describe the growth of an oxide layer on a metallic substrate. More precisely, this paper offers a study of oxygen dissolution into a solid, and its consequences on the apparition of mechanical stresses. They strongly influence the oxidation processes and may be, in some materials, responsible for cracking. To realize this study, mechanical considerations are introduced into the classical diffusion laws. Simulations were made for the particular case of uranium dioxide, which undergoes the chemical fragmentation. According to our simulations, the hypothesis of a compression stress field into the oxidised UO2 compound near the internal interface is consistent with the interpretation of the mechanisms of oxidation observed experimentally.