Theoretical Study of Coupling Mechanisms between Oxygen Diffusion, Chemical Reaction, Mechanical Stresses in a Solid-Gas Reactive System

TL;DR

This study integrates mechanical stresses into oxygen diffusion models in solids, specifically uranium dioxide, revealing how stress influences oxidation and cracking, with simulations aligning with experimental observations.

Contribution

Introduces a coupled model of diffusion and mechanical stresses in solid-gas reactions, applied to uranium dioxide oxidation, enhancing understanding of oxidation-induced cracking.

Findings

Compression stress fields align with observed oxidation mechanisms

Mechanical stresses significantly influence oxygen diffusion and cracking

Simulation results support the hypothesis of stress effects on oxidation processes

Abstract

This paper offers a study of oxygen dissolution into a solid, and its consequences on the mechanical behaviour of the material. In fact, mechanical strains 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 some oxidation mechanisms of oxidation experimentally observed. More generally, this work will be extended to the simulation to an oxide layer growth on a metallic substrate.