0000000000195349
AUTHOR
Isabelle Sallès-desvignes
Coupling between Diffusion, Stress Field and Chemical Reaction in a Metal-Gas Oxidation
International audience
Near-coincidence lattice method for the determination of epitaxy strains during oxidation of metals
Abstract A theoretical method is proposed to evaluate the strains due to epitaxy between a metal and its oxide. Based on Bollmann’s approach of two adjoining grains, it uses the quantitative texture analysis of the two materials separated by the phase boundary. Our study of the Zr/ZrO 2 and Mo/MoO 3 systems reveals strong correlations between the criterion of best fit proposed by Bollmann and the orientation distribution function obtained by a quantitative texture analysis. The results of this study are used in a thermo-mechano-chemical simulation of the oxidation process of zirconium, which leads to this observation: two different zirconia orientations induce two different oxidation kineti…
Mechanical Stresses: Inhibitor of Catalyst of High Temperature Oxidation?
Oxidation of metals is a complex reaction in which mechanical and chemical phenomena occur. A dynamic and macroscopic model is developed in order to simulate oxidation kinetics of a metal. It includes the stress/diffusion coupling in the bulk and the interfacial phenomena at metal/oxide interface. Its application to the Zr/ZrO 2 system shows the important role of stress field distribution in oxide on kinetic behavior. According to the sign of stress gradient in the oxide scale, the oxidation rate can speed up or slow down. The calculated kinetic curves could he fitted using a k p .t 1/n law where n and kp vary all over the process, like for the experimental kinetic curves.