X-ray diffraction: A tool for the study of solid-gas reactions (advantages and developments)

Zirconium oxidation mechanism can be studied by X-ray diffraction methods : in fact, the interactions between chemical (oxide growth, phases proportion) and physical process (oxide scale texture, mechanical stresses) are observed The oxide formed is composed of two allotropic structures, monoclinic ZrO2 (highest proportion) and tetragonal ZrO2 (trace). XRD studies show : 1) phases analyses: phases gradient are revealed by XRD variable incidence. 2) textures: Spatial evolution of monoclinic zirconia texture through the oxide scale is shown, and quantified 3) mechanical stresses : several relaxations of the oxide compressive stresses occur at different times of the oxidation. They are correlated to kinetics breakaway, revealed by other methods. A structural mechanism of the oxide formation is then proposed, which prove the XRD interest in the heterogeneous kinetics researches.