Zirconia Layer Formed by High Temperature Oxidation of Pure Zirconium: Stress Generated at the Zirconium/Zirconia Interface.

Oxidation of pure zirconium metal at high temperature (500 and 600 °C) under air at normal atmospheric pressure was investigated using the Raman Spectroscopy technique. Analysis of the absolute intensities as well as the positions of the Raman bands for the tetragonal and the monoclinic zirconia phases was performed. Evolution of the thermal stress has been presented and discussed in comparison to the Raman mode shift recorded in situ during cooling. Ex-situ analyses of cross-sections confirm the presence of tetragonal phase preferentially located close to the metal/oxide interface and show the existence of a relaxed and highly disordered tetragonal phase preferentially located in the outer part of the scale. Using a micro tension--compression machine, it is shown that compression loads lead to a significant intensity change of the Raman peaks for the tetragonal zirconia. The effect of tension load appears less clear which demonstrates that the relation between Raman peak shift and stress is not as simple as generally considered. [ABSTRACT FROM AUTHOR]