The oxidation kinetics of Zircaloy-2 have been studied in the temperature range 450-600°C under the atmosphere of flowing Ar/5%H2, CO2/1%CO, and CO2. Using the micro-balance technique, the weight change of the specimen has been measured as a function of time. The results showed that the oxidation kinetics of Zircaloy-2 obeyed the cubic rate law rather than the parabolic one. The effect of oxygen partial pressure on the rate constant was not found under the present experimental conditions. On the other hand, the activation energies of the oxidation were 145, 171, and 188 kJ/ mol for Ar/5%H2, CO2/1%CO, and CO2 atmospheres, respectively. It was shown from the X-ray diffractometry that the specimens oxidized under the conditions of this study consisted mainly of monoclinic zirconia and, to a minor degree, of tetragonal one. It is suggested that the lateral cracks observed with scanning electron microscopy (SEM) may cause the slow diffusion of oxygen in the oxide phase.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics
- Materials Science(all)
- Nuclear Energy and Engineering