The roles of the hydride precipitation and integrity of the oxide layer in the accelerated corrosion of Zircaloy-4 are investigated by determining the critical ratio of P_H2/P_H20 using TGA(Thermo-Gravimetric Apparatus) and studying the effect of hydr...
The roles of the hydride precipitation and integrity of the oxide layer in the accelerated corrosion of Zircaloy-4 are investigated by determining the critical ratio of P_H2/P_H20 using TGA(Thermo-Gravimetric Apparatus) and studying the effect of hydride precipitation on the oxidation kinetics. Under hydrogen-water mixture environment hydriding reaction takes place much faster than the oxidation reaction at early stage and soon later growing oxide begins to retard the hydriding reaction and completely prevent from the hydriding in the second stage. It turns out that even in this stage the oxidation rate is enhanced with increasing P_H2/P_H20 ratio. In the final stage, the oxide breakdown occurs, thus, massive hydriding takes place again. Intermittent weight gain measurements using autoclaves also confirm these results.