The Kinetics of Oxidation of Zircaloy‐4 in Steam at High Temperatures

The kinetics of oxidation of Zircaloy‐4 in steam were examined under isothermal conditions from 900° to 1500°C. Rate curves describing the growth of the reaction product layers, oxide‐ and oxygen‐stabilized alpha, were obtained at 50°C intervals under carefully defined and documented experimental conditions. The early stages of oxidation for temperatures above 1000°C were shown to be virtually ideally parabolic; below 1000°C, the growth of the oxide layer was nonparabolic. Statistical evaluations of the data in terms of the rate constants and their Arrhenius parameters established the high degree of self‐consistency of these measurements. The features of the experimental apparatus and techniques that were necessary to insure accurate measurements are discussed.