Role of hydrogen in the high‐temperature corrosion of zirconium and its alloys. II Oxidation of unalloyed zirconium in steam and in oxygen

Abstract

The film capacities and weight gains of specimens of Kroll zirconium exposed to steam and to dry oxygen at 325° have been compared. The results show that the initial growth of uncracked oxide films is more rapid in steam, and that subsequent film cracking is also more severe, presumably as a result of effects due to hydrogen. Films on Van Arkel zirconium are more resistant to cracking in both steam and oxygen. At a late stage of oxidation in both steam and oxygen the film capacities reach constant values indicating that the mean thickness of the protective part of the film in each case also tends to a constant value. However, a comparison of the oxidation rates at this stage shows some discrepancies in relation to the initial oxidation rates and a modified picture of film growth and breakdown is proposed.