Hydrogen Pickup During Aqueous Corrosion Of Zirconium Alloys

Abstract Hydrogen absorption during the corrosion of zirconium alloys has been studied in 600 and 680 F water and 750 F 1500-psi steam. Results on binary sponge-base alloy series indicate that, of the alloying elements found in Zircaloy-2, nickel at increasing levels markedly increases hydrogen absorption. Tin has little or no effect, while iron and chromium additions reduce hydrogen absorption. Antimony additions also reduce hydrogen absorption. However, additions of arsenic, antimony, bismuth, or tellurium to Zircaloy-2 do not affect the amount of hydrogen absorbed during corrosion. It is postulated that in zirconium alloys containing iron, chromium, or nickel the compounds of these elements are cathodic to the zirconium matrix. The resulting potential difference is sufficiently high to anodically polarize the zirconium and thus improve corrosion resistance. Apparently iron and chromium compounds readily depolarize hydrogen and thereby decrease the possibility of its passage through the oxide film. Nick...