Uranium and U–Zr and U–Ru alloy corrosion rates in the transpassive state

• Published in: Journal of alloys and compounds 2007-10, Vol.444, p.345-351
• Main Authors: Maslennikov, A., Bessonov, A., Peretroukhine, V., Budanova, N., Gedgovd, K., Bulatov, G., Tsivadze, A., Delegard, C.
• Format: Article
• Language: English
• Subjects: Alloys; Corrosion; Electrochemical; ELECTROCHEMICAL CORROSION; ELECTROLYTES; OXIDATION; PASSIVATION; PH VALUE; RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; RUTHENIUM ALLOYS; transpassive; U-Ru; U-Zr; URANIUM; uranium alloy; URANIUM ALLOYS; ZIRCONIUM ALLOYS
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2007.06.078

Electrochemical studies of reactor-grade uranium metal and its alloys with Zr and Ru in neutral electrolyte (0.1 M NaClO 4, pH 3.0–9.0) in the potential region close to uranium's transpassivation threshold were performed. Transpassivation potentials from 320 mV/Ag/AgCl (U–1.3 at.% Zr) to 470 mV (U–10.5 at.% Ru) were found to be weakly affected by added alloying element concentration and electrolyte pH. Comparison of I– t curves registered on U metal, U–1.3 at.% Zr, and –1.2 at.% Ru electrodes indicate that the electrochemical oxidation rate of alloyed uranium was lower than that of pure U metal. The difference of the electrochemical oxidation rates was dependent on electrolyte pH. The calculated corrosion rates of uranium metal and alloy increased from 0.89 mg cm −2 h −1 (U–1.3 at.% Zr, E = 300 mV/Ag/AgCl) to 40.4 mg cm −2 h −1 (U metal, E = 600 mV/Ag/AgCl) and were found to be independent of alloy addition and electrolyte pH. The contribution of spallation of non-oxidized uranium species from the electrode surface to the observed corrosion rates was made.