Use of electrochemical techniques to study the corrosion of metals in model fluoride melts

Stéphanie Fabre (1) , Céline Cabet (2) , Laurent Cassayre (3) , Pierre Chamelot (3) , S. Delepech (4) , Jorgen Finne (1) , Laurent Massot (3) , Didier Noël (1)

1 EDF R&D MMC - Matériaux et Mécanique des Composants
2 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
3 LGC - Laboratoire de Génie Chimique
4 LECIME - Laboratoire d'Electrochimie, Chimie des Interfaces et Modélisation pour l'Energie (LECIME - UMR 7575)

Molten fluorides are appealing coolants for innovative nuclear systems but structural alloys may undergo corrosion at high temperature. Because corrosion primarily occurs via electrochemical reactions, electrochemical techniques are ideal for the study of corrosion thermochemistry and kinetics. Examples are given. An electrochemical series was established using voltammetry in LiF-NaF at 1173 K. Stability increases in the following order: Na, Cr, Fe, Ni, Mo/W, Ag, Au. Various alloys were also classified according to their oxidation resistance. A cathodic protection method was developed to curb the intergranular attack of some nickel alloys in molten LiF-CaF₂-MgF₂-ZrF₄ containing tellurium vapor at 953 K. Voltammetry and polarization resistance measurement were used to estimate the rate of chromium selective dissolution for nickel base alloys immersed in LiF-NaF at 1073 K and 1173 K.

Mots clés: Corrosion alloy; Oxidation resistance; Electrochemical reaction; Nickel

Domaines: Génie chimique; Matériaux et structures en mécanique [physics.class-ph]; Matériaux et structures en mécanique [physics.class-ph]; Energie électrique

Stéphanie Fabre, Céline Cabet, Laurent Cassayre, Pierre Chamelot, S. Delepech, et al.. Use of electrochemical techniques to study the corrosion of metals in model fluoride melts. Journal of Nuclear Materials, 2013, vol. 441, pp. 583-591. ⟨10.1016/j.jnucmat.2013.03.055⟩. ⟨hal-00877440⟩