Effect of Electrolyte Type (H3BO3, NaCl, or Na2SO4) and Temperature on the Stability of the Passive Layer of AA 5052

In this work, the corrosion behavior of AA 5052 aluminum alloy, a candidate material for nuclear fuel cladding, was studied using potentiometry, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) in three electrolytes (NaCl, H3BO3, and Na2SO4) at two temperatures (25 and 38°C). The corrosion products were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the corrosion potentials (Ecorr) of AA 5052 in Na2SO4 and H3BO3 electrolytes are similar and higher than that of AA 5052 in NaCl electrolyte. Depending on the potential and chemical composition of the electrolyte (presence or absence of H2BO3–, Cl–, and SO42– anions), passivation and different types of corrosion (pitting, uniform, and partial corrosion) occurred for AA 5052. In Na2SO4 and H3BO3 electrolytes, AA 5052 exhibits acceptable passivation behavior: the passivation current density (ipass) is low, and the passivation potential range (ΔEpass) is extended. However, in NaCl electrolyte, the passive layer is not very stable: ipass is high, and ΔEpass is limited. Additionally, the stability of the passive layer decreases with increasing NaCl concentration. In all three electrolytes, the passivation current density (ipass) and corrosion current density (icorr) increase, and the passivation potential range (ΔEpass) is limited when the temperature increases from 25 to 38°C.