Treatment of zinc surface with cerium(III) nitrate to prevent zinc corrosion in aerated 0.5 M NaCl

It has been reported that CeCl3 is an effective inhibitor for corrosion of zinc in an aerated 0.5 M NaCl solution by the formation of a thick film composed of cerium-rich oxide and hydroxide. In this study, a protective film was prepared by treatment of a zinc electrode in an aqueous solution of 1 x 10(-3) M Ce(NO3)(3) at 30 degreesC for 30 min and examined in an aerated 0.5 M NaCl solution at 30 degreesC by polarization measurements after immersion of the electrode in the NaCl solution for 4-240 h. The film comprised oxides and hydroxides of Ce(III) and Ce(IV) ions mostly. The protective efficiency of the film against zinc corrosion was maintained remarkably high. more than 91% during immersion in 0.5 M NaCl for 240 h. Little pitting corrosion was observed on the electrode surface. However, this film could not heal the scratched surface of zinc electrode in the NaCl solution. (C) 2001 Elsevier Science Ltd. All rights reserved.