Synergistic inhibition of zinc corrosion in 0.5 M NaCl by combination of cerium(III) chloride and sodium silicate

Abstract

The synergistic inhibition effects of cerium(III) chloride, CeCl 3 and sodium silicate, Na 2Si 2O 5 (water glass) on corrosion of zinc in an aerated 0.5 M NaCl solution at 30°C were examined by polarization measurements. Equimolar mixtures of these inhibitors were markedly effective, indicating that the inhibition efficiencies of the mixture at 1×10 −4 of each inhibitor were 95.9 and 93.6 after immersion of a zinc electrode in the solution for 3 and 120 h, respectively. X-ray photoelectron spectra revealed that a protective layer composed of hydroxylated or hydrated cerium-rich oxide and small amounts of zinc hydroxide and silicate formed on the zinc surface. A high inhibition efficiency of 1×10 −3 M Na 2Si 2O 5, 97.7% was obtained for corrosion of a zinc electrode which was previously treated in the NaCl solution of 1×10 −3 M CeCl 3 at 30°C for 30 min.