Effect of Rare Earth Ce<sup>3+</sup> on the Microbial Induced Corrosion Behavior of Aluminum Alloy LY12CZ

Abstract

The effect of rare earth Ce~(3+) on the growth of sulfate reducing bacterial(SRB) and the microbial induced corrosion(MIC) of aluminum alloy LY12CZ was studied by ultraviolet spectrophotometry(UVS), maximum probable number(MPN),cyclic anodic polarization,electrochemical impedance spectroscopy (EIS),and epi-fluorescence microscopy(EFM).The results showed that the low concentrations of Ce~(3+) could promote the growth of SRB while high concentrations had an inhibiting effect.Cyclic anodic polarization curves indicated that the pitting sensitivity of LY12CZ became lower in solutions containing rare earth Ce~(3+).EIS confirmed that corrosion resistance increased with an increase in the concentration of Ce~(3+).However,when inoculated with 1%SRB,the corrosion resistance was optimal at a Ce~(3+) concentration of 0.376 mg·L~(-1) because of a synergistic effect between the biofilm and the rare earth conversion film.The growth of SRB was inhibited with an increase in the Ce~(3+) concentration which prevented the biofilm forming completely on the surface of the matrix.At the moment,the effect of MIC was more notable than the protection of rare earth conversion film that formed on the surface of aluminum alloy.