稀土铈对铝合金LY12CZ微生物腐蚀行为的影响

摘要

The effect of rare earth Ce3* 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 Ce3* 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 Ce3*. EIS confirmed that corrosion resistance increased with an increase in the concentration of Ce3*. However, when inoculated with 1% SRB, the corrosion resistance was optimal at a Ce3* 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 Ce3* 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.%采用紫外分光光度法(UVS)、最大可能数法(MPN)、循环阳极极化法、电化学阻抗谱(EIS)和表面荧光显微法(EFM)研究了不同含量稀土Ce3+离子对硫酸盐还原菌(SRB)生长及LY12CZ铝合金微生物腐蚀行为的影响.结果表明:低浓度的Ce3+离子能够促进SRB生长,而高浓度时则抑制其生长;循环阳极极化曲线表明,稀土Ce3+离子的加入使铝合金LY12CZ的点蚀敏感性降低;电化学阻抗谱表明,在纯培养基中,随稀土Ce3+离子浓度的增大,铝合金耐蚀性增大.而在接种1％ SRB的培养基中,当Ce3+浓度为0.376 mg·L-1时,生长旺盛的生物膜与Ce3+间产生协同作用,增加了基体铝合金耐腐蚀性能.随着Ce3+浓度的增加,SRB生长受到抑制,不能形成致密的生物膜.此时SRB的存在促进铝合金腐蚀,显著减弱Ce3+对基体铝合金的保护作用.