【作者】 赵勇；

【导师】 刘宏芳；

【作者基本信息】 华中科技大学 ， 应用化学， 2012， 硕士

【摘要】 由于铝合金具有比重轻、比强度高和价格便宜的特点，因而被广泛应用于电子产品、汽车工业、船舶业、建筑业、机械制造、近海工业、航空航天业等行业。然而，没有经过处理的铝合金由于其耐腐蚀性能差，而不能直接使用。随着飞机整体油箱微生物腐蚀事故报道的增多，相继引起了人们的关注。本文采用了紫外可见分光光度法、循环阳极极化法、电化学阻抗谱和表面分析技术（扫描电镜和荧光显微镜）相结合的方法，研究了稀土铈元素对硫酸盐还原菌的影响。并对不同浓度稀土铈含量下，铝合金LY12CZ的微生物腐蚀行为进行了研究。同时，也研究了经过微弧氧化处理后，铝合金LY12CZ的微生物腐蚀行为，取得的进展和结果如下：1．紫外可见分光光度法结果表明：当体系中稀土Ce³⁺浓度为0.376mg·L^-1时，表现为促进SRB生长。而当其浓度高于1.13mg·L^-1时，则表现为抑制其生长。采用循环阳极极化曲线和电化学阻抗谱研究了稀土铈离子在接种SRB前后的耐蚀性能，同时应用扫描电镜和荧光显微镜对其微观形貌进行分析。循环阳极极化曲线表明，稀土铈离子的加入，可以提高铝合金的击穿电位，降低其点蚀敏感性。电化学阻抗谱表明，SRB的存在可以加速铝合金的腐蚀。在纯培养基中，随稀土离子浓度的增大，其电荷转移电阻也增大；而接种1%SRB体系中，由于生物膜和稀土转化膜之间的协同作用，则表现为当稀土铈离子浓度为0.376mg·L^-1，其电荷转移电阻最大。2．通过开路电位跟踪、pH的监测、电化学阻抗谱、极化曲线和SEM等方法，研究了铝合金LY12CZ不同厚度的微弧氧化膜层下，其耐蚀能力。结果表明：由于微弧氧化膜疏松层较易吸附SRB，加剧腐蚀。因此，相比80μm厚的微弧氧化膜层，30μm厚的微弧氧化样更耐微生物腐蚀。3．通过腐蚀失重法和扫描电镜研究了母材和接头区的耐腐蚀性能。浸泡实验表明，焊核区的耐蚀性能最佳，其次为热影响区。微弧氧化能显著改善由于焊头热应力所引起的局部组织耐蚀能力变小的倾向。更多还原

【Abstract】 Owing to its excellent light weight, high strength and cheap price, aluminumalloy are widely used in the electronic products, automobile industry, shipbuildingindustry, construction industry, mechanical manufacturing, offshore industry,aerospace industry and some other industries. However, aluminum alloy can not beused directly for its poor corrosion resistance. With reports of the aircraft accident bythe cause of microbial corrosion increasing, people pay more attention to theanti-corrosion methods for the existence of microorganism.In this paper, we used the methods of ultraviolet spectrophotometry （UVS）,cyclic anodic polarization, electrochemical impedance spectroscopy（EIS） and surfaceanalysis techniques（Scanning electron microscopy and epi-fluorescence microscopy,EFM） to study the effect of rare earth Ce to the growth of sulfate reducingbacteria（SRB）. We also studied the microbial induced corrosion （MIC） behavior ofaluminum alloy LY12CZ under different concentrations of rare earth Ce. Furthermore,we also studied the MIC of aluminum alloy with micro-arc oxidation （MAO）. Themain progress and results are listed as follows:1．The results of UVS showed that it promoted the growth of SRB when theconcentrations of rare earth Ce3+was0.376mg·L^-1.But when it was more than1.13mg·L^-1, the growth of SRB was inhibited. By using the cyclic anodic polarizationcurves and EIS, the anti-corrosion property of aluminum alloy which caused by rareearth in culture medium with and without SRB was studied. Meanwhile, themorphology of matrix after coupon tests was observed by SEM and EFM. Cyclicanodic polarization curves showed that the pitting sensitivity of aluminum alloybecame lower in the solutions containing rare earth Ce3+. EIS results showed that SRBincreased the corrosion of aluminum alloy. In culture medium, with an increase in theconcentration of Ce³⁺, the charge transfer resistance increased also. When inoculatedwith1%SRB, because of a synergistic effect between the biofilm and the rare earthconversion film, the charge transfer resistance was the biggest when the concentration of rare earth Ce3+was0.376mg·L^-1.2．By tracking the open circuit potential, monitoring pH, EIS, polarization curvesand SEM, the anti-corrosion property of aluminum alloy with different thickness ofMAO coating was studied. The results indicated that SRB can be found on the surfaceof the matrix with MAO by EFM. The adsorption of SRB to the loose layer of MAOcoating increased corrosion. Therefore, compared with30μm micro-arc oxidation film,the matrix with80μm micro-arc oxidation had a better ability to inhibit MIC.3．The corrosive properties of welding butts were investigated by weight lossmethod and SEM. In the immersion test, the results indicated that the anti-corrosionproperties in the weld nugget zone was the best compared with heat affect zone.Micro-arc oxidation can significantly improve the change of anti-corrosion propertiescaused by the welding thermal stress.更多还原