静磁场作用下硫酸盐还原菌生长特性及腐蚀行为

发布时间：2018-03-17 12:40

本文选题：微生物腐蚀　切入点：腐蚀规律　出处：《华中科技大学》2015年博士论文　论文类型：学位论文

【摘要】：微生物腐蚀(MIC)是材料服役失效的主要因素,也是工业领域的共性问题,由此造成的经济损失巨大。磁处理技术在工业、农业、医疗、石油和水处理行业等领域的应用广泛,磁场的存在严重影响金属的腐蚀过程。但是关于磁场对微生物腐蚀的影响还未引起重视。本文利用电化学噪声结合表面分析技术系统研究了静磁场对硫酸盐还原菌(SRB)诱导的微生物腐蚀机制的影响,主要研究结果如下： (1)磁场对SRB细菌生长规律和生物膜影响研究表明：4mT低强度磁场显著抑制了浮游SRB的生长；4mT磁场和150mT中强度磁场都延缓了浮游SRB的衰亡。两种强度磁场都延缓了金属表面固着SRB生物膜的形成,但磁场同时显著加速了固着SRB生长速度。此外,短期磁场处理能快速剥离金属表面附着的生物膜,4mT磁场的剥离效果比150mT更明显。磁处理不仅能改变腐蚀过程中形成的腐蚀产物的化学成分,而且能快速改变已形成的腐蚀产物的化学组成,将无磁场条件下的腐蚀产物硫铁化合物转化为铁氧化合物。磁场作用下,培养基中SRB代谢产物H2S最终含量为800μmol/L,远大于空白条件下的20μmol/L。 (2)磁场对不易磁化不锈钢和易磁化碳钢在SRB介质中MIC的影响规律研究表明：通过小波变换对电化学噪声数据进行统计分析,能实现对微生物腐蚀过程进行分类,还能定量分析腐蚀的强度,从而实现对微生物腐蚀过程的跟踪研究。无磁场条件下,304SS在SRB菌液中先发生活性溶解,随后发生亚稳态点蚀：随后生物膜进入对数生长期,亚稳态转变为稳态腐蚀；在生物膜衰亡期,304SS腐蚀受到抑制。在4mT磁场条件下,304SS在整个研究周期内以钝化为主,伴随轻度亚稳态点蚀。说明4mT磁场能有效保护304SS,这主要是归因于低强度磁场对SRB的生长的抑制。150mT加速了304SS的腐蚀。腐蚀形态最初以亚稳态点蚀为主,逐渐出现稳态腐蚀。到了生物膜衰亡期,亚稳态点蚀和稳态腐蚀同时发生。另一方面,磁场促进了Q235在SRB菌液中的腐蚀,150mT磁场比4mT磁场效果更显著。无磁场下,Q235电极先主要发生均匀腐蚀,随后以点蚀为主。4mT下,Q235电极发生的腐蚀演变规律和无磁场条件下一样,不过电流幅值更大,说明腐蚀更重。150mT下,从生物膜迟缓期到衰亡期,局部腐蚀程度越来越重。与不易磁化304SS有所不同,易磁化Q235在磁场中会被磁化,产生了磁场自增强效应,增强了的磁场促进了Q235的腐蚀。 (3)磁场对受应力Q235在SRB介质中MIC的影响规律研究表明：在无菌培养基体系中,Q235腐蚀经历了3个阶段：均匀腐蚀、亚稳态点蚀,晚期出现腐蚀开裂。SRB介质中,在生物膜形成初期,Q235主要发生均匀腐蚀：进入对数生长期后,Q235发生腐蚀开裂,说明SRB促进了腐蚀开裂的发生。4mT下,在生物膜迟缓期,碳钢发生腐蚀开裂；在生物膜对数期,Q235出现钝化;但是到了衰亡期,试样再次出现腐蚀开裂,呈现出断裂的非连续性。4mT磁场下Q235的断裂属于脆性断裂。150mT条件下,C型环断裂连续进行,这可能是由于MF对体系提供能量所致。MF和SRB协同作用极大地加速并恶化了碳钢的MIC。
[Abstract]:Microbial corrosion (MIC) is the main factor of material service failure, it is also a common problem in the industry, resulting in huge economic losses. The magnetic treatment technology in industry, agriculture, medical treatment, application of oil and water treatment industry and other fields widely, the existence of the magnetic field influence the corrosion process of metals. But the effect of magnetic field on the microbial corrosion has been noticed. The electrochemical noise of static magnetic field on sulfate reducing bacteria (SRB) surface analysis technique system induced by the effect of microbial corrosion mechanism, the main results are as follows:
(1) SRB magnetic field on bacterial growth rules and effects of biofilm research show that: 4mT low intensity magnetic field significantly inhibited the growth of planktonic SRB; 4mT and 150mT in the magnetic field strength magnetic field have delayed the decline of planktonic SRB. Two kinds of magnetic field strength are delayed fixing metal surface SRB biofilm formation, but also a significant magnetic field accelerate the fixed growth rate of SRB. In addition, the magnetic treatment can short-term biofilm attached on the surface of metal rapid stripping, stripping 4mT magnetic field effect is more obvious than 150mT. Not only can change the chemical composition of corrosion products formed in the corrosion process of the magnetic treatment, and can quickly change the chemical composition of corrosion products has been formed, there will be no transformation the corrosion products of iron sulfides in magnetic field under the condition of iron oxides. Magnetic field, cultivation of metabolites of SRB H2S content in medium was 800 mol/L, far greater than the blank under the condition of 20 mol/L.
(2) study of the effect of magnetic field on the hard magnetization of stainless steel and carbon steel easy magnetization in the medium of SRB MIC shows that the wavelet transform on the electrochemical noise data for statistical analysis, to achieve the classification of the microbial corrosion process, corrosion strength analysis can be quantitatively, and realizes the tracking research on microbial corrosion process. Without magnetic field under the condition of 304SS first life dissolved in SRB solution, followed by metastable pitting and biofilm into the logarithmic growth phase, metastable transition to steady-state corrosion; biofilm in the decline phase, 304SS corrosion is suppressed. The magnetic field in the 4mT condition, 304SS mainly passive throughout the study period. Accompanied by a mild metastable pitting. 4mT magnetic field can effectively protect the 304SS, which is mainly attributed to the inhibition of.150mT low intensity magnetic field on the growth of the SRB accelerated 304SS corrosion. The corrosion morphology initially in metastable State of pitting corrosion. The corrosion. The gradual emergence of steady-state biofilm decline phase, metastable pitting and steady corrosion occurred at the same time. On the other hand, the magnetic field promotes the corrosion of Q235 in SRB solution, 150mT 4mT magnetic field than the more significant effect. No magnetic field, Q235 electrode uniform corrosion occurs first, followed by the the pitting corrosion.4mT, Q235 corrosion electrode evolution and without magnetic field, but the current amplitude is greater, indicating that the corrosion is more important.150mT, from the biofilm of lag phase to decline phase, the local corrosion degree is more and more heavy. Different from the hard magnetization 304SS, easy magnetization in a magnetic field will be Q235 the magnetic field magnetization, self enhancement effect, enhances the magnetic field promoted Q235 corrosion.
(3) the effect of magnetic field on the law of Q235 in the medium of SRB MIC showed that in the sterile culture medium system, Q235 corrosion has experienced 3 stages: uniform corrosion, metastable pitting, late corrosion cracking in.SRB medium, at the beginning of the formation of biofilm, Q235 uniform corrosion occurs: enter the log growthphase, Q235 corrosion cracking, which indicated that SRB promoted.4mT corrosion cracking, suspended late in the biofilm, carbon steel corrosion cracking; biofilm in logarithmic phase, Q235 passivation; but in the decline phase, the corrosion cracking again, showing a fracture of non continuous fracture Q235.4mT magnetic field belong to brittle fracture under the condition of.150mT, C type ring continuously, this may be due to the MF system to provide the energy caused by.MF and SRB synergistic effect and greatly accelerate the deterioration of carbon steel MIC.

【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TG172.7

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