本文選題：微生物腐蝕　切入點：腐蝕規(guī)律　出處：《華中科技大學》2015年博士論文　論文類型：學位論文

【摘要】：微生物腐蝕(MIC)是材料服役失效的主要因素,也是工業(yè)領域的共性問題,由此造成的經(jīng)濟損失巨大。磁處理技術在工業(yè)、農(nóng)業(yè)、醫(yī)療、石油和水處理行業(yè)等領域的應用廣泛,磁場的存在嚴重影響金屬的腐蝕過程。但是關于磁場對微生物腐蝕的影響還未引起重視。本文利用電化學噪聲結(jié)合表面分析技術系統(tǒng)研究了靜磁場對硫酸鹽還原菌(SRB)誘導的微生物腐蝕機制的影響,主要研究結(jié)果如下： (1)磁場對SRB細菌生長規(guī)律和生物膜影響研究表明：4mT低強度磁場顯著抑制了浮游SRB的生長；4mT磁場和150mT中強度磁場都延緩了浮游SRB的衰亡。兩種強度磁場都延緩了金屬表面固著SRB生物膜的形成,但磁場同時顯著加速了固著SRB生長速度。此外,短期磁場處理能快速剝離金屬表面附著的生物膜,4mT磁場的剝離效果比150mT更明顯。磁處理不僅能改變腐蝕過程中形成的腐蝕產(chǎn)物的化學成分,而且能快速改變已形成的腐蝕產(chǎn)物的化學組成,將無磁場條件下的腐蝕產(chǎn)物硫鐵化合物轉(zhuǎn)化為鐵氧化合物。磁場作用下,培養(yǎng)基中SRB代謝產(chǎn)物H2S最終含量為800μmol/L,遠大于空白條件下的20μmol/L。 (2)磁場對不易磁化不銹鋼和易磁化碳鋼在SRB介質(zhì)中MIC的影響規(guī)律研究表明：通過小波變換對電化學噪聲數(shù)據(jù)進行統(tǒng)計分析,能實現(xiàn)對微生物腐蝕過程進行分類,還能定量分析腐蝕的強度,從而實現(xiàn)對微生物腐蝕過程的跟蹤研究。無磁場條件下,304SS在SRB菌液中先發(fā)生活性溶解,隨后發(fā)生亞穩(wěn)態(tài)點蝕：隨后生物膜進入對數(shù)生長期,亞穩(wěn)態(tài)轉(zhuǎn)變?yōu)榉�(wěn)態(tài)腐蝕；在生物膜衰亡期,304SS腐蝕受到抑制。在4mT磁場條件下,304SS在整個研究周期內(nèi)以鈍化為主,伴隨輕度亞穩(wěn)態(tài)點蝕。說明4mT磁場能有效保護304SS,這主要是歸因于低強度磁場對SRB的生長的抑制。150mT加速了304SS的腐蝕。腐蝕形態(tài)最初以亞穩(wěn)態(tài)點蝕為主,逐漸出現(xiàn)穩(wěn)態(tài)腐蝕。到了生物膜衰亡期,亞穩(wěn)態(tài)點蝕和穩(wěn)態(tài)腐蝕同時發(fā)生。另一方面,磁場促進了Q235在SRB菌液中的腐蝕,150mT磁場比4mT磁場效果更顯著。無磁場下,Q235電極先主要發(fā)生均勻腐蝕,隨后以點蝕為主。4mT下,Q235電極發(fā)生的腐蝕演變規(guī)律和無磁場條件下一樣,不過電流幅值更大,說明腐蝕更重。150mT下,從生物膜遲緩期到衰亡期,局部腐蝕程度越來越重。與不易磁化304SS有所不同,易磁化Q235在磁場中會被磁化,產(chǎn)生了磁場自增強效應,增強了的磁場促進了Q235的腐蝕。 (3)磁場對受應力Q235在SRB介質(zhì)中MIC的影響規(guī)律研究表明：在無菌培養(yǎng)基體系中,Q235腐蝕經(jīng)歷了3個階段：均勻腐蝕、亞穩(wěn)態(tài)點蝕,晚期出現(xiàn)腐蝕開裂。SRB介質(zhì)中,在生物膜形成初期,Q235主要發(fā)生均勻腐蝕：進入對數(shù)生長期后,Q235發(fā)生腐蝕開裂,說明SRB促進了腐蝕開裂的發(fā)生。4mT下,在生物膜遲緩期,碳鋼發(fā)生腐蝕開裂；在生物膜對數(shù)期,Q235出現(xiàn)鈍化;但是到了衰亡期,試樣再次出現(xiàn)腐蝕開裂,呈現(xiàn)出斷裂的非連續(xù)性。4mT磁場下Q235的斷裂屬于脆性斷裂。150mT條件下,C型環(huán)斷裂連續(xù)進行,這可能是由于MF對體系提供能量所致。MF和SRB協(xié)同作用極大地加速并惡化了碳鋼的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.

【學位授予單位】：華中科技大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TG172.7

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