摘要
海洋環(huán)境中碳鋼的腐蝕是一個涉及物理、化學(xué)、生物等多方面因素的電化學(xué)過程，而海洋環(huán)境中的微生物更是加速碳鋼腐蝕的一個重要因素，給碳鋼在海洋工程上的使用帶來了很大的安全隱患和經(jīng)濟損失。隨著人們對海洋的廣泛開發(fā)和利用，海洋環(huán)境中的海底輸送管線、海上采油平臺、海底采礦設(shè)備等金屬材料構(gòu)建物的 MIC 引起了人們廣泛的關(guān)注。目前在這一領(lǐng)域已有較多的研究，主要集中于微生物腐蝕機理方面，特別在鐵細(xì)菌、硫酸鹽還原菌、脫硫腸狀菌屬以及排硫桿菌等微生物腐蝕方面的研究已取得了可喜的成果。然而，對于假單胞菌對碳鋼的腐蝕行為的研究卻較少。
本文是采用微生物學(xué)法在海水中分離、提純出假單胞菌，測定假單胞菌的生長曲線，確定假單胞菌的生長周期。然后，在實驗室中模擬假單胞菌在海水中的生活環(huán)境，以45鋼為研究對象，運用電化學(xué)測量技術(shù)，如：開路電位的測量、動電位循環(huán)掃描極化曲線和交流阻抗譜測試等方法，對海水體系中假單胞菌對45鋼的腐蝕過程進(jìn)行跟蹤研究，從而獲得碳鋼在海水中的腐蝕電位、阻抗隨時間的變化趨勢以及陽極和陰極極化特征，揭示假單胞菌對45鋼在海水中腐蝕的電化學(xué)行為影響。
用最大可能菌數(shù)法（MPN）測定了海水中假單胞菌的數(shù)量，繪制生長曲線，得到了海水中假單胞菌的生長規(guī)律（分為四個生長周期：遲緩期、對數(shù)生長期、穩(wěn)定生長期、衰亡期）。用自腐蝕電位、極化曲線和電化學(xué)阻抗譜的電化學(xué)特征有效的評測了45鋼在假單胞菌-海水體系作用下的電化學(xué)腐蝕行為。生長曲線表明，海水中假單胞菌的生長期分為遲緩期、對數(shù)生長期、穩(wěn)定生長期、衰亡期四個周期，在海水條件下假單胞菌可以在相對長的時間內(nèi)穩(wěn)定生長。自腐蝕電位表明，完整生物膜的形成不會改變電極陰極的極化類型和控制步驟，假單胞菌的新陳代謝作用決定了45鋼電極的性質(zhì)和腐蝕速度。電化學(xué)阻抗譜表明，腐蝕產(chǎn)物層和雙電層的雙層作用而導(dǎo)致的陰極反應(yīng)的電荷和物質(zhì)在兩相界面的傳輸速率的變化是控制45鋼海水腐蝕的主要因素。
關(guān)鍵字：微生物腐蝕；假單胞菌；45鋼；電化學(xué)

Abstract
In the marine environment , corrosion of carbon steel is the electrochemical process, influenced by physical, chemical, biological and other factors. Microbiology is a more important factor of accelerated corrosion of carbon steel, and has been given a lot of security risks and economic losses for use of carbon steel in marine engineering. With a widly development and utilization of marine resources, the microbiologically influenced corrosion (MIC) has been given much attention in marine environment concerned of all kinds of structure constructions, such as undersea pipelines, offshore oil platforms, seabed mining equipment, etc. Presently, most researches focus on the corrosion mechanism of microbiology in this area and especially the researches of the iron bacteria, sulfate-reducing bacteria, desulfotomaculum bacteria and sulfur bacteria have made encouraging results. However, the corrosion behavior of carbon steel by pseudomonas is few.
In this paper，the growth curve of pseudomonas was measured in order to know the growth cycle. Pseudomonas isolated and purified from carbon steel corrosion products by biology techniques. Then, the living environment of pseudomonas is simulated in the laboratory. The process of the corrosion of 45 steel was tracked in seawater with pseudomonas by electrochemical measurement techniques, which contain open circuit potential measurement, potentiodynamic cyclic polarization curve and AC impedance. Those can be obtained the corrosion potential, Rp trends curve with time and characteristics of the anode and cathode polarization from those. Some conclusions of the formation rule on corrosion of 45 steel can be achieved in seawater with pseudomonas.
The number of pseudomonas in different time was measured by method of most probable number (MPN) methed in seawater experiment.Growth curve of pseudomonas was described in order to investigate the vegetal rule of seawater (four periods:logy periods,logarithmic periods,steady growth periods,contabescence periods). The variety of the corrosion behavior of the 45 steel are investigated by the open circuit potential, polarization curves and electrochemical impedance spectroscopy in seawater with pseudomonas. Growth curves shows that the growth phase of pseudomonas divide into logy periods, logarithmic periods, steady growth periods, contabescence periods and can be a relatively long period of time in the steady growth periods in seawater and pseudomonas. The open circuit potential shows that full biofilm formation does not change the cathode electrode polarization type and control steps and the metabolism of pseudomonas determines the electrode nature and electrode corrosion rate of the corrosion of 45 steel. Electrochemical impedance spectroscopy shows that the transmission rate of charge and material of cathode reaction in the two-phase change interface is the main factors of the corrosion of the steel by product layer and double layer.
Keywords: MIC;Pseudomonas,;electrochemistry















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