【摘要】 现场调查和实验研究均证实了微生物致裂的存在并提出了合理的机理模型,但是缺乏微生物致裂的热力学和动力学理论分析。基于Gutman的力学-化学交互作用理论、微生物能量学和腐蚀电化学理论,本文尝试给出SRB/NRB致裂的热力学和动力学解释。热力学计算结果表明,应力和SRB/NRB共同作用下金属材料腐蚀反应的摩尔Gibbs自由能下降,腐蚀反应向环境释放出更多的热量,从热力学上来说具有更高的腐蚀趋势。与SRB腐蚀和SRB致裂相比,铁基金属材料NRB腐蚀和NRB致裂具有更强的热力学倾向。动力学分析表明,外加应力和微生物共同作用下金属材料腐蚀速率和微裂纹扩展速率加快。本工作的研究结果能丰富人们对金属材料菌致开裂行为的认识。更多还原

【Abstract】 Microbiologically influenced corrosion(MIC) is one of the most common corrosion types of buried pipelines. Many investigations in field survey and laboratory simulation studies have verified that microorganisms in soil and applied stresses can synergistically participate in and significantly affect the crack initiation and propagation of pipeline steels. This phenomenon was named as"microbiologically assisted cracking(MAC)". Relevant mechanisms, such as pitting mechanism, hydrogen damage mechanism, have been proposed to illuminate this phenomenon. However, there is still a lack of thermodynamic interpretation of MAC and the dynamic analysis deriving from thermodynamic interpretation. In the paper, the thermodynamic interpretation and the dynamic analysis for sulfate reducing bacteria(SRB)/nitrate-reducing bacteria(NRB)-assisted cracking were proposed based on the mechano-chemical interaction theory, bioenergetics and corrosion electrochemistry. The thermodynamic results showed that under the combined actions of SRB/NRB and external stress, the changes of Gibbs free energy of the corrosion reactions decrease and the releasing energies increase accordingly, revealing the stronger corrosion tendency in thermodynamics. For Fe-based alloys, NRB corrosion and NRB-assisted cracking are the more thermodynamically favorable processes, as compared to SRB corrosion and SRB-assisted cracking, respectively. The dynamic results showed that the corrosion rate and the crack propagation rate increase under the combined actions of applied stresses and microorganisms.更多还原