DH36钢在需钠弧菌、芽孢杆菌以及混菌腐蚀体系中的腐蚀行为

目的研究需钠弧菌与芽孢杆菌分别单独培养以及混合培养时对海洋工程钢DH36腐蚀行为的影响,为海洋环境下材料的腐蚀发生规律探讨以及微生物腐蚀防治提供依据。方法通过扫描电子电镜、能谱仪、电化学设备等仪器,分析DH36钢在不同腐蚀体系中的腐蚀形貌信息以及电化学特征。结果SEM图显示,芽孢杆菌在DH36钢表面上的贴附量较大,需钠弧菌与混菌腐蚀体系中,生物膜、锈层构成的混合层存在很多的裂纹、缝隙,致密性较差。电化学结果显示,试样表面均出现两个时间常数,在低频处出现感抗特征。芽孢杆菌腐蚀体系中的腐蚀速率先增大后减小,浸泡3 d后需钠弧菌腐蚀体系中的腐蚀速率介于芽孢杆菌与混菌腐蚀体系之间。与单菌种腐蚀体系相比,混菌腐蚀体系中的开路电位最低,且浸泡7 d后的腐蚀速率最大,达到13.53μA/cm^2。结论在浸泡后期芽孢杆菌显示出腐蚀抑制效果,在需钠弧菌与混菌腐蚀体系中,由于细菌代谢产生了腐蚀性产物以及形成了致密性较差的混合层,试样腐蚀速率不断加快,但混菌的促进作用更显著。

Corrosion Behavior of DH36 Steel in the Corrosion System of Vibrio natriegens, Bacillus sp. and Vibrio natriegens-Bacillus sp. Mixed Species

The work aims to provide theoretical basis for the research of corrosion laws and microbial corrosion prevention in the marine environment by studying the corrosion behavior of marine engineering steel DH36 in Vibrio natriegens,Bacillussp.and Vibrio natriegens-Bacillus sp.mixed species.The corrosion morphologies and electrochemical characteristics of DH36 steel in the different corrosion systems were tested by the scanning electron microscope,energy dispersive spectrometer,electrochemical testing equipment and other methods.SEM images showed that there were large amounts of Bacillus sp.adhered on the surface of DH36 steel.The mixed layer of biofilm and rust layer in the corrosion system of Vibrio natriegens and Vibrio natriegens-Bacillus mixed species had lots of cracks and crevices,thus leading to poor compactness.The electrochemical results indicated that there were two time constants existed in the surfaces of the samples,and the inductive impedance characteristics appeared in low frequency.In the presence of Bacillus sp.,the corrosion rate increased at beginning and then decreased with increasing immersion time.The corrosion rate in Vibrio natriegens corrosion system was between those of Bacillus sp.and the mixed species corrosion system after 3 d of immersion.Compared with the single-bacteria corrosion system,open circuit potential in Vibrio natriegens-Bacillus corrosion system was the lowest during immersion time and corrosion rate was the highest after 7 d of immersion,which was 13.53μA/cm^2.Bacillus sp.shows the corrosion inhibition effect in the late immersion stage.The corrosion rate increases in Vibrio natriegens and Vibrio natriegens-Bacillus corrosion system because of the corrosive metabolites and porous mixed layer.Meanwhile,the corrosion behavior of DH36 in the Vibrio natriegens-Bacillus sp.system is more serious.