海洋环境腐蚀与生物污损重点实验室知识库

铜作为海洋环境及其它工业环境中的重要材料正面临着严重的微生物腐蚀问题，因此，研究铜的微生物腐蚀机理和防护具有重要的意义。本文以纯铜为研究对象，探讨了硫酸盐还原菌（SRB）所致纯铜的微生物腐蚀（MIC）机理并且在铜表面构建了超疏水薄膜。通过控制SRB所需的有机碳源和生存空间，研究了纯铜在SRB培养液中的腐蚀特性和规律。通过与SRB所致碳钢的腐蚀机理进行比较，从实验的角度验证了SRB所致纯铜的腐蚀机理为新陈代谢产物-微生物腐蚀（M-MIC）。这与SRB所致碳钢的腐蚀机理-胞外电子传输-微生物腐蚀（EET-MIC）有本质的不同。本文的研究不仅丰富了纯铜的微生物腐蚀理论，为其微生物腐蚀防治提供了重要的理论依据，还证明了铜基超疏水表面在腐蚀防护方面广阔的应用前景。主要研究内容如下：

（1）研究了SRB在不同有机碳源条件下所致铜的腐蚀机理。随着有机碳源的增加，铜的腐蚀程度加深。在100%的有机碳源条件下，铜的腐蚀最严重。为了更好的理解SRB所致铜的腐蚀机理，本文进一步研究了SRB在不同有机碳源条件下所致C1018碳钢的腐蚀机理。通过对SRB所致铜与碳钢的腐蚀进行比较，揭示了SRB引起的铜的腐蚀属于代谢产物引起的微生物腐蚀（M-MIC），而SRB引起的C1018碳钢的腐蚀是由胞外电子传输引起的微生物腐蚀（EET-MIC）。

（2）研究了SRB在不同生存空间下对铜的腐蚀机理。不同的生存空间一方面影响了SRB的生长活性，另一方面也影响了溶解的H₂S的浓度。随着生存空间的增加，SRB生长活性更加良好，然而其溶解的H₂S浓度却随之降低。在有限的生存空间下，随着生存空间的减小，SRB生长活性减弱，但铜的腐蚀却得到了加速。进一步验证了SRB引起的铜的腐蚀为第二类微生物腐蚀，即代谢产物引起的微生物腐蚀（M-MIC）。

（3）铜基超疏水表面的制备及其耐蚀性的研究。采用化学刻蚀法，通过控制刻蚀时间，在铜表面得到了不同形貌的微纳米结构，进一步利用全氟硅烷（PFDS）进行处理，成功制备了超疏水表面。解析了表面微纳米结构的形貌和疏水性之间的关系。刻蚀时间为10 min时，表面呈现出致密的尖锐的针状结构，此时，表面疏水性最好，静态水接触角达到最高。盐粒在此表面进行潮解时，可以在潮解完全之前轻松地滚离表面。保持了表面的清洁和干燥，抑制了液膜形成，有效地阻碍了电化学腐蚀反应的进行。

（4）化学刻蚀得到微纳米表面结构之后，通过电沉积的方法在CuO的表面成功地制备了WO₃薄膜。CuO-WO₃复合超疏水薄膜展现出了超强的耐酸特性，在0.1 M H₂SO₄溶液中浸泡48 h以后，静态水接触角仍然可以达到160^o。同时，平面放置的样品表面的盐粒会在自我潮解之后，互相融合且滚离表面，保持了表面的清洁和干燥，阻碍了液膜的形成和电化学反应的进行。对CuO-WO₃超疏水表面的微生物附着进行了初步的探讨，发现其具有良好的抑制微生物附着的作用。

Copper, as important material in marine environment and other industrial environment, is facing severe microbiologically influenced corrosion (MIC) problem. So, it is significant to research the mechanism of copper MIC and its protection. Pure copper was used as research object in this paper. The mechanism of copper corrosion induced by sulfate reducing bacteria (SRB) was studied and super-hydrophobic films were fabricated on copper. The organic carbon source and headspace were controlled to research the characteristics of SRB corrosion. Compared to the mechanism of carbon steel corrosion induced by SRB, the different mechanism of SRB corrosion of copper was verified experimentally to be the type of metabolite-microbiologically influenced corrosion (M-MIC). This is entirely different from mechanism of carbon steel corrosion induced by SRB which is extracellular electron transfer-MIC (EET-MIC). This research enriched the understanding of mechanisms of MIC, provided theoretical basis for diagnosis, prevention and mitigation for MIC and verified the wide prospect on prevention of MIC by using a super-hydrophobic film on copper. The main research contents are following:

(1) The mechanism of copper corrosion induced by SRB with different carbon source levels was investigated. With the increase of carbon source in the culture medium, the extent of copper corrosion was more severely. With 100% carbon source in the culture medium, copper caused most severe corrosion. Furthermore, the mechanism of C1018 carbon steel corrosion induced by SRB with different carbon source level was researched for comparison. The characteristics of copper and C1018 carbon steel corrosion by SRB were compared to verify that the mechanism of copper corrosion belong to M-MIC while C1018 carbon steel corrosion belong to EET-MIC.

(2) The mechanism of copper corrosion induced by SRB in vials with different headspace volume was investigated. The headspace to culture medium liquid volume ratio affected both of SRB growth and the concentration of dissolved H₂S. With an increase of headspace, the SRB grew better while the concentration of dissolved H₂S was decreased. With a small headspace space, SRB did not grew well but it resulted in a high concentration of H₂S in the culture medium which accelerated the copper corrosion. This further verified that the mechanism of copper corrosion by SRB belongs to M-MIC.

(3) Super-hydrophobic surfaces on copper was prepared and their barrier effect against corrosive media was researched. Using the chemical etching method, different micro-nanostructures were obtained by controlling the etching time. After that, the surface was immersed in a perfluorodecyltrichoxysilane (PFDS) solution for further treatment. Finally, the super-hydrophobic surfaces were obtained. The relationship between the morphology of micro-nano structure and hydrophobicity was discussed. When the etching time was controlled at 10 min, the surface presented a dense and sharp needle structure. Under this condition, the surface possessed perfect hydrophobicity with the highest static water contact angle. NaCl salt particles were deliquesced and rolled away from the surface before it deliquesced completely. The surface remained dry and clean. A liquid film could not form on the surface and then this prevented electrochemical corrosion.

(4) After obtaining the micro-nano structure with chemical etching, a WO₃ film was deposited on the CuO surface through the electro-deposition method. The composite super-hydrophobic CuO-WO₃ film presented very high corrosion resistance. After immersion in 0.1 M H₂SO₄ solution for 48 h, the static water contact angle reached 160^o. Meanwhile, the salt particles deliquesced on a horizontal surface and merged with each other and then rolled away from the surface. The surface remained dry and clean. This prevented the formation of a liquid film on the surface and electrochemical corrosion. The attachment of microbes on super-hydrophobic CuO-WO₃ surface was discussed preliminarily and found that the surface possessed good inhibition of attachment of microbes.