Pure Copper Corrosion Induced By Microbes And Preparation Of Anti-Corrosive Super-hydrophobic Surface On Copper

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 C1018carbon 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.