Sol-Gel Derived Protective Coatings to Prevent Microbial Induced Corrosion

摘要

Microbial Induced Corrosion (MIC) is a very aggressive form of corrosion. To prevent this type of corrosion a novel coating system based on sol-gel chemistry was developed. Newly designed and synthesized as well as commercially available molecular precursors were used for the preparation of a green alternative to the coatings and solutions currently used up to protect large iron and steel infrastructures against damages caused by MIC.The molecular precursors were comprehensively analyzed using FT-IR, ~1H, ~(13)C and ~(29)Si NMR spectroscopy. The initial stages of hydrolysis and condensation reactions under acidic conditions were examined with solution ~(29)Si NMR spectroscopy. For the deposition of the different precursor systems we used dip-coating as well as painting. In addition to curing with conventional heating cabinets we used infrared emitters. The protection behavior of these coatings was studied as a function of coating material, thickness and curing method.The performance of the coatings to protect against classical corrosion was verified using electrical impedance spectroscopy (EIS). In order to proof the protective behavior in a MIC environment sea water was used. Coating morphology was investigated by scanning electron microscopy (SEM). By use of CP/MAS ~(29)Si NMR the chemical structures of the coating materials were analyzed.The EIS-tests proved that the obtained coatings provide very good protection against corrosion. The coating resistance after one month of immersion in saline water solution (3.5% NaCl) was >>10~(10) Ω cm~2. Besides, these coatings showed low water uptake.