Aerobik bakterilerin korozyona etkisinin incelenmesi
Tabrizi, Amirparviz Farshchi
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In this doctoral thesis study, the corrosion effect of Pseudomonas aeruginosa, Aeromonas eucrenophila, Clavibacter michiganensis and Delftia acidovorans bacteria, Which is defined by 16S rRNA gene sequence analysis and isolated from the rust specimens taken from the field on Fe, Co, Ni, and Cu metals surfaces. These metal surfaces have been investigated via electrochemical techniques, Scanning Electron Microscobe-Energy Dispersive X-ray (SEM-EDX), and analytically the bacterium ? metal solutions pH values have also been recorded. In electrochemical studies, Open Circuit Potential (OCP), Quartz Crystal Microbalance (QCM), Linear Scanning Voltametry (LSV) and Electrochemical Impedance Spectroscopy (EIS) techniques are used. The morphology of the corroded layer and formed biofilm on metal surface due to microbial activity have been displayed and analyzed by SEM-EDX. Moreover, during the vital activity of bacteria, the existence of the reducing groups on the surface of the resultant biofim layer is shown by Fourier Transform Infrared Spectroscopy (FTIR) and effect of these groups on surface corrosion has been emphasized.In this thesis study, working electrodes of Fe, Co, Ni, Cu which examined bacterial resistance to corrosion, electrodepozited in electroplating baths by chronoamperometry (CA - Chronoamperometry) technique and were prepared homogeneously and approximately 100 nm thickness. In QCM experiment, the coatings have been carried out on gold (Au) surfaces, and in other experiments, brass (Cu-Zn alloy) and ST-42 mild steel surfaces have been used. All the experiments were carried out with fresh bacterial samples prepared from the exponential phase of bacterium culture. Coating the surface of working electrodes (R=5.1 mm), secreted by the biomass of the bacteria in exponential phase takes five hours, approximately. This period of time is determined by SEM and OCP, and has been accepted as an optimum operating time, in this thesis.The scope of this doctoral thesis with the experiments, contaminated/polutted invironments with bacteria increase the rate of corrosion of metals and as a result of the vital activity of bacteria in relation to the first steps of the biofilm formation, the result is shown in general.