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The aims of this study were to determine the corrosion behavior of pure copper in the presence of Desulfovibrio sp. and also to investigate the effects of glutaraldehyde (GD) and isothiazolinone (ISO) on the corrosion behavior of pure copper in the presence of this sulfate-reducing bacteria (SRB) strain by using electrochemical techniques. Electrochemical measurements of pure copper were carried out at specified time intervals (0, 8, 24, 48, and 96 hr) over a period of exposure. Corrosion rates of pure copper from anodic and cathodic Tafel slopes and corrosion potential (E c o r r) were determined. Biofilm and corrosion products on the copper surfaces were observed by Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-Ray Spectrometry (EDS) analyses. The effects of solution types (PC (Postgate's C medium) and SRB (Desulfovibrio sp.)) and exposure times of copper and biocides (ISO or GD) on the corrosion rates of pure copper were evaluated by statistical analyses. As a result of the FESEM analysis, biofilm formation was observed on the surfaces of pure copper exposed to the Desulfovibrio sp. cultures both with and without the biocides. The results show that the pure copper was corroded by Desulfovibrio sp. However, the addition of GD or ISO to the Desulfovibrio sp. culture resulted in a decrease in the corrosion rate of the pure copper. It was also observed that both of the biocides showed a similar effect on pure copper's corrosion rate caused by Desulfovibrio sp.

Nowadays, some of the steel parts have been applied induction hardening for better mechanical properties in the automotive and aerospace industry sectors. Induction hardening is commonly used in steels, are high magnetic permeability. Martensite formation was observed application as a result of non-diffusion transformation after induction hardening. At this period, there were chosen three factor such as power supplied, scan rate, distance between work piece and coil, were affected material properties. Developed response variables such as surface hardness and case depth were determined after the experiments were done in the industrial conditions. In this study, data were taken by Taguchi method using L27 experiment orthogonal arrays table. Analysis of Variance (ANOVA) was employed with the help of data taken and regression equation was determined. As a result of these experiments and analyses, the optimization of the process conditions for induction hardened steel was investigated. As a consequence of the optimization, microstructural characterization using Light microscopy was carried out to determine the effects of the hardness from the outer surface to the center and nevertheless transformations associated with structural changes are investigated and so that results are determined.

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