جستجوی مقالات مرتبط با کلیدواژه « آزمون پلاریزاسیون تافل » در نشریات گروه « فنی و مهندسی »

In this study, the inhibitory effects of two organic corrosion inhibitors, 2-amino-5-nitrothiazole (Enheptin) and 2- Aminoethanesulfonic acid on carbon steel 4130 in hydrochloric acid solution were investigated using Tafel polarization tests and Density Function Theory (DFT) (using Gaussian 09W software). The results showed that with increasing the concentration of inhibitors in acidic environment, the percentage of inhibition increases and both organic inhibitors affect the cathodic (hydrogen reduction) and anodic (metal dissolution) reactions so can be classified as mixed inhibitors. With increasing concentration of inhibitors, the inhibitor efficiency of Enheptin was more than 2-Aminoethanesulfonic acid. The results and parameters derived from the DFT also showed the more chemical and electron affinity of the of the Enheptin atomic orbitals in comparison with 2- Aminoethanesulfonic.

An imidazoline based inhibitor was synthesized using oleic acid and diethylenetriamine (DETA). The characteristic properties of the synthesized inhibitor were investigated by FTIR and HNMR tests. Tafel polarization technique and electrochemical impedance spectroscopy (EIS) were used to study the electrochemical and corrosion inhibition properties of the inhibitor in CO2 saturated 3% NaCl solution. Potassium iodide was added to the corrosion media to enhance the inhibition efficiency of the inhibitor. The measured corrosion rates were optimized by Design Expert 10.0.7 software using central composite design and response surface method. Temperature and inhibitor concentration were selected as the most effective parameters. Analyses of variance (ANOVA) were performed on the results of the designed experiments. It was found that temperature and inhibitor concentration effects on corrosion rate and inhibition efficiency are complicated and their interactions. Addition of KI to the inhibitor system had a synergistic effect on the corrosion inhibition. It almost eliminated the dependency of the corrosion rate to temperature and inhibitor concentration which is a great achievement in inhibitor applications in oil and gas industries. DOE data revealed that the best inhibition of corrosion occurred at 25oC with 37.7ppm of synthesized Imidazoline inhibitor and 2000ppm KI. It is estimated by the software that at this point the corrosion rate is 6µm/year and polarization resistance is 30788Ω. The synthesized inhibitor conforms perfectly to the Langmuir adsorption isotherm.

In this study, Inconel 617 alloy was welded to A387-Gr.11 low-alloy steel using ER309L filler metal via gas tungsten arc welding (GTAW). First, the corrosion behavior of Inconel 617, A387-Gr, and the weld metal was evaluated by the Tafel polarization test and electrochemical impedance spectroscopy (EIS) in acidic (H2SO4), neutral (NaCl), and combined (H2SO4 + NaCl) solution at ambient temperature. The results of polarization and EIS measurements in all corrosive solutions indicate that the corrosion resistance decreases from 617 alloy to weld metal and from weld metal to low-alloy steel, respectively. The Comparison of the polarization curves of the base metals and the weld metal showed susceptibility to galvanic corrosion between Inconel 617 / weld metal in 1M NaCl solution. The behavior of galvanic corrosion of this pair was evaluated using the mixed potential theory and the electrochemical noise measurement. The results showed that in a galvanic couple of alloy 617 / weld metal, the weld metal acts as anode and corrodes in such a way that its corrosion rate increases from 0.22 μA/cm2 before joining to 1 μA /cm2 after joining.