| Popis: |
This study investigates the morphology, composition and corrosion resistance of hot dip galvanized (HDG) steel bolts in fresh water, 1% NaCl saltwater in the presence of protective compounds L-Tryptophan and three conventional corrosion inhibitors: Inhibitor 1-VCI (amine-carboxylates-based), Inhibitor 2 (based on carboxylate acid), and Inhibitor 3 (water-based, carboxylate acid). Quantitative tests performed include gravimetric analysis and electrochemical techniques, such as linear polarization, Tafel extrapolation, and Electrochemical Impedance Spectroscopy (EIS). Electrochemical measurements determined the polarization resistance Rp, corrosion rate vcorr, and corrosion potential Ecorr. Furthermore, Scanning Electron Microscopy (SEM) and ATR-FTIR spectrometry were used to evaluate and characterize the formed layers on the surface of hot-dip galvanized steel samples. The results reveal that upon corrosion new compounds are formed onto the exposed areas of the treated bolts such as zinc-carbonates, zinc-hydroxides, etc. The presence of these compounds on the surface of the HDG steel bolts hinders the corrosion process by reducing the rate of the anodic and cathodic reactions. The gravimetric test showed that L-tryptophan in distilled water has mass increase, resulting from the formation of white deposits on the sample surface. In fresh water and distilled water, the best corrosion resistance was achieved with Inhibitor 1-VCI, while L-tryptophan showed best results in 1% NaCl solution. |
