An amide, namely N-[2-[(2-hydroxyethyl) amino] ethyl]-amide, extracted from the fatty acids contained in the coffee bagasse, has been investigated as a possible green corrosion inhibitor for copper in 3.5% NaCl by using potentiodynamic polarization curves and electrochemical impedance spectroscopy measurements. Results were complemented by detailed scanning electronic microscopy, FTIR and gas chromatography studies. Results have shown that N-[2-[(2hydroxyethyl) amino] ethyl]-amide is a good, mixed type of corrosion inhibitor, with an efficiency that increases with its concentration but it decreases with a rise in the temperature. It adsorbs chemically onto the copper surface by following a Langmuir type of adsorption isotherm.
A Ti6Al4V alloy was plasma-oxidized at 600 °C during 1, 2, 3, 5 and 8 h and corroded in an artificial saliva solution. Electrochemical evaluation was performed by using potentiodynamic polarization curves, linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) measurements during 100 h. Corroded specimens were characterized by using Raman spectroscopy and scanning electronic microscopy (SEM). All tests indicated that the highest corrosion resistance was obtained for specimen oxidized during 3 h since the noblest free corrosion potential, lowest passive and corrosion current density values, as well as the highest polarization resistance values were obtained under these circumstances. EIS measurements indicated that the highest impedance and phase angle values obtained for this specimen exhibited a high capacitive behavior typical of a very compact passive film.
The effect of plasma pre-oxidation on the effect of the inhibition performance of N-[2-[(2-hydroxyethyl) amino] ethyl]-amide extracted from coffee bagasse for Cu in 3.5% NaCl has been investigated by using electrochemical techniques. Electrochemical impedance spectroscopy, potentiodynamic polarization curves and linear polarization resistance (LPR) measurements were the employed techniques. Results have shown that the corrosion rate of Cu was decreased and the properties of the passive film formed by the inhibitor were improved. Corrosion protection given by the inhibitor and pre-oxidizing treatment improves as time elapses due to an increase of the surface area covered by the corrosion products layer. This has been explained in terms of a better adherence of the inhibitor-formed film to the metal which by pre-oxidizing.
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