In this study, the corrosion inhibition of a Phalaris canariensis extract on brass in a CO₂-saturated 3.5% NaCl solution is evaluated with the aid of potentiodynamic polarization curves and electrochemical impedance spectroscopy tests. The results indicate that the Phalaris canariensis extract is an excellent CO₂ corrosion inhibitor with an efficiency that increases with its concentration, reaching its maximum value of 99% with an inhibitor concentration of 100 ppm, decreasing the corrosion current density by more than two orders of magnitude. The addition of the Phalaris canariensis extract increased the pitting potential, decreased the passive current density values, and affected cathodic reactions, behaving as a mixed type of inhibitor. The corrosion process was under charge transfer control, and it was neither affected by the addition of the inhibitor nor by the elapsing time. The main compounds found in the Phalaris canariensis extract included antioxidants such as palmitic and oleic acids.

The corrosion behavior of 1018 carbon steel in LiCl/H₂O mixtures has been evaluated by using potentiodynamic polarization curves, electrochemical noise and electrochemical impedance spectroscopy techniques. Two different concentrations of LiCl were employed, namely 35 and 40 wt. %, and the testing temperatures included 25, 35 and 70 °C. It was found that the steel showed a passive zone; the corrosion current density value increased with an increase in the solution temperature and concentration. The pitting potential value decreased with an increase in the testing temperature and the solution concentration. The corrosion process was under charge transfer control. This mechanism was unaltered either by the solution temperature or concentration. The charge transfer resistance value decreased with an increase in both the solution temperature and concentration. A localized, pitting type of corrosion dominated the corrosion morphology at 25 and 35 °C, whereas at 70 °C, the main type of attack was a mixed type of corrosion.

In this investigation, Cu–Ni alloys with different aluminum additions were synthetized under a vacuum atmosphere to reduce the material density. Annealed alloys in a He atmosphere with low aluminum concentration exhibited a coarse dendritic structure, while samples with high aluminum concentration exhibited a refined dendritic structure. Structural defects analyses have shown relatively low vacancy concentrations. Hardness evaluations indicated an increment by approximately 5 times i.e., 370 HVN, more than that for the alloyed samples compared with the as-cast and unalloyed samples. Compression tests have shown a noticeable strengthening improvement (360 MPa), mainly in samples heat treated with 10 at.% Al, while samples with 5 at.% Al showed an acceptable resistance (270 MPa) as well. In general, the sample with 10 at.% Al presented the best performance to be considered as potential structural material.

In the present research work, the corrosion behaviour of pure Al in methyl esters with different degree of unsaturation and chain length, present in biodiesel, has been investigated by using electrochemical techniques. Evaluated methyl esters included methyl acrylate (C4H6O2) and methyl linoleate (C19H34O2) which were added to methyl propionate, (C4H8O2) and methyl oleate (C19H36O2 ) respectively. Electrochemical techniques involved electrochemical impedance spectroscopy and electrochemical noise, and were supplemented by detailed studies of scanning electronic microscopy. Results have shown that the corrosion rate and the susceptibility to localized type of corrosion such as pitting increased with an increase in the number of unsaturations and in the chain length. Corrosion process was under charge transfer and was not affected neither by an increase in the number of unsaturations nor in the chain length. The charge transfer resistance value decreased by an increase in the number of unsaturations nor in the chain length.

In this work, the potential use of Neolentinus lepideus extract as a green corrosion inhibitor for carbon steel in acidic media was investigated, together with its prospects as a renewable and biologically derived corrosion-control material for potential industrial applications. To achieve this, an experimental investigation was conducted using gravimetric measurements, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). The results demonstrated that the N. lepideus extract effectively suppressed the corrosion of 1018 carbon steel, with the inhibition efficiency increasing progressively with extract concentration and reaching a maximum value of 89% at 400 ppm. The potentiodynamic polarization curves revealed no evidence of passive film formation and indicated that the extract acted as a mixed-type corrosion inhibitor, with a more pronounced influence on the cathodic reaction. In the absence of the inhibitor, the corrosion process was predominantly governed by charge-transfer reactions and remained essentially under the same control mechanism upon the addition of 400 ppm of Neolentinus lepideus extract. However, at lower concentrations of 100 and 200 ppm, the corrosion process appeared to be affected by the adsorption and desorption of intermediate species at the steel/solution interface. The incorporation of Neolentinus lepideus extract into the corrosive medium resulted in an increase in the charge-transfer resistance and a concomitant decrease in the double-layer capacitance, supporting the formation of a protective interfacial film on the steel surface. The inhibitory action of the extract may be associated with its content of phenolic compounds, amides, and polysaccharides, whose heteroatoms and functional groups can interact with the steel surface and contribute to the formation of a protective adsorbed layer. The calculated Gibbs free energy values of adsorption (ΔG_ads), which were less negative than −20 kJ mol⁻¹, indicated that the adsorption of Neolentinus lepideus constituents onto the steel surface was predominantly physical in nature. Furthermore, the adsorption process was satisfactorily described by the Freundlich isotherm, suggesting heterogeneous adsorption involving surface sites with different adsorption energies.

In this investigation, Cu-Ni alloys for possible fixed dental prostheses (FDPs), with different aluminum additions were produced using vacuum atmosphere. Annealed alloys (He atmosphere) with low aluminum concentration showed a coarse dendritic structure, while samples with high aluminum concentration showed a refined dendritic structure. Structural defects analyses have shown a relative low vacancy concentrations. Hardness value increases approximately five times for the alloyed samples compared with the as-cast and unalloyed samples. Compression test results have shown a noticeable strengthening improvement, mainly in samples heat treated with 10 at % Al, while samples with 5 at % Al presented also acceptable resistance. Results are discussed in terms of dislocation mobility and hardening precipitation mechanism.