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The inhibiting effect of the expired meloxicam on the corrosion of mild steel (MS) in 1 M HCl was tested by the weight loss, electrochemical frequency modulation, potentiodynamic polarization (PP) and electrochemical impedance spectroscopy techniques. The PP curves showed that this drug acts as mixed type inhibitor. This drug was adsorbed chemically on the MS surface following the Temkin adsorption isotherm. Some thermodynamic parameters were computed and discussed. The results indicated that the protection efficiency increases by raising both the doses of the inhibitor and the temperature of the medium. The morphology of the MS surface was analyzed by scanning electron microscopy, atomic force microscopy, and Fourier transform infrared spectroscopy. All of the obtained results from different techniques are similar.

In this study, the inhibition effect of Tamarix Boveana (TB) extract on Cu corrosion in 1 mol L–1 (HNO3 + H3PO4) mixture was studied. Electrochemical techniques such as (potentiodynamic polarization (PP), electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM)) and non-electrochemical technique such as mass loss were used. Results showed that TB extract has good inhibition efficiency (IE), follows Langmuir adsorption isotherm and all of the methods are in good agreement. The IE increased by increasing the concentration of the extract and decreased by increasing the temperature so, the extract adsorbed on Cu surface physically. The IE depends on the concentration of the extract and reaches 73.5% at 300 ppm of the extract. PP results revealed that the (TB) extract doings as mixed type one. Surface analysis revealed that the extract components are adsorbed on Cu surface forming a film.

The corrosion performance of α-brass in 1 M HNO3 and in the presence of polyethylene glycol (PEG) has been investigated using AC impedance spectra (EIS), potentiodynamic polarization (PP), electrochemical frequency modulation (EFM), and mass reduction (MR) techniques. The outcome data of EIS showed a rise in the resistance charge transfer (Rct) and a decrease in the capacitance double layer (Cdl). Protection efficiency (IE) of PEG has been obtained by varying the dose of the PEG and temperature. PEG adsorbed on α-brass in acidic solution follows isotherm Langmuir. The polarization curves displayed that PEG acts as a mixed-kind inhibitor. The parameters obtained from thermodynamic activation of corrosion α-brass in 1 M HNO3 were obtained and debated. The results obtained from all tests were in excellent agreement.