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Ni-Cu-P/nano-Al2O3 composite coatings are prepared on mild steel from an alkaline electroless plating bath containing different concentrations of Al2O3 nanoparticles. The protective effect of codeposited nanoparticles on the corrosion behaviour of the coatings is studied in 0.5 M H2SO4 solution. The electrochemical methods, that is, electrochemical noise (ECN), electrochemical impedance spectroscopy (EIS), and polarization measurements, are used to characterize the corrosion properties of the coatings. The results show that the inclusion of nanosized particles leads to significant improvement of corrosion resistance of the coatings. The highest corrosion resistance is obtained at 20 ppm of nanoparticles concentration in the plating bath. The ECN measurements results are in good agreement with results obtained from two other electrochemical methods after trend removal. The SEM images prove that nano-Al2O3 particles were embedded in the Ni-Cu-P matrix and are dispersed uniformly on the coating surface. [ABSTRACT FROM AUTHOR]

The inhibition performance of Basic yellow 13 dye on mild-steel corrosion in hydrochloric acid solution was studied at 25 °C using weight loss and electrochemical techniques. The effect of inhibitor concentration on inhibition efficiency has been studied. Inhibition efficiency increased with increase of Basic yellow 13 concentration. The results showed that this inhibitor had good corrosion inhibition even at low concentrations (95% for 0.005 M Basic yellow 13) and its adsorption on mild-steel surface obeys Langmuir isotherm. Δ Gads was calculated and its negative value indicated spontaneous adsorption of the Basic yellow 13 molecules on the mild-steel surface and strong interaction between inhibitor molecules and metal surface. The value of Δ Gads was less than 40 kJmol−1, indicating electrostatic interaction between the charged inhibitor molecules and the charged metal surface, i.e., physical adsorption. [ABSTRACT FROM AUTHOR]

Abstract: The inhibiting behavior of 1-butyl-3-methylimidazolium bromide [BMIM]Br on mild steel corrosion in 1.0M HCl as corroding solution at 25°C was evaluated by various corrosion monitoring techniques. The obtained results showed that [BMIM]Br is a good inhibitor for mild steel in 1.0M HCl solution. Potentiodynamic polarization data indicated that the [BMIM]Br acts essentially as a mixed-type inhibitor. The effect of inhibitor concentration on zero charge potential (ZCP) of the mild steel in 1.0M HCl was studied and its comparison with OCP has been made for evaluation of the mechanism of adsorption of [BMIm]+ cation. The effect of temperature on corrosion behavior of mild steel in 1.0M HCl with addition of [BMIM]Br was studied in the temperature range of 25–45°C. The inhibition efficiency decreases with the rise of temperature. [Copyright &y& Elsevier]

Abstract: The corrosion inhibition effect of 3H-phenothiazin-3-one, 7-dimethylamin as a new inhibitor was studied using different electrochemical and weight loss methods. It was found that this compound acts as a strong inhibitor for mild steel in 1M HCl even at very low concentration (1ppm). Results showed that this compound acts as a mixed type inhibitor. As the inhibitor concentration increased, the charge transfer resistance of mild steel increased and double layer capacitance decreased. The results of EN measurements after trend removal were in good agreement with other methods results. It was found that this inhibitor acts through adsorption on the metal surface. Also, adsorption obeys the Langmuir isotherm. [Copyright &y& Elsevier]

Mild steel was electroless coated with nickel–phosphorus alloy from a bath containing sodium hypophosphite and glycin–citrate complexing agents. The effect of coating time on phosphorus content, thickness, structure and hardness of the deposits were analyzed. Corrosion parameters such as current density, corrosion potential and corrosion rate were obtained from tafel polarization curves and immersion corrosion tests in aerated 3.5% NaCl solution. The X-ray diffraction (XRD) patterns, anodic polarization curves and scanning electron microscopy (SEM) of heat-treated specimens obtained in various coating times were also studied. The X-ray diffraction patterns showed that by changing the coating times, amorphous or crystalline structure could be obtained. The coatings containing 11.1–13.1% phosphorous were amorphous, and showed better corrosion resistance than microcrystalline structure. The heat-treated specimens obtained in different coating time had more hardness and corrosion resistance than unheated samples. According to the polarization studies and scanning electron microscopy images, the heat-treated samples with 10.8 and 10.1% phosphorous show the intergranular corrosion, while the coatings with 11.7 and 12.2% of phosphorus have the least corrosion rate. Immersion corrosion test data at the 4-month interval had good agreement with electrochemical polarization results. [Copyright &y& Elsevier]

Inhibition effects have been carried out on carbon steel in solutions containing different amines. These compounds were dissolved in some petroleum–water corrosive mixtures containing of acetic acid and NaCl. Corrosion inhibition afforded by ethylenediamine (EDA), hexylamine (HA), butylamine (BA), tert-butylamine (t-BA), propylamine (PA) and iso-propylamine (i-PA) has been studied by cyclic polarization (CP), electrochemical impedance spectroscopy (EIS) and optical micrography with a carbon steel rotating disk electrode at 25 °C. The best corrosion inhibition was obtained for the 4% of EDA, which is able to act as polarizing agent on the carbon steel surface. Thus, analysis of the change of inhibitor structure and its concentration in the solution allowed us to find the optimum parameters for obtaining the best inhibition. The observed difference in behavior of the additives can be attributed to the differing of solubility in various solvents ratio and to the differing of strict hindrance of the compounds to metal surface. [Copyright &y& Elsevier]