Portugaliae
Electrochimica Acta

The effect of the extract of Lupinus varius l. on corrosion of Al in 1 M NaOH solution using the weight loss technique was investigated. Lupinus varius l. extract inhibited the corrosion of Al in 1 M NaOH solution and the inhibition efficiency increased with increasing the concentration of the extract and decreased with increasing temperature. The adsorption of the inhibitor molecules on Al surface was in accordance with Langmuir and Temkin adsorption isotherms. A first-order kinetic relationship with respect to Al was obtained with and without the extract from the kinetics treatment of the data.

This paper reports an experimental study of corrosion characteristics of electroless Ni-P-TiO2 nanocomposite coatings. Coating process parameters are optimized for maximum corrosion resistance based on L9 Taguchi orthogonal design with four process parameters, viz., concentration of nickel source solution, concentration of reducing agent, concentration of TiO2 powder and bath temperature. Corrosion behavior of the electroless Ni-P-TiO2 nanocomposite coatings was evaluated in 3.5 wt.% NaCl aqueous solution by using polarization technique. Scanning electron microscope (SEM) and Energy dispersive X-ray spectroscopy (EDS) analysis were used for studying the surface morphology and chemical composition of the electroless Ni-P-TiO2 nanocomposite coatings. The results showed that incorporation of TiO2 in coating causes increasing of corrosion resistance and improves surface morphology. Finally, optimum conditions were achieved as, concentration of nickel source solution: 50 g L-1, concentration of reducing agent: 10 g L-1, concentration of TiO2 powder: 10 g L-1, and bath temperature of 85 °C.

The corrosion behaviour of welded maraging steel in hydrochloric acid solutions was studied over a range of acid concentration and solution temperature by electrochemical techniques like Tafel extrapolation method and electrochemical impedance spectroscopy. The corrosion rate of welded maraging steel increases with the increase in temperature and concentration of hydrochloric acid in the medium. The energies of activation, enthalpy of activation and entropy of activation for the corrosion process were calculated. The surface morphology of the corroded sample was evaluated by surface examination using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS).

An investigation about the corrosion resistance of SS316L alloys in artificial blood plasma environments in presence and absence of amoxicillin has been carried out by using electrochemical techniques. Tested alloys included 18% Cr, 12% Ni, 2.5% Mo, <0.03 C, balance iron, using artificial blood plasma solution. Electrochemical techniques included potentiodynamic polarization curves, linear polarization resistance and AC impedance spectroscopy. Different techniques have shown that generally speaking, SS316L alloys show a more corrosion resistance in artificial blood plasma in the presence of 100 ppm amoxicillin than in the presence of 50 ppm of amoxicillin and in the absence of amoxicillin. Their corrosion resistance is increased as the quantity of amoxicillin is increased in artificial blood plasma.

Aluminium is the most widely used non ferrous metal. It is very needful to prevent this metal from corrosion .Corrosion inhibitors are one of the widely used methods to control corrosion. The purpose of this paper is to make people aware of organic corrosion inhibitors. Organic inhibitors are mainly present in natural products. It has been found that plant extracts and natural products show inhibition efficiency up to 98%. They are also non –toxic, eco- friendly, very cheaper. In the present work, natural products are used at various conditions and their inhibition efficiency is calculated by different methods; they obey various adsorption isotherms; the protective films formed by the inhibitors are analyzed by techniques such as electrochemical methods, FTIR, HPLC-RP, SEM, EDS.