The inhibitive effect of Curry leaves extract (CLE) on the corrosion behavior of aluminum in sulfuric acid (pH = 3) was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques in the temperature range of 30 °C to 50 °C. The study was done by varying the concentrations of inhibitor from 0.05 g L−1 to 0.4 g L−1. The surface morphology was studied using scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDX). Inhibition efficiency was found to increase with increase in inhibitor concentration and decrease with increase in temperature. CLE acted as an anodic type inhibitor at lower concentrations of inhibitor and behaved as a mixed type at higher concentrations of inhibitor and underwent both physisorption and chemisorption on the surface of the metal and followed the Langmuir adsorption isotherm.
The purpose of this paper is to understand the effect of 2Cu+2Ni addition on electrochemical corrosion behavior of thermal treated Al-6Si-0.5Mg alloy in 0.1M NaCl solution. The corrosion of the thermal treated samples was characterized by electrochemical potentiodynamic polarization technique consisting of linear polarization method using the fit Tafel plot and electrochemical impedance spectroscopy (EIS) techniques. Generally, from the linear polarization, the corrosion rate decreases at thermal treated Al-6Si-0.5Mg-2Cu-2Ni alloy (Alloy-2). The corrosion behavior of the Alloy-2 in the 0.1M NaCl solution showed better resistance than the Alloy-1. The EIS test results also showed that the changing of charge transfer resistance (Rct) is significant with the combined addition of 2Cu+2Ni to Al-6Si-0.5Mg alloy. The magnitude of the noble shift in the open circuit potential (OCP), corrosion potential (Ecorr) and pitting corrosion potential (Epit) increased with the addition of 2Cu+2Ni to Al-6Si-0.5Mg alloy.