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This study focuses on investigating the effect of Terminalia chebula Ritz. extract (TCE) for corrosion inhibition of Al in phosphoric acid (H3PO4) using potentiodynamic polarization (PDP) technique. In this study, the effect of concentration of TCE extract, the concentration of H3PO4 acid medium, and temperature (T) was investigated on the corrosion current density (icorr) and inhibition efficiency (IE). The TCE was characterized by FTIR analysis, and the adsorption of TCE was justified with the help of kinetic, thermodynamic, adsorption isotherm parameters. The surface morphology study was done using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDXS), and atomic force microscopy (AFM). The study also focuses on identifying the optimum process parameters for obtaining the maximum IE by applying the response surface methodology (RSM) and desirability function approach. The maximum IE of 83.24% was achieved at a temperature of 30 ℃, the concentration of TCE extract of 500 ppm, and H3PO4 acid concentration of 0.5 M. Regression analysis, Pareto chart, normal chart, main effect, and interaction effect plots are employed to acquire an in-depth understanding of process variables on IE. The IE obtained from the experiments and the predicted model is in a close match and a high value of the coefficient of determination (R2 = 99.98%) displays that the generated model was able to estimate the IE accurately from the selected process variables.

This work describes the use of polymer dextran to enhance the corrosion protection of epoxy coating applied on 6061 Al-15% (v) SiC (p) composite material (Al-CM). Initially, conditions were established to obtain optimum inhibition efficiency of dextran. Electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy were adopted for the corrosion rate measurements. Later, the same techniques were employed to study the corrosion rate of the epoxy resin coated composite material (EC-CM) before and after the addition of environmentally benign dextran polymer. Detailed investigation of the surface morphology of the coated Al-CM was carried out using scanning electron microscopy, energy dispersion X-ray analysis, and atomic force microscopy techniques. The work which is done with dual purpose, establishes not only the anticorrosive property of dextran, but also proves its ability to improve the coating characteristics of epoxy resin on Al-CM.

The Inhibitive and adsorption properties of aqueous extract of seeds of Garcinia indica extract (GIE) have been studied for corrosion control of aluminium in 0.5 M phosphoric acid solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques at 30 ∘ C to 50 ∘ C. The effects of inhibitor concentration on the inhibition action were investigated. Polarization measurements showed that the GIE acted as mixed inhibitor and the inhibitor molecules followed chemical adsorption on the surface of aluminium. The adsorption of GIE on metal surface obeyed Langmuir adsorption isotherm. The surface morphology of aluminium, in the absence and in the presence of GIE in 0.5 M phosphoric acid solution, was studied using scanning electron microscopy (SEM). Results obtained from both of the electrochemical techniques were in good agreement with each other.

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