Comparative study on inhibitory performance of an ionic liquid on corrosion of 6061 Al-10(vol.%) SiC(P) composite material and base alloy

Inhibitive performance of 1,3 dimethyl imidazolium dimethyl phosphate (DIDP) towards the corrosion of 6061-Al (10 vol.%) SiC(P) composite (Al-CM) and base alloy in 0.1 M HCl medium was studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques at different temperatures. Optimization of inhibitor concentration was done to get maximum inhibition efficiency. Thermodynamic parameters were calculated by fitting the results into a suitable adsorption isotherm. Scanning electron microscope (SEM), energy-dispersive X-ray (EDX), and atomic force microscope (AFM) analyses were performed to understand surface morphology, elemental mapping, and surface roughness before and after the addition of DIDP. UV-visible and X-ray diffraction (XRD) tests were performed to confirm the adsorption of inhibitor on the surfaces of materials. Studies revealed an increased rate of corrosion for Al-CM than for the base alloy. The maximum inhibition efficiency for the base alloy was found to be 80.48% for the addition of 1000 ppm, and for Al-CM, it was found to be 87.38% for the addition of 1400 ppm at 303 K. As the temperature increased, the inhibition efficiency decreased. The inhibitor was adsorbed physically on the surface of the metal by obeying the Freundlich adsorption isotherm. Surface studies confirmed the adsorption of DIDP on the surfaces of both Al-CM and the base alloy.