Corrosion Inhibition Study of Al-Cu-Ni Alloy in Simulated Sea-Water Environment
A study on the inhibition of Al-Cu-Ni alloy in simulated sea-water environment was investigated using Sodium Chromate as inhibitor. The inhibitor concentration was varied as control, 0.25, 0.5, 1.0, 1.5 and 2.0 Molar. Al-Cu-Ni alloy was sand cast into cylindrical bars of 20 mm x 300 mm dimension. The corrosion of the sand-cast and treated alloys in 3.5wt% sodium chloride solution at temperatures 30oC, 50oC and 70oC over 1-5 hrs was evaluated using the weight loss method. It was observed that the corrosion rate of the treated alloys decreases with increase in inhibitor concentration. The decrease in corrosion rate on addition of the inhibitor can be attributed to the adsorption of the inhibitor onto the surface of the alloy. The attachment is by physical adsorption as the values of heat of adsorption were less than -10 kJ/mol. The plots obtained were linear meaning that they obey the Langmuir and Temkin adsorption isotherms. The inhibition efficiency increases generally with increase in temperature and inhibitor concentration.
KEYWORDS: inhibition, simulated sea-water, corrosion, alloy, concentration, adsorption