Inhibition of Copper Corrosion by Self-Assembled Thin Films of Schiff Bases in Acidic Media

One of the most important methods for protection of the metals against corrosion especially in acid media is the use of inhibitors. Acid solutions are generally used in several industrial processes، such as HCl. Copper has a wide range of industrial applications due to its good mechanical and electrical properties. Although copper and its alloys are generally known to be good corrosion resistant materials، they still suffer different forms of corrosion depending on the service environment، which limits greatly their application in practice. One effective approach that can be taken to solve this problem is surface modification using Self Assembled Mono layers (SAM). SAMs provide a flexible and simple system that act as an insulating film and prevent chloride penetration to surface. In this report، two new synthesis Schiff base، N،N''- bis (salicylidene) -1،3 propanediamine and N،N''- bis (4-methoxysalicylidene) -1،3 propanediamine، has been proposed as new corrosion inhibitors. These two inhibitors where self-assembled on copper and their corrosion inhibition performance in 0. 5 M HCl solution was investigated by using polarization curves and electrochemical impedance spectroscopy (EIS) methods. The polarization measurements suggest that the SAMs act as mix inhibitors and suppressed both the anodic and cathodic reaction. Increasing curves diameter in the impedance measurements showed that the SAMs act as good inhibitors. The results from polarization and impedance measurements are in good agreement and show inhibition efficiency gradually increase by increasing concentration. Login methoxy groups in the benzene ring of the Schiff inhibition efficiency increases that could result from the electron donors effects and the effects of the hydrophobic group.