EVALUATION OF NEW CATIONIC SURFACTANT AS CORROSION INHIBITOR FOR CARBON STEEL IN A METAL WORKING FLUID

Abstract

Metal working straight oil contain large quantities of additive such as corrosion inhibitors, in this paper we study the following additive as corrosion inhibitor before will be use. The corrosion inhibition of carbon steel by di dodecyl benzyl tri ethyl ammonium chloride (CS) is investigated in 1M H2SO4 using weight loss measurements and galvanostatic polarization curves. The corrosion rate decreases with the inhibitor concentration from 10 to 130 ppm. It is found that the corrosion rate decreases with immersion time from 5 to 20 days and then tends to be constant. The results have shown that the lowest corrosion rate is for 75 ppm for (CS). The effect of temperature on corrosion inhibition has been studied and the activation energy for optimum conditions of the inhibitor has been evaluated. The corrosion inhibition of carbon steel in 1M H2SO4 containing (CS) has been attributed to adsorption of inhibitors over the carbon steel surface. Results are correlated will to the chemical structure of the inhibitor. Some electrochemical parameters such as Icorr, Ecorr, ba and bc are evaluated from galvanostatic polarization technique. The results of inhibition efficiency evaluated from galvanostatic polarization technique are in a good agreement with those obtained from weight loss technique. Furthermore, Scanning Electron Microscopy (SEM) is used to examine the surface morphology of the carbon steel samples both in absence and presence of each inhibitor at optimum conditions.