New Trends for Corrosion Inhibition of Steel

Abstract

Mild steel is considered to be the main constructing materials in industry. There is a great need to protect mild steel material from corrosion by using corrosion inhibitors. However the use of chemical inhibitors has been limited because of the environmental threat. A recent trend is devoted to employ environmentally friendly compounds as corrosion inhibitors for mild steel

In this study different extract of herbs were investigated as corrosion inhibitors for mild steel during acid cleaning process and that used in reinforcing concrete. The environmentally friendly investigated compounds in this. study were Arghel, Coriander, Thyme, Marjoram, Fennel and Henna. The inhibition efficiency of these herbs extract and its action on the• corrosion of mild steel was investigated using spectophotometry, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) techniques. The iron count measurements in the presence of herbs extract showed that the dissolution of mild steel was characterized by a prolonged induction period and retardation of dissolution of mild steel in sulfuric acid solution. Potentiodynamic polarization curves indicated that the studied inhibitors exhibited Tafel-type behaviour. The presence of this herbs shifted of the corrosion potential into the anodic direction depending on the type of herbs and its concentration. The addition of the inhibitors studied did not alter the mechanism of either the proton discharge reaction or the anodic reaction step.