Inhibition of stainless steel pitting corrosion in acidic medium by 2-mercaptobenzoxazole

The corrosion behavior of stainless steel samples (304L and 316L) in HCl and H2SO4 solution has been studied using potentiodynamic, cyclic voltammogram, EDX and scanning electron microscope (SEM) techniques. The inhibition characteristics of 2-mercaptobenzoxazole (MBO) on 316L stainless steel (316L SS) in HCl solutions were investigated at different temperatures (25, 40, 50 and 60 8C). MBO compound has proven to be efficient inhibitors for general and pitting corrosion of 316L SS in HCl solution. The inhibitive property of MBO may be argued to the formation of very low soluble bis-benzoxazolyl disulfide (BBOD) layer and a compact Fe–MBO complex film on the electrode surface. Some samples were examined by scanning electron microscope. The inhibition efficiencies increased with the increasing of MBO concentration but decreased with increasing temperature. The activation energy and thermodynamic parameters were calculated.