Investigation of the surface activity of corrosion inhibitors by XPS and time‐of‐flight SIMS

Abstract

AbstractX‐ray photoelectron spectroscopy (XPS), time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) and infrared spectroscopy (IR) have been used to study the interaction of two corrosion inhibitor blends of unknown composition with an iron surface. The analysis has precisely identified quaternary ammonium and tertiary amine compounds that are key ingredients of each inhibitor blend and has shown that inhibitor A forms a thicker and more effective layer than inhibitor C. Further analysis by angle‐dependent XPS has revealed that, for both inhibitors, the quaternary ammonium and tertiary amine molecules adopt a layered arrangement on the iron surface. No evidence of direct chemical bonding between inhibitor and substrate is identified and no evidence of molecular association of inhibitor molecules is found. A mechanism involving the organized interaction of discrete quaternary ammonium molecules to the iron surface is proposed.