AFM and electrochemical study of the effect of dodecylamine on carbon steel corrosion

The effect of dodecylamine on carbon steel corrosion was investigated using atomic force microscopy (AFM) and electrochemical process. The topography of the sample surface was measured with a commercial AFM system operated in contact mode, and the image was simultaneously measured by applying a bias voltage of 0.5 V between the sample and the Au-coated conductive tip. It was observed that the inhibitor addition negligibly changes the open circuit potential, anodic and cathodic tafel slopes, which indicates that the carbon steel corrosion inhibition is due to geometric blocking effect of the dodecylamine. Each dodecylamine molecule averagely replaces 2.32 water molecules on the metal surface and forms a monolayer on carbon steel surface. The absorption of dodecylamine molecules greatly decreased the conductivity of the carbon steel surface, and the force curve exhibited adhesive force features at the dodecylamine adsorption areas.