Influence of Multi- walled Carbon Nanotube Addition on the Zinc-Rich Paint Coating Corrosion in NaCl solution

Zinc-rich paints (ZRPs) are one of the most effective coatings used to protect steel from corrosion [1]. They are used in many aggressive medium: sea water, marine and industrial environments.For solvent-based zinc-rich paints, it seems to be established that, at least at the beginning of immersion, zinc particles provide a cathodic protection of the steel substrate [1,2]. Then, a long term protection develops due to the formation of zinc corrosion products, reinforcing the barrieraffect of the paint [1, 3]. The effect of addition of conductive pigments like multi-walled carbon nanotubes on thecorrosion behavior of zinc-rich paints (ZRP) coated steel in 3.5% NaCl solution was investigated. Open circuit potential measurements were used to characterize the cathodic protection ability andduration. Electrochemical Impedance spectroscopy and Tafel analysis was performed in order toidentify the corrosion rate and to follow the corrosion mechanism. Also, the Scanning Electron Microscope (SEM) analysis was used for study the morphology changes in the coating due to corrosion. Two different effects were pointed out: increase of the porosity induced by multiwalledcarbon nanotubes addition and a galvanic action between zinc and multi-walled carbon nanotubes.

Keywords:

zinc-rich paint , Corrosion , Electrochemical Impedance spectroscopy , Multi-walled carbon nanotubes , Tafel