凯发

Graphene and its derivatives feature excellent barrier properties, high aspect ratio, flexibility and transparency, which make it an unique barrier reinforcement for anticorrosive coatings. The major challenge for the preparation of the graphene reinforced anticorrosion coatings is the agglomeration of graphene. The chemical states of graphene were carefully tailored, aiming for a nanoscopic dispersion of graphene, as well as promoting the understanding of the critical factors on anticorrosion properties of graphene reinforced composite coatings. 

Graphene oxide, mildly reduced graphene oxide (RGO) and functionalized graphene were added to waterborne polyurethane (PU) matrix as the anticorrosive reinforcement, respectively. The graphene reinforced organic coatings were applied on galvanized steel surfaces by a bar-coater. The anticorrosive properties of the graphene derivatives reinforced PU composite coatings were characterized by Electrochemical Impedance Spectroscopy (EIS) and salt spray tests. The dispersion states of graphene in PU matrix varied with the chemical states of graphene. The correlations between the chemical states, dispersion states of graphene, and anticorrosive properties of the composite coatings were discussed. The superior anticorrosive properties of the graphene reinforced PU composite coatings were achieved by the addition of 0.2 wt% of RGO. The EIS results showed that the under-painting corrosion did not occur after 235 h immersion in 3.5 wt% NaCl electrolyte and the impedance modulus at 0.1 Hz remained at 109 Ω, barely changed for 235 h.