Study on conductive mechanism of graphene conductive and anticorrosive coatings on steel bar surface in concrete

Abstract

When conductive and anticorrosive coatings are applied on the surface of reinforcing bars, electrochemical protection measures can be taken when the construction need secondary maintenance. Because graphene is a sp2 hybrid honeycomb structure, higher conductivity can be obtained by adding a small amount of graphene in the coating. In this paper, graphene-based conductive anticorrosive coatings were prepared with mixed conductive fillers (acetylene carbon black, conductive carbon black, graphite, graphene and zinc powder). The conductive mechanism was determined by studying the effects of conductive properties on the change of the content of different conductive fillers and analyzing the microstructural characteristics of conductive coatings with XRD, SEM, TEM and Raman spectroscopy tests. The results show that the conductivity of mixed fillers with different shapes in coatings is better than that of single filler in coatings when the filler content is the same. Because of the flexible structure and thin layer of graphene, the isolated fillers and conductive paths in different areas of the coatings can be connected with it and the conductive efficiency can be improved. The conductive paths are formed by the contact among conductive fillers in the coatings. Finally, the conductive mechanism model of graphene conductive and anticorrosive coatings was established.