Anti-corrosion And Tribological Properties Of Polyurethane/Graphene Composite Coatings

Among numerous material protection strategies,the simplest and most cost effective one is painting protective coatings on the substrate surface.Polyurethane(PU)has been widely used in anti-corrosion and wear resistance for materials due to its excellent properties.With the increasing rigorous demand,PU needs to be modified to further improve its anti-corrosion and tribological performance.In this work,taking advantage of well dispersed graphene and surface texture,a series of regular textured graphene/polyurethane composite coatings were prepared,which was based on the excellent anti-corrosion and tribological properties of PU.The anti-corrosion and tribological properties were investigated systematically.In addition,the anti-corrosion and tribological mechanisms of composite coatings were analyzed on the micro scale.Firstly,to investigate the effect of NCO/OH ratio on the anti-corrosion and tribological performance of PU coatings,a series of PU coatings with NCO/OH molar ratio of 0.5,1.0 and 2.0 were prepared.The results indicated that the anti-corrosion and tribological properties of PU coatings were improved with the increase of NCO/OH molar ratio,which may be attributed to the enhancement of hardness and crosslinking density of PU coating.PU with the NCO/OH molar ratio of 2.0 displayed the best anticorrosion and tribological properties.Secondly,a series of graphene/polyurethane and graphene oxide/polyurethane composite coatings with 0 wt%,0.25 wt%,0.5 wt%,0.75 wt% and 1.0 wt% of filler content were prepared by chemical modification and physical dispersion method.We investigated the influence of filler content on the anti-corrosion and tribological performance of composite coatings.The results indicated that both of graphene and graphene oxide enhanced the anti-corrosion and tribological comprehensive properties of polyurethane composite coatings due to the barrier and lubrication properties provided by them.And the optimized additive range was between 0.25% and 0.5%.In comparison with graphene/polyurethane coatings,graphene oxide/polyurethane coatings exhibited better tribological property but worse anti-corrosion property.They are both due to the abundant oxygenated groups of graphene oxide,which not only provide more reaction sites for chemical modification to get better dispersion but also destroy the graphene lattice structure against barrier property.Finally,taking advantage of well dispersed graphene and surface texture,a series of regular textured graphene/polyurethane composite coatings with different texture density were prepared.We explored the relationship between texture density and anticorrosion property.The results indicated that the presence of surface texture and graphene resulted in the hydrophobicity and barrier effect of textured graphene/polyurethane composite coating,which slowed the kinetics of the corrosion process and improved the anti-corrosion performance of textured graphene/polyurethane composite coatings.The graphene/polyurethane coating with the highest texture density displayed the best anti-corrosion performance.