Mechanical, bonding and tribological performances of epoxy-based nanocomposite coatings with multiple fillers

Epoxy nanocomposite coatings play an important role in the wear protection of steel exposed in harsh service environments. How to improve the mechanical and wear resistance of coatings through filler addition is necessary to meet the industry application requirements. In the present paper, an epoxy-based nanocomposite coating was developed with addition of titanium dioxide (TiO2), graphite, short carbon fibers (SCFs), and zinc sulfide (ZnS) for enhancement in mechanical, bonding to steel, and tribological performances. The reciprocating friction and wear performances of the coatings were investigated at room temperature and 100 degrees C. The addition of nanometer sized TiO2 and SCFs increased the tensile properties remarkably, while the addition of graphite and ZnS deteriorated the tensile properties. The fillers of graphite and ZnS had no obvious weakening effect on the interfacial shear strength between the coatings and steel, despite the solid lubrication of graphite and weak stiffness of ZnS. Compared with the epoxy sample, the wear rate of the coating filled with optimized filler combination (TTGCS5) was reduced by 19.5 times at room temperature and 25.9 times at 100 degrees C. Addition of ZnS increased the wear resistance more pronounced compared to that of graphite at 100 degrees C, which was attributed to formation of a compact, continuous and stable self-lubricating transfer film on the coating surface. The optimized content of fillers was established for an epoxy coating to obtain the best friction rates of 0.51 and 0.56 (10(-4) mm(3)/[N.m]) at 25 and 100 degrees C, respectively.