Enhanced tribological properties of epoxy-based lubricating coatings using carbon nanotubes-ZnS hybrid

In this work, a facile and efficient method to overcome the poor dispersion of carbon nanotubes (CNTs) in the polymer matrix by in-situ synthetizing ZnS nanoparticles onto their surfaces was developed. The as-prepared CNTs/ZnS hybrid was then used as lubricating additive to enhance the friction-reducing and anti-wear properties of epoxy (EP) coatings. The microstructure and composition of CNTs/ZnS were characterized using HRTEM, FESEM, XRD, and RS. The ZnS nanoparticles with the size of about 20-30 nm were coated onto CNTs surface homogeneously in the form of wurtzite structure phase. Besides, the enhancement mechanisms of CNTs/ZnS on the tribological properties of EP coating were studied systematically. The results revealed that as the content of CNTs/ZnS was 1.25 wt%, the corresponding coatings possessed the lowest friction coefficient and highest wear resistance. Moreover, the EP coatings with the different weight fraction of CNTs/ZnS hybrid showed much better tribological properties than those with CNTs or acid-CNTs. The excellent tribological properties were mainly related to good dispersion of CNTs or ZnS as well as good synergism between CNTs and ZnS.