Solid–Liquid Core–Shell Composite Micro-Nanoparticles: Tribological Properties as Lubricant Additives for Epoxy Resin Coatings

Core–shell micronano particles have proved to be promising lubricant additives. The introduction of liquid lubricants into core–shell micronano particles could further improve tribological properties by forming soft/hard/fluid three-phase composite micronano particles. In this paper, given the excellent structural and chemical properties of polytetrafluoroethylene @dendritic fibrous nano silica core–shell (PTFE@DFNS) particles, soft/hard/fluid three-phase core–shell composite micronanoparticles were fabricated via the adsorption of a liquid lubricant through the vacuum impregnation method. Then, the epoxy resin (EP) coating was selected as the matrix for the study of the tribological properties. The morphological and chemical structure of the PTFE@DFNS@ILs core–shell particles were examined by using transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, and X-ray photoelectron spectroscopy. Moreover, nanoindentation and tribological testing revealed that the composite coatings exhibit a higher Young’s modulus, hardness, and superior antifriction and wear-resistant properties compared to neat epoxy coatings. Further analysis reveals that the excellent tribological properties of PTFE@DFNS@ILs solid–liquid lubricant additives are attributed to the combined effects of the lubricating nature of PTFE as a soft material, the rolling element action of dendritic fibrous silica, and the synergistic lubrication from the tribochemical reactions of ILs, particularly the formation of a transfer film. These results provide a method for the introduction of liquid lubricants into micronanocomposite particles and imply that solid–liquid core–shell particles are materials with potential for a wide range of applications.