Self-Lubrication Mechanism of Surface-Textured Polymer-Matrix Composites under the Induction of Frictional Stress

Polymer-matrix composites have been widely used in the manufacture of seals, bearings, electrical insulators, and self-lubricating films as engineering applications move toward lighter weight, higher strength, and corrosion resistance. However, the high-speed shear effect of the friction pairs in relative motion leads to localized heating of the polymer surface, resulting in deformation or softening of the device. Herein, acer mono maple and canna leaves were used as templates to construct polymer-matrix sulfonated polyether-etherketone/polytetrafluoro-wax (SPEEK/PFW) composites with a surface-textured structure. As the bionic texture reduces the level of direct contact between the friction pairs, the frictional thermosoftening of SPEEK occurs in the localized areas of the bumps and leads to the release of PFW stored in textures, resulting in the formation of a soft polymer sliding layer in the worn area and greatly enhancing the frictional stability. By investigation of the tribological properties of textured SPEEK/PFW composites under different loads and sliding speeds, the mechanisms from surface wear to matrix softening and spontaneous construction of a slipping layer are summarized. The results of scanning electron microscopy and three-dimensional profilometer characterization of the wear scars show the surface state of SPEEK/PFW after friction, revealing the friction-thermotropic deformation of the surface texture. The results of this study not only improve our understanding of the frictional heat-induced surface self-lubrication mechanism of textured polymer composites but also provide a reference for the development of multiphase hybrid polymer-matrix composites with excellent self-lubrication properties.