Experimental study on the synergistic effect between components and tribological properties of modified dendritic nanosilica PI/EP–DFNS composite coatings

Purpose The aim of this paper is to prepare dendritic nanosilica/polyimide/epoxy (PI/EP–DFNS) composite solid lubricant as solid lubricant coatings for bearings to improve the friction and wear performance of bearings. Design/methodology/approach Modified dendritic fiber nanosilica (DFNS) was prepared by microemulsion method and mixed with PI/EP to form a composite coating. The tribological properties were evaluated under dry sliding conditions (30–40 N load) using a ball and disk friction and wear tester. The wear mechanisms were systematically characterized by surface profilometry, ultra-deep microscopy and scanning electron microscopy. Findings Uniform dispersion of DFNS within the matrix was achieved. The 4 Wt.% DFNS composite exhibited optimal performance: microhardness increased by 53%, friction coefficient decreased by 26.8% and specific wear rate dropped two orders of magnitude. Practical implications This paper elucidates the wear mechanism of composite coatings and tests the tribological effects of different working environments on the coatings. Originality/value In this paper, KH550 was used to modify DFNS, and DFNS was homogeneously dispersed in PI/EP composite materials to prepare PI/EP–DFNS composite coatings. The friction performance of the composite coating is compared with that of the pure EP coating to prove the superiority of the composite coating.