Synergistically assembled RGO/Si₃N₄ whiskers hybrid aerogels to endow epoxy composites with excellent thermal and tribological performance

Epoxy resin (EP) composites with satisfactory thermal and tribological performance are highly required for engineering moving components. However, the simple addition of fillers leaded to the serious filler agglomeration and limited promotion in tribological properties. In this work, we constructed a new kind of three-dimensional (3D) reduced graphene oxide (RGO)/Si₃N₄ hybrid aerogel for EP composites, which was prepared by a facile hydrothermal self-assembly method followed by freeze-drying technique. As a result, the dispersibility of Si₃N₄ whiskers was greatly improved through wrapping of polydopamine–polyethyleneimine copolymer (PDA–PEI) copolymer and physical spacing of 3D skeleton. Furthermore, benefiting from the synergistic effect of RGO and Si₃N₄@PDA–PEI in the thermal network, the thermal conductivity of RGO/Si₃N₄ hybrid aerogel (GSiA)–EP increased by 45.4% compared to that of the neat EP. In addition, the friction coefficient and wear rate of GSiA–EP decreased by 83.7% and 35.8%, respectively. This work is significant for opening a tribological performance enhancement strategy though constructing 3D hybrid architecture.