Preparation of Liquid Metal-based SiC/Graphene Binary Hybrid Nanofluid and Its Basic Properties as Hydraulic Transmission Medium

Liquid metal (LM) with good room-temperature fluidity and high-temperature stability is an ideal base fluid for extreme high-temperature hydraulic transmission medium. However, the low viscosity and high density of LMs are not conducive to the sealing and lubrication performance of hydraulic components. Using Ga_68.5In_21.5Sn₁₀ as the base fluid and SiC nanoparticles and graphene with good self-lubricity as a dispersed phase through homogenization and grinding, the novel LM-based SiC/Graphene binary hybrid nanofluid were prepared. The basic physical properties, rheological properties and lubricity at 25–200 °C of LM-based SiC/Graphene binary hybrid nanofluid at 0% 5 vol. %, 10 vol. %, 20 vol. % and 30 vol. % of nanoadditives were also explored. Compared with existing high-temperature hydraulic medium, LM-based SiC/Graphene binary hybrid nanofluid has excellent thermal stability, excellent heat dissipation performance, smaller temperature-viscosity changes, and good high-temperature lubricating performance. We selected 20 vol. % of the samples with the most suitable rheological and lubricating properties for hydraulic transmission medium and evaluated the volumetric efficiency and wear of the gear pump by introducing the samples into a hydraulic system. The results show that compared to pure LM, 20 vol. % of the sample can improve the volumetric efficiency of the gear pump and demonstrate good anti-wear performance.

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