Study on Tribological Properties of ILs-MWCNTs/MoS2 Hybrid Nanofluid

ILs-MWCNTs/MoS2 hybrid nanofluid was prepared by a “two-step” method. Multi-walled carbon nanotubes (MWCNTs) were non-covalently modified by using ionic liquids (ILs) [EMIm] BF4, which is a green lubricating medium with excellent thermal conductivity, thermal stability, and lubricity. The [EMIm]BF4 can be adsorbed on the surface of MWCNTs under π-π interaction and works together to improve the dispersion effect of MWCNTs in the base fluid. The influence of three different stabilizers on suspension stability of hybrid nanofluid was compared with Cary 60 UV–visible spectrophotometer. The tribological properties of hybrid nanofluid with different ratios of MWCNTs and MoS2 were studied by HRS-2M high-speed reciprocating friction tester, surface profiler, ultra-depth-of-field 3D microscope, and contact angle measuring instrument. The chemical compositions of the wear scar surface were analyzed by the X-ray photoelectron spectrometer (XPS), and the anti-wear and anti-friction mechanism of the hybrid nanofluid was further revealed. The results showed that ILs could effectively disperse MWCNTs and Arabic gum (GA) had the best effect as suspension stabilizer. When the mass ratio of MoS2 to MWCNTs is 2:1, the hybrid nanofluid has the best wettability to the metal surface and the best anti-wear and anti-friction properties. The sandwich structure is formed by two nanoparticles plays the role of “bearing-like” and forms a lubricating film in the friction pair through physical adsorption and chemical reaction, thus greatly improving the friction performance.