Dispersion stability and enhanced heat transfer of cutting use nanofluids prepared by composite of carbon nanotubes and Dialkyl pentasulfide

Dialkyl pentasulfide (DPS) filled carbon nanotubes (CNTs) composite was synthesized and then applied in the nanofluid that used for cutting. The effects of acidification time, CNTs type & content, surfactant and testing conditions on the dispersion stability, thermal conductivity and viscosity of the nanofluid were investigated. The results showed that the filling ratio of DPS into CNTs was about 28%. For the preparation of nanofluid with the best dispersion stability, the combined surfactant has been explored with the ratio of sodium dodecyl benzene sulfonate(SDBS) to tween-80(TW-80) being 5:5. The optimal ratio of combined surfactant to the composite was 5:1. The thermal conductivity of base liquid could be increased by 130% by the stable and fully dispersed composite that acidified for 9 h, and the shape factor of CNTs had the most significant influence on the thermal conductivity. The prepared nanofluid was a non-Newtonian fluid, and the viscosity reached minimum when surfactant content was about 0.6%. Compared with the nanofluid prepared by acidified CNTs, the nanofluid prepared by the composite had higher thermal conductivity and lower viscosity, which was mainly due to that the non-polar groups of DPS that outside of the CNTs molecule maybe make the composite combine with surfactant more fully, and exhibit a better dispersion stability in the base liquid.