Experimental study on turning performance of a novel nanofluid prepared by composites of MWCNTs

In this work, novel DPS/MWCNT composites were synthesized through filling multi-walled carbon nanotubes (MWCNTs) with dialkyl pentasulfide (DPS) using a wet-chemical method. A nanofluid that use the DPS/MWCNT composites as additives was then developed for achieving a high-performance turning. The performance of the developed nanofluid including dispersion stability, heat transfer capacity, and wettability was evaluated using thermophysical analytical methods. The machining performance of the DPS/MWCNT composites nanofluid was systematically investigated in the turning of AISI 52100 alloy steel, using a commercial emulsion coolant as a benchmark. The lubrication mechanism of the nanofluid involved in the turning process was reveal with the aid of X-ray photoelectron spectroscopy (XPS). The results showed that DPS was successfully filled into MWCNTs with a filling rate of around 25.7%. The nanofluid had an excellent dispersion performance and produced respective 105.0% and 23.6% improvements in the heat transfer and wetting performance, in comparison to a base fluid. During turning, the composites suspended in the nanofluid acted as microbearings to reduce the friction of sliding, while the DPS filled in the MWCNTs was released under pressure to generate a complex lubricating film at the tool-chip interface, leading to a low resistance to cutting. This thus resulted in 15% and 25% reductions in the cutting force and temperature as well as 16% and 22% improvements in the surface roughness and tool life, in comparison to a conventional turning.