Developing high-efficiency lubricant additives and high-performance green cutting fluids has universal significance for maximizing processing efficiency, lowering manufacturing cost, and more importantly reducing environmental concerns caused by the use of conventional mineral oil-based cutting fluids. In this study, a nanocomposite is synthesized by filling sulfurized isobutylene (T321) into acid-treated carbon nanotubes (CNTs) with a liquid-phase wet chemical method. The milling performance of a nanocutting fluid containing CNTs@T321 composites is assessed using a micro-lubrication technology in terms of cutting temperature, cutting force, tool wear, and surface roughness. The composite nanofluid performs better than an individual CNT nanofluid regarding milling performance, with 12%, 20%, and 15% reductions in the cutting force, machining temperature, and surface roughness, respectively. The addition of CNTs@T321 nanocomposites improves the thermal conductivity and wetting performance of the nanofluid, as well as produces a complex lubricating film by releasing T321 during machining. The synergistic effect improves the cutting state at the tool–chip interface, thereby resulting in improved machining performance.
The process of lubricant penetration into frictional interfaces has not been fully established, hence compromising their tribological performance. In this study, the penetration characteristics of deionized water (DI water) containing an electroosmotic suppressant (cetyltrimethylammonium bromide (CTAB)) and an electroosmotic promoter (sodium lauriminodipropionate (SLI)), were investigated using steel-on-steel friction pairs. The results indicated that the lubricant with electroosmotic promoter reduced the coefficient of friction and wear scar diameter, whereas that with an electroosmotic suppressant exhibited an opposite behavior compared with DI water. The addition of SLI promoted the penetration of the DI water solution, thus resulting in the formation of a thick lubricating film of iron oxide at the sliding surface. This effectively reduced the abrasion damage, leading to a lower coefficient of friction and wear loss.
Background:
Multi-walled carbon nanotubes (MWCNTs) were filled with dialkyl pentasulfide (DPS) to prepare
MWCNTs-DPS composite (nanocomposite) additives for used in nanofluid-based machining.
Methods:
The nanocomposite was prepared by a liquid phase wet chemistry method, and was then added in pure water
with surfactant to form the nanofluids. This study comprehensively uncovered the effects of additive concentration, acid
treatment time, testing temperature and electrowetting conditions on the electrical conductivity and wettability of the
nanofluids.
Results:
The nanocomposite was successfully produced with a maximum filling rate of 27.4%. Meanwhile, its additives
produced an optimal performance at a concentration of about 0.1%. As a result, the electrical conductivity and wettability
of the nanofluids increased by more than 13.7% and 6.35%, respectively compared to individual MWCNTs additives.
Under the electro-wettability conditions, the wetting performance of the nanofluids produced by the nanocomposite
increased with the growth of charging voltage. Moreover, the nanofluids with a higher additive concentration perform
better wetting performance due to higher conductivity and greater charge capacity.
Conclusion:
The modification and filling activate the surface activity, electrical conductivity and capacitance property of
the MWCNTs, which arose out of the enhanced performance.
Sulfurised isobutylene (T321) was filled into the cavity of multi-walled carbon nanotubes (MWCNTs) in order to synthesise MWCNT/T321 composites. Tribological properties of water-based nanofluids with composites as additives were systematically investigated using a four-ball configuration. The results showed that MWCNTs were filled by T321 with a filling rate of 22.5%. The nanofluids prepared by the composites produced a significantly lower coefficient of friction and wear loss, in comparison with the lubricants containing only MWCNTs or T321. Such improvement was attributed to the fact that during sliding the T321 filled into composites was released onto the rubbing surface to generate a lubricating film, resulting in a low resistance to shear, whilst the MWCNTs served as nano-bearings on the formed lubricating film.
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