Tribological Properties of Oil-in-Water Emulsion with Carbon Nanocapsule Additives

Abstract

An experimental investigation was performed on the coefficients of friction (COFs) and wear properties of pure water and oil-in-water (O/W) working fluids containing carbon nanocapsules (CNCs) with concentrations ranging from 0 to 1.0 wt.%. For the O/W working fluid, the ratio of oil to water was set as 6%. It was shown that for the water working fluid, the COF decreased by around 20% as the CNC content increased from 0 to 1.0 wt.%. In contrast, the wear volume increased by 50% as the CNC addition increased from 0 to 0.5 wt.%, but it fell to a value slightly lower than that achieved using only pure water (i.e., no CNCs) as the CNC content was further increased to 1.0 wt.%. For the O/W emulsion, the addition of 0.8 wt.% CNCs reduced the COF by around 30% compared to that of the emulsion with no CNCs. Overall, the results showed that while the addition of a small quantity (6%) of oil to the water working fluid had a relatively small effect on the wear performance, the addition of an appropriate quantity of CNCs (i.e., 0.8 wt.%) resulted in a significantly lower COF and an improved wear surface.

Tribological properties of water‐based nanofluids prepared by multi‐walled carbon nanotubes composites filled with sulfurised isobutylene

“…For instance, Wu prepared water‐based nano‐lubricants using TiO 2 nanoparticles and evaluated their application in hot steel rolling, and the result demonstrated that TiO 2 nanoparticles had significant effect on polishing of the work surface roll 12,13 . Various carbon nanoparticles are also applied to prepare nanofluid used for cutting, such as graphite, diamond particles, carbon spheres, carbon nanocapsules, C60, carbon nanotubes, and so on 14–17 …”

“…10,11 For instance, Wu prepared water-based nano-lubricants using TiO 2 nanoparticles and evaluated their application in hot steel rolling, and the result demonstrated that TiO 2 nanoparticles had significant effect on polishing of the work surface roll. 12,13 Various carbon nanoparticles are also applied to prepare nanofluid used for cutting, such as graphite, diamond particles, carbon spheres, carbon nanocapsules, C60, carbon nanotubes, and so on [14][15][16][17] Nanotubes consisted of monolayer or multi-layer graphite sheets curled around the center at certain angles, this structure was first proved by Iijima in 1991. 18 As a kind of lubricant additive, multi-walled carbon nanotubes (MWCNTs) or their chemical modifiers can significantly improve the tribological properties of the base fluid according to the research of Qian et al [19][20][21] Peng used concentrated acid to conduct the oxidation treatment for MWCNTs and adopted Four-Ball method to measure the tribological properties of water-based lubricant containing MWCNTs modifications, and the result indicated that the extreme load of the lubricant was 3 $ 7 times higher than that of pure water.…”

Investigations on the Scuffing and Wear Characteristic Performance of an Oil Free Water-Based Lubricant for Gear Applications

“…Several studies on water-based or watercontaining fluids have been conducted. For example in [23][24][25] experimental investigations were carried out with mineral-oil, pure water and oil-in-water working fluids containing carbon nanocapsules. In [26] synthetic polymers are examined regarding their surface interactions and in [27] the coefficient of friction of a water-based fluid is determined for different shear rates.…”