- 期刊
Influence of Size and Weight Fraction of Multi-Walled Carbon Nanotubes Dispersed in Gear Oils for Improvement of Tribological Properties
摘要
The paper investigates the effect of size, and weight fraction of multi-walled carbon nanotubes (MWCNTs) dispersed as an additive in the gear oil to enhance the tribological properties. The method of modifying the surface of multi-walled carbon nanotubes with a surface modifying agent before mixing in the oil improved dispersion stability. Studies were carried out to evaluate the size and shape of MWCNTs before and after ball-milling. The electron microscopy and Raman spectroscopy are used to characterize the nanotubes. The pristine long nanotubes and ball-milled nanotubes are mixed in EP 140 gear oil in 0.25, 0.5& 1.0 weight per cent and the stability of the oils measured using light scattering techniques. The anti-wear, anti-friction and extreme pressure properties of oils dispersed with nanotubes were tested on a four-ball wear tester. Using Raman spectroscopy, it was identified that ball-milling for ten hours didn't create any flaws on the periphery of Multi-wall carbon nanotubes. Ball-milling for prolonged time resulted in the formation of defects on the surface of MWCNTs, thereby lowering their advantage as oil additives. The stability of the oil and the anti-wear, anti-friction and extreme-pressure properties have considerably enhanced with the dispersion of short MWCNTs. It is found that length and weight per cent of MWCNTs strongly impact the stability, anti-wear and anti-friction properties of the oil. Further, the Multi-wall carbon nanotubes loading in oil beyond certain weight fraction results in deterioration of properties. Shortening of nanotubes resulted in the use of lower weight fractions for the enhancement of tribological properties.