Frictional Reduction with Partially Exfoliated Multi-Walled Carbon Nanotubes as Water-Based Lubricant Additives.

In this work, partially exfoliated multi-walled carbon nanotubes (Px-CNTs) were prepared by oxidizing multi-walled carbon nanotubes (MWCNTs) and applied into water-based lubricant as a kind of new additives, resulting in an outstanding anti-friction effect. The Px-CNTs have the structures of both MWCNTs and graphene oxide nanoribbons (GONRs). The special structure could prevent aggregation in water-based lubricant and reduce friction effectively. At the same time, Px-CNTs generate both sliding and rolling friction like MWCNTs and GONRs simultaneously. The friction force of Px-CNTs tended to go up after declining with increasing its loading, suggesting the existence of optimum additive amount of additions. Compared with water, water with 0.5 wt% Px-CNTs further reduced the friction force up to 66.4%. Compared with CNTs-COOH and GONRs dispersed in water via a similar method, Px-CNTs in water displays remarkable friction characteristic, suggesting that the friction force of water with 0.5 wt% Px-CNTs is decreased by 19.82% and 13.82% compared with water with 0.3 wt% MWCNTs and GONRs.