A Novel Nanomaterial of Graphene Oxide Dotted with Ni Nanoparticles Produced by Supercritical CO₂-Assisted Deposition for Reducing Friction and Wear

Abstract

Graphene oxide dotted with nickel nanoparticles (Sc-Ni/GO) was synthesized by chemical deposition with the assistance of supercritical carbon dioxide (scCO2). The deposited Ni nanoparticles with diameters less than 5 nm are uniformly anchored on the surfaces of GO nanosheets. The as-prepared Sc-Ni/GO composites were employed as lubricating additives in paraffin oil and their tribological properties were tested using a four-ball tribometer. The results demonstrate that the Sc-Ni/GO composites are efficient lubricant additives. Adding 0.08 wt % Sc-Ni/GO into paraffin oil can reduce the friction coefficient and wear scar diameter by 32 and 42%, respectively, in comparison with the pure oil. In addition, Sc-Ni/GO composites exhibit superior lubricating performances than nano-Ni, GO nanosheets, and Ni/GO composites produced without the aid of scCO2. Such excellent lubricating properties of the Sc-Ni/GO composites derive from the synergistic lubricating actions of Ni nanoparticles and GO nanosheets during the rubbing process. The synergistic lubricating actions are closely related to the microstructure of the nanocomposites and the characteristic features of transfer film formed on the contact steel balls. The anchored Ni nanoparticles with smaller size and more uniform distribution on GO surfaces and the thin transfer film formed on the contact balls favor the full play of the synergistic actions.

Lubricating performances of graphene oxide and onion-like carbon as water-based lubricant additives for smooth and sand-blasted steel discs

“…GO was synthesized from natural graphite powders (Qingdao Dongkai Co., Ltd., China) using a modified Hummers' method [26,27]. Details of the synthesis process are presented in our previous report [28]. OLC was synthesized from candle soot with an improved approach [23,29].…”

Supercritical Fluid‐Facilitated Exfoliation and Processing of 2D Materials

“…[267] Updated mechanistic and wear analyses have recently been provided, [268] and interactions of such nanosheets with various functionalization at fluid-fluid interfaces have been reviewed. [83] Decreases in COF were 17% and 32%, respectively, relative to Ni/GO and LP controls, and decreases of 24% and 43% in WSD were reported, respectively, for these same controls. Controlled depressurization after 2 h yielded Sc-Ni/GO nanosheets uniformly covered with nickel nanoparticles.…”

Macroscale Superlubricity Achieved With Various Liquid Molecules: A Review

“…Through the generation of a GO-adsorption film on the contact surfaces, GO can separate the contact surfaces and reduce the wear (Wu et al, 2018;Zhao et al, 2018). However, the macroscale COFs of GO are generally in the range of 0.02-0.1 (Meng et al, 2015;Jaiswal et al, 2016;Fan et al, 2018;Wu et al, 2018;Zhang et al, 2018;Zhao et al, 2018), indicating a near-superlubricity state or traditional lubrication state.…”