Review of two-dimensional nanomaterials in tribology: Recent developments, challenges and prospects

From our ordinary lives to various mechanical systems, friction and wear are often unavoidable phenomena that are heavily responsible for excessive expenditures of nonrenewable energy, the damages and failures of system movement components, as well as immense economic losses. Thus, achieving low friction and high anti-wear performance is critical for minimization of these adverse factors. Two-dimensional (2D) nanomaterials, including transition metal dichalcogenides, single elements, transition metal carbides, nitrides and carbonitrides, hexagonal boron nitride, and metal-organic frameworks have attracted remarkable interests in friction and wear reduction of various applications, owing to their atomic-thin planar morphologies and tribological potential. In this paper, we systematically review the current tribological progress on 2D nanomaterials when used as lubricant additives, reinforcement phases in the coatings and bulk materials, or a major component of superlubricity system. Additionally, the conclusions and prospects on 2D nanomaterials with the existing drawbacks, challenges and future direction in such tribological fields are briefly provided. Finally, we sincerely hope such a review will offer valuable lights for 2D nanomaterial-related researches dedicated on tribology in the future.

Extraordinary Antiwear Properties of Graphene-Reinforced Ti Composites Induced by Interfacial Decoration

The expected excellent lubricant effect of graphene in metals during friction and wear is rarely achieved because of the difficulty in synthesizing suitable interfaces. Particularly, the situation is more challenging in titanium (Ti) matrix composites (TMCs) because of the high chemical-interface-reaction tendency between graphene and Ti during composite fabrication. In this study, few-layered graphene (FLG) decorated with SiC nanoparticles (SiCp) was synthesized as reinforcement in Ti-6Al-4V alloy to improve the interface of the composites. It was found that interfacial SiCp not only strengthened the interface bonding by the Si solid solution but also inhibited the chemical reaction between FLG and the Ti matrix with reduced sp3 defects. The composite with 30 wt % SiC-decorated FLG showed an 86.8% decrement in wear rate compared to the unreinforced matrix, resulting in exceptionally high antiwear enhancing efficiency, which was around fourfold of the available values of other TMCs in the literature. The antiwear mechanism was investigated by thorough characterization of the interfaces and microstructures of the composites. The idea of interfacial decoration can be potentially applied to other nanocarbon/metal composites with the advantages of retaining the function performance of nanocarbon materials.

Multiwalled carbon nanotubes enhanced the friction layer evolution and self-lubricating property of TiAl-10 wt% Ag-1 wt% MWCNTs sample

The necessity of reducing energy consumption and usage of material in aerospace and aviation industries drives the further optimization of friction and wear properties of TiAl alloys.

Wear and friction behaviour of TiAl matrix self-lubricating composites filled with WS2, MoO3 or multilayer graphene

FESEM micrographs of cross-sections of worn surfaces of TiAl matrix self-lubricating composites filled with WS₂ (a), MoO₃ (b) or multilayer graphene (c).

Improving the tribological properties of NiAl matrix composites via hybrid lubricants of silver and graphene nano platelets

This work presents a comprehensive study of the synergistic tribological effect of combined solid lubricants of silver and graphene nano platelets (GNPs).

Tribological behavior of a TiAl matrix composite containing 10 wt% Ag investigated at four wear stages

Ag was uniformly spread out on a wear scar to form a lubricant film at STABLE, thus resulting in the acquiring of excellent surface textures, a lowering of subsurface hardness of a wear scar, as well as improving of tribological behavior.

Analytical model and experimental validation of the local damage mechanism of solid lubricant films for metal matrix self-lubricating composites

Schematic representation of the local damage mechanism of solid lubricant films during the sliding friction process.