Tribology

Tribology is the interdisciplinary science of friction, wear and lubrication that governs the interactions of contacting surfaces in relative motion. It underpins the design and performance of bearings, gears, seals and myriad sliding or rolling contacts in sectors as diverse as transportation, energy generation, manufacturing and biomedical devices. At its core lie three interrelated phenomena: friction, which dissipates energy; wear, which abrades material and limits component life; and lubrication, which seeks to separate surfaces with a fluid, film or self-lubricating layer. Classical lubrication regimes range from boundary lubrication—where only a monomolecular film prevents asperity contact—to mixed and full hydrodynamic lubrication, in which fluid pressure alone sustains the load, and elastohydrodynamic lubrication, where elastic deformation and fluid viscosity combine under high contact stresses. Advances in surface engineering, additive chemistry and modelling have enabled tailored interfaces—from nanocomposite coatings and texturing to mechanochemically active additives—that achieve ultralow friction and prolonged service life under extreme conditions. Improving tribological performance yields profound global benefits: wear and friction losses can account for up to a quarter of industrial energy consumption and substantial CO₂ emissions. Contemporary challenges include extending superlubricity concepts to macroscopic devices, harnessing bio-inspired hydration lubrication for medical implants, integrating real-time surface monitoring and data-driven control, and designing sustainable tribosystems for a circular economy.

Research from Nature Portfolio

Transforming plant proteins into cross-linked microgels has emerged as a strategy for high-performance aqueous lubrication. These microgels lower boundary friction by an order of magnitude compared to native proteins and rival conventional oil-in-water emulsions, owing to their deformable cores and surface-anchored hydration layers. Building on this, the self-assembly of plant protein protofilaments within a biopolymeric hydrogel has yielded friction coefficients approaching superlubricity under moderate to high contact pressures. Multiscale experiments combined with molecular dynamics simulations reveal that hydrophobic domains anchor to the substrate while the surrounding hydrated network supports a resilient lubricating film. In a biomedical context, a microgel-reinforced, hydrogel-based lubricant has been benchmarked against commercial saliva substitutes for xerostomia therapy. Both dairy- and plant-derived formulations demonstrate 40–99 % better boundary lubrication and markedly lower desorption from oral-mimetic surfaces, highlighting their promise as long-lasting, biocompatible lubricants.

Research from all publishers

A comprehensive review of fluid-film bearing design addresses extreme performance requirements in metrology, aerospace and precision manufacturing. Analyses of fluid selection, groove geometry and surface finish under ultrahigh speeds, heavy loads and temperature extremes provide guidelines to achieve stable hydrodynamic support and minimal drag losses. In fretting fatigue studies of an α/β titanium alloy, cyclic sliding with oxidation refines the subsurface to nanometre grains and induces hetero-microstructural zones that accelerate crack initiation, pinpointing mechanisms that must be mitigated for reliable long-term operation. A survey of tribo-induced or pre-designed heterostructures synthesises recent findings on multiscale discontinuities—combining gradient nano-grains, engineered twin boundaries and second-phase precipitates—to suppress strain localisation. These heterostructures achieve friction coefficients and wear rates unattainable in homogeneous materials, offering a blueprint for next-generation surface design.

Tribology publication trend

The graph below shows the total number of articles in tribology across all publications each year (not limited to Nature Index journals).

Technical terms

Tribology: The science and technology of friction, wear and lubrication in interacting surfaces.

Hydrodynamic lubrication: A regime where a continuous fluid film fully separates sliding surfaces under load, carrying the load by fluid pressure.

Boundary lubrication: A regime where surface asperities interact through adsorbed molecular films when the fluid film is insufficient.

Mixed lubrication: A transitional regime combining fluid film support and direct asperity contact.

Elastohydrodynamic lubrication (EHL): A high-pressure regime where elastic deformation of surfaces and hydrodynamic effects in a highly viscous film occur simultaneously.

Superlubricity: A state of near-zero friction achieved through incommensurate contact or self-lubricating films at nano- or microscale interfaces.

Hydration lubrication: A mechanism where tightly bound water layers around charged groups act as nanometre-thin lubricants in aqueous environments.

Wear: Progressive loss of material from contacting surfaces due to mechanical or chemical action.

References

1. Introduction and Basic Concepts of Tribology.
2. A review of recent advances in tribology. Friction (2020).
3. Influence of tribology on global energy consumption, costs and emissions. Friction (2017).
4. Transforming sustainable plant proteins into high performance lubricating microgels. Nature Communications (2023).
5. Self-assembly of sustainable plant protein protofilaments into a hydrogel for ultra-low friction across length scales. Communications Materials (2024).
6. Benchmarking of a microgel-reinforced hydrogel-based aqueous lubricant against commercial saliva substitutes. Scientific Reports (2023).
7. Design and optimization of fluid lubricated bearings operated with extreme working performances—a comprehensive review. International Journal of Extreme Manufacturing (2024).
8. Microstructural evolution and oxidation in α/β titanium alloy under fretting fatigue loading. Friction (2023).
9. Mitigating friction and wear by pre-designed or tribo-induced heterostructures: an overview. Materials Research Letters (2024).