Solid lubrication using carbon nanotubes: Fundamental understanding of transfer layer formation and sliding mechanisms through atomistics and experimental nanoanalysis

Project description

Friction and wear cause annual costs of around 5% of gross domestic product in highly industrialized countries. At the same time, there is increasing pressure to switch from environmentally harmful liquid lubricants to sustainable alternatives. Typical solid lubricants such as MoS₂ and graphite could be an alternative, but they quickly reach their limits: they only work under specific conditions and have a limited range of applications. This project therefore investigates the potential of carbon nanotubes (CNTs) as an alternative to conventional lubricants.

CNTs have excellent mechanical, physical, and chemical properties and, in combination with suitable deposition processes and defined surface topographies, could be used as solid lubricants—especially under extreme conditions such as vacuum, high temperatures, high contact pressures, and sliding speeds.

The aim of the project was to elucidate the microscopic mechanisms of CNT lubrication, in particular:

• Transfer layer formation at contact surfaces
• Sliding mechanisms at the interfaces
• CNT degradation under high pressure loads
• Transport of CNTs within the tribocontact

Fraunhofer IWM was the lead partner and responsible for:

• Atomistic simulations and modeling of the CNT structure and its interactions with surfaces
• Nanoanalytics: high-resolution characterization of transfer layers and CNT degradation mechanisms
• Multiscale modeling: coupling atomistic findings with macroscopic tests
• Analysis of the failure mechanisms of CNTs under mechanical stress