Fundamental study of trapped individual alkane/fuel molecules during sliding ordered and disordered contacting metallic interfaces
Abstract
Understanding the influence of the surrounding environment on sliding contact between two solid surfaces in liquids is of utmost importance for fundamental study of the dynamics of formation and rupture of single contact junctions, as well as for applications such as Micro/Nano electro mechanical systems, colloidal systems etc. Yet, although ongoing technology advancement into the nanoscale, some of the underlying mechanisms of tribology (i.e. friction, lubrication and wear) remain unclear. Here I propose to investigate the effect of organic liquid surroundings on the contact interaction between two metallic crystalline and amorphous surfaces in. Specifically, this proposal sets to experimentally and theoretically study the physical mechanisms of ÒlubricatingÓ effect manifested by the presence of individual molecules that can get trapped within the contact. Using Atomic Force Microscopy (AFM), adhesion and friction forces can be probed with high resolution from the contact and relative motion between the AFM tip and a surface of interest under an application of a predetermined sliding velocity and normal load. Current understanding is that the direct contact between the tip and the surface in liquid surrounding is dry, as liquid molecules are expelled from the contact due to the pressure applied on it. This means, that the presence of liquid media does is considered not to be involved with the friction process, and as such, its dynamics is related solely to the properties of the two contacting materials. Recently, our group reported that the surrounding media plays a role on the damping and dissipation mechanisms at the contact during friction. The contact and friction interaction of metallic ordered crystalline surfaces (such as Mo, W, Ta, Ru, Au, Pt) and amorphous surfaces (such as metallic powders) in the presence of complex organic liquid environments (such as alkanes like decan, hexadecane, dodecane, dilinoleic acid/propanediol copolymers, fuels) using AFM. The resolution of the interaction will be studied in the nanoscale, using sharp AFM tips with apex of several nanometers, and on the meso-scale with colloidal probes with radii of several to tens microns. This will enable to scale the interaction from single asperities to a multi-asperity contact area. The experimental measurements will be accompanied with numerical simulations (based on the Prandtl-Tomlinson model), incorporating new modeling approached to include the contribution of the trapped molecules to the interaction potential, and implementation of PerssonÕs relatively new contact theory approach. The output of this study can pave the way for possible future design of interfaces with controllable and/or superior capabilities in considerable wear reduction, and performance in extreme environments.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 27, 2023
- Source ID
- W911NF2310284
Entities
People
- Ronen Berkovich
Organizations
- Army Contracting Command
- Ben-Gurion University of the Negev
- United States Army