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Structural Superlubricity

Towards Motion with Vanishing Energy Dissipation

Friction is a ubiquitous phenomenon encountered during everyday activities as common as walking, and also holds primary importance in mechanical processes as the main mechanism responsible for energy dissipation. Within this context, developments in our understanding of friction and its controlled mitigation at relevant interfaces and time as well as length scales are expected to yield significant returns in the form of energy savings. 

In The Baykara Laboratory led by Dr. Mehmet Baykara at UC Merced, we develop material systems involving nanometer- and micrometer-scale interfaces that exhibit minimal friction under ambient conditions. To achieve this goal, we exploit the idea of “structural superlubricity”, the theoretical expectation that friction should diminish at an interface formed by two atomically flat and molecularly clean crystalline surfaces with different lattice parameters and/or incommensurate orientation, due to atomic-scale structural mismatch.
 
Our efforts have recently resulted in the demonstration that  structural superlubricity can indeed be realized under ambient conditions in a material system involving gold islands on a graphite substrate [1]. Further work has shown that this behavior is not limited to gold, and can be extended to other noble metals such as platinum [2].  Shown here on the left, is an SEM image of a graphite surface decorated with gold islands of various size after post-deposition annealing at 650°C. Scale bar, 500 nm.    

Our current activities focus on extending structural superlubricity to larger interfaces relevant for conventional engineering applications by the use of novel materials, including but not limited to bulk metallic glasses (BMGs). Our ultimate goal is to realize motion with vanishing energy dissipation in a wide variety of applications at different length scales, which would enable tremendous opportunities in fields ranging from energy harvesting to space travel.

[1]: E. Cihan, S. Ipek, E. Durgun, M.Z. Baykara, Structural Lubricity under Ambient Conditions, Nature Communications 7, 12055 (2016). 
 

[2]: A. Ozogul, S. Ipek, E. Durgun, M.Z. Baykara, Structural Superlubricity of Platinum under Ambient Conditions: The Effects of Chemistry and Geometry, Applied Physics Letters 111, 211602 (2017).