IMX/IPHYS Talks - Towards Robust Structural Superlubricity

Tribology, the study of friction, wear and lubrication, plays a pivotal role in various technological applications and scientific disciplines. One of the most fascinating phenomena in modern tribology is structural superlubricity, a near-zero friction state enabled by incommensurate interfaces, allowing virtually frictionless sliding. However, its practical application is hindered by several factors such as interfacial misorientation, lattice defects, and contact-induced deformation, which are still not fully understood.
In this talk, I will present recent multiscale experimental efforts aiming to address these challenges. We have developed assembly and manipulation techniques for atomically flat, single-crystalline heterogeneous layered material pairs(e.g., graphite-hBN), which suppress the commensurate rotation observed in homogeneous interfaces, thereby enabling robust microscale superlubricity. Scaling up structural superlubricity towards macroscopic dimensions inevitably involves forming junctions between polycrystalline surfaces. At corrugated graphene grain boundaries, we observed unusual atomic frictional behavior, including negative friction coefficients and non-monotonic velocity dependence. Using advanced atomic force microscopy, we identified the dominant energy dissipation mechanism as dynamic (un)buckling of dislocation protrusions at grain boundaries. Additionally, we discovered a novel frictional dissipation mechanism associated with moiré patterns in grain regions, where the moiré ridges deform under the single-asperity contact, storing elastic energy that is abruptly released upon instability, leading to an increase in energy dissipation. To overcome these limitations, we proposed a “strong adhesion–crystallographic alignment” strategy to construct layered material/single-crystal metal systems. This approach eliminates grain boundaries and suppresses moiré undulations, paving the way for scalable, dry superlubric contacts. Our findings provide critical insights into the physical limitations of superlubricity in large-scale vdW contacts and offer new design principles for controlling friction.

Bio: Dr. Yiming Song is currently a Postdoctoral Researcher in the Department of Physics at the University of Basel. He previously held postdoctoral positions at both the University of Basel and University of Giessen (Germany) and has since returned to Basel to continue his research on tribology, surface science, and two-dimensional materials. He received his Ph.D. in Mechanical Engineering from Tsinghua University, where his research focused on micro- and nanotribology as well as the development of in-situ characterization and testing instruments. His research interests lie at the intersection of tribology, nanomechanics, two-dimensional materials, and surface science, with a particular emphasis on structural superlubricity and fundamental mechanisms of energy dissipation in sliding contacts. Dr. Yiming Song has published 17 papers in prestigious international journals, including Nature Materials, Physical Review Letters, Nature Communications, PNAS, Nano Letters, ACS Nano and has authored one book chapter. His outstanding achievements have been recognized with the “Spark” grant from the Swiss National Science Foundation (SNSF).