Mechanochemical Reconstruction Principles for Two-Dimensional Material Adaptation to Applied Stresses

University Of North Texas, Denton TX

Investigators

Abstract

Friction and wear remain the greatest problems in moving systems since they lead to energy waste and loss of functionality in numerous devices and machines. The majority of current liquid lubricant and coating solutions are limited in their efficiency, cost-effectiveness, and environmental friendliness, especially when operating under harsh conditions. Use of two-dimensional (2D) layered materials may help in solving these issues but there is a lack of knowledge of their behavior during sliding. Hence, the goal of this project is to understand how 2D materials change their structure and function under loading and shear stresses. To this end, the researchers will investigate the fundamental origins of solid-state interactions, unraveling the processes occurring at contacting surfaces during sliding, why some materials show better stability than others, and how one can use these novel 2D materials for mitigating friction and wear. This project will create opportunities for international collaboration through research, educational, and outreach activities in the fields of physics, materials science, and surface science. By engaging more students, especially women and minorities, the project will create a more diverse and inclusive scientific community, enabling new discoveries and innovations in the STEM fields. The understanding of dynamical, structural, and compositional modifications of layered materials at contacting interfaces is a key for the scale-up of frictionless and wearless sliding towards realistic macroscopic contacts, especially under high normal loads, velocities, and temperatures, and in the presence of contaminants. This project aims to address the challenge by unraveling adaptive mechanisms leading to inherent interfacial lattice incommensurability between the shearing surfaces of 2D materials. Using a synergistic experimental and modelling effort, the researchers will employ nanoscale transition metal dichalcogenide (TMD) flakes, with and without MXenes, within mesoscale metallic contacts to establish their dynamical structural, chemical, and orientational adaptivity towards external load and shear stresses. The experimental strategy will involve systematic macroscale pin-on-disk measurements and nanoindentation studies complemented by in-situ and ex-situ characterization analyses to unravel variations in the structural integrity and surface chemistry of the adaptive TMD/MXene-based interfaces. A multi-scale computational approach will combine first-principles calculations, atomistic molecular dynamic simulations, and coarse-grained modeling to rationalize the experimental results and to predict composition-structure-function relations. Acquiring this essential knowledge will aid in comprehending the influence of dynamical adaptation on the response of 2D material systems to mechanical stresses, which will have a significant broad impact on enhancing the performance and extending the lifetime of mechanical components. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.