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

摩擦和磨损仍然是移动系统中最大的问题，因为它们会导致许多设备和机器的能量浪费和功能损失。目前大多数液体润滑剂和涂层解决方案在效率、成本效益和环境友好性方面受到限制，特别是在恶劣条件下运行时。使用二维（2D）分层材料可能有助于解决这些问题，但缺乏对其在滑动过程中的行为的了解。因此，该项目的目标是了解二维材料在载荷和剪切应力下如何改变其结构和功能。为此，研究人员将研究固态相互作用的基本起源，揭示滑动过程中接触面发生的过程，为什么一些材料比其他材料表现出更好的稳定性，以及如何使用这些新的二维材料来减轻摩擦和磨损。该项目将通过物理、材料科学和表面科学领域的研究、教育和推广活动，为国际合作创造机会。通过吸引更多的学生，特别是女性和少数族裔，该项目将创建一个更加多样化和包容性的科学界，从而在STEM领域实现新的发现和创新。了解层状材料在接触界面处的动态、结构和成分变化是将无摩擦和无磨损滑动扩大到现实宏观接触的关键，特别是在高正常载荷、速度、温度和污染物存在的情况下。该项目旨在通过揭示导致二维材料剪切表面之间固有界面晶格不可通约性的自适应机制来解决这一挑战。通过协同实验和建模，研究人员将在中尺度金属接触中使用纳米级过渡金属二硫化物（TMD）薄片，无论是否含有MXenes，以建立其对外部负载和剪切应力的动态结构、化学和取向适应性。实验策略将包括系统的宏观盘上针测量和纳米压痕研究，辅以原位和非原位表征分析，以揭示自适应TMD/ mxeni界面的结构完整性和表面化学变化。多尺度计算方法将结合第一性原理计算，原子分子动力学模拟和粗粒度建模来合理化实验结果并预测组成-结构-功能关系。掌握这一基本知识将有助于理解动态适应对二维材料系统对机械应力响应的影响，这将对提高机械部件的性能和延长机械部件的使用寿命产生重大的广泛影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.