Graphene Nanoparticles for Ultralow Friction at Extremely High Pressures and Temperatures

This study uses the molecular dynamics approach to design graphene nanoparticles from the graphene sheets seeded randomly and investigates their lubricity. These nanoparticles are found to provide stable lubrication at extremely high pressure and temperature of up to 15 GPa and 2000 K, respectively. From the influences of both nanoparticle and graphene, the friction between the diamond slab and the nanoparticles shows ultralow values of the friction coefficient of 0.0034–0.0162 under 1–15 GPa and 300 K and 0.0065–0.0338 under 300–2000 K and 1 or 10 GPa. Providing stable lubrication and ultralow friction under these conditions is the large advantage of graphene nanoparticles.本研究采用分子动力学（molecular dynamics）方法，以随机成核的石墨烯片层为前驱体制备石墨烯纳米颗粒（graphene nanoparticles），并对其润滑性能开展系统性研究。实验结果表明，该类纳米颗粒可在最高分别达15吉帕斯卡（GPa）与2000开尔文（K）的极端高压高温环境下实现稳定润滑。经分析纳米颗粒与石墨烯的协同作用效应后发现，金刚石滑块与该纳米颗粒间的摩擦表现出超低摩擦系数（friction coefficient）：在1~15 GPa、300 K条件下，摩擦系数范围为0.0034~0.0162；在300~2000 K、1或10 GPa条件下，摩擦系数范围为0.0065~0.0338。在上述极端工况下实现稳定润滑与超低摩擦，正是该石墨烯纳米颗粒的核心优势所在。