A multidisciplinary research team led by Prof. Quanshui Zheng at the Center for Nano and Micro Mechanics (CNMM) in Tsinghua University has achieved a breakthrough in superlubricity. The research result, titled “Observation of microscale superlubricity in graphite”, has been published in the flagship physics journal Physical Review Letters. The first author Mr. Ze Liu is a PhD student under Prof. Zheng’s supervision.
Friction between solid objects, for example between a wheel and an axle, is a challenging topic that humans have struggled to control and minimize for thousands of years, and is one of the most challenging physics phenomena. Approximately one-third of the world's energy resources in present use are wasted overcoming friction in one form or another. In industrialized countries, the friction loss accounts for 5%-7% of GDP. With modern mechanical manufacturing developing toward high precision and miniaturization, and the resulting increase in the area-to-volume ratio of micro- and nano-mechanical systems, interfacial friction is becoming a dominant factor.
Superlubricity (or structural lubricity) is a phenomenon proposed by Motohisa Hirano in the early 1990s, where the friction force almost vanishes between two solid surfaces. The effect occurs when there is structural incommensuration between two crystalline solid surfaces, typically due to a relative rotation of their lattices, leading to the systematic cancelling out of the friction force on the atomic scale. Superlubricity is an ideal solution to reduce friction and wear, and thus its real and wide applications would mark a big step in civilization. But in the past twenty years, superlubricity was only observed on the nanometer scale and under high vacuum conditions. Such conditions significantly limit the practical application of superlubricity. It has even been suggested that superlubricity may not exist on a larger size scale.
[update: 2012-06]
