Copper submicrospheres induced by pulsed laser-irradiation with enhanced tribology properties

Lubrication is widely recognized as one primary strategy to address the issue of enormous energy losses and device failure caused by nearly ubiquitous friction and wear in mechanical operation. Herein, we report a simple and valid laser assisted growth strategy for reshaping the morphology of metal particles. Regular copper (Cu) submicrospheres are grown by irradiating common Cu nanoparticles in ethanol solution with a nanosecond pulsed laser under ambient conditions, which includes a surface melting and subsequent morphological reshaping process. More importantly, compared with the raw irregular Cu nanoparticles and pure paraffin liquid, the Cu submicrospheres as lubricating additives exhibited excellent friction reduction and wear-resistant properties, which benefit from their spherical morphology and good solubility in different commercial lubricants. The spherical shape makes sliding friction transform into rolling friction easily under low load. Besides, a self-repairing effect is also found on worn friction pairs.