Meng Yuan, Su Fenghua, Chen Yangzhi
School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou, 510640, P. R. China.
Sci Rep. 2016 Aug 4;6:31246. doi: 10.1038/srep31246.
Silver nanoparticle-decorated graphene nanocomposites were synthesized by a facile chemical reduction approach with the assistance of supercritical CO2 (ScCO2). The silver nanoparticles with diameters of 2-16 nm are uniformly distributed and firmly anchored on graphene nanosheets. The tribological properties of the as-synthesized nanocomposites as lubricant additives in engine oil were investigated by a four-ball tribometer. The engine oil with 0.06~0.10 wt.% Sc-Ag/GN nanocomposites displays remarkable lubricating performance, superior than the pure engine oil, the engine oil containing zinc dialkyl dithiophosphate (ZDDP), as well as the oil dispersed with the single nanomaterial of graphene oxides (GOs) and nano-Ag particles alone. The remarkable lubricating behaviors of Sc-Ag/GN probably derive from the synergistic interactions of nano-Ag and graphene in the nanocomposite and the action of the formed protective film on the contact balls. The anchored nano-Ag particles on graphene expand the interlamination spaces of graphene nanosheets and can prevent them from restacking during the rubbing process, resulting in the full play of lubricating activity of graphene. The formed protective film on the friction pairs significantly reduces the surface roughness of the sliding balls and hence preventing them from direct interaction during the sliding process.
在超临界二氧化碳（ScCO2）的辅助下，通过简便的化学还原方法合成了银纳米颗粒修饰的石墨烯纳米复合材料。直径为2 - 16纳米的银纳米颗粒均匀分布并牢固地锚定在石墨烯纳米片上。采用四球摩擦磨损试验机研究了所合成的纳米复合材料作为发动机油中润滑添加剂的摩擦学性能。含有0.06~0.10 wt.% Sc-Ag/GN纳米复合材料的发动机油表现出卓越的润滑性能，优于纯发动机油、含有二烷基二硫代磷酸锌（ZDDP）的发动机油，以及仅分散有氧化石墨烯（GOs）和纳米银颗粒单一纳米材料的油。Sc-Ag/GN卓越的润滑行为可能源于纳米复合材料中纳米银与石墨烯的协同相互作用以及在接触球上形成的保护膜的作用。锚定在石墨烯上的纳米银颗粒扩大了石墨烯纳米片的层间间距，并能防止它们在摩擦过程中重新堆叠，从而使石墨烯的润滑活性得以充分发挥。在摩擦副上形成的保护膜显著降低了滑动球的表面粗糙度，从而防止它们在滑动过程中直接相互作用。
