"Non-layered" two-dimensional nanodiamond plates as nanoadditives in water lubrication

Nanodiamond plate (NDPL), a novel "non-layered" two-dimensional material, has received significant attention thanks to its excellent physical and chemical properties. However, the tribological behavior of the NDPL as a nanoadditive remains unexplored. Owing to the structural differences between nanodiamond particle (NDPA), the distinct performances of NDPA and NDPL as nanoadditives require further investigation. In this paper, the tribological behavior of "non-layered" materials as nanoadditives has been reported for the first time. Ball-ondisk rotational friction tests were conducted to investigate the tribological properties of NDPA and NDPL as nanoadditives. Steel balls and Si/SiO2 plates were used as the counterparts for the friction tests. The NDPL suspensions provided better lubrication than NDPA suspensions at concentrations higher than 2.5 mg/mL. The sliding between the NDPLs or that between the NDPL and the counterparts and structural transformation from sp3 to sp2 carbon are critical for lubrication and wear resistance.