Tribological performance of carbon nanospheres as lubricant additives: insights from molecular dynamics simulation and experimental analysis

Abstract To investigate the lubrication mechanism of carbon nanospheres and compare their tribological performance with carbon powder, this study presented a comprehensive analysis of their potential as lubricant additives through both experimental testing and molecular dynamics simulations. Carbon nanospheres were synthesized using the hydrothermal method. Extensive comparisons were conducted between carbon powder and carbon nanospheres, focusing on material characterization, dispersion stability, antifriction performance, and antiwear capability. Findings revealed that carbon nanospheres outperformed carbon powder as lubricant additives in polyalphaolefin 10 (PAO 10) owing to their smaller particle size and spherical shape. Specifically, at a concentration of 1 wt%, a load of 50 N, a disk speed of 10 rpm, and a temperature of 25 °C, the addition of carbon nanospheres reduced the friction coefficient by 34% and wear volume by 35%. The improved tribological performance was linked to the ability of carbon nanospheres to fill the pits, improving the interface smoothness. Molecular dynamics simulation of carbon nanospheres effectively reflected substrate roughness in the bulk region and further confirmed that the filling effects increased the lubricant's load-bearing capacity, which contributed to the reduction of friction and wear. This study provided significant insights into the development of innovative high-performance lubricant additives for oil-based lubrication in metal friction pairs.