Synthesis, characterization and tribological performances of nano-CeO2/biodiesel carbon soot composites as a novel lubricant additive in polyalphaolefin

This study fabricated nano-CeO2/biodiesel carbon soot (BCS) composites using the raw material BCS, which is the byproduct of biodiesel combustion and cerium salt and used as a novel lubricant additive to PAO6 for steel/steel contact. Oleylamine modified nano-CeO2/BCS composites comprise abundant lipophilic groups, and thus nano-CeO2/BCS composites exhibit good dispersion in PAO6. The tribological results showed that nano-CeO2/BCS composites significantly improved the lubricating performances of PAO6. In case of 0.1 wt% nano-CeO2/BCS composites dispersed in PAO6, the friction coefficient and wear volume were reduced by 17.3 and 35.2%, respectively. The improved tribological properties were attributed to the composites rolling and forming of a lubricating film on the friction surface and the presence of BCS and CeO2 in composites exerting a synergistic lubricating effect, which simultaneously improved the tribological properties of PAO6. This discovery contributes to the conversion of BCS into valuables and promotes the high value utilization of BCS as a lubricating additive.