Superior Lubricity and Antiwear Performances Enabled by Porous Carbon Nanospheres with Different Shell Microstructures

Good dispersibility and proper structural strength are both critical to the use of nanomaterials as lubricant additives to improve antiwear and friction-reducing ability. Herein we report the synthesis of porous carbon nanospheres (PCNs) with distinct shell properties and demonstrate their significance and effectiveness in enhancing the tribological performances when used as lubricant additives. PCNs with a carbonaceous resin-based shell and an amorphous disordered/graphite phase hybridized carbon shell have been successfully prepared based on a facile template-free interfacial polymerization and carefully selected carbonization temperatures. A low carbonization temperature (≤700 °C) leads to PCNs with a carbonaceous resin shell, which helps to improve dispersibility in the base oil PAO-10. Therefore, the oil film effect is dominant and the coefficient of friction can be reduced from 0.198 to 0.085 after adding 0.4 wt % carbonaceous resin. Amorphous disordered/graphite phase hybridized carbon shells, obtained at higher temperatures (>700 °C), possess good structural strength and robustness, thus resulting in excellent friction-reducing performance (friction coefficient of 0.086), high load capacity (950 N), and reduced wear volume (80%) at the additive content of 0.4 wt %. These findings will open up new possibilities for achieving good tribological performance by using polymer-derived carbon materials.