HKUST-1 derived carbon nanocomposites as grease additives for friction and wear reduction

Lubricating greases are widely used in mechanical engineering, especially in rolling bearing. Carbon-based materials show promise as lubricant additive for formulating high-performance grease. However, the enhancement of lubrication performance of carbon-based materials limits by the simple lubricating mechanism. This work demonstrates that nanocomposite of metal–organic frameworks (MOFs)-derived carbon as a grease additive can improve the tribological properties of bentone grease. HKUST-1 was synthesized by a solvent method and converted into HKUST-1derived carbon (HDC) via one-step pyrolysis sacrifice template method. After pyrolysis of HKUST-1 at 350 °C, Cu²⁺ was reduced to zero-valence copper. With increasing pyrolysis temperature from 350 to 950 °C, both the particle size of copper in HDC and the degree of graphite defect increased gradually. Types of HDCs as base grease additives significantly improved friction-reduction and anti-wear performance of bentone grease. Compared with the base grease, HDC-950 °C with the amount of 2 wt% addition reduced friction coefficient and wear volume loss by 35.5% and 97.0%, respectively. The superior tribological performance of the HDC-950 °C is attributed to the synergistic effect of carbon and copper nanoparticles to induce tribochemical reaction, which form a stable protective film on the friction surfaces. This study highlights the potential of MOFs-derived carbon for developing high-performance grease additives.

Graphical abstract