Interface‐Engineered Graphene‐Coated Titanium Dioxide Nanoparticles for High‐Performance Grease Lubrication

ABSTRACT Lubricating greases play a vital role in reducing friction and wear under dynamic loading, but their performance is often limited by poor dispersion and compatibility of nano‐additives. In this study, graphene‐coated titanium dioxide (TiO ₂ @G) hybrids were synthesized via carbothermal treatment and incorporated at 0.5 wt% in lithium grease, alongside pristine graphene, TiO ₂ , and their physical mixture for comparison. Tribological and thermal behavior were evaluated using ASTM‐standard testing, profilometry, transmission electron microscopy and Hamrock–Dowson line‐contact film‐thickness modeling. The TiO ₂ @G‐800 hybrid demonstrated an 85.7% reduction in wear scar diameter, a 22.0% decrease in operating temperature and a modest increase in calculated film thickness (∼1.5%) relative to the control. Lubrication regime analysis based on Stribeck and Tallian parameter (λ) confirmed mixed lubrication across all samples, with slightly higher λ ratios for TiO ₂ @G‐800 and graphene, consistent with improved film retention and wear protection. The superior performance of TiO ₂ @G is attributed to its engineered core–shell morphology, wherein the graphene sheath improves interfacial lubricity and thermal conductivity while the TiO ₂ core provides structural reinforcement. These findings highlight nanoscale interface engineering as a promising approach for developing next‐generation high‐performance greases with applications in energy, transportation and advanced manufacturing.