Enhanced ability of halloysite nanotubes to form multilayer nanocrystalline tribofilms by thermal activation

To improve the antiwear properties of halloysite nanotubes as an oil-based additive, the effect of thermal activation on the tribological properties of halloysite was investigated. The results showed that the anti-wear properties of the halloysite and calcined products are improved by 34.54% and 45.45 –54.76%, respectively, compared with the base oil. The outstanding wear resistance of the surface lubricated by the calcined product is attributed to the faster and easier formation of a multilayer nanocrystalline tribofilm, which mainly contains the nanocrystalline transition layer, the oxide film (composed of nanoscale iron oxide , Al 2 O 3 , SiO x ) and the amorphous carbon film . The findings here provide new insights into optimizing the tribological properties of phyllosilicate and enrich the tribological mechanism of halloysites.