Insights of nanostructure and nanomechanical properties of the tribofilm derived from CoAl-hexametaphosphate layered double hydroxide on sliding steel surfaces

Publication Name

Tribology International


This study successfully synthesizes CoAl-hexametaphosphate layered double hydroxide (HMP-LDH) via anion exchange. The application of HMP-LDH leads to substantial wear and friction reduction of 88% and 25%, respectively, outperforming the PAO-4 base oil. In-depth characterizations of tribofilms formed on wear scars and tracks were conducted using various techniques, including Raman, X-ray photoelectron spectroscopy, scanning transmission electron microscopy - energy dispersive X-ray spectroscopy, and cryo-electron energy loss spectroscopy. It was found that the predominant composition of the tribofilm consists of mixed oxide and phosphate species. Notably, metallic cobalt is observed near the tribofilm-steel interface. Nanoindentation and nanoscratch were performed on the HMP tribofilm. The relationship between the nanostructure and nanomechanical properties and their influence on friction and wear have been revealed.

Open Access Status

This publication may be available as open access



Article Number


Funding Number


Funding Sponsor

Australian Research Council



Link to publisher version (DOI)