Tribological properties of attapulgite/La₂O₃ nanocomposite as lubricant additive for a steel/steel contact

Abstract

Attapulgite is a layered silicate with good friction-reduction and self-repairing properties. In order to further improve its tribological properties, the present work mainly focuses on the preparation of attapulgite/La₂O₃ nanocomposite and study on its tribological behaviors. The tribological properties of mineral lubricating oil (150SN) containing attapulgite/La₂O₃ nanocomposite were investigated through an Optimal SRV-IV oscillating friction and wear tester. The rubbing surfaces and generated tribofilms were characterized by SEM, EDS, XPS and nanoindentation. Results indicated that the friction-reducing ability and antiwear property of the oil were both remarkably improved by attapulgite/La₂O₃ nanocomposite. A tribofilm mainly composed of Fe, Fe₃C, FeO, Fe₂O₃, FeOOH, SiO, SiO₂ and organic compound was formed on the rubbing surface under the lubrication of oil with attapulgite/La₂O₃ nanocomposite. The tribofilm possess excellent self-lubricating ability and mechanical properties, which is responsible for the reduction of friction and wear.