Iron phosphate nanoparticles as oil additives to enhance anti-wear properties

Abstract

In recent years, nanomaterial lubricant additives have been widely studied in tribology. In this work, a new iron phosphate (FeP) nanoparticle was synthesized to enrich the anti-wear oil-based additives for titanium alloys. A series of tribological experiments were conducted using a reciprocating ball-on-disc tribometer. It has been confirmed that, as additives in polyalphaolefin 8 (PAO8), FeP nanoparticles exhibit excellent friction-reducing and anti-wear properties for TA5 titanium alloys. Compared with the pure PAO8, the friction coefficient (COF) and wear rate (WR) can be significantly reduced by 69.89 % and 99.57 % at a concentration of 30 wt%. The SEM and EDS confirmed that FeP nanoparticles can play a surface repair role and deposit on the titanium alloy surface to form a deposition layer, which was the key to anti-wear property. Besides, XPS characterization demonstrated that the formation of the deposition layer was attributed to the P–O–Ti bond at the interface, through which the phosphate in FeP can bind to and adsorb on the titanium alloy surface. This deposition layer containing FeP can greatly reduce the adhesive wear of the titanium alloy. Meanwhile, the rolling effect of nanoparticles inside the deposition layer promoted the friction-reduction.