Preparation and tribological properties of modified MWCNTs by Schiff base Cu (II) complexes as lubricant additives

Abstract

Four modified multi-walled carbon nanotubes (MWCNTs) with diamion-N,N′-bis (salicylidene) Schiff base Cu (II) complexes were successfully prepared by a simple and effective ultrasonic method. Friction and wear properties of 0.1 wt.% of modified MWCNTs were tested in triisodecyl trimellitate, DE and trihydroxymethylpropyl trioleate on 30 N by a microtribometer, respectively, and compared with those of graphene oxide. The structures and morphologies of the nanocomposites were investigated by Fourier-transform infrared (FTIR) spectra and transmission electron microscopy, the topography of worn surfaces of the disks were also tested by a white light interferometer. The results show that modified MWCNTs dispersed evenly and displayed better friction-reduction and anti-wear performance. As modification by a diamion-N,N′-bis (salicylidene) Schiff base Cu (II) complex can decrease twining of MWCNTs and promote its depolymerization and orderliness; Furthermore, the function as “filling” and “insulation” of modified MWCNTs between friction pairs improved the worn surface morphology. The modification of MWCNTs with o-phenylenediamine salicylaldehyde Schiff base copper (II) complex will not only promote the agglomeration of a-MWCNTs, but also indicate better tribological properties than that of graphene oxide.