Lubricated tribology of hybrid AMMC–steel sliding contact: A comparative investigation between fully formulated commercial engine oils and surfactant functionalized MWCNT–base oil formulation

Abstract

The aim of the present study is to investigate the feasibility of developing surfactant-assisted multiwalled carbon nanotube (MWCNT)-laden lubricant for hybrid aluminum metal matrix composite (h-AMMC)/steel (EN31) pair sliding contact. For the preliminary screening, three grade-I base oils, two SAE grade fully formulated commercial oils, and two types of particle additives are used for the tribological investigation. Based on the detailed pilot study, a suitable grade of base oil (SN500), a fully-formulated commercial oil (SAE 20W50) and a solid particle additive (MWCNT) are finalized for the comprehensive tribological investigation. An amphiphilic surfactant, Sorbitan mono-oleate (SPAN 80) is added to MWCNT-in-oil dispersion to functionalize the MWCNT particles. For better insight of the lubrication and friction-wear mechanism, thermophysical properties of prepared suspensions and characterization of the worn-out surfaces of h-AMMC is carried out using various techniques such as scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and Raman spectroscopy. The study reveals some interesting insights on the performance of MWCNT-laden lubricants in the presence of surfactant, which might be connoted for the future development of the lubricants to be used in the industrial applications.