Elucidating the Effect of MoS2 on the Mechanical and Tribological Behavior of AA7075/Si3N4 Composite

Abstract

In the current work, a novel self-lubricating AA7075-based composite has been developed with silicon nitride (8 wt.%) as the ceramic reinforcement and varying MoS2 (0-6 wt.%) content by using stir casting method. The effect of solid lubricant (MoS2) addition on the microhardness, compression and microstructural behavior has been studied. Unidirectional sliding wear tests were carried out to study the effect of the reinforcement addition on the coefficient of friction and wear. The testing has been carried out at three different sliding speeds (1, 4 and 7 m/s) to elucidate the effect of sliding speed on the wear and friction behavior. The mechanical strength of the developed composites exhibited a decreasing trend with an increase in the MoS2 content. However, a 37% decrease in the COF was also observed with an increase in molybdenum disulfide (MoS2) content. With an increase in the normal load, COF exhibited an increasing behavior. The wear loss also exhibited an increasing trend with an increase in normal load as well as speed. The worn surface analysis exhibited a shift of wear mechanism from severe abrasion toward mild abrasion in the case of composites with higher content of MoS2. EDS also revealed the formation of mechanically mixed layer (MML) and oxide formation. The developed composites with better anti-friction properties have wide scope in sliding applications, particularly in automotive sector.