Friction and Wear Characterization of Spark Plasma Sintered Hybrid Aluminum Composite Under Different Sliding Conditions

Abstract

Friction and wear behaviors of hybrid aluminum matrix self-lubricating nanocomposite, containing varying amount of nano-aluminum oxide (Al2O3) and graphene nanoplatelet (GNP) particles were investigated under dry and boundary lubrication sliding conditions. All the specimens were prepared by ultrasonic probe mixing followed by high-energy mechanical ball milling and spark plasma sintering fabrication route. The objective of this present study is to determine the tribological behavior of GNP as nanoreinforcement under dry and wet lubricating conditions. The wear test was carried out at room temperature on a ball-on-disc reciprocating tribometer with a contact load of 5 N, a frequency of 30 Hz, a stroke of 2 mm, and a sliding distance of 120 m. The chromium-plated chrome steel ball is used as the counter body for tribo-testing. From the results, it has been observed that GNP, as the solid lubricant reinforcement, reduces the friction by 25.33% and 68.14% under dry and wet lubricating conditions, respectively, for the hybrid composite. Reduction in wear volume by 91.15% and 90.50% is observed under dry and wet lubricating conditions, respectively, for the hybrid composite in comparison to the base eutectic Al–Si alloy. The reduction in the coefficient of friction and wear volume for the hybrid composite is attributed to the multilayer two-dimensional GNP nanoparticles that cause easy shearing by forming a conformal protective film layer on the sliding interface. Ultra-mild to severe wear regime was obtained for different composition samples including base composition to hybrid composition.