Microstructural analysis and tribological behavior of aluminum alloy reinforced with hybrid alumina/nanographite particles

Abstract

Aluminum metal matrix composites represents one of the light weight and high performance materials. The performance of these materials can be tailored for a variety of applications by numerous reinforcements in forms of fibers, whiskers, or particulates. The main purpose of this study is to examine the microstructure of developed composites having a matrix of LM6 aluminum alloy reinforced with hybrid Al2O3 and nanographite particles (2.5% + 1%, 5% + 3%, 10% + 5%, and 15% + 8%) processed by stir casting process and to investigate the dry sliding behavior using a pin-on-disc tribometer. The developed composites were characterized by optical micrograph, scanning electron microscope, X-ray diffraction, measurement of microhardness, and wear rate. It was found that uniformity of reinforcement distribution was better at lower levels and clustering started above 10% reinforcement. Increased hardness at higher levels of alumina reinforcements reduced the wear rate. Further, presence of graphite leads to lower coefficient of friction due to self lubricating properties and greater surface area of nanographite produces graphite adherent tribolayer at contact surface which reduces wear by reducing the frictional force. The composite with 10% Al2O3 and 5% nanographite showed the best tribological properties. Overall results indicated a positive response of metal-ceramic hybrid composite for wear resistance and light weight applications, mainly in the field of aerospace and automobile sectors.