INVESTIGATIONS ON MECHANICAL AND WEAR PROPERTIES OF Al MATRIX COMPOSITES REINFORCED WITH HYBRID SiC AND Al2O3 MICRO-PARTICLES

Aluminium metal matrix composites (AMMC) are now a group of new advanced materials preferred for its lightweight, high strength, low coefficient of thermal expansion, and high wear resistance properties. Although many processes are used for the development of particulate reinforced aluminium composites, stir casting is proved to be one of the prominent and economical routes for the processing of metal matrix composites. The present work is focused on the effect of hybrid ceramic particle reinforcements on the mechanical and tribological properties of AMMC. Three different volume fractions of Al2O3 particulates namely 2, 4 and 6 weight percent along with 4 common weight percent of SiC reinforcements in all the samples in the average particles size range of 35-40 mu m were added to the liquid melt of AA7075 and stirred at 500 rpm for 15min. The micro-structures of the composites were examined using a metallurgical and scanning electron microscope. The reinforcements are found to be distributed uniformly within the matrix. The effects of hybrid reinforcement on mechanical properties were investigated. The wear rate of composite material decreased significantly with increase in reinforcements. The mechanical properties increased significantly due to the high load bearing capacity of the SiC and Al2O3 particulates. The coefficient of friction was found to reduce due to the increased weight percent of Al2O3 particles, which acted as the solid lubricants during sliding.

Automated summary

Aluminium metal matrix composites (AMMC) are advanced materials preferred for their lightweight, high strength, low coefficient of thermal expansion, and high wear resistance properties. Stir casting is an economical route for processing metal matrix composites with uniform distribution of reinforcement particles. This study investigated the effect of hybrid ceramic particle reinforcements on the mechanical and tribological properties of AMMC, and found that the mechanical properties increased significantly and the wear rate decreased with the increase in reinforcements.