Tribological Characterization of Particulate MMC Developed by STIR Casting Process

Abstract

The present work aims at the development of particulate metal matrix composite using Aluminum alloy (AL 7075) as the matrix material and alumina (Al 2 O 3), Silicon Carbide (SiC) and Hybrid (Al 2 O 3 +SiC) as Reinforcement. Al 2 O 3 is reinforced in the weight fraction of 3%, 6%, 9% and 12% with the particle size varying between 50 microns to 150 microns. SiC in the weight fraction of 3%, 6%, 9% and 12% & Al 2 O 3 +SiC in the weight fraction of 3%+3%, 6%+3%, 9%+3% and 12%+3%. The aluminum alloy was melted at 700°C in an electrical heating furnace for 20 minutes and the reinforcement is heated separately at 350° C was added in the form of powder. The molten metal was stirred for 5 minutes at the temperature of 700°C, followed by pouring in to the metal mold. Optical micro graph of the developed composite was obtained to demonstrate the distribution of the reinforcement in the matrix. The hardness tests was carried out to determine the effect of reinforcement on the hardness of the composites. The hardness of the composite was found increases with the increase in reinforcement weight fraction. The wear test carried out at various speed, load and sliding distance which indicates improvement in the mechanical properties of the composites. The wear resistance of the composite reduces with the increase in the Reinforcement weight fraction. The wear resistance reduces with the increase in speed, Also wear rate increases with the increase in applied load. As the sliding distance increases the wear of the MMC increases for all specimens. The coefficient of friction was reduces at higher weight fraction as compared to lower weight fraction of reinforcements.. The noise during running the test was reduced in case of Hybrid composite as compared to composite with either alumina or silicon carbide as reinforcement. The investigation carried out will lead to development of the composite system with high strength, improved wear resistant, light weight for automobile parts like disc brake, piston, cylinder liner, drive shaft etc. KEY WORDS Wear, Al7075/Al 2 O 3 , SiC, Hybrid, Stir casting, Weight fraction.